Show Notes

• Snowball Earth
• Google+: Fraser, Pamela
• Galileo mission legacy website
• High Gain Antenna problems and solutions — JPL
• Paper: Galileo Mission High Gain Antenna Anomaly Workarounds – IEEE (subscription required)
• Various images and artist renditions of the spacecraft, showing both intended and actual antenna configurations
• Scientific results of the Galileo mission — NASA
• Asteroid Gaspra — JPL
• Asteroid Ida — JPL
• Jupiter’s Rings – Universe Today
• Io and Lava — Planetary Exploration
• The Geysers of Io — Windows to the Universe
• The Discovery of Ganymede’s Magnetic Field by the Galileo Spacecraft — Nature
• Ice on Europa — NASA
• Galileo Spacecraft Crashes into Jupiter (Sept. 21, 2003) — Universe Today
• Will Galileo Turn Jupiter into a Star? — Bad Astronomy

Download the transcript

Fraser: Welcome to Astronomy Cast, our weekly facts-based journey through the Cosmos, where we help you understand not only what we know, but how we know what we know. My name is Fraser Cain; I’m the publisher of Universe Today, and with me is Dr. Pamela Gay, a professor at Southern Illinois University – Edwardsville. Hi, Pamela. How are you doing?

Pamela: I’m doing well. How are you doing, Fraser?

Fraser: Good. Well, this is our first show after we got back from Dragon*Con and after our summer hiatus, and so all of you are going to notice a great big gap from May ‘til September, and that’s because we uh… took the summer off, and took a break — but that’s not actually true. I’m actually sort of “retcon-ing” our history and the reality is that we actually fell behind over the course of the entire year because of both of our busy schedules, and because of Pamela’s crazy travel schedule, so we would sort of catch up and try and get some episodes done after the fact, and backdate them so nobody missed an episode, and at some point, we kind of surrendered and gave up, and cut it off and then brought it back now, and so the…we’ve actually got a bunch of things we’re going to put into the feed. There’s this show, which is the official Astronomy Cast show, and then we’ve also got several episodes that we did at Dragon*Con: we did a live show, we did a kids’ show, and we did a sort of “ad hoc” show that we…sort of became an impromptu Astronomy Cast episode about weird things in the Universe, mostly in the Solar System, so you’ll see those in the feed when you see them.

Pamela: And we learned I’m not as smart as a second-grader. It was very, very…I don’t know what Snowball Earth is …I have no clue what Snowball Earth is.

Fraser: You got stumped. Yay! Do a little more research on Snowball Earth — that would be great. But that was the whole…so the other thing that’s really interesting is that we have been recording episodes of Astronomy Cast as Google hang-outs, so if you’re interested in joining us and watching us record Astronomy Cast live, we will post announcements that we’re about to record, and then eight lucky/unlucky listeners can join our hang-out and watch as we do the recording, so if you’re interested in doing this, it’s super-fun. You just need to circle either me or Pamela (probably me because I think I’m a little more active on Google Plus than Pamela is, but um…), and then you’ll sort of see the announcements and then you’ll see the invite to do the hang-out, and then you can just join us if you can get in. And there’s only ten people allowed in the hang-out right now, but we’re trying to get into the Hangouts On Air, which is this new service that Google’s going to be allowing where you can have more people actually watching it than joining it so… and if there’s any Google listeners right now, please, please, please — we would love to have access to the Hangouts On Air, so… whew! So let’s get on with…over-announcing, right…let’s get on with this week’s show. In last season’s thrilling cliff-hanger, we talked about astronomer super-hero, Galileo Galilei. Would a mission be named after him? The answer was “yes.” NASA’s Galileo spacecraft visited Jupiter in 1995 and spent almost eight years orbiting, changing our understanding of the giant planet and its moons. OK, Pamela, so Galileo — this is another one of those missions that has this long and tortured history of its initial inception in the hey-day of NASA’s, you know, conquering of the Solar System to the point where it actually launched and actually arrived at Jupiter, so let’s hear the…when did the idea for the Galileo spacecraft first come up?

Pamela: Well, the idea dates back to the ending of the Apollo era, as we started to look out and say, “OK, what’s left? What else do we need to go and explore?” We had the Voyager probes on their way to the outer Solar System, but they were just fly-by missions that would go in get their data and go out, but not really linger anywhere and scientists knew that as soon as we got all of that data back, we’d want to have those dedicated missions that went out and spent time studying Jupiter, spent time studying Saturn, and Jupiter was our first big target of, “this is what we want to go look at.” And so the Galileo mission really started to be conceived in the early ‘70s as we were preparing for the space shuttle. It was designed to launch on the space shuttle, which is part of where its fate became particularly tortured…

Fraser: But not just a fly-by, I mean, we’re talking: go into orbit and study the planet, its moons for as long as possible.

Pamela: Yeah, carry a whole bunch of different instruments, be prepared to image it in different parts of the electromagnetic spectrum, be prepared to measure all of the radiation levels, be prepared to — through a variety of different things — look at the magnetospheres, the plasma, the dust…a whole variety of science from a whole lot of different instruments was planned.

Fraser: Right. OK, so the plan was you know, build this spacecraft, launch it on the space shuttle, and straight to Jupiter, and “boom!” you’re done, you should be there, you know…

Pamela: In a few years…

Fraser: Yeah, a few years! So what really happened?

Pamela: So the idea originally was to launch it on the STS-23 back in 1982, but the shuttle launched ’81 successfully, but it took them a while to get everything they needed done, to figure out a lot of the issues, and get to the point that they were completely ready to launch the spacecraft, and so this allowed for more development of the probe, no one was particularly upset, they added four years to the timeline, which for a spacecraft is really nothing.

Fraser: Yeah, it’s pretty normal.

Pamela: Yeah, so Plan B was launch in 1986 aboard the space shuttle Atlantis…

Fraser: Uh-oh.

Pamela: Yeah, so unfortunately 1986 was the year of the Challenger disaster, and that changed how we fly the space shuttle. It changed what orbits we go to, it changed what we carry in the cargo bay, and it’s that second part that really affected Galileo because to get a mission all the way out to Jupiter, you can’t just carry it to low Earth orbit and give it a nice shove. You have to put a rocket booster on it, and the plan was to mount it on a (Atlas) Centaur G, which is a liquid hydrogen-fueled booster…

Fraser: Right.

Pamela: And you can imagine that they weren’t exactly excited to be launching a cargo bay filled with explosives.

Fraser: Right.

Pamela: Yeah.

Fraser: So these safety concerns about launching a bomb into space overrode the being able to send that mission directly.

Pamela: Exactly, so in the end, it’s ended up finally launching in 1989 and they had to completely rethink how they were going to end up launching it. They still ended up launching it on a space shuttle, but they couldn’t launch it with the rocket attached, so they had to change how it gets to Jupiter. Instead of firing away and going “full-tilt boogie” and getting there fairly quickly, they decided to instead use a couple of gravitational boost exercises where they did fly-bys of Earth and Venus, went through the asteroid belt a couple of times, and used the gravity of our planet and Venus to assist it in adding more and more velocity.

Fraser: Yeah, if you see the path that Galileo actually took — it’s amazing. It went out and then back and then out again, and then back until finally, making its way out to Jupiter, getting the velocity it needed to reach Jupiter. I mean — it’s brilliant! I mean, it really is one of those situations where I can just…I don’t know… all of these little moments, like you have it in the Apollo 13, right? Where someone dumps out all this junk on the table and says, “This is what the astronauts have. Build them a carbon dioxide filter!” [laughing] or all of the missions, I mean it’s amazing…in almost every mission there are these situations where you find out what kinds of constraints the scientists are dealing with, I mean you can’t just go and open up the spacecraft and replace the part that you need, and put it back together again. It’s so far away and you’ve only got what you’ve got, you’ve got to re-program it on the fly…it’s amazing, and I think Galileo was one of those missions where the space scientists working on it just never gave up. I mean, they just…they really had constraint after constraint, problem after problem, and they never gave up. And I don’t know if you want to talk about the antenna…

Pamela: [laughing] Oh, Geez…so this poor mission — it gets shelved for awhile while they figure out exactly how they’re going to get it to Jupiter, and when you shelve a spacecraft, it can have bad side effects, and one of the side effects here was, well, one of the things they tried to do fairly early on, they launched in October of 1989, and a year and a half later, in April of 1991, they tried to open up it’s high-gain antenna, which looks a lot like an umbrella, except the problem was, some of its spokes seemed to have gotten bent, or jammed, or something, and when they tried to open it, it said “no.” And it’s theorized that maybe some of the lubricant evaporated, or something got bent – we’ll never know exactly what happened to the antenna. What we will know is that NASA tried everything it could to get it open: they cycled the power, they basically hit the on, open close open close open close a bazillion times trying to get the thing to shake loose, and nothing worked, so they had to, on the fly, change how the mission compresses its data, so instead of sending things back on the hundreds of kilobytes high-gain antenna, they’re sending things back on the tens of bits per second antenna — and that wasn’t fun. That really limited what we were able to do scientifically, but they still did such amazing science.

Fraser: Yeah, it’s great, you can actually see this in the pictures, so if you ever look at some of the pictures of the Galileo mission, and I’m sure we’ll link some from the show notes, you have this situation where you’ve got…you can actually see this spacecraft and it’s got this crumpled umbrella high-gain antenna, and so it’s really funny because whoever was doing the artwork for the mission, they went back and redid the artwork to accurately match what the antenna must look like with the spacecraft currently going in, you know, when it actually reached Jupiter. That was a nice touch [laughing].

Pamela: [laughing] Well, I’m sure there were members of the public keeping them honest, but yeah, this was a real challenge, and the other thing about this mission is it’s so old — it’s technology – they were recording all of the data to magnetic tape. Think like old-style cassette.

Fraser: That’s…just a flash-drive – that would have been nice.

Pamela: Yeah, I’m sure they would have given anything for one of those 32-gigobyte, size-of-your-thumbnail flash-drives that’s out there today. So they’re recording everything to, basically, an audio or videocassette, and at one point the sucker got stuck in reverse, and they had to figure out, “OK, how do we get it out of reverse?” They did that, and then there’s this concern that…

Fraser: “What if it reaches the end of the tape?!”

Pamela: [laughing] Well, hitting the end of the tape definitely happened and they were very concerned that this had done damage to the end of the tape, so they had to permanently not use that section of tape, and never fully unwind the tape for fear that it would come off the spindle, so not only were they limited by the fact that they’re writing to a tape which doesn’t hold that much, but then they can’t even use the entire tape, and the only way they can empty the tape is to use their low-gain antenna, and so it was just problem after problem, but they solved them — and that’s the awesome thing.

Fraser: Yeah, but, I mean, for a lot of that mission, they were really just nursing its various components, and its data systems, and its communications systems, and it was constantly having to give and take and say, “Well, I can’t receive information because I need that,” and “You’ve got to wait,” and I can just imagine the negotiations and the meetings and the conversations, and you know, at one part, it’s quite exciting because the problems are where people really shine, but at the other end, I can just imagine how awful it was to like have to wait for your data and having to prioritize and, you know, all these terrible choices that the mission directors would have to make on who gets what, and so on and on…so it’s just amazing. So after this big, long, convoluted trajectory, Galileo with its bad high-gain antenna makes it to Jupiter – bring on the science. So, what happened?

Pamela: So, it finally made it there in December of 1995, but what’s kind of awesome is some of its best science actually did get to come before that, which is a good thing, so these poor, innocent scientist who started planning this mission in the ‘70s, and they had to wait and wait over a decade to start getting data, and they started getting data first during the two passes through the asteroid belt. So we had the first encounter with asteroid Gaspera, which was in October of 1991. It flew within in 1600 km; it was the first time we actually got good images of an asteroid, and then I think this is the image all of us have seen and no one really remembers this is from Galileo. In August of 93, Galileo took images of the asteroid Ida, and found its little moon, Dactyl, and that was amazing science realizing, “Yes, asteroids really do have their own moons,” and as Galileo came up on Jupiter from behind, it was the only thing in the Solar System able to watch the chunks of comet P/Shoemaker-Levy 9 impact into Jupiter. From where we were here on the planet Earth, the impacts were happening on the far side of the planet where we just couldn’t see them. We had to wait for Jupiter to rotate to see the splash points.

Fraser: That’s amazing! When you think about it, I mean, to see a comet break up, and all of the various pieces collide with Jupiter, and scientists didn’t really know what was going to happen. I mean, were they just going to disappear into Jupiter? Were they going to cause fairly large explosions on the surface? Would it dig up material from underneath the top cloud layer? This is one of those pretty deep questions that scientists, if they had known that P/Shoemaker-Levy 9 was going to colliding into Jupiter, they would have like made a mission, and sent it just to study this event, so the fact that Galileo happened to catch this just as a happy accident is pretty amazing, like “Oh yeah, by the way, here’s a bonus, you know — comet colliding with Jupiter!”

Pamela: And that was one of those times where we really didn’t know what was going to happen. I was working at Kitt Peak that summer and we were all told, well something might happen, but really expect absolutely nothing, and that’s what we told the public, and then the images started coming in and this was the first time I remember really using the worldwide web. This was back in the days where we were all using Mosaic, and it was amazing.

Fraser: Gopher, yeah…

Pamela: Gopher…and we were downloading the pictures from Antarctica and praying for all the clouds to go away, and just to see the images coming in from everywhere in the Solar System was kind of awesome.

Fraser: Yeah, yeah, that was quite a time, so I mean, this is all the bonus science, but the real science, I mean, the stuff that Galileo was actually tasked to do…what was its, you know, what did it discover once it finally…where did it go and what did it do once it was in the Jovian system?

Pamela: So once it finally got there in December of ‘95, it did 34 orbits. This is one of those things…I personally always have to rescale my brain because, I don’t know about you, but I’m used to thinking of orbits as being things like 90 minutes – yeah! Orbits are short.

Fraser: Yeah, once a month for the moon, right?

Pamela: Right, and here it was on a basically two-month orbit, and as it went round and round, it brought us back images of the Jovian rings, it allowed us to realize that it’s the constant impact of small asteroids, meteorites, chunks of other ice and rock hitting Jupiter and her moons that are constantly feeding those small gossamer rings. There was the realization that Jupiter’s radiation field is a whole lot worse than anything we ever thought, it was the realization that Jupiter has these amazing lightening storms. And then, of course, there’s all the science that came out of studying the moons. Io — we realized had lava that could fill areas the size of Arizona, and…[laughing] in a year or so, no big deal…

Fraser: The huge geysers of lava that go hundreds of km into space and rain back down around on the moon — crazy!

Pamela: Yeah, it was somewhere beyond crazy, and into the land of “Oh my God, that’s insane!” We found that the moon Ganymede has its own substantial magnetic field, so I mean, we always talk about on the show how radiation is the big thing humans need to worry about when we travel into space…well, going to Ganymede — not as big a deal. It has its own magnetic field to keep you safe.

Fraser: Yeah, then you just have to worry about the space madness.

Pamela: Yeah, yeah, and the cold — things like that. Then we found that Europa, Ganymede and Callisto all have salt water beneath their visible surface, and with Europa, there’s the potential for life beneath its icy surface, and just the idea that somewhere between the icy oceans of Europa and the lava-covered surface of Io, we found everything in between. It was just this fabulous look at the diversity of what our solar system has to offer.

Fraser: Yeah, yeah, just amazing! And I know that as the mission was going on, they got more and more risky. I mean, this is amazing because I mean the mission itself was falling apart right from the beginning, but they just kept taking bigger and bigger risks – getting closer to Jupiter and finding out what they could do with the spacecraft before they killed it.

Pamela: [laughing] Yes. Well, they had their initial mission where they had basic science goals to study the atmosphere, plot the radiation belts, but they didn’t want to get too close to the moons because there’s always the risk that you’re going to accidentally end up on the moon, instead of flying past the moon, and so during the extended mission, this was where they started doing things like probing the radiation environment around Io and getting very close to Io to take these amazing images of the lava fields. This was where they started getting particularly close to the surface of Jupiter and probing its magnetic…magnetosphere, and in the process, they kept running into problems due to radiation, and in the end, it was problems with radiation that caused them to basically call an end to the mission. As they got particularly close to the moon Amalthea, they took a huge dose of radiation to the point that the LEDs they get used to work with the tape drive basically stopped lighting up, and they had to figure out how to re….. the LEDs remotely by changing the voltage through them and providing constant power and all sorts of crazy remote electronic repairs that I’m just in awe of what they were able to figure out how to do, but if they hadn’t been able to do that, they wouldn’t have been able to get the final data off of the tape.

Fraser: Yeah, yeah…right and as the spacecraft was starting to get more and more damaged by the radiation, it was a bit of a clock winding down. They had to figure out a way to end this mission gracefully, and not have the spacecraft crash into one of the moons.

Pamela: Right. So, the concern is that there wasn’t particular care taken to make sure that bacteria and viruses didn’t end up on Galileo – this was not a sterile spacecraft, and as we realized that there was potentially liquid oceans, in particular beneath Europa’s surface, but also potentially beneath some of the other surfaces…well, you don’t want to end up basically carrying small pox-covered blankets to these alien worlds, and that’s essentially what Galileo might have been. Imagine it goes and it crashes onto Europa, and human viruses and bacteria escape, and we go on experiment 20 years later and find out we’ve killed Europa’s oceans. We didn’t want to do that, and so they “suicided” the mission into Jupiter’s atmosphere. The polite way of saying it is that they “de-orbited” it into Jupiter’s atmosphere, but no, they killed it.

Fraser: It’s almost as if Galileo was orbiting around the Jovian system for hundreds and possibly even thousands of years, it would be almost inevitable that it would collide with one of the moons.

Pamela: Right.

Fraser: You just can’t calculate all of orbital perturbations?

Pamela: Perturbations.

Fraser: Yeah, so they decided to de-orbit it, and so they crashed it into Jupiter, and when did they do that?

Pamela: 2003…so it was April of 2003, it got to hit its greatest distance away from Jupiter, capture some stunning images, and then they plunged the sucker to its death.

Fraser: And do you remember when they were talking about how they were going to do this, people were threatening or worrying that Galileo was going to somehow turn Jupiter into another star because of the plutonium onboard or something like that?

Pamela: Oh, that was just crazy talk. So, in April it gets to its greatest distance, takes these stunning images…this is the same time that we’re starting to talk more and more about brown dwarf stars, and people somehow make the crazy connection that, “Oh no! Jupiter’s really a failed star, and we can ignite it!” and so as Galileo is starting its final journey to its death in September, you get these crazies who were calling, “You can’t do that! You shouldn’t do that!” because somehow the amount of mass on this little, tiny spacecraft that would fit in a big room is capable of igniting Jupiter into being a star, and the thing is that, while there’s brown dwarfs that are roughly the same diameter as Jupiter, that’s just because of the way gas dynamics works. You have to add 15 times Jupiter’s mass to get to a star, and the issue is you have to have the inside of the object, the planet star thing hot enough and dense enough that nuclear reactions can happen.

Fraser: Yeah.

Pamela: Jupiter’s just not that hot or dense.

Fraser: Right, so unless Galileo had like, whatever, 70 times the mass of Jupiter packed into it somehow, nothing is going to happen, and nothing did happen, but I’m sure that if they have to do the same thing with Cassini, people will freak out again, and…yeah, it’s ridiculous.

Pamela: And Cassini will have to be de-orbited as well because there’s, well, we have Titan, and we don’t want to go and pollute Titan.

Fraser: And so Galileo fell into Jupiter’s gravity through the top cloud layer and got squished.

Pamela: It got squished, and it sent back data along the way. So between it and the Galileo probe that had dropped through the atmosphere when Galileo first got to Jupiter, we got to actually learn things about Galileo’s atmosphere…we got to learn…not Galileo…we got to learn things about Jupiter’s atmosphere, we got to learn that it just doesn’t have quite as much water vapor as we thought, we got to learn that there’s high-speed winds, and so we got to study meteorology for the first time, really, in detail around another planet.

Fraser: It was a noble sacrifice.

Pamela: Death can be good.

Fraser: Alright, well, thank you very much, Pamela.

Pamela: It’s been my pleasure. I’ll talk to you later.

Fraser: Bye.

Pamela: Bye-bye.

Show Notes

• Dragon*Con
• Cassini mission website
• History of Saturn Observations
• Inside the Cassini spacecraft
• Much Ado about Cassini’s Plutonium (article from 1997 on CNN)
• Problem of not having enough plutonium 238 — Planetary Society
• Info and papers from Cassini’s flyby of Jupiter — Nature
• First images of Phoebe
• Slideshow of Huygens images of Titan — ESA
• Huygens probe to Titan — video
• Dagobah (Star Wars)
• The Mars Curse — Why Have so many  missions to the Red Planet Failed? — Universe Today (info about string of failed missions)
• Cassini and Enceladus
• Edge-on rings – Science@NASA
• Hexagon on Saturn — Universe Today
• Iapetus and Cassini
• How will the Cassini mission end?
• Methane rain on Titan
• Spokes on the rings
• Twists, ropes, mountains in the rings
• Carolyn Porco and CICLOPS
• Planetary Blog
• Unmanned Spaceflight

Download the transcript

Fraser: Welcome to Astronomy Cast our weekly facts-based journey through the cosmos where we help you understand not only what we know, but how we know what we know. My name is Fraser Cain, I’m the publisher of Universe Today, and with me is Dr. Pamela Gay, a professor at Southern Illinois University Edwardsville. Hi Pamela. How are you doing?

Pamela: I’m doing well. How are you?

Fraser: I’m doing really well. This is still the worst summer ever, although again, because we’re recording in July, but it’s really the April, people will wonder why it’s a bad summer, but yeah, it’s a terrible summer.

Pamela: We’re just prognosticating the weather.

Fraser: Yeah, I predict that in July 2011 near Vancouver Island the weather will be horrible. Yeah, did you have any more reminders? We’re going to be doing the live episode of Astronomy Cast at Dragon*Con Labor Day weekend.

Pamela: And we’re going to be doing a special Astronomy Cast with Chloe, with your daughter.

Fraser: We are. Right.

Pamela: Yeah.

Fraser: O.K…at Dragon*Con

Pamela: Yeah, we’re going to do a half-hour show with Chloe.

Fraser: “Questions from a nine-year-old…” She’s got all kinds of questions, but there’s going to be…lots of our friends are going to be there: Phil…um…

Pamela: Kevin Grazier

Fraser: Kevin Grazier …so we’ll probably do a live show with all of them as well.

Pamela: And we’re also going to do… Matt Lowry and I are going to do a physics demonstration show where we attempt to not kill each other with things like beds of nails.

Fraser: Cool! That sounds great!

Pamela: So…yeah, come out, come watch us be nerdy dorks doing pressure shows, and playing with lasers and blowing up balloons inside of balloons ‘cause we can, and uh, stuff like that.

Fraser: That’s cool! I’m trying to think how you do that. Is it like a black balloon inside a white balloon?

Pamela: You get one of those transparent balloons like they have at floral stores that you put teddy bears inside, and you fill with either dark purple or dark blue or one of those really dark sets of small balloons, shine a green laser through the clear balloon and shine it on the dark colored balloon, and the dark colored balloon will expand and explode — and it’s a glorious thing.

Fraser: That’s really cool. I want one of those blue lasers. I hear they’re terrifying. I’m already scared about my green laser, so I can’t even imagine having a blue laser. Alright, let’s get on with the show. So last week we talked about the Italian astronomer, Giovanni Cassini; this week we’ll talk about the mission that shares his name: NASA’s Cassini Spacecraft. This amazing mission is orbiting Saturn right now sending back thousands of high-resolution images of the ringed planet and its moons. Alright Pamela, let’s talk about Cassini, and I’ll just go like right from the beginning: Cassini is like the highlight mission of my life.

Pamela: Really?

Fraser: Yeah, I think so. I think of all the missions I’ve been most excited about, reporting Universe Today — you know, it launched around the time that I started working on the site and got to Saturn…what 2004? And I’ve been…it’s like followed pace of my entire career, so it’s uh yeah, I’m really excited about Cassini. And it’s got a really long history. It goes back to like before we were born, I think.

Pamela: [laughing] Not quite…it goes back to elementary school.

Fraser: Perfect. Yeah, what’s the beginning of Cassini?

Pamela: Well, back in 1982, folks were trying to figure out: “What next? What do we do?” And this was when we were still working off the Voyager probes…were out there still sending back data. We still had the Mariner missions, and this was supposed to be part of the Mariner Mark II set of missions. It was going to be…it wasn’t called Cassini back then — it had a long complicated name involving, as you might guess, Saturn, and then there was also a sister mission, a comet rendezvous asteroid fly-by, and the idea was that these were both going to be Mariner missions, had very similar hardware, have basically…save money by doing two things that were very similar, except then there wasn’t money to do two missions, and well, with only enough money to do one, the decision was made that Saturn was the much more interesting target, and Cassini became a stand-alone, highly-specialized mission that was optimized to learn as much as possible about Saturn.

Fraser: Right, and this is the first time…although missions had been sent toward Saturn before then…you’d had the Pioneer, and the Voyagers — they were fly-by missions, and so the goal with Cassini was not to fly past the planet, but to actually go into orbit and then get…do fly-bys of all the moons and gather a lot more science really close up,.

Pamela: Right, and so there was this really nice laundry list of science missions where we were trying to better understand the dynamics of the rings. Are things like the spokes that had been seen real? We were trying to figure out what is the surface history of all the different moons. Do they share the same history? Do they have different histories due to differences of origins. Then, there’s just the weird things like Iapetus being a two-colored object, and well, we didn’t even really know before Cassini how long it took Saturn to rotate on its axis. So all these different things about all of the different moons and about the magnetosphere, and about, well, Saturn itself and its clouds — all of these different things got piled on to the future of Cassini, but along with piling on the goals, they piled on the instruments, and this is a mission that had a healthy enough budget that it was able to do all the things that it wanted to do. It came in at 3.26 billion dollars, which is a hefty price tag, but it worked.

Fraser: It’s a big spacecraft, and so it’s really well-equipped to do this work. So when did the mission finally come together then?

Pamela: It finally launched in 1997, so you were getting Universe Today started, I was contemplating my first year of graduate school and was completely oblivious to the entire thing. What’s interesting though is it almost died many times between its 1982 conception and its 1997 launch. Congress kept trying to kill it off in the 90s and what saved it is this mission, while a sweetheart of the U. S. space program, and while largely funded by the U. S. space program, was actually one of the missions that helped really heal our relationships with the European Space Agency and its different member nations. In the late 80s/early 90s, we worked to make this a really solid collaboration, where the Huygens probe, for instance, came from the Europeans, and many of the instruments came from the Europeans, and every time Congress tried to kill off this little mission, this really huge, giant mission actually, NASA was able to step forward and say, “you probably don’t want to do that. We like the Europeans and we want them to like us back.”

Fraser: It’s interesting as we’re going through this, as we’re recording this — it’s the same story, you know, about the James Webb, and now the space shuttle is closed, but that’s been the ongoing stories: missions almost killed. So when a mission actually makes it off the planet and you can’t take it back, you know, then that’s, you know, that’s when you’ve finally arrived. So yeah, launched in ‘97, but it had to take a pretty circuitous route to Saturn, right?

Pamela: Circuitous – I’ll go with that. Right, so it didn’t have the most powerful engines any satellite has ever had, and so it got gravitational assists from Venus more than once, it whipped past the Earth, got some good images of Earth as it went by, and finally headed out toward Saturn via Jupiter, and got some pictures of Jupiter as it went by that, so we have a spacecraft that basically took a full tour of the Solar System on its way out.

Fraser: And there was a big controversy if you remember when it was about to launch, there was this big controversy because it had that big plutonium reactor on board, and so it was actually, you know, kind of filled with poisonous plutonium, and people were worried that, you know, when it would launch if there was a problem — a launch disaster — it would spread plutonium around the Earth. And as well for the subsequent fly-bys when it had to go past the Earth, there was another, you know…people were kind of freaked out.

Pamela: Right. So this mission has…you can’t use solar panels when you’re out at Saturn, there’s just not quite enough sunlight out there, so it has roughly 70 pounds or 32.7 kg of plutonium 238, which is a nicely radioactive, producing-heat-as-it-decays element, and it’s from that heat that they’re able to generate electricity, and the concern was that it could either blow up on launch and release all of that radioactive material into the atmosphere, or…on its one lone fly-by they ran models, and in a worst case scenario, if the mission came through at just the right perfect, absolutely-miraculous-shouldn’t-actually-have-much-probability-of-happening-if-it-came-up-at-just-the-right-angle, it could completely burn up in the atmosphere and distribute all of the plutonium through the atmosphere and cause an additional 5000 cases of cancer per population of the planet Earth.

Fraser: But it didn’t happen, so…

Pamela: It didn’t happen, and they took the risk because the probability said it wouldn’t happen.

Fraser: Yeah, but you can imagine that being the ongoing controversy for any of these flights that are going to be going out, you know, beyond the warm embrace of the Sun. You’re going to have…you’re going to need something like plutonium.

Pamela: We might actually be avoiding that problem due to current Senate cuts. We actually aren’t currently producing plutonium 238, and we’re running out of these engines. I believe there’s less than five left, and they’re all allocated to projects already, and so if we want to continue building into the future, we need to turn back on the plutonium 238 production, and that was part of the upcoming budget, but it’s one of the items, along with the James Webb space telescope, that’s currently axed.

Fraser: So Cassini makes this…you know, fly-bys of Earth and Venus, and then made this wonderful fly-by of Jupiter and sent back amazing images…and what was great was the Galileo spacecraft was at Jupiter at the time, and so the two sent back these amazing images in concert together, and they actually were able to sort of combine science from these two spacecraft. It was quite a time.

Pamela: Well, it’s one of those rare instances where you can get the up-close view of the spacecraft that’s in orbit, and get the big picture view that allows you to see all the context from the further away spacecraft, and so if you’ve ever done the going back and forth between binoculars and eyepiece, or binoculars and your eyes…well, they were able to do that going back and forth between two satellites.

Fraser: Yeah, and so if you do a search for Jupiter, like Google images and stuff like that, a lot of the full pictures you’ll see of Jupiter were actually taken by Cassini, even though Galileo spent so much time at Jupiter. Galileo was up a lot closer, so it didn’t just get as much nice views from afar, and so they still really rely on those images from Cassini, when they’re showing images of Jupiter. So Cassini then made it all the way out to Saturn in…what was it? 2004?

Pamela: It made it out in 2004, and on its way in as it started what was one of the scarier orbital insertions ever because you’re kind of dodging moons, dodging rings, trying to get yourself into all of it…they had to first rotate the spacecraft so that its large dish would basically protect all of its instruments from the dust and debris of flying through the rings, not through the rings, through a gap, but then they had to turn the spacecraft around so that it could fire its engines in the direction of its motion to radically slow it down for orbital insertion. So this was all sorts of crazy maneuvering, and the spacecraft just took it all in stride, and it was able in June 2004 to send us pictures of the little battered moon, Phoebe, and in July zip through and put itself into orbit because NASA likes to do everything on national holidays, and Fourth of July seemed like a perfectly good time to celebrate another orbital achievement.

Fraser: It’s not Canada Day…I don’t see what’s happening then. Anyway, and the images coming back from Phoebe were just amazing. As soon as you saw those images, you knew we were dealing with something…you know, this was a whole new way of seeing photographs from space, I mean, they were so good…and then?

Pamela: And then, well, the entire time this very large spacecraft was carrying a parasite with it. So the Huygens mission was latched on and sucking power from its plutonium drive and was carried all the way up until December, and on December 25, the European Space Agency separated off their Huygens probe from Cassini, and it began its long journey to Titan, and it was on January 14 that we were finally able to see the surface of another world that had active geology from atmospheres, from weathering, from rivers, from deltas…and so that symbiotic relationship with the European Space Agency allowed us to basically get two major scientific missions for the price of one.

Fraser: Yeah, and there are some amazing videos now — after the fact. I remember when it was first coming out, the images were pretty rough, and it was really hard to really get a sense of what you were seeing until you actually saw the images on the ground, but since then people have gone and done a lot with the images and sort of built these really neat animations you can see the [missing audio] from space, watching the [missing audio] or from a really high altitude watching what Huygens was seeing as it was descending through Titan’s atmosphere all the way pretty much down to the surface of the moon, you can see just these great, you know, the sort of spinning vistas of the surface of the moon until it actually plunked down into the — what was it…mud on the surface of Titan. It blows your mind. You’re seeing these kind of rolling hills with boulders of rock and muck with ammonia and…

Pamela: It was like Dagobah with no vegetation.

Fraser: Yeah, yeah, just astounding to think what had gone through to make that happen. So then Cassini no longer had Huygens, but it had done a really nice fly-past of Titan, still had gotten rid of its parasite you know and then kept moving, right?

Pamela: Yeah, and one of the amazing things about Huygens is they realized after launch, after the mission was good and far away from the planet Earth, that Huygens had a rather fatal flaw and they were able to figure out how to compensate for that in real – well, not in real time, they figured it out ahead of time, but they figured out how to compensate in mid-stream. As we’ve talked about before on this show, when an object is in motion, its light its radio, its wavelengths get Doppler-shifted, and they had tuned Cassini to listen to Huygens as it dropped through the atmosphere of Titan and the firmware forgot to take into consideration that there’d be this Doppler shift of the signal, and so when they tested things they realized, “(many expletives), it won’t be able to catch the signal!” and they figured out how to change the way things were aligned, and they were able to figure out how to make it work so that they could catch all of the data and nothing was lost in the end.

Fraser: Yeah. In this…this is around a string of problems. Remember, there was the… What were the other ones? The polar…

Pamela: Mars Polar Lander?

Fraser: Polar Lander? No, yeah…there was one that just smashed into the atmosphere and disappeared, there’s the Beagle II that just disappeared, and there’s another that they had used the wrong imperial metric system, so there was just a string. That happened right during a string of big problems, yet there was a lot of great engineering successes as well, where people had figured out how to make other missions run on like a single gyro, things like that. Now, how come…? You know, there’s a lot of those missions where like with the rovers, where they keep going and going and going, but like pretty much once Huygens was done, that was all we saw of it. Like it sent back a couple of images and then we didn’t hear anymore news from Huygens.

Pamela: Battery life? So Huygens was a happy little parasite on Cassini drawing energy off of its plutonium thermocells basically up until that December 25 launch separation moment, and once it separated, it wasn’t carrying its own nuclear fuel cells, so it was working on chemical batteries, and the chemical batteries had a finite life and the mission had a finite life and they weren’t sure it would even survive impact, but it lasted a couple of minutes past impact, and it just wasn’t designed to keep going and going and going. You have to cut weight somewhere, you have to cut costs somewhere, and in the end, not knowing what they’d land on, they budgeted to get as much data for the parachute ride down as they possibly could, and it then ended, so…

Fraser: Yeah, yeah, I can kind of imagine if they’d used some of the newer technology, right? Can you imagine if they’d made some of the Rover technology, or had done something like that then that would have been a much better way to…you know, some of the newer technology with the Spirit of Opportunity — that would have been amazing.

Pamela: Well, the problem they ran into was they had no way of knowing if they needed a dust buggy or a swamp vehicle, and when you’re not sure if you need to float, or if you need to roll, it’s hard to plan for that.

Fraser Yeah. Alright, so we got the cool landing at Titan, and if you want more detail, we’ve done a whole show on Titan, we’ve done a whole show on Saturn, we’ve done a whole show on Saturn’s moons, so, you know, we’re more talking about the mission than actually about the discoveries on the moons and the planet. So then we…and, I mean, that was like the first fly-by of Titan, but they did Iapetus, they did…so many fly-bys.

Pamela: And with Enceladus we were able to, for the first time, start to get a sense of what’s rejuvenating the rings by the discovery of the geysers coming off of that water-pressurized moon. And what’s amazing is just like the Mars Exploration Rovers, this is the spacecraft that also won’t die. And so here it is, it’s in its second mission extension at this point. They decided to extend it through the equinox that occurred in 2009, which is where we saw the rings completely edge-on and seemed to disappear into the starlight, and they’re now extending it into the next solstice period, so we’ll get to see the other pole of Saturn from Earth while Cassini gets to watch how does the atmosphere of Saturn change as the sunlight changes. And what’s neat is one of its discoveries was this rather terrifying vortex on the pole of Saturn, and it’ll be neat to see are there any changes in that eyewall as the thermodynamics of the system changes.

Fraser: They found that strange hexagon-shaped storm, right?

Pamela: Yeah.

Fraser: In fact, we added that to one of our “Mysteries of the Solar System” show, I think.

Pamela: Right. So there’s this strange vortex on Venus, the strange vortex on Saturn — I’m kind of glad we don’t have a strange vortex on Earth. It’s just kind of amazing and the only thing that’s scary right now is while it has been extended out through the next solstice, there are concerns that right now they’re doing senior review of all of the NASA missions that are on extended missions. There’s limited funding and the fear is that maybe this, Maybe LRO, maybe…who knows? All of these different missions that are up for an extension are being reviewed, and they could die as part of the 2.2-3 trillion dollar budget cuts in the U.S. government.

Fraser: Uhhh…

Pamela: Yeah, so here’s to hoping LRO survives, James Webb survives, Cassini survives…uh, we want our missions.

Fraser: But as we alluded to earlier in the show, this is the story, its almost like no mission ever gets out alive, you know? They all get beaten up at some point and really just the toughest ones… it’s like some kind of gladiator fight to get a mission launched. So what would say are some of the big highlights, what are some of the big discoveries Cassini made as part of its mission at Saturn?

Pamela: So, I have to say my favorite is realizing what the heck happened to Iapetus to cause this two-toned moon to exist and look chewed-up the way it does. This is the moon that when you look at it, it has one face that is black, black, black, black, and the other side is this shiny, white, highly-reflective ice, and what they were able to figure out is at some point in the past — this moon, it’s rotating so slowly that it has one edge that tends to lead around the orbit, and that edge just collected dust and that dust made the surface darker, and the darker surface heated up, and the ice didn’t melt, it sublimated, but any dust and gas that was trapped in that sublimating ice was then revealed and it became this feedback system where the hotter the surface got, the more it sublimated, the darker it got as more dust was revealed, and it’s now thought to be several centimeters deep in this black, carbonaceous, gross substance that does not like to reflect light.

Fraser: And it’s got that really weird seam. I don’t know if they’ve really closed the book on that yet, have they?

Pamela: No. That one they’re still trying to figure out. I mean, at a certain level it’s part of the outer solar system that’s had the tar beat out of it, but exactly what caused that we don’t know.

Fraser: Right. So we got a handle on why Iapetus has that strange two-toned color – thanks, Cassini, and we found the Hexagon – thanks, Cassini.

Pamela: And we found some new moons. It’s always fun to find new moons, hiding out in the rings. Titan just…we keep getting awesome new ideas on Titan. This is the moon…you know, if I was given a choice of Europa or Titan to send real exploration vehicles to, I’m not sure which one I’d choose.

Fraser: Europa — submarines looking for life…

Pamela: Yeah, but then the back of my head is like…but Titan is so much more likely to be successful. Yeah, I agree the return on Europa is likely to be much greater, but we’re learning so much about Titan, and the mission is planning to do actually one terrifyingly close fly-by that will then send it on an orbit that makes it just a few thousand kilometers above Saturn’s clouds, and it’s going to do two of those close fly-bys, and the second of those close fly-bys will actually send Cassini on a death orbit into the atmosphere of Saturn. They don’t want Titan or Enceladus or any of the other moons that have liquid to potentially get polluted with Earth goobers, and so rather than let our bacteria get to the surface of one of those moons, they’re going to suicide the satellite.

Fraser: They get pretty reckless with these missions near the end; they did that with Galileo as well. “Now, let’s get some extreme science,” and then they send it closer and closer and more radiation and then finally went, “oh well, we can’t kill it this way, let’s just drop it in,” but a big part of it is that whatever they do, they don’t want to infect any part of the Saturnian system with microbes from Earth, so in the end, Cassini is going to be shut off, and it’s going to be shut off, or it’s going to be crashed into the planet when they still can talk to it. If it suffers some kind of big damage, or its system runs out of power and they can’t control it anymore, then it’s too late, so they’re going to shut it down sooner than they have to because it’s not working anymore. We talked about some other discoveries, right? The discovery of liquid on Titan…

Pamela: Right. Methane rain, methane lakes — it’s a completely different geology than we’re used to, and it’s absolutely amazing. Yeah, there’s just so much stuff.

Fraser: The ice geysers on Enceladus, the tiger striping…

The rings were confirmed to have spokes, and have these weird gravitational interactions. They’re not as symmetric as you might expect them to be, and so we’re slowly learning more and more about the dynamics of the rings, finding twists and ropes in the rings.

Fraser: Yeah.

Pamela: And uh, what’s kind of amazing is as well as doing all this science, NASA has reached out through the forms of unmanned spaceflight and said, “Hey, we’d also just like to get some beautiful Kodak moments,” and they’ve asked the public to contribute what are those times that we should try, and I heard Carolyn Porco talking once how they’ve had to do these crazy maneuvers. As they’re flying past a moon they’re rotating the spacecraft and accelerating and imaging and doing all of this stuff at once, but the result is being able to do some absolutely amazing videos and almost everything can be found on Emily Lakdawallas’ blog, the Planetary Society blog, and what’s amazing about what Emily does: if she can’t find the image she wants, she gets into the planetary data system and she downloads the images and she processes them. So she has some really amazing stuff.

Fraser: Yeah, you gave three quick shout-outs there, we should slow them down, right? Unmanned spaceflight is a fantastic forum for talking about various missions, um I highly recommend it as well. Carolyn Porco, she is the primary investigator, science investigator, for the Cassini mission, and has done a better job than pretty much anybody in the whole industry in getting the word out about her mission. I mean, even when I started Universe Today, way back in the day, if I made a mistake, Carolyn was sending me an email right away, saying, “Oh yeah, you missed this, you made a mistake there,” but she was also really good about helping me get the word out about things that we were doing for her missions, so I think anyone else who’s going to be involved in this kind of a public affairs mission, look at what she’s done, she’s done TEDtalks, she’s just been fantastic.

Pamela: And she’s done a Star Trek, you can’t leave that one out, that’s just kind of full of whim.

Fraser: And then Emily Lakdawalla, she’s the one at the Planetary Society who’s the hardest working person in space media. As you said, she’s fantastic. She will produce images that nobody else has, and she just does a fantastic job, so…groovy! I think we’re kind of reaching the end, so when will Cassini end? Where are we at right now?

Pamela: Well, right now we’re waiting for the U. S. Congress to get its act together, so barring that, it’s going to keep going until 2017 and allow us to see well the next solstice.

Fraser: Right, and that’s six more years from when we’re recording that, and that’s like for sure at that time they’ll have to de-orbit it.

Pamela: Well, nothing’s for sure, they have to look and see how the spacecraft is doing, how the spacecraft is behaving, but like you said, if there’s the slightest hint of something going wrong, they’re going to pull the plug before it has to…you just can’t risk a mission that you know has bacteria on it potentially landing on Titan where, as we’ve talked about in earlier episodes, there is hints of not statistically certain, but hints of evidence that there’s potentially bacteria there, so just no risks allowed.

Fraser: Yeah. Yeah. Alright, well, thanks a lot, Pamela. That was great. We’ll talk to you next week. We’re going to do the third part in the series. We’re going to do the discussion of Christiaan Huygens, right?

Pamela: Yep, Huygens.

Fraser: Yeah. Awesome. Well, we’ll talk to you next week.

Pamela: Sounds great! Talk to you later, Fraser.

Download the transcript

Fraser:

Welcome to Astronomy Cast Episode 222 for Monday, February 28, 2011: The Decadal Survey. Welcome to Astronomy Cast, our weekly facts-based journey through the Cosmos, where we help you understand not only what we know, but how we know what we know. My name is Fraser Cain, I’m the publisher of Universe Today, and with me is Dr. Pamela Gay, a professor at Southern Illinois University at Edwardsville. Hi Pamela, how are you doing?

Pamela:

I’m doing well. How are you doing?

Fraser: Doing great! Alright, so in episode 198 we explained how space missions are chosen, and we introduced the Decadal Survey. Since the time we recorded that episode, the full Decadal Survey for planetary science has been released. Explain the science goals for planetary geologists over the next 10 years. We thought we’d take an episode and give you an overview of all the science coming your way. Whew! So for those of you who want to read this on their own as we do this episode, or before or after, where can people get their hands on the Decadal Survey?

Pamela: The National Academies of Sciences Press has copies that you can download for free on line of the pre-published version, and all you have to do is be willing to give the National Academy your email address, and that’s pretty simple.

Fraser: Right, but they’ll need that later when they need to send you your Nobel Prize, so…. Yeah, so you can get it by going to NAP.edu/catalog/13117.html, and you have to give your email address, and you can download the full Decadal Survey, and this is all of the cool, planetary science that the scientists want to get done over the next ten years, starting in 2013. Now, you were part of this process, right?

Pamela: I was part of the process on the astronomy side. There’s actually two different Decadal Surveys. There’s the astronomy/astrophysics one, which goes from 2010 – 2020 (and was ironically released in 2011), and then there’s the planetary science Decadal Survey, which goes from 2013 to 2022, and being an astronomer who simply likes geo-physics, rather than practices planetary science, I simply watched as an enthralled outsider the planetary sciences Decadal Survey process.

Fraser: Right, and we’ve already explained the ones that you worked on and looked through, so now we’re going to talk about the planetary science ones. I’m not sure… how do you want to approach this? Should we give some highlights? Who were the people behind this? Who came together for this one?

Pamela: Well, just like in the astronomy community, they started by getting together people that they felt were community leaders, and then asked the entire community from graduate students up through the oldest of emeritus faculty to please write white papers and give input as well. So while there was a definite attempt to get the best and brightest of our senior researchers together to lead the process. Every one of them was asked for input, and I think it’s worth noting that this process was in some ways distinctly different from the astronomy process. In astronomy, we were asked, “What are the most important things we can do? Dream large. Give us guidance.” And there was also the inclusion of education public outreach. How can we better mentor? How can we better teach? And we looked to find the ways in which we could make our community better, both as a community, and as a group of people trying to better understand our universe. And there was really no boundary put on what we could dream. At a certain level, everyone knew there are financial constraints, there are limits on what NASA and the National Science Foundation can facilitate us being able to achieve, but we dreamed big. On the planetary sciences side, the situation was very different. Planetary science…it’s not a bunch of professors like we have in astronomy. It’s a bunch of people working – in some cases there are professors, but there are also all the research scientists at places like the Lunar and Planetary Institute, the Southwest Research Institute, Jet Propulsion Labs…at all these research centers, the staff work 100% of their time off of NASA and National Science Foundation funding. This means that they’re not getting nine months out of twelve months salary from teaching, and that radically changes what you are able to do because if you’re a professor where nine months of your salary comes from teaching, during those nine months, you’re still doing research. You’re doing it at a reduced rate, but you’re still doing research that’s getting paid for by your university, and there’s lots of astronomers out there, who that nine months salary is enough for, and they’ll spend their summer putzing on their personal projects using existing resources to continue doing research. A planetary scientist doesn’t have that freedom necessarily. They’re writing grants, writing grants, writing grants…and they’re only allowed to do what their grants fund them to do. So if you’re a planetary scientist funded 100% of your time to study volcanoes on Mars, and you have this wild curiosity about volcanoes on Io, you can’t go dedicate the time that you’d like to to study those volcanoes on Io, but a professor – they can. Planetary Scientists, as a result, have a much more pragmatic approach of “What can we do that we’ll actually get funded to do?” and that pragmatism is carried on into how they do their Decadal Survey. When they created their model for: “Here’s what we want to do,” they said, “What can we do within the limits of the projected budgets?” So they worked to find out “What does everyone think NASA’s budget will be? What does everyone think NSF’s budget will be?” and they constrained their dreaming to the financial realities that they thought they were going to have.

Fraser: And so what was the process then? They all submitted white papers, and then some group looked through them and tried to find overlap?

Pamela: Right, so it was a many-step process where there were committees put together, panels put together, for instance, an inner planets panel. Mars gets its entire own planet panel because we know Mars is important. There were people dedicated to the giant planets, to satellites, and each of these panels got together, accepted white papers… They actually traveled and they did town hall meetings all across the United States and they actively sought input from the community. They then looked at all of this information and looked for guiding themes. They then judged the guiding themes based on “What has the greatest potential to generate science, to generate new technology, and to be completable within the constraints of the budget?” And it’s based on that “How do we get the best science? How do we get the best future technology? And how do we do it all without going into the red?” that led to the results that we now have in the Decadal Survey for Planetary Science.

Fraser: And so in theory, now that this plan has been provided, how will that turn into missions?

Pamela: This is a guiding document, and so suggestions are made. For instance, they proposed which flagship missions should be built, and what typically happens, what’s happened in the past is NASA and the Congress and National Science Foundation have all looked at the results of the Decadal Survey (this is basically a wish list from the entire community) and said, “OK, you’ve provided us guidance. We’re now going to write proposals, not proposals…we’re now going to write calls for proposals, and ask you to propose exactly how we’re going to carry through on each of these different ideas.” So in some cases it was quite specific. In both the Astronomy and Planetary Science Decadal Surveys, both came forward and said, “We need to fund the Large Synoptic Survey Telescope.” This is a very large telescope that’s being built in South America that will every three nights image the entire sky that’s viewable. That’s a very specific recommendation.

Fraser: Right, but you can imagine how it has dual purpose, right?

Pamela: Exactly, so this many-purpose mission that’s just going to bury everyone in data, it was specifically named. Now, there’s other cases where within the survey it said, “we suggest that you fund one of the following…we suggest you fund three of the following…” so for instance, one of the things that they did…there’s a NASA program called New Frontiers. These are medium-sized missions. They do a new call for these every few years, and they put together a list of five different concepts that they think it’s important to design missions around. And they said that during the New Frontiers Mission 4 call for mission proposals that the ones that are funded and the exact number that can be funded (that’s going to depend on how the missions are designed) should come from five specific concepts. There should perhaps be one that does a comet surface return mission. This is where you send a spacecraft out and you actually take part of a comet and you bring it back! So that’s just kind of cool, and highly complicated and really awesome in a lot of different ways. There was an idea put forth that another necessary-to-pick-from idea is to go to the lunar south pole Aitkin basin, grab a rock and bring it back…so this is another sample return mission. There was a proposal put forward that maybe one of these missions should be another Saturn probe, that maybe we should go to the Trojan asteroids and do rendezvous missions, like Dawn is doing with the nearby asteroid belt, and there was a Venus Situit explorer proposed. So there are five different candidates and they won’t all be chosen. There will probably be two of them chosen – it all depends on the funding situation. And they said that in the next call, take whatever you didn’t fund from those and add to those an Io observer to go observe the volcanoes of Io, and a lunar geophysical network: this is the idea of building seismic stations like the ones we have across the planet earth — instead, scatter them across the moon.

Fraser: You’re already starting to give some of the highlights, so how many missions have been proposed overall?

Pamela: The problem is they were very narrow in how they dreamed, but they recognized in writing this that they were going to make certain guiding principles that basically said, “in the best case, this is what you should do,” but there isn’t a best case, so altogether they’re recommending that you should put some emphasis on small missions. No matter what, do not get rid of the small missions. And they put no science guidance on these, other than to consider things like a Mars trace gas orbiter, so for the most part they said, “let’s take this program — it’s highly successful. We’re not going to give you a whole lot of guidance, but you’ve got to keep funding this.” They said, “OK, medium missions are necessary. We’re going to give you the following funding caps that are different than the old ones, and here are the guiding principles, but we’re not going to tell you exactly how many.” The committee did recommend (and here I’m going to read it) that NASA select two new Mars Frontier missions in the decade 2012 – 2022. These are referred to as Mars Frontiers mission 4 and mission 5. So they’re saying, “of the first list I’ve read, pick one, and from the second list I’ve read, pick one.” So that’s kind of depressing, but everyone hopes that if something happens, that they’ll be able to add, so there’s ideas for “if a third mission is selected, one of these should be the following…” Now you have to be flexible because some of the things are so expensive and so risky that it may be worth making the decision instead of building, for instance, a mission to go explore Jupiter in detail, instead of building a mission to go and return rocks from the surface of Mars, let’s not have a large mission. And that would be heartbreaking for many individuals, but at the cost of one large mission… These are multi-billion dollar projects, where the Mars return mission was de-scoped — it was made smaller — and it’s 2.5 billion dollars!

Fraser: Can you imagine…for some rocks from Mars? Yeah…

Pamela: And the medium-sized missions are capped at 1.5 billion. So you can get two smaller missions for the price of getting rocks from Mars.

Fraser: So based on your experience so far, you know, in how this works, and how the funding works, what do you think this will realistically turn into? Because when I think back over the last ten years, I mean, there were dozens of missions launched. I mean, there were tons: there was New Horizons, and Messenger, and you know…there were a lot of missions. There was the Lunar Orbiter…so what do you think this will realistically turn into over the next decade?

Pamela: I think the steady stream of small missions, things like Dawn, that no one quite imagined and someone had a really excellent idea and proposed it — that steady stream of really excellent small missions — those are going to keep happening. And those are the ones that the Decadal Survey says, “Keep doing this. We’re not going to give you a whole lot of guidance, but this is important.”

Fraser: But these missions haven’t really been planned out yet.

Pamela: Right, now when it comes to the giant missions that we’ve gotten used to…these are the things like the Curiosity Mars Lander, the Mars Laboratory that’s going to be taking off later this year – those giant flagship missions have consistently been outlined in the Decadal Surveys, and if we’re able to get those giant missions…those are the exact ones we’re looking at right now on the Decadal Survey. The community is very good at sticking to its wishes. The biggest question mark is always Congress. The thing that I think I will remember as one of the best and most falsely foreshadowing the future events I ever saw was in 2003 at the Lunar and Planetary Sciences conference down in Houston. It was a very strange meeting because this was the same week that we went to war with Iraq, so that was kind of casting a bad aura over the meeting, especially with Johnson Space Flight Center there — we had military aircraft flying overhead, but in the shadow of all of that weirdness, there was NASA administrator whose name has been lost to me over time who stood in front of us, and she was a very dynamic speaker. And she said you gave us your survey, and here are the missions that we have funded that will answer every single one of your scientific requests. And she went down the list and she said “here’s your goal, here’s your mission; here’s your goal, here’s your mission.” Now unfortunately, subsequently, many of those were canceled due to the fact that our economy isn’t very good right now, and so that moment of glorious “you came together as a community, you came together around ideas and here’s how we’re going to answer you” — that was awesome. Today the message is different. Today the message we’re getting is “as a community, if we want to see our dreams come to a reality, we have to be proactive in dealing with Congress.” It’s no longer enough anymore to simply do amazing science that inspires. Now you have to do amazing science that inspires and personally be inspiring, personally go out there and talk to your congressman, talk to your legislators and say, “this is important.” One of the things that gets lost a lot is when you discuss cutting funding to science, you’re cutting jobs, and the jobs that get lost first are the people that haven’t been employed yet: the future funding for students, the future funding for post-doctoral researchers, the future funding for people who are currently working on their degrees and need to have early degree research scientist jobs to step into later. Those are the positions that get lost first, and every time we cut funding to a mission, all the jobs associated with that mission go away, and we need to communicate this better so that people understand funding science is funding what we know, is funding the people that tell us what we know, it’s funding the engineers that build the spacecraft and while there is a lot of money that gets tied into launch vehicles, and a lot of money that gets tied into the electronics… At the end of the day, it’s all human beings that put that together.

Fraser: So, let’s get some real highlights because I think you’ve dropped a bunch of mission ideas across this podcast so far, but I think, can you give a succinct list of the big missions that might happen?

Pamela: So the list of large potential flagship missions includes a Mars Trace Gas Orbiter. This is a mission that would occur jointly with a European space agency and would do what it says it’s going to do. It would go and it would measure the composition of Mars’ atmosphere.

Fraser: Right, they’re looking for life through the methane emissions, among other things, to try and conclusively…OK, cool.

Pamela: So there’s that. That’s going to go forward. Sorry, these are overview, it’s not just the flagship. They’re recommending that there should be two New Frontiers missions, two New Frontiers missions…so these are the “pick one…pick one that includes going and exploring Io, going back to Jupiter.” These are the wonderful medium-size missions that get us out into the outer solar systems.

Fraser: What’s an example of a mission we’ve already got? New Horizons?

Pamela: Yeah, New Horizons is a good example.

Fraser: So did they actually list out the mission ideas?

Pamela: There are mission concepts, but the way this works is once the funding gets allocated of “yes, we’re going to go do this,” they put out a call for proposals and that’s when the teams get built. You have to put the funding in front of the people funded.

Fraser: Right, so you may get 20 or 30 proposals for these Frontier missions, and then in the end, two will probably be selected, maybe a third.

Pamela: Yeah, and it will be along the lines of “here are the five concepts that are recommended by the Decadal Survey. Go write proposals related to these five concepts,” and each one of those concepts will probably get just a handful of proposals. So you’re looking at maybe 20 proposals for all five ideas. And then from those, they will select one of those proposals to get funded in each of the two calls for proposals.

Fraser: Got it. OK. Yeah.

Pamela: So the big flagship that’s currently getting recommended over and above the rest is a project called MAX-C. This is the first part in a mission to go and grab rocks from Mars and bring them back. This is a bit scary of a mission in my opinion — very exciting scientifically, technologically very terrifying because this is where we need two spacecraft to land side by side, and as I mentioned in our last episode, we know how to land things in rather large landing ellipses; side by side is a challenge we still need to figure out, but one thing they’re recommending is in the increase in the amount of funding that goes to research and development of new technologies. So they’re recognizing through the Decadal Survey that in order to keep moving forward, to keep doing new and interesting things, to build toward our dream of exploring under the waters of Europa, exploring the outer solar systems, the lava caves on Mars, and all these interesting scientific ideas, we have to develop technology.

Fraser: So, Mars Sample Return Mission…

Pamela: Right.

Fraser: OK.

Pamela: The next one, you know, you can say this two ways and one of them sounds much worse than the other: it’s a Uranus Probe. [laughing]

Fraser: [laughing] We didn’t laugh, children; we didn’t laugh. There’s nothing funny about that — purely scientific. OK, a probe to the planet Uranus. Understood. Again, to study the planet, its moons…OK?

Pamela: This is going to be another mission along the lines of Galileo, Cassini, where you go out, you have an orbiter that orbits and orbits and orbits and drops something through the atmosphere.

Fraser: Yeah, to think we’ve only seen that planet once, briefly. All the images we have were taken by Voyager as it moved past… OK, more!

Pamela: So beyond this there’s a recommendation that, you know, if the budget picture gets nice, if we have more funding than was anticipated – let’s go orbit Enceladus. Let’s go see the geysers up close and personal for a good period of time to understand exactly what’s going on with this little moon.

Fraser: That would be amazing! OK…

Pamela: The alternative to that (because even when you dream big, you recognize you’re only likely to get one wish come true)…the alternative is a Venus climate mission to go study that insane, acidic, gas, greenhouse effect planet, and so that’s another interesting mission laid on the table.

Fraser: But an orbiter…

Pamela: An orbiter, yes.

Fraser: OK, I choose the Enceladus one, please. So anything else?

Pamela: Beyond that it starts getting into the “big picture” ideas. This is where they want to increase the amount of funding that’s going to research and technology to make sure there’s better ground-based technology, so this is where funding for the Arecibo radio dish was brought up, the idea that we need to build the Large Synoptic Survey Telescope. So we need to keep having good, ground-based support for all missions that go forward as well.

Fraser: So, I mean it sounds very loose, you know, like it doesn’t sound very tight in the actual, specific missions. So what’s going to happen next?

Pamela: Well, this is a multi-year plan – ten years, so while there isn’t a “we have a mission, it’s name is such and such, it’s going to have the following five instruments on it…” while we don’t know that, we know “here are guiding principles. Today we recommend these three things, pick one of the three.” And as we go through the next three decades as the funding comes in we’ll know, yes, going to Uranus is the right thing to do, going to Europa, which is still on the table, but is not one of the higher ranked ones, we know that is still on the table…so there’s guiding principles. Each year as the funding comes out, NASA will determine what calls for proposals it can put forward. I believe, based on all of the discussion I’ve heard, that we’re going to consistently have calls for small missions, and that medium-sized missions — there will be two calls for those in the next ten years.

Fraser: Now, can you give me an example of a small mission? Would that be something like Gravity Probe B?

Pamela: It’s planetary, so this is where we’re really looking at Dawn, at Stardust…

Fraser: At Dawn, at Stardust – OK, yeah, those are amazing missions, too.

Pamela: Exactly.

Fraser: Any word of the Terrestrial Planet Finder? Did you see anything in there?

Pamela: No, but that’s in the Astronomy side, so this is where you end up with a fascinating “if it’s inside the Oort Cloud, it’s planetary, if it’s outside the Oort Cloud — which means extra-solar planets and the rest of the universe – that’s astrophysics.”

Fraser: Maybe there’s still some hope there, no, there wasn’t anything in the astrophysics either

Pamela: No, it’s dead.

Fraser: Alright, well thanks a lot, Pamela. So over the next ten years, you can reference this podcast as we see what reality came from the fantasy.

Pamela: And if you want to see it become a reality, take the time out to let your congressman know and help be a part of the process.

Fraser: OK. Take care!

Pamela: Thank you. I’ll talk to you later.

Fraser: Bye.

Pamela: Bye-bye.

Download the transcript

Fraser: Welcome to Astronomy Cast, our weekly facts-based journey through the Cosmos, where we help you understand, not only what we know, but how we know what we know. My name is Fraser Cain, I’m the publisher of Universe Today, and with me is Dr. Pamela Gay, a professor at Southern Illinois University Edwardsville

Hi Pamela How are you doing?

Pamela: I’m doing well, how are you doing, Fraser?

Fraser: I’m doing really well — that’s it. That’s all I got to say about that, but I can’t wait to talk about Planck so let’s move right on – no chit chat! Another mission named after a famous physicist. Last week we talked about Max Planck, this time we’re going to talk about the Planck Mission, designed to study the cosmic microwave background radiation across the entire sky. Like the previous WMAP mission, this will help astronomers understand the first moments after the Big Bang. Planck – now Planck wasn’t its original name, was it?

Pamela: Well, none of these missions start with whatever the published name that you hear is. So Planck started with the rather horrid name of COBRAS/SAMBA, which might make a good music genre, but is a bit complicated to say for a mission.

Fraser: Right, but if you were keeping your eye on the COBRAS/SAMBA mission, it’s had its name changed.

Pamela: Exactly.

Fraser: Right, and so what was Planck’s goal, its purpose?

Pamela: It is one of the very few single-purpose missions that we’ve launched. It is an intellectual successor, you might say, to the Wilkinson Microwave Anisotropy Probe (WMAP), and it’s job is to go out, look up and do nothing more and nothing less than map the cosmic microwave background radiation and nearby wavelengths of light to the highest resolution ever done for the purpose of measuring cosmological parameters.

Fraser: And this is this continuing job …what was it? The KOBE was one of the first ones and then the WMAP did another level of accuracy, and then this is just going to do the same job but do it again. It’s like they’re taking the same spot and they’re just searching it deeper and deeper and deeper. I guess in this case it’s the whole sky, but they’re doing the same job, they’re just doing a better job with better technology.

Pamela: Right. And WMAP did the entire sky as well and it’s known for creating those weird blue and red mottled ovals that people have seen and this is — we’ve talked about this before — all good things come from the cosmic microwave background. There are so many questions that can be answered if you just get good enough data, but here from the surface of the planet we can’t get that data because we have this sky that has “opaqued” the wavelengths that we’re most interested in. We have all of these heat sources that are contaminating the light that we’re trying to see, sort of like trying to take a picture with a thousand suns in the room. And when you put all of these things together, it means you just can’t do the resolution you want, even if you’re launching balloons into the upper atmosphere, so we put satellites out in awkward locations, this particular one is in the L2 Lagrange point, where it’s out, if you imagine a straight line from the sun through the earth and then add a million or so miles – that’s where the L-2 position is.

Fraser: Kind of like in this shadow of the Earth from the sun.

Pamela: It’s not the literal shadow of the Earth, but it’s 1.5 km away from the planet Earth.

Fraser: Right, right. In a bit of a bigger orbit than us. It’s remaining in that position.

Pamela: Exactly.

Fraser: And we’ve got a whole show on the Lagrange point and why that’s a nice, stable place to put a spaceship.

Pamela: And so it’s hanging out there, it’s already completed more than one map of the sky, and watching this mission is painful, in some ways, because with missions like Hubble, like Herschel, like all of these other beautiful imaging missions. They go up, they send down pictures, science comes out, and you can do all of these different questions, you can do them to a certain degree in a very short turnaround period, but with Planck you have to wait while it patiently paints the sky over and over and over collecting data until you can layer all of this data on top of one another to can get all of the depth all of the resolution you need to start answering fundamental questions.

Fraser: And at the time that we’re recording this, we actually don’t have much data yet, do we?

Pamela: No, at this point, they’re getting interesting results, but the interesting results have nothing to do with the primary questions. The interesting results come from the things that they have to correct for. So when we look at the sky in the microwave, the maps that we see they’ve all been corrected for this “stuff” that’s between us, and when the cosmic microwave background was released, and we’ve done entire shows on this, this is what’s often referred to as the surface of last scattering. This is the light that was emitted at the moment that the universe finally became opaque, and there’s all sorts of things that have interfered with this surface, and it’s not that this is the edge of the universe. If I were to pick myself up and move 15 billion light years to the right, I’d still see cosmic microwave background. It would have different details than the one I see now, but it’s still there. There’s always this at-the-same-distance surface that’s constantly moving away. So it’s the same distance for the same time, but as time changes the distance changes. There’s this surface that that sphere of space at a given moment released these photons in all directions, and we’re just receiving the ones that had time to get to us. Now, as those photons have made that extremely long journey, there’s stuff that gets in the way. So we see holes in the cosmic microwave background that are created by what’s called the Sunyaev–Zel’dovich effect, which is perhaps one of the things I’ve most correctly pronounced on this show [laughing].

Fraser: [laughing] You can pronounce some Russian, that’s right.

Pamela: So random things get pronounced correctly, and the Sunyaev–Zel’dovich effect…it’s an effect that as the light passes through giant clusters, these are places where you end up with scores and scores and scores of galaxies all packed together with gas in between all the clusters, and as the light passes through, as the cosmic microwave background passes through this cluster, the photons interact with the electrons that are within the cluster. They get affected by thermal effects and kinematic effects, and all these effects add up to change the color of those photons, so that they’re no longer part of this flux from the cosmic microwave background, and so where these clusters exist we see little blank spots in the cosmic microwave background. This is annoying if you’re trying to study the cosmic microwave background, but it’s rather awesome if you’re trying to find galaxy clusters because galaxy clusters like to be invisible. They like to blend in to the mix of foreground galaxies and background galaxies and just not reveal themselves.

Fraser: Now will these galaxy clusters be pretty far away or will they be closer to us?

Pamela: The ones that they’ve been finding have typically been, well for galaxy clusters is commonly called red shift and if you read older papers it’s actually called high red shift. They’re Zs 0.3 or less. This is corresponding to about 5 billion light years away or less, so not huge, but when you’re trying to find clusters of galaxies, those galaxies get faint pretty fast, so this is still very impressive results.

Fraser: No, but I could imagine if they were further away, then they would be smaller on the sky, and then they wouldn’t pollute the data because they’d just be too small to see. But in this case they’re just big enough for us to see them and wonder what these little blank spots are.

Pamela: Right, and one of the annoying things about trying to study galaxy clusters is the largest ones did form fairly early on, but your nice, healthy moderate cluster it got that way over time, so if we’re looking at things that will become today’s mid-sized galaxy clusters, in the past they were a lot smaller, and something that’s smaller isn’t going to have as large of an effect on the cosmic microwave background, so as you’re looking back in time, you’re looking at things that just haven’t had the chance to get big enough to affect the cosmic microwave background yet.

So now you say they’ve been trying to correct, so is this like a process where they find one of these little spots and then they have to look at it with some other method, like Hubble, and see if there is indeed a galaxy cluster there, and that way they can rule it out?

Pamela: Well, so it’s a two-step process. The first process is identifying all these little, “Hm, that looks like it could be a galaxy cluster — spots in the cosmic microwave background,” and so far they’ve identified 189 candidates at varying degrees of statistical significance, and whether or not they prove out to be a galaxy cluster, they’re still defects in the map that have to be corrected for, and they’re working on trying to confirm that these are all indeed clusters. And to confirm that they’re clusters, you can look at them with Hubble, but these things are more distant and if you’re looking in the wavelength that Hubble looks in, if you’re looking in optical and infrared colors and ultraviolet colors, you’re going to see everything that’s in the front of the cluster, you’re going to see everything that’s in the back of the cluster, and unless you take a spectrum of every single galaxy in your image, you can’t tell what’s a cluster member or not, so there’s no way to say, “I’m looking down a filament in the sky” vs. “I’m looking at a cluster of galaxies.” So what generally gets done instead is all of the hot gas that sinks down into the core of the galaxy cluster wind up releasing X-rays, so instead of following up with Hubble, we actually follow up with telescopes like XMM-Newton and Chandra, and a study looking at 30 of these potential galaxy clusters has confirmed 21 out of the 25 that it’s looked at so far, so the goal is to look at 30; it’s looked at 21 of 25. I saw two conflicting websites on this. The paper was 21 out of 25, having confirmed with XMM-Newton, so it’s working — they’re finding clusters,

Fraser: And now they weren’t finding these in the WMAP data? Is it because it’s so much more precise?

Pamela: It’s that much more precise, and I think you just have different people publishing different results at this point, so some of these were known, some of these are newly-known, so of those 189 cluster candidates, some of those will probably correspond to things we already know about.

Fraser: OK, so we’ve got…I mean I know it’s been there…I’m actually looking at the website right now…at the time we’re recording this it’s 679 days since the launch, and they’ve completed their fourth all-sky survey, no, they started their fourth all-sky survey.

Pamela: And they’ve published one set of data-released papers based on one [missing audio] bit of all-sky maps. So one thing that they do that’s kind of terrifying, in some ways, is they don’t put out a call for telescope proposals like Hubble might do. They instead put out a call for proposals to get to write papers with their data. So if you have an idea for a research study you want to do, you have to submit for permission to do the research study using the data.

Fraser: Really? Even though the data is publicly available?

Pamela: Well, it’s not public yet.

Fraser: Right, so you have to request the data. That’s very different from things like the Sloan Digital Sky Survey where anyone can go on and look through it and make discoveries.

Pamela: And this is a matter of where you are in the timeline of the mission. This is a young mission. It’s still getting ongoing data; it’s still defining new questions that can be asked with the data it’s producing. Sloan does data releases, we’ve gone through a number of data releases, but for the first “n” months, where I think for Sloan, the “n” is six, for the first six months or so the Sloan scientists get sole access to that data and they can publish as much as they want. Now, they have media officers and things like that that coordinate when the publications come out, but there is still that proprietary period pretty much all data has a proprietary period, and we’re still in that proprietary period for Planck.

Fraser: And so, as we discussed earlier, though, the real goal here is to do that detailed map of the cosmic microwave background radiation, so how much better will this be than WMAP, and then what will that tell us that’s different from what WMAP told us? I mean, WMAP told us that the universe is 13.7 billion years, it found additional evidence for dark energy and as we keep joking, I mean, so much traces its roots back to the microwave background, so when will it find its data? How precise is it going to be? And what will this tell us that we didn’t already know?

Pamela: Well, “How good is it going to be?” — that’s always a bit of a “please dear mission please keep working we really like you mission please keep working,” so nominally, the mission ends at the end of 2011, but there’s always that hope that the mission will still be bright and happy and working and have people engaged and that this will allow it to keep going, so the main mission with the main set of instruments is going through 2011, it looks like the satellite will keep being fine and one of the other instruments is extended through the end of 2012, and there’s always the potential that it will get extended again, and all of these different extensions, when you add the data together, are what define how good your final results are.

Fraser: Now is this one of those situations where the spacecraft is going to run out of some kind of cryogenic fluid? Or is it going to be able to keep going for years and years and years beyond its expected lifespan?

Pamela: It depends instrument to instrument. This is something that the mission…you have a number of things that “age out” the number of instruments.

Fraser: OK, OK so 2012…

Pamela: And what I’ve been hearing is we will get results that are orders of magnitude better. Now, that’s a cagey way of saying “we’re not going to give you exact numbers right now.” But the questions that it will be able to answer are I think where the really interesting things lie. So there’s things like there’s this cold spot that was spotted in the WMAP data, and this is a feature about 5 degrees across that is markedly colder than you would expect to find something that size to be, and by colder I mean how much below the average value of the cosmic microwave background that point is.

Fraser: Yeah, and it’s not much, I mean the variations in temperature are so tiny.

Pamela: Right, so there are scientists that have argued that if this particular spot was located anywhere else on the sky, it’s deviation of roughly –20 micro-kelvins, probably wouldn’t have been noticed, but because it happens to be located in the middle of a deviation that’s +20 micro-kelvins, it stands out and it’s been noticed and there have been some really interesting things in the media. One scientist, Laura Mersini-Houghton, she said, “maybe this is where our universe and a parallel universe are coming together” — that’s not the predominant theory. The predominant theory is that there’s just a gap with a red shift of about one that has nothing in it. That gap is causing that section to appear colder for a variety of effects — but we don’t know! And this cold spot – if it is a super-void, if there is a giant empty spot, we’ll be able to tell that there’s a giant empty spot using the Planck data.

Fraser: So it won’t be a data error anymore. We will know that it exists.

Pamela: Exactly. Exactly.

Fraser: Or it will disappear.

Pamela: Right, and that’s always the possibility. We’ve all seen the images of the face on Mars – it looks like a fabulous face in the old Viking data. You look at it with something like High Rise, and suddenly it’s like, “Oh, that’s a mountain, that’s very clearly a mountain.”

Fraser: OK, so we’re going to be able to rule out, or find intriguing new evidence about the cold spot…I’m assuming we will still know that the universe is 13.7 billion years, but maybe it will be what 13.777?

Pamela: Right so here it’s the continued lockstep motion forward of using the cosmic microwave background. We look at all of those fluctuations, and this is going to sound non-intuitive, but if you measure the size of each fluctuation and make a histogram of size of fluctuation vs. number of fluctuations, you can actually get a sense of what size the universe was, and what composition the universe had at the moment that light was released. This is sort of like measuring the size of a Coke bottle by listening to the harmonics of someone blowing into it. Because the harmonics were created at different moments in time, they all add together to create basically the sounds of a Coke bottle that’s 20 ounces, 1 liter, ½ liter, all resonating together. We can see, in these different size spots, all these different sound waves adding together in interesting ways that tell us the composition and the size of the universe at the moment of release, and when you add that together with our understanding of the current expansion rate of the universe, with our growing understanding of the history of the expansion rate of the universe, with our knowledge of the composition of the universe, it’s by adding together our knowledge of composition now, what we’re learning about composition then, our understanding of the geometry of the expansion rates, we’re able to beat down all of these error terms, smaller and smaller and smaller. Now, one of the things that excites me most, though, is this also starts to put better limits on our understanding of the size of the universe.

Fraser: How does it do that?

Pamela: Well, you remember that show we did where we talked about the universe potentially being shaped like a soccer ball?

Fraser: Or a Taurus, or a saddle… Right.

Pamela: So there’s all kinds of crazy things people come up with for the shape of the universe, and in many of these different models, as you put them together you realize, well, if the universe is this size, the light from over here that’s coming directly toward us should also have enough time to wrap around the other side of the sky. And we can start looking for smaller features that reflect that “wrapping around the sky.” At WMAP resolutions we’re able to start putting constraints with some models it was saying the visible universe, what you see when you look left, right, up, down and measure the distances of the cosmic microwave background. What we see is no more than 4% of the universe. Now, this will start to be able to put better constraints on well, how big is the universe? And potentially answer the question if we see light wrapping around.

Fraser: Now could we still come back with the answer that it’s possibly infinite?

Pamela: That’s unfortunately one of the cases that we end up in. It’s either we see the light wrapping around and we know how big the universe is, or we place a limit on it and say, we are no more than X% of the universe, in which case we could be 4% or we could be .00004%. In one case we’re a lot smaller a part than the other part.

Fraser: Or 1 divided by infinity, unless I got my math wrong. We’re “one-infinitith” of the universe. Right, so OK we’ll get then a sense further ideally I mean wouldn’t that blow your mind, right? If we actually see the back of our spacecraft, which we’re not going to see, but we’re going to see the evidence that light behaves or that the universe behaves in this way that we’ve talked about, that if you look in one direction long enough, you’ll see the back of your own head.

Pamela: And there’s other random science (that to the scientist doing it, it’s not random), but when you start talking about the cosmic microwave background, it feels that way. People who do star forming can actually use the cosmic microwave background; people studying the Oort cloud can use the cosmic microwave background, so this is where “all good things come from the cosmic microwave background” come into play. They’ve already released a catalog of what are called “cold cores.” These are the cocoons in which stars are forming in dark, cold regions of dust…dark molecular clouds. As we look out across the galaxy in microwave eyes, you see all these “cold cores” sitting there blocking your way to the cosmic microwave background, and these represent all the places we should go in and start studying star formation.

Fraser: I mean it’s funny how we have a spacecraft that’s designed to do one thing, but that one thing is so useful in so many branches of astronomy that it’s going to keep astronomers busy for decades.

Pamela: And this is where you’re able to now and then justify funding single-purpose telescopes. There’s not many of them. There’s the Planck Mission, there’s Kepler, which is single-purpose: it’s going to find planets. And it’s finding planets and it’s doing such an amazing job. And there is ancillary science with variable stars, and you have Gravity Probe B that is studying — was studying gravity. These single purpose mission are either answering fundamental questions we just can’t answer any other way, or doing things that the science is just so good that you say, “OK, we’re going to commit a major portion of the very-limited resources we have to answering this one fundamental question with this one mission.”

Fraser: Right. It’s going to be amazing. So then if people wanted to keep their eyes peeled in the news for the big announcements, when should we expect to see them?

Pamela: I’m kind of expecting that we’ll see the first round of pretty cool things coming out…scientists like to save things for big conferences, and I suspect that they will either have their own big conference sometime in the beginning of 2012, or they’ll be presenting things at the American Astronomical Society meeting. So one of those places is probably a pretty good bet. So look for things the beginning of 2012. The big, big results are likely to start coming out a year after that. It takes time to go through all of the data, but if you want to follow things day to day, you can actually follow them on Twitter, and I don’t think I’ve ever promoted a mission on Twitter before, but their Twitter feed actually promotes some pretty interesting stuff now and then. They’re just “@ Planck.” One of the things they’ve recently promoted is they have a neat-looking mission, and on their website they have a cardboard cut-out model that allows you to put together the mission, and there’s some videos posted up on how to follow the videos to put the model together — and it’s just silly, but it’s fun, so you can learn how to do this and the Planck model is actually designed by Stuart Lowe who we’ve worked with who does the “Jodcast” and “Astronomy Blog” and helps with the “365 of Astronomy,” and who’s responsible for all of the ending credits.

Fraser: Go, Stuart!

Pamela: So Stuart built this model and it’s on their Twitter feed, and it’s just a great way to engage a little bored child in building a spacecraft.

Fraser: They’ve actually got a bunch of these models for a lot of these missions. My kid sand I built one that came out a few years ago. It was like a dodecahedron, and it was the entire sky. It was really neat.

Fraser: OK good, well thanks a lot, Pamela. So look for that in 2012, probably 2013, titles like: “Age of the Universe Further Refined,” “Astronomers Have a New Estimate for the Size of the Universe,” “Astronomers Find Where Our Universe is Colliding with Another Universe,” or “The Cold Spot…”

Pamela: “Cold Spot Solved and Erased!”

Fraser: “Cold Spot Solved,” yeah… that’d be great! OK cool, well thanks a lot Pamela.

Pamela: Sounds good, talk to you later, Fraser.

Show Notes

Download the transcript

Fraser: Welcome to Astronomy cast, our weekly facts-based journey through the Cosmos, where we help you to understand, not only what we know, but how we know what we know. My name is Dr. Fraser Cain, I’m the publisher [missing audio] today, and with me is Dr. Pamela Gay, a professor at Southern Illinois University at Edwardsville. Hi, Pamela, how are you doing?

Pamela: I’m doing well. It’s snowing here!

Fraser: Yeah, and we are having the most horrible rainstorm ever — flood warnings.

Pamela: That’s not good.

Fraser: Yeah, I’m really sick of the winters here on the West coast, I gotta say. Anyway, but let’s think of another hostile environment.

Pamela: Exactly.

Fraser: So, the twin Mars Exploration rovers, Spirit and Opportunity, have been crawling around the surface of Mars since early 2004 – years longer than they were expected to live, and what they have discovered there on Mars has given scientists their best understanding of Martian geology over the last few billion years. Let’s investigate these amazing rovers and their ongoing mission. You know, when we started this astronomy cast, we were amazed at how long the Martian rovers had been going, “Oh, it’s amazing! It’s been years and years!” That was in 2006. Now, we’re in 2010 almost into 2011 – amazed at how long the Spirit and Opportunity have been going.

Pamela: Well, we might have actually lost Spirit. It’s a sad, sad realization that has kind of gotten swept under the rug, but we may be down to one sad little rover.

Fraser: Well, let’s go back then and talk about the history because it’s an amazing, amazing mission.

Pamela: Well, these are part of the NASA Mars Exploration program. They’re two cute little rovers. They’re actually cute! They stare you in the eye with a panoramic camera with two lenses that actually look like eyes, and are spaced similarly to human eyes that give the rovers 3-dimensional vision, similar to human vision, but just make them very personable little robots.

Fraser: That is one of their most amazing things is that they look like people. They look very…you know I’m sure we anthropomorphize them – we look at them and say, “Aw, look at those adorable robots! Here’s another billion dollars for future Mars Missions.”

Pamela: Well, it’s not quite “billion” dollar, it’s more like “oh, here’s another hundred million,” which is at least an order of magnitude less.

Fraser: No no, I’m saying it’s for the future, right? They make these ones cute, and that way the future missions will get funded.

Pamela: And well, Mars just does “cute” well because these missions build on the experience that we got from launching the Mars Pathfinder probe back in 1997, which was basically every little kid’s Tonka truck come to life, roving around on the Martian surface.

Fraser: Yeah, absolutely. Well, we should put this all into context right because, you know, I mean, we’ve talked about this in other shows: that the NASA scientists, at least the international community of scientists, have been very careful and deliberate about how they’ve gone about researching. What’s really the sweet prize in the end is the discovery of life on Mars. That’s what they want, but they’ve actually really sort of stretched it out and gone after fairly incremental scientific discoveries, one after the other, and the Mars exploration rovers really fits into this structure quite well and really shows you how they’re deliberately going about it.

Pamela: Right, so it really began back with the Viking missions back in 1976 when we landed less cute little landers on Mars and took pictures and took soil samples and started trying to figure out if there were organic compounds, if there were chemical reactions that resembled life. And it was inconclusive, so we figured out “OK, what do we need to do next?” And what we needed to do next was two things: one, be able to take samples of more than one location, there’s places on earth that if you grabbed a handful of sand there’d be no evidence of life. And we also needed to have different chemical experiments, different imaging — different technologies on board. So, in 1997, we launched we very inexpensive little mission: Mars Pathfinder, which was basically a technology test. It was a child’s 3-wheeled scooter-sized robot that roved around like an animated Tonka truck that took samples and took images and paved the way for the Mars Exploration rovers to get sent in 2003, and then land in January of 2004.

Fraser: Right, I mean this is a situation where you had a rover that you could remotely control, and it could drive around — not in real time — but you could say “go check out that rock,” and it would drive over to that rock and examine it, and “go check out that rock,” so you could see, and there also the technology — the whole landing technology — was really pioneered by what they did with pathfinder, where they had this airbag system, and you know, a much less expensive way of putting a payload onto the surface of Mars.

Pamela: Right, these are fabulous. These are the bouncy ball landing techniques, and it literally was drop something, have a parachute to slow it down, but recognize that you’re not going to get it slow enough, but surrounded in airbags and let it bounce around until it settles down, and the Mars Exploration rovers were encased in these geometric containment vessels that had flaps that each individual flap was capable of flipping the entire lander if it needed to, so if it landed solidly on basically the roof, it could right itself and get the rovers upright and horizontal just be how it opened up the various flaps.

Fraser: So, why were there two rovers chosen?

Pamela: Well, it’s a redundancy issue. Building two doesn’t cost that much more than building one; you get all of the skills building one. It’s sort of like with the Hubble space telescope. We actually built two of them and only launched one of them, so there’s a tradition of “let’s build two,” and in this case “let’s actually launch two.” This gave us a chance to check out two very different parts of the Martian surface, and these were built not to look for life, but to go look for different signs of water, and so we wanted to be able to look on a part of Mars that looked like old shoreline, and to look in areas where we knew that there were minerals that could only be created in water environments, and so we chose two very different parts of the surface and dropped these two very identical little rovers, and sent them off on what we thought was a 90-day mission.

Fraser: Right, right. So the goal for these rovers was search for evidence of past water on Mars — so not life, not current water, but past water, and to really try to build up the history of when water appeared on the surface of Mars, how long it lasted, when it went away, and what kind of forms it took — you know, was it big nice warm lakes, of was it salty water brine hiding under rocks? And that’s really what they were looking for.

Pamela: And the neat thing about these is because they have the ability to wander around, just like the Apollo astronauts on the moon, they can go from one place to another, grab a rock, sample it, figure out what it’s made of, and use those samples from a variety of different locations. Now, admittedly, the greatest wandering they’ve done is only 20 km, but still, for a little robot, that’s pretty good!

Fraser: It’s amazing.

Pamela: So, grab these different rocks and calibrate the orbital information we have, so they’re able to basically say, “OK, yes, Mars Reconnaissance orbiter detected [missing audio] in this location.” Here are the rocks that correspond to this location, and yes things line up

Fraser: And so then, they had two very different landing spots

Pamela: Right, so we had one of them landed in Gusev crater, which is a nice, big crater that allowed you to — just like you might go up on the edge of a highway cut-out, look at the different layers in the terrain, and you could do similar sorts of things over in Gustav crater.

Fraser: Right, now this is a really big crater. I mean, you can’t tell that it’s inside a crater it’s so big.

Pamela: Right, right. We started off with Spirit, and there’s a great Twitter feed name called “Free Spirit.” Spirit started out in Gusev Crater, and this area was selected in part because it had hematite noticed in the area, and hematite is a mineral that can only form in water, and it’s a common rock that we have here on Earth. If you go to a mall that has a display of rocks that you can buy, the ones that kind of look like Mercury became a solid. Those are hematite.

Fraser: Right, right — kind of metallic, gray, shiny rocks — they polished them up.

Pamela: Yeah, they’re pretty. So we sent Spirit into the Gusev crater following basically the traces of water, and went exploring and Spirit basically explored all around, and the most interesting area that it explored actually wasn’t so much in Gustav crater, but once the escape took place. So, Spirit escaped and went to an area called home plate, and this is where a lot of interesting research ended up happening, where all sorts of mineral collections, all sorts of [missing audio], or dust devils, unfortunately, tied in with all of the exciting science. Spirit got stuck.

Fraser: And then there was a whole other mission too, so we’re going to have to switch back and forth as we go.

Pamela: This is kind of schizophrenic – we have two robots!

Fraser: Yeah, yeah, “Now cut to Opportunity…”

Pamela: “Now cut to Opportunity…” Opportunity landed on (this is where I mispronounce something once per show) Meridiani Planum. It’s a large, flat area, and it was thought to perhaps be an area that had formed as a seashore, and so this was selected as another place to be geologically interesting, to go and basically see what could be seen…looked for past water life, found what we think was signs of sedimentation, this is basically where all of the minerals come together and form a rock. You’ve probably seen this along the beach.

Fraser: What’s the most amazing thing about Opportunity is that it landed in a crater — and not a very big crater. It landed in a very small crater it landed in a crater that’s only a few meters across.

Pamela: Yes, Eagle Crater.

Fraser: So, when it landed in the crater, the scientists are like, “This is amazing. Uh oh, we’re not even sure we’re going to be able to get out of this crater.” So, it was like a one in a million landing that then might have trapped the spacecraft for the rest of its mission. It couldn’t go anywhere else except in this tiny crater, but in the end they were able to figure out a path to break it out.

Pamela: But while it was down there, it found all sorts of amazing geological structures because, in a way, a crater’s a kind of cool place to land because you have all of these rocks that revealed right there right in front of you, and it was in this crater that they found something they dubbed “blueberries,” and these are hematite spheres that are basically little tiny nodules that formed when the hematite formed.

Fraser: And this is that first real evidence of past water on Mars. Opportunity was the one that picked it up first, but it wasn’t the only …

Pamela: No, no and what’s amazing is that this little robot basically explored and explored and explored Eagle crater and then it did get itself out, and then it took off roving, and it made its way to Endurance Crater making it there four months after landing in late April of 2004, and there it kept looking at all the different layers of rocks. This one it circumnavigated, took lots of detailed images where you can see all of the cuts through the land.

Fraser: Right, so I mean up until this point, both of the rovers had been performing amazingly — already well beyond the expectations. They had discovered evidence of past water, thanks to Opportunity.

Pamela: And then Spirit had the Humphrey Rock as well, which was a rock that had minerals in it specific to water. Again, we have both of these suckers picking up rocks and finding indications of water.

Fraser: And different kinds, like you know, different chemicals, different deposits so it’s just again and again and again discovering that there was water, and that there was probably large amounts of warm water, you know, liquid water on the surface of Mars, long enough to ideally to evolve life.

Pamela: and NASA’s not quite willing to go that far, but yeah, there was water and Humphrey Rock actually is a rock that formed from magma, so we know there’s volcanism, we know there’s water all at the same time, and that’s one of the models we have for how life formed on earth: take volcanoes, insert water, add lightening.

Fraser: We hope, we think.

Pamela: We have no idea.

Fraser: Right. Now, up until this point it was, you know, like I said, it was baffling, both rovers way beyond their expected life span, but, you know, it couldn’t last forever.

Pamela: No, and in 2005, Opportunity decided to, well, do what many of us have done with cars and that is to dig itself into the sand. It was happily exploring more than a year after its launch. And it found itself in what mission planners called Purgatory Dune. They ended up having to do simulations. There are actually twins to both Spirit and Opportunity here on Earth, so we have two that we can literally…NASA scientists take these suckers out to sandboxes trying to figure out how to free them. And after getting stuck in April, they managed to get poor little Opportunity free in 2005, June and get it roving again and get it onto firmer ground, and they took off roving again, this time off to yet another crater.

Fraser: And I remember they were running different simulations on you know how can you make it work with only 5 wheels, 4 wheels, or how can you make it walk? They test and then they had to re-upload all this code to teach it how to get itself out of these situations but spirit had its own problem, too.

Pamela: Spirit took a little longer to get stuck. Spirit got stuck on Home Plate, which is an interesting place to say that a rover got stuck. In 2009, Spirit was roving along and hit a sand dune and hasn’t quite figured out how to get out of the sand dune, and so that’s been a great issue, and in January of 2010, after months of attempting to free the rover, they basically gave up, and NASA said we’re going to turn it into a stationary mission platform. And this is the awesome thing is even after Spirit has basically gotten itself stuck to the point that the best rover drivers couldn’t figure out how to unstick it and they tried all sorts of crazy stuff. If you’ve ever gotten your car stuck, you know how you do all the crazy “OK, wheels right, gently touch, wheels left touch hard” – all of that craziness that you do — they did it with the rover, couldn’t get it out, so they figured out “OK, so we still have working cameras, we still have lots of working cameras. They, of course, examined everything they could reach, but it was sand. They turned it into basically an observing platform to observe the stars, to figure what is the wobble of the planet, to observe the weather. It’s kind of neat to think that basically Spirit for a while was a weather station. If we’re ever going to start getting human beings living on Mars, we really need to get the weather in detail. You only have so many things you can look at and if it’s a choice of terrain or clouds, most scientists are going to say give me those pictures of the landscape. And for a while Spirit helped us understand the weather and helped us understand planetary wobbles by just looking at how the stars positions change.

Fraser: But I think the most interesting part of probably the whole mission was Opportunity’s sort of roving up to the edge of the Victoria Crater and then crawling down inside because I know that right before Opportunity got to Victoria, there were a lot of dust storms and all of its solar panels got covered with sand, and so they weren’t sure that it was going to have enough power to get down into the crater, and then you get the dust storm and then you get these dust devils which was totally surprising

Pamela: 2007 (the latter half of 2007) was kind of a scary time for Mars scientists because both rovers got fairly covered in dust, and that was the original dust scenario for these two little guys. They’d get covered in dust and wouldn’t get enough solar power to keep themselves warm and that’s what kills the rovers is if their batteries get too cold. They just can’t keep going. They also have to keep their joints warm. There is a problem with the shoulder in Spirit where its shoulder froze up, but there always was that one gust of wind that came along and cleared off the solar panels, but in 2007, if the clouds of dust are so great that sunlight can’t reach the rovers, it really doesn’t matter how little or how much dust is on the rovers themselves, and these dust clouds just never seemed to end, and they went through all sorts of crazy “OK, we’re going to re-program the rovers to do this instead of what we’d originally intended in hopes that by doing this slightly different shutdown scenario that we can keep them going,” and they managed to keep them going through the dust storms.

Fraser: And so this is a really special place. Victoria crater is a pretty big crater where you know a space rock had carved out enough of the landscape that you could really look back in time — it was like a time machine that you could do, but once again scientists were unsure if they could get opportunity even into the crater, and then if they could get it in, could they even pull It back out again.

Pamela: And what is amazing is that they pulled out both. So, it got to Victoria Crater in 2006, started figuring out how to get back down in 2007. At the beginning of the year they also had a software problem, where Spirit went into basically “freak-out mode” for a little while and they had to figure out how to re-program the memory on both spacecraft. [Spirit] survived the software upgrade (and if you’ve upgraded a computer, you know how scary that is), survived the dust storms of June 2007 and onwards, and then just explored all over inside of Victoria crater. There’s an area called Duck Bay that in late 2007 Opportunity went down and was able to look at all the cuts of the inner slope and examine all of the different layers. It exposed years and years of sedimentation, and in mid-2008, Opportunity climbed back out and is now on a massive 12-km trek to get to the 22-km-wide Endeavor Crater, which is an even more interesting crater to try to explore.

Fraser: And sort of when Opportunity was doing this work around Victoria Crater, that’s when the Mars Reconnaissance arrived in orbit around Mars and so you get these amazing pictures of Opportunity perched at the rim of the crater and you can see its tracks as it’s moving around, you know. I highly recommend you search for those photographs. We had them on the show once. It’s amazing! It really brings everything together because the photos are so clear and you can see exactly what Opportunity was staring at. You see the point of view from Opportunity looking at the rim of the crater, and then you see the images from the Mars Reconnaissance orbiter above. You can see what an amazing terrain it was. So, I guess, when recording the show right now (we;re in late 2010) Spirit is not moving.

Pamela: Probably lost.

Fraser: Probably lost, but Opportunity is still going, and it’s going to hope to make it to Endeavor Crater.

Pamela: And it’s stopping at all sorts of little craters or not-so-little craters along the way, so it’s been a really interesting scientific journey, where even if it never makes it all the way to it’s final destination, these missions are doing more science than anyone ever imagined they could do.

Fraser: So, put this into perspective then: where do you think this takes us along that continuum of the search for life on mars? That really is the goal.

Pamela: Well, with these missions, they were really the preliminary that led to Phoenix landing in the polar regions. They were sent to the equatorial regions where you had a lot more sunlight, they were sent to areas where we thought that there was past water, proved that yes, the mineralogy does indicate there was past water, and opened the door to say “OK, let’s go find current water in the riskier land in polar regions.” What they’re doing now is just geologic gravy. They’re basically getting to do the robotic equivalent of wandering around in the [missing audio] Zion area of the western United States and they’re just looking out on these amazing vistas and examining what’s in all of the cut-throughs down through the layers and layers of sedimentation. If they’re mapping geology, I have to admit I’m an astronomer and I’m notorious for going to geology meetings and having to randomly ask people “what’s this new vocabulary word?” and it’s these missions that are forcing me to learn “why do people care about hematite?” It’s shiny and pretty, but well, they care because it’s filled with water, and they’re doing all that cool geology.

Fraser: Yeah, and so the next big mission then is going to be the Mars science laboratory Curiosity. Yeah, and that’s going to landing this year, right?

Pamela: It takes off this year, and then it takes a while to get there. That’s a big heavy mission. It’s not going to get bounced around on the surface.

Fraser: No, but it is an SUV-sized laboratory equipped with the stuff that could detect life. I mean: this is it. This is serious.

Pamela: This is the [missing audio] Miami Hummer filled with equipment basically.

Fraser: …yeah, with arms, and its own nuclear reactor. Yeah, it’s going to be quite the mission.

Pamela: But, I really do encourage all of you to go not just look at the Mars Reconnaissance orbiter mission images, but also look at all the vast panoramas that have been captured by Mars exploration rovers, and get yourself a pair of 3-D glasses.

Fraser: Yeah, they did a lot of stereo pictures because they had these two eyes. They could take these stereo images.

Pamela: And it looks just like it would look like for human beings because of the height of the eyes and the separation of the eyes, so you can actually see what it would be like to stand on the surface of Mars.

Fraser: Yeah, if you don’t have a set of 3-D glasses — a lot of stuff sent over by NASA, a lot of the images — they’ll release these 3-D images quite a bit, and it’s great to have them, so have a set of 3-D glasses sitting beside your computer if you want to look at these kinds of photographs. Alright well, I think that was great, Pamela, and we will talk to you next week.

Pamela: Sounds good, Fraser, I’ll talk to you later.

Show Notes

• Astrogear for Astronomy Cast stuff
• TAM Australia
• NASA’s Great Observatories Program
• Compton Gamma Ray Observatory
• Chandra X-Ray Observatory
• Hubble Space Telescope
• Spitzer Space Telescope
• Spitzer image gallery; images, wallpaper
• Collection of articles/images from Spitzer on Universe Today
• Bok Globule image/information
• Rayleigh Scattering — University of Texas
• Scientists See Light that may be from First Objects in the Universe — Spitzer Telescope website
• The Spitzer Telescope “talks” about its warm mission — Universe Today
• Buckyballs in space
• JWST

Transcript: The Spitzer Space Telescope

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Fraser: Astronomy Cast Episode 208 for Monday November 22, 2010, The Spitzer Space Telescope. Welcome to Astronomy Cast, our weekly facts-based journey through the cosmos, where we help you understand not only what we know, but how we know what we know. My name is Fraser Cain, I’m the publisher of Universe Today, and with me is Dr. Pamela Gay, a professor at Southern Illinois University Edwardsville. Hi, Pamela, how are you doing?

Pamela: I’m doing well, Fraser. How are you doing?

Fraser: Great. So just another plug… ‘cause we’re in this plugging mood… to clear out Pamela’s spare bedroom. You can buy cool Astronomy Cast gear at astrogear.org, so check that out and support the show and impress your friends with your ?? t-shirt.

Pamela: And if you’re in TAM Australia this week, which I know is very, very few of you because it’s a very, very small event, we will have—and by we I mean I—will have some Astronomy Cast shirts there that the skeptic’s booth has been friendly enough to allow me to sell there.

Fraser: Yeah, you’re going to be… last minute, right… you’re going to be doing part of The Amazing Meeting. You’re going to be doing a talk there?

Pamela: Yeah, I have to admit I don’t know what day I’m talking on yet. I’m going to be giving a talk on basically using curiosity and the scientific method to inspire curiosity and awe.

Fraser: Cool. And this was just last minute… I know that you… a month ago…

Pamela: Totally last minute…

Fraser: Yeah, you didn’t even know that you were going to be there. Sorry we didn’t announce it better. We really had no idea this was going to happen.

Pamela: There’s nothing like a last-minute trip 180 degrees around the planet.

Fraser: Gee… whatever… travel—you’re used to it. I just assume you’re in a constant state of travel, unless told otherwise. Ok, well let’s get on with the show. So last week we talked about Lyman Spitzer, and this week we’ll take a look at the orbiting observatory that bears his name; the Spitzer Space Telescope. Designed to see into the infrared spectrum, Spitzer has returned images of objects that were previously hidden to astronomers by thick shrouds of gas and dust. Now I think you had kind of given a sneak peek of this week with last week about Spitzer, formerly known as SIRTF… which doesn’t roll off the tongue as nicely.

Pamela: But it’s kinda cool.

Fraser: What did SIRTF stand for?

Pamela: It was the Space InfraRed Telescope Facility. I think SIRTF sounded kind of cool… it sounds like a surf shop, but that’s ok. You can laugh at me here… insert laughter…

Fraser: No, no, it’s genuine! So… Space InfraRed Telescope Facility… so this was a from the ground up an infrared observatory but designed to be a space observatory. But I know that infrared is one of those wavelengths that do get through the atmosphere, so you don’t necessarily need to go to space to see infrared.

Pamela: Well, actually you do. There’s only very narrow bands in the infrared that get down to the surface of the earth. So if you’re lucky enough to see what you want to see in these very narrow bands and at very high altitudes and on very dry days, and enough of these very-difficult-to-align characteristics all come into reality at the same time, then yes, you can get ground-based images. But the majority of the infrared wavelengths are best observed from outer space. There’s also the problem that infrared is thermal energy, so from the surface of the planet, we’re essentially looking through a brightly-glowing atmosphere. So even in the dead of night on the coldest of nights on the planet Earth, that sky is giving off its own infrared radiation. It’s kind of like trying to observe the stars’ invisible light at noon… sure, you could try but you’re only going to be able to see the very brightest stars and you’re never going to see them well because the sunlight is drowning you out. In the infrared, the atmosphere’s thermal heat is drowning you out.

Fraser: Right. So for the perfect environment, you really need not only a cold telescope but a cooled telescope that’s even colder than the background of space. That’s when you can see those really subtle differences. Ok, so where did the concept of an infrared telescope space observatory come from?

Pamela: In the 70s and 80s NASA started developing the idea to have a set of Great Observatories. This began to become a reality in the 90s. The plan was to have the Hubble Space Telescope, an X-ray observatory, a gamma ray observatory, an infrared facility, and today those four great plans have become the Compton Gamma Ray Observatory, Chandra, which observes in the X-ray, Hubble, which is still going strong, and Spitzer which is now on the warm part of its mission. It does require an essentially expendable fuel in the form of helium. This one mission has gone through an amazing redesign from its conception to its launch. When they were designing these four missions, the plan was we were going to do everything all the time with the US Space Shuttle. It was going to be the wonderful device that went to space on a weekly basis, able to stay up there 30 days at a time, able to carry things up, carry them down, it was going to be a reliable pick-up truck that could haul anything. And it wasn’t.

Fraser: A shuttle to space.

Pamela: Yes.

Fraser: Yeah. As opposed to a very complicated and delicate powerful vehicle that it turned out to be.

Pamela: Right. It’s kinda like borrowing Grandpa’s farm truck. You’re pretty sure it’s going to get you to the mall and back, but you’re never completely convinced.

Fraser: Right… right… and so Spitzer… Hubble was carried on the shuttle, and Spitzer was designed to be carried on the shuttle, but that’s not how it turned out.

Pamela: They actually had to redesign it. The original plan for this mission is, in retrospect, absolutely ludicrous. The idea was they were going to carry it up into space inside the space shuttle, use it attached to the space shuttle, bring it back on the space shuttle and just tote it to and fro so they could refurbish the liquid helium needed to cool it off on a regular basis. The problem with these missions is that even when you put them in space, they’re still getting heated up by the planet Earth. So if you have an infrared facility that’s orbiting the planet, it’s going to blow straight through all of its coolant trying to protect the spacecraft not just from the heat of the sun but the reradiated heat of the earth. It was a great idea up until, unfortunately, we had the Challenger explosion. Challenger forced a lot of things to change. One of the things that happened was not only did they say, ok no more carrying stuff back down from space, but they also said some of the chemicals you’re planning to launch with SIRTF, you can’t launch anymore. So they had to take this wonderfully strangely-planned yo-yo of an infrared telescope and redesign it to launch on a smaller Delta rocket and the smaller Delta rocket and the not bringing it back down to the planet on a regular basis meant that the coolant couldn’t get regularly recharged. Not only that, but due to weight considerations, they couldn’t carry as much coolant. And this set of complications led to an actually really revolutionary design. Some concepts of which are getting stolen for the James Webb Space Telescope.

Fraser: Can you give me some examples?

Pamela: The biggest example is the sun shade that it has. If you look at images of the Spitzer Telescope, there’s the standard telescope tube in the center, but then the spacecraft components are on basically supports with a gap between the electronic parts of the spacecraft and the tube and optical assembly of the space telescope. Then inside all of this is this weird “why is that there” basically fin of material, or section of a tube of material, and that random extra bit that sticks off the side—that’s providing the spacecraft with shade… protecting it from getting heated up by the sun’s light.

Fraser: So it’s like it’s carrying around its own umbrella to protect the spacecraft from just even a slight amount of heating from the sun. That allows its coolant to last longer.

Pamela: A pre-installed parasol, you might say.

Fraser: Yeah, and if you see the models… you’re exactly right. If you see the model of the James Webb, they’ve taken that to the next level. There’s this huge sun shade being used to keep the spacecraft cool.

Pamela: And the other neat thing that they’re doing with Spitzer that’s different than what they’re doing with James Webb is with both spacecraft you want to protect them from Earthshine to allow their coolant to last absolutely as long as possible. With James Webb they’re sticking it out basically in the shadow of the moon. With Spitzer what they’re doing instead, instead of having it orbit the planet Earth, they’re having it orbit the sun. So when it got launched, it got launched with an escape velocity that put it in a trailing orbit where every year it lags a little bit further and further behind the earth. Right now if you look at maps showing from a top-down perspective on our solar system where Spitzer and the planet Earth happen to be located, if the solar system were a clock, they’re about an hour and a half to two hours apart on that clock.

Fraser: That’s crazy that you would want to keep the telescope away from the earth so that it wouldn’t be heated up by the reflected sunlight bouncing off the earth… but they’re serious about keeping this spacecraft cold!

Pamela: This mission was all about insane things to get good IR data. So if you’re not going to treat it like a yo-yo on the space shuttle, then stick it in a screwy but completely successful orbit.

Fraser: And this is great… with Hubble, they wanted to keep it close and they wanted to be able to upgrade it, and that’s one whole philosophy. And it’s worked quite well… they’ve gone back up to Hubble and they’ve repaired it. In some ways they’ve repaired it in ways that no one had ever expected they’d have to repair it. But you take this other philosophy and you say let’s put it in the most useful place it could be to get the best science but let’s build it right the first time and not or not even… let’s make due with what we’ve built and not think of ways to upgrade it later. Both philosophies make a lot of sense… Spitzer is that second philosophy which is that it’s going to become unreachable and so it had to be done right the first time.

Pamela: And part of that difference that you’re seeing is the difference in when they were built. Hubble was the first of the great observatories to be assembled, and Spitzer was the last. Hubble was already complete when the Challenger had its accident. Because of that it basically was done. They weren’t going to retrofit it in any way to rescue it from the changes that were forced upon it by all of the new regulations. It was designed to come back down to Earth, it didn’t get to do that. Instead, we redesigned how we handled it. With Spitzer, it wasn’t assembled yet, so they had the chance to go through and rethink their design and re-engineer what was getting done to meet the mission’s goals in a new and very creative way.

Fraser: So it was launched, as you said, launched in 2003… August 25, 2003, on a Delta-2 rocket into a solar orbit trailing the earth… and then what happened?

Pamela: Then it started changing our perspective on the universe. It’s really made a series of amazing discoveries over the course of its life. For the first several years… in fact up until May of 2009… it was cooled with liquid helium down to a temperature of about 4 Kelvin. This allowed it to not just peer into the interstellar medium but peer through the interstellar medium to see what was on the other side of all the clouds of gas, all the clouds of dust that blocked our view of the center of the galaxy. It allowed us to see in detail the star formation going on in neighboring galaxies and to basically see fragments of stellar remnants, details of planetary nebula that we never quite imagined.

Fraser: This is really significant. You can imagine as an analogy you look around your town and there are patches of fog that you could just never see into. You had no idea… you had an idea that there were probably buildings in there…. but you have no idea what’s in them. For the first time this observatory could actually pierce through the stuff and reveal. If you see them…. so many of the images that you’re going to see on Universe Today and others, are these Spitzer images. It’s become such a valuable instrument for peering through this stuff. We’re seeing pictures that nobody had any way of seeing before Spitzer.

Pamela: And some of the most fascinating ones are the images of the Bok globules. In visible light, these are giant clouds of nothing… it’s the Neverending Story eating the galaxy. But then you look at these nothings with Spitzer, and suddenly you’re seeing starlight from the other side.

Fraser: And so what’s the process that’s going on here? Why are we not able to see this stuff, and then we’re able to see it with Spitzer?

Pamela: Well, what happens is as light in all the different colors of the electromagnetic spectrum passes through the different media, gas… dust… various materials, it gets absorbed. The colors of the light that get absorbed depend on two different things. One, the shorter wavelengths in the visible light are the first to go. This is in many cases just simple Rayleigh scattering. The blue light passing through gets absorbed and then re-emitted in all sorts of random directions. This diminishes the amount of blue light that goes straight through the cloud. This is where certain nebula if you view them face on with a bright star behind the nebula and you look through the nebula at that bright star, you see it as red. Whereas if you see the light reflected off to the side where the star is to the left and the cloud is straight in front of you, then the nebula will appear blue because you’re not seeing the direct light from the star, you’re only seeing the reflected blue light from the star. As more and more of the blue and the yellows, as all of these visible wavelengths get scattered in random directions, that only leaves the infrared to make it through the gas and clouds and dust. So that’s where we have to go to see through the dust is we have to look in the wavelengths that can traverse that distance of material.

Fraser: And with Hubble… Spitzer has turned up discoveries that I don’t think the astronomers ever suspected that they were going to be finding. It’s been used to look for extrasolar planets, to look at newly-forming stars, it’s been looking at the core of galaxies, it’s looking out to the limits of the universe… So what are the big highlights to come out of Spitzer?

Pamela: Well, I think my favorite result to come out of it was the astronomers Alexander Kashlinski and John Mather they went back and looked at one of the original test images that was taken with Spitzer… one of the original pretty pictures they took to prove the telescope worked. When they looked at it they realized that once they accounted for all the known sources of light, all the things they knew were there from visible images, there was still numerous blobs left behind. They realized that this background light, this glow, was probably from stars that formed as early as 100 million years after the Big Bang. So quite by accident we captured the first starlight while making a pretty picture.

Fraser: And this is one of those situations where the telescope gives you this tantalizing glimpse at what might be these first stars, and this is where James Webb should come along and give us the real view. But still, the earliest stars is amazing. Spitzer was the first to directly observe an extrasolar planet.

Pamela: And that’s part of its continued warm mission. Unfortunately, about a year ago… well, not even that… more than a year ago now… back in 2009, Spitzer ran out of helium. But some of its instruments were designed to keep working even once the telescope warmed up to its current temperature of tens of degrees Kelvin.

Fraser: Yeah, this is all part of the plan.

Pamela: And so they still have a working telescope, it’s still within communications of the Earth… at some point it’s going to pass behind the sun and we’re going to lose our ability to talk to it for a while, but we can still talk to it, it’s still functioning just fine, and as we find planets that transit in front of their parent star, Spitzer’s able to catch the reflected sunlight. We’re also discovering weird stuff with it. There have been planets found that don’t pass directly in front of their parent star, they pass above and below it as they go round and round on a tilted orbit. We’ve noticed that there’s hot spots on some of these planets, and the hot spots aren’t at the noon position in the atmosphere. They’re not directly on a line between the center of the planet and the star. Trying to understand how you get this weirdly-located hot spot is leading atmospheric planetary scientists to have to work all sorts of cool stuff with their models.

Fraser: But… I mean… that is mind-bending.

Pamela: Yeah…

Fraser: You know, that Spitzer is seeing the atmospheres of planets orbiting other stars with such a resolution that they can see where the hot spots in the atmosphere is and it doesn’t match up with their expectations… so it’s another puzzle. But, you know… atmosphere! Hot spots in atmospheres of other planets!

Pamela: And here it starts to just become a matter of combining excellent data with just really brilliant thinking. We can only see 50% of a planet at a time… that’s one of the problems with only being able to see things that appear in the flat of the sky. By timing when we see a planet brightening, we can figure out where east to west as it rotates a bright spot appears. So we don’t know exactly where the hot spot is, but thanks to timing, we can figure out where along a band on a planet these hot spots are located. It’s just amazing science that they’re still pulling out of this. They’re studying active galactic nuclei, they’re finding Bucky Balls… carbon molecules shaped like soccer balls… and obscured supernovae. These are just all fabulous things that we just can’t get at from the surface of the earth.

Fraser: The youngest star ever seen was found a couple of years ago. I think one of my absolute favorite images… I wasn’t there for this, but I think you were there at the American Astronomical Society… where they had just spent hundreds of hours observing the Milky Way, the central core of the Milky Way and out into the arms, and they blew up these huge posters of these images and had them available at the meeting.

Pamela: Yeah, this was one of those times where in order to see what they had done at roughly full resolution—I don’t think it was even at full resolution—they had to cover a convention center wall down much of the length of the wall with this printout of this survey. It was an infrared image of across the center of our Milky Way. That was just fabulous.

Fraser: And it completely changed our understanding of the structure of the center of the Milky Way. Once again, once you can see past this fog, you’ve just got all this additional information you can get. It’s just astonishing. It’s been going for 7 years… we can spend 2… 3 shows talking about all of the wonderful science that has come back from Spitzer. But, what would you say is the core science that is kind of leading astronomical thinking these days? I know a lot of this has sort of gone into the planning for the James Webb, right?

Pamela: I would have to say that this is one of those times where NASA built an extremely versatile instrument that hasn’t just taken one area of science and brought it leaps and bounds further along, but instead it has built an instrument that’s allowed science ranging from the study of asteroids in our own solar system to studies of the chemistry of clouds in our Milky Way to studies of the accretion disks around black holes in other galaxies to studies of the very first stars turning on in the first hundred million years of our universe. All across all the different times of our universe and scales at which we study things, Spitzer has been able to have an impact. That really speaks to the power of building these great observatories.

Fraser: And so where we stand right now, as you said, we’re a couple of years after the helium ran out. So what science can it no longer gather?

Pamela: It can’t go into the longest wavelengths that it used to be able to study. So it’s not going to be able to see the same sorts of things embedded in the interstellar media, it’s not going to be able to do the same studies of newly-forming stars, and perhaps saddest of all, it no longer is able to use its fabulous spectrographs… so our ability to study the chemistry of many of these different things is completely gone until we get a new telescope. But it still has its imaging abilities in the shortest of its wavelengths so we’re still doing the extra solar planets, we’re still doing the asteroid studies, we’re still looking at AGNs. So, we can’t measure the chemistry any more, can’t peer through the same levels of dust and gas, but there’s still lots of fabulous stuff that it can do.

Fraser: And then what is the overlap between the capabilities of Spitzer and the James Webb? Because the James Webb… a lot of people say it’s the successor to the Hubble Space Telescope, but I think it’s much more appropriate to say that it’s the successor to Spitzer.

Pamela: I completely agree with that. Yeah, Hubble does infrared but it’s not what it was designed for as its fundamental mission. Spitzer is definitely the intellectual parent to the James Webb. The way I think of it is the difference between a really cruddy kind of hard to focus old television stolen from Grandpa and a brand new high definition plasma screen… if that’s the superior technology… I admit I’m not up on my TVs.

Fraser: Right, but the kinds of instruments are going to be very similar, it’s just that you’re going to have a much more sensitive telescope to see further and deeper.

Pamela: It’s the double whammy of both being able to see much fainter objects because it’s a much larger light-gathering area and it’s a much more sensitive set of instruments, but not only are you going to be able to see the much, much fainter objects which gives you a greater contrast, but you’re going to be able to see them at a much, much higher resolution. So it’s this combination of more pixels and more sensitive pixels that are essentially going to allow us to see the beginnings of everything.

Fraser: Yeah. And so at some point we’ll cover James Webb in more detail. We keep waiting… we keep waiting for it to launch. Then we’re like… oh, should we talk about it before it launches and really go into it? Or wait until there’s some science results?

Pamela: At some point we’re going to give in because Webb just keeps getting pushed further into the future. But what’s interesting is that we’ve now covered many of the named observatories: Kepler, Hubble, Spitzer, Chandra. All of these missions were named after they had successfully sent images back down to earth, although Hubble’s images were a bit out of focus. Spitzer was in fact named by public opinion. It was one where they allowed the public to have a say in what it should be named. James Webb wasn’t named after a scientist so much… and it was named pretty much as soon as it was funded, so this is a major break from tradition and there is this back of the heart oh no is that like wishing an actor good luck instead of break a leg. But hopefully we haven’t cursed it with Congress or anything like that.

Fraser: Great… well, I think that’s great. If you’ve got a little time, go to Google and type in Spitzer telescope, click on images and just look at some of the beautiful images because like Hubble the pictures from Spitzer are beautiful. They’re meaningful for science and they’re just gorgeous to look at. You would be happy to have them on your wall or as your screen saver.

Pamela: And if you have an account in Second Life, they’ve done this amazing fully walk-through exhibit of the large survey that Spitzer did. This is the GLIMPSE and MIPSGAL survey… Galactic Legacy Infrared Mid-Plane Survey Extraordinaire… the one that we were talking about from the conference wall. You can actually walk through that in the virtual reality of Second Life at the Astronomy 2009 Island… and that was put together by Adrienne Gautier.

Fraser: Cool! Well thanks, Pamela, and we’ll talk to you next week.

Pamela: Sounds good. Talk to you later, Fraser.