Transcript: Mysteries of the Solar System, Part 1

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Fraser: Astronomy Cast Episode 174 for Monday January 25, 2010, Mysteries of the Solar System, Part 1. 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're you doing?

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

Fraser: I'm doing great! So this week… well, we know a lot about our solar system, and there's an awful lot that is a complete and total mystery. Today we're going to begin a series of unknown length examining some of these mysteries and explain the best theories that astronomers have so far. So I think that one of the problems that we do is that we kinda come up with an idea for a show, and we have a schedule, and I'm often rushing Pamela to kind of meet the schedule, meet the time. Well, I'm not going to be time's slave anymore… so we have no idea how many part series this is going to be. Could be a one-part series… but, you know, more likely no… it'll probably stretch on further. But, it's so cool… and you know what's kind of interesting is… now, I'm kinda going off on a tangent–sorry… my daughter is studying space and astronomy in her school, and I'm going to come in and give a presentation to her class that is essentially the podcast we're going to do today, which is a collection of crazy mysteries in the solar system and the best ideas that we have. But I get to show pictures to the class… you'll just have to use your imaginations… or follow along on the web as you go… so, let's get on with it! These are big mysteries in the solar system… in some cases astronomers have some idea of what we're talking about… in other cases–no idea. Should we start with the Pioneer anomaly?

Pamela: Let's go ahead and start with that. It's kind of the oldest of the mysteries, I think.

Fraser: Alright, let's do it. So, in case you weren't aware, there is a weird situation where the Pioneer spacecraft aren't where they're supposed to be. So what's going on?

Pamela: Well, as they're moving out towards the edge of our solar system, as they move out towards leaving our solar system we have calculations on how much they should be slowing down as they go because the sun and the solar system's gravity is pulling on them, we have calculations on… ok, we fired the rockets here this amount… We should know everything about how these suckers are moving through space. We know that there might be some factors to correct for… they fire off radio transmissions toward Earth–that might have an effect. They get heated up by the sun–that might have an effect. And when you put all these pieces together and you figure out where they should be–they're not there. It turns out that for reasons we can't really explain–and this is true for Pioneer I and Pioneer II–both the missions seem to be slowing down more than they should be, and we can't explain it.

Fraser: So, they're not as far from the sun as we would expect them to be.

Pamela: Right.

Fraser: And even when you plug in Newton's formulas for gravity and then you try Einstein's formulas for gravity and you include all that stuff–the additional push of them using the radio transmitters… that's a pretty weak amount of push that they must be getting–they're still slowing down too quickly.

Pamela: Right. And the thing is, all of these things that we've tried to blame the Pioneer anomaly on–the fact that that they are using their antennae to blast radio signals… that should be accelerating them away from the solar system, the fact that the sun is heating them on one side and not the other… that should be pushing them away from the solar system… So, for some reason those things aren't pushing them out of the solar system, or at least there's something else keeping them in the solar system with an even stronger force. And all we can really do is go over the numbers again and start scrutinizing how we built the missions. And the crazy thing is, within error, it looks like we might have the exact same results for the Cassini and Galileo missions as well on their way out to Jupiter and Saturn.

Fraser: What about the Voyagers?

Pamela: The Voyager missions… and now we're going to hopefully have New Horizons as another case study to look at. But we're not sure how to explain how these different missions all have, with their different architectures, seemingly the same anomaly. Now the thing is so far, Cassini, New Horizons, and Galileo haven't gotten that far out and we have a completely different design for those missions than we have for the older ones. And we also, more importantly, have a different way of transmitting and storing the data. And one of the things that's being scrutinized is are changes in how we look at the data… are those differences over all the years and all the different format changes–are those the responsible party? Or does it actually have something to do with the spacecraft and its fuel cells perhaps giving off heat in one direction but not the other.

Fraser: And so it's either a measurement error…

Pamela: Yep.

Fraser: It's an unknown… sort of something going on with the spacecraft, some interaction that we're not thinking of, like…

Pamela: One side is hot due to the fuel cell, and that side is the one that's away from the sun and that heat from the fuel cell is creating a force.

Fraser: Or, it is deep and fundamental… that there is some understanding of basic physics of about how things move in space over long distances that we just don't understand.

Pamela: And that's the most painful one to deal with because when we look at the orbit's of the Kuiper Belt objects—they make sense. When we look at the orbits of Uranus and Neptune–they make sense. When we look at the orbits of even all of their moons–they make sense. So, whatever it is, if it is fundamental physics, is only working on this radial axis from the sun, and it's not affecting things orbiting the sun. And that just seems crazy.

Fraser: So, things moving away from the sun experience this thing… whatever it is. And it could be, you know…

Pamela: Just the way we built the suckers causes them to behave differently… that could be it.

Fraser: Right. And this is one of those things… it's so great because it's so simple. It could be either… oh, yeah, we have a slight modification to our math… oh, we wrote down the numbers wrong, or we don't understand gravity… you know…. It's quite a wide range of possibilities, so… anyway… so that's it–mystery! We don't know… stay tuned! So, mystery number two–the strange axes of Uranus and Venus. So, Venus is flipped completely upside down, so…

Pamela: 177.3 degrees off of normal.

Fraser: Right, so imagine you take the earth spinning… you flip it upside down but still keep it spinning in the same direction… from your perspective looking at the planet now… it's going the wrong direction. Venus rotates backwards to all the other planets in the solar system. Uranus has just been rolled only onto its side, so, you know, sometimes it's pointing its south pole at the sun, and other times it's pointing its north pole at the sun, and… you know… is spinning on its side.

Pamela: It's tilted 97.7 degrees. So neither of them are quite dead on… but, wow they're close.

Fraser: So what is up with that?

Pamela: Well, we don't quite know.

Fraser: Right, the earth has an axial tilt of 23.5 degrees… Mars is kinda similar… Mercury is kinda similar… Jupiter, Saturn, they're all close to that.

Pamela: So, we have two different mainstream theories. The first is that in both cases… take a planet, whack a planet with another planet, and it flips over. With Uranus, that starts to get a little bit troubling because you need to get things really big to hit it, and we just don't know if there was anything that big hanging out doing the colliding back then.

Fraser: But couldn't just time do the trick for you? You hit it with something… I don't know… Mars-sized, and then you just give it 4.5 billion years to roll over?

Pamela: No, because these things tend to either keep rolling once set into motion–it's "things in motion stay in motion" that's a problem–or, once you whack it, it just stays put. That's the way it normally works out is you just whack something into a new stability. Rotating objects are very consistent in keeping their axes pointing in one direction–this is how gyroscopes work on space stations, on spacecraft. Without this characteristic of spinning objects, we wouldn't be able to move spacecraft around. Planets are just spinning tops, they're their own form of gyroscopes so they're spin-stabilized is one way to think of it.

Fraser: Right, and here on Earth we have the precession, right… where we have a bit of a wobble, but that wobble stays within that very specific range, and so you still have the wobbling of the top but it's not like it wobbles over to one point and then just stays there… it's always kind of moving back and forth and back and forth.

Pamela: And so here… it could be that we played "Whack-a-World" but the other option is…. well, maybe this is just tidal effects, maybe this is resonances. One of the things about the formation of the solar system that people are playing with is it's hard to explain how to explain how Uranus and Neptune could have formed where they are located today. But, what is easier to imagine, is that all of the gassy planets, all of the two ice giants and the two giant gases–Jupiter and Saturn, Uranus and Neptune–what if they all formed closer to the sun but Saturn and Jupiter hit a resonance where their resonance caused all sorts of crazy things to happen. There are several different ways of modeling this that start out with all four planets basically tumbling in a gas-giant ball and then moving apart and you basically end up flinging Uranus and Neptune out to the outer solar system. Other cases they start out as four distinct orbits but Saturn ends up on a more and more elliptical orbit over time due to a resonance with Jupiter until it finally settles into an almost circular much larger orbit and in the process also flings Uranus and Neptune out to the outer solar system.

Fraser: So it's almost like you need one process to start the movement and then a second process to stop it. You need the start, and then you need the brakes… to kick on the brakes again to make it stop.

Pamela: And this is where ending the resonance is essentially putting the brakes on.

Fraser: Right, right. Because, I mean, we have examples of asteroids that are tumbling in two directions… they're rotating and they're also tumbling because… and they'll never stop because nothing's ever stopping them from doing the tumbling part.

Pamela: Right. And with Venus it's thought that maybe some sort of a chaotic process where it was getting gravitationally beat up by the planet Earth in some ways was what got it into its situation. If you look at how long its day is… it's a resonance with how often Venus and Earth and the Sun all line up into a nice straight line. So it's possible that this is just the pull of gravity over time gradually tilting and tilting and flipping through all the different resonances in the solar system. Venus just happened to be the one that was susceptible to being put on its head.

Fraser: So why are Uranus and Venus… they're axial tilts off the plane of the ecliptic? It's a mystery. Alright, mystery number three… what is underneath the ice on Europa?

Pamela: Hopefully water.

Fraser: Hopefully water… right, so once again, we've got the situation where Jupiter has its four Jovian moons: Io, Europa, Ganymede, Callisto, and the tidal flexing from the gravity of Jupiter is kinda squishing these moons and then… keeping them softer than they ought to be. With Io, it's full-blown volcanism with huge… magma and lava coming out, with Europa it's not quite as devastating, but you can see… astronomers are pretty certain that there's a shell of ice and underneath that is a great big liquid water ocean… maybe?

Pamela: Maybe. And this is what we're hoping. What we do know is that when you look at images of Europa, it's one of the most beautiful moons in the solar system, I think, it in many ways looks like some sort of a blown-glass ball covered in cracks in the glaze. It highlights in blues and in oranges in many of the different Galileo images. This strange little icy world is actually the reason that we plunged Galileo into the Jovian atmosphere. This moon, through cracks in its surface, is constantly resurfacing. What this means is craters that form on Europa don't get to stay there. They instead get filled in. Basically, a geophysical Zamboni is constantly clearing the ice of Europa.

Fraser: I was going to use the Zamboni reference! That's exactly what it is, right? Every now and then the ice gets all smoothed over again.

Pamela: Right, and the easiest way to explain this is the Zamboni method…. you just spray the sucker with liquid and the liquid refreezes and you're back to a nice smooth surface.

Fraser: And where's the spray coming from?

Pamela: And that's the question… we don't see it directly, but more likely we simply have this slow coming-up, this slow puddling… more like what you see if you go to Yellowstone and visit the bubbling mud pots than if you go and visit the geyser of Old Faithful. So somehow liquid is coming up to the surface, and if liquid is coming up to the surface, that means there is liquid below the surface.

Fraser: Right.

Pamela: And the models… some of them say the ice is a kilometer deep, some of them say it's tens of kilometers deep… but no matter how deep it is, there's probably an active rocky core underneath that's doing the heating.

Fraser: Io… what's happening to Io is happening to the core of Europa… it's being flexed and heated, and putting out heat, but it's not turning into great big plumes of lava… it's just keeping this ocean warm.

Pamela: And the amazing thing to think about–and there are a few papers related to this–is it could be that you have mid-European ocean volcanoes and basically lava plumes just like you find in the deep trenches here on the planet Earth. And it's those deep ocean plumes that are so rich with life that never sees any sunlight, so we know that this form of volcanism under water is capable of supporting life. This makes people wonder, very honestly, could there be life supported under the ice on Europa?

Fraser: Yeah, people don't realize you could destroy the sun and there would still be life on Earth.

Pamela: Until it cooled off…

Fraser: Until it cooled off, but for billions of years you would have the geothermal heat heating the oceans, keeping life going… no problem. So, who knows what's under there… Now, is there going to be any way that we're going to know? I know there were ideas to send a probe that could melt down through the ice and try to make its way down to the ocean.

Pamela: Like so many problems, this is one that comes strictly down to money. There are robots being designed and tested right now that, if you drop them into an underground lake, are capable of going down and on their own exploring and mapping what exists down beneath the surface of the planet Earth. Then they come back and they radio their results. So what we need is to develop a robot that takes this one step further and digs a hole for itself through the ice and drops itself into what is hopefully not too far down… liquid water, and then digs itself back up to the surface and beams its results back.

Fraser: Or, leaves a tether behind, right… some kind of communication tether… it leaves that up on the surface, melts its way or bores its way down through the ice, gets down to the ocean, leaves that as a way to communicate and then travels down into the ocean to see what's below. It's a monumental engineering challenge to make that work.

Pamela: And beyond just the budget difficulties, anything that's swimming around underneath the ocean of Europa… or underneath the ice of Europa, rather… won't be able to use solar panels. To continue exploring the outer solar system, and to explore places where literally the sun doesn't shine, we need to use radioactive fuel cells, we need to use radioisotopes. Right now, here in the United States, we have a shortage of these. We're simply not developing the fuels that are needed to power spacecraft. A lot of international treaties govern what nuclear isotopes you develop and you process and you refine and all those other different things. And under treaty, it's unclear if we can create fuel cells we need for our space program.

Fraser: So, who knows… this is one of those situations where I'll bet you someone's going to come up with a clever way to analyze the ice on the surface and detect evidence of life's outputs… right? Micropoop in the ice on Europa… so we'll stay tuned on that one…
Ok, so next… mystery number four… what is creating the methane on Mars?

Pamela: Yeah, we don't know that one either…

Fraser: No, I know… but this is huge!

Pamela: This is one of those amazing discoveries!

Fraser: Yeah, so once again, to set the scene… the European Space Agency's Mars Express spacecraft discovered the faintest whiff of methane in the atmosphere of Mars. This is really shocking and surprising because methane is destroyed by sunlight in a very short period of time so there has to be some source replenishing the methane. What's creating it?

Pamela: And during the northern summer, they were actually finding as much as 30 parts per billion of methane in the Martian atmosphere, and methane is something that gets actively destroyed by the sun. Sunlight… ultraviolet light hits methane… methane stops being methane, it's happy to do that. So this is something that's being actively produced, and we only know of two sources of methane.

Fraser: Source number one?

Pamela: …is lava, geophysical activity, something indicative of the planet being alive geophysically.

Fraser: And that would be very exciting to discover… we could see Olympus Mons erupt again…

Pamela: I'm not quite sure we could go that far… but it does mean that there is some sort of process going on that–well, it's always cool when rocks are alive–but the other process is… well, life produces methane. Meet a cow–you've met a methane-producer. Small biological entities, bacteria, single-celled organisms in all their different forms, there's many different ways to produce methane and so if Mars is as geophysically dead as we've been teaching for, well, as long as I've been alive, that means that there's methanogens or some other form of methane-producing life in Mars.

Fraser: And, I mean, if they can find that, the ramifications of that are gigantic. That means that there's life on Earth and there's life on Mars. And if there's life on two planets, then life could be all over the place in the universe. And you would, in theory, eventually be able to find the source and be able to study it and see if the two are connected. Did life begin on Earth and separately on Mars, or are they somehow interconnected? Do they share a common ancestor? The ramifications of this are mind-boggling. Now there are plans to get to the bottom of this mystery.

Pamela: Yes, and everything from the upcoming Mars Science Laboratory to most of the plans for the future for Mars all include going and digging in the surface and looking for signs of life. One of the most exciting ideas that I haven't seen any missions attached to yet, is going and… there's several different places that we've seen along the volcanoes on Mars skylights into deep dark caves that are likely completely protected from radiation. If we can go and explore in those caves… those caves may represent our best bet for places capable of supporting human colonies and supporting life that exists in the dark.

Fraser: And there's also been some orbital missions proposed that will map out the methane concentrations with more accuracy and try and even find out exactly where it's coming from.

Pamela: And everyone just wants to go dig… because who doesn't like digging in the dirt?

Fraser: Oh, for sure… but I mean this discovery… this could change everything.

Pamela: Yes.

Fraser: So if there's one mystery that we've really got to get to the bottom of… it is this one. But, let's move on… so, mystery number five–where did Titan's atmosphere come from? Titan is Saturn's largest moon… second largest moon in the solar system… and it has an atmosphere that is thick… like as thick as Earth's… and rich in hydrocarbons which scientists think is a very similar environment that we had here on Earth early on. How on Earth… ha, ha! How on Titan could you get an atmosphere like that so far out in the solar system orbiting Saturn? It should just be a block of ice, right? A ball of ice…

Pamela: Right, right… and this is where Titan gets to be a really interesting planet to look at.. it's not even a planet, it's a moon… it gets to be a really interesting object to look at from a geophysics perspective because it doesn't just have a thick atmosphere, but it has a "insert the expletive of your choice" thick atmosphere. This is atmosphere that is 1.5 atmospheric pressure–or atmospheric bars, rather. That's thicker than the atmosphere on the planet Earth.

Fraser: You could take off your spacesuit and not freeze-dry… you would merely freeze!

Pamela: And the thing about having an atmosphere this thick is… I love this… it's a low-gravity world. It's a tiny, tiny moon–compared to the size of the planet Earth–and so with this low gravity, if you attached a pair of Icarus' wings to your arms, you could actually fly around in this really thick atmosphere. Now, the majority of the atmosphere is nitrogen–it's 98.4% nitrogen. But, along with that nitrogen, there's another 1.6% composed of methane and other organics, and like I just said about Mars, methane is destroyed by the sun. So, somehow there's something about Titan that's causing it to constantly generate methane that's getting replenished in its atmosphere. People have looked to see… well, maybe it just captured the methane and it still hasn't had enough time to all be destroyed from the solar nebula. No, that model doesn't work. Well, maybe it just comes from getting clobbered by comets. No, that doesn't work either… the composition ratios are all wrong. Somehow, something inside Titan is generating this, and one of the really awesome things about the combination of Titan being really cold, really tiny, and having this carbon-atom rich environment, is it can have geophysical processes that carve rivers, that carve canals, that in many ways look just like the processes that we have with water here on Earth. So, for Titan, the methane in the atmosphere is like the water in the Earth's atmosphere. It can rain, it can form rivers on the surface, it can freeze, and so you can have an entire environmental cycle built out of methane… but we don't know where it's coming from.

Fraser: Right. So, methane is too short-lived to have been left over from the solar nebula, so some thing is either protecting or replenishing it on Titan.

Pamela: Exactly.

Fraser: Crazy. Alright, well I think we're actually out of time. We've gotten through five, and we've got more. So this is going to at least be a two-part series, so stay tuned for next week. Thanks Pamela!

Pamela: Sounds good Fraser.

Transcript: The Herschel Space Observatory

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Fraser: Astronomy Cast Episode 173 for Monday January 18, 2009 2010 [ed.], the Herschel Space Observatory. 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. Hey Pamela, how're you doing?

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

Fraser: I'm doing great. Now I understand that you have a task you wish to get some help with from the listeners.

Pamela: I do. I have a homework assignment for all of you. Now when we look at our Google stats, it gives us a vague idea of where people coming to our site are coming from, but it doesn't give us personality, it doesn't help us explain to other people who our audience is. So I'm going to ask you to do something that I hope is simple. Go get a postcard of where you live, and just send it to us. No matter where on the planet you are. We have a P.O. box… you can reach us at Astronomy Cast, P.O. Box 804, Edwardsville, IL, 62025, and we can post that address on our website. So all I want is a postcard, just a postcard, simple postcard… say Hey! Hi!

Fraser: Having fun… wish you were here… Here's a picture of the Acropolis…

Pamela: And give us a face to who you are.

Fraser: That would be cool. Last week we talked about Herschels–the people… William Herschel, his sister Caroline, and his son John. This week we're going to look at the Herschel Space Observatory… Herschel the robot! A mission launched in 2009 to reveal the coldest and dustiest regions in the universe. Alright, so lets talk a little bit about the Herschel telescope, then. So, what is it?

Pamela: It's a telescope.

Fraser: Thank you for that…. but what is it?

Pamela: It's an infrared observatory that was launched May 14, 2009, that is the biggest and the most infrared observing of the infrared observatories that have been launched into space so far.

Fraser: So we're going to compare this to Spitzer, then, right?

Pamela: It's actually something entirely new. It has a mirror that is about four times bigger than what has been seen before, and it goes further into the infrared than we've been able to go before.

Fraser: Alright, so infrared is on the electromagnetic spectrum on the more red side… beyond red… we've done a whole show on infrared. Herschel starts where and ends where?

Pamela: The Herschel mission goes roughly from about 55 microns out to about 670 microns. So this is way, way smaller wavelengths once you start getting down to the 50 micron than anything that can get through our atmosphere. So, what we run into when we start dealing with infrared, is our atmosphere in particular… the water in it, in many cases, removes infrared light and it never reaches the surface so we have to launch telescopes into space if we want to start studying things like molecular transitions, things like galaxies forming at the edge of the universe. And infrared has this neat feature where it lets us look through dust, which is always a good thing.

Fraser: Right, so this is a region of the electromagnetic spectrum… in the infrared, but it's the part of the infrared, the longer wavelengths, that are blocked by the earth's atmosphere.

Pamela: Yes.

Fraser: And if I can kind of remember from our previous show on infrared, this is stuff… sort of enshrouded by dust, that the light would normally be blocked, but infrared can see through that. We're seeing like protoplanetary systems, into nebulae, into the heart of the Milky Way, and then we're also seeing out to the very distant edges of the universe where the light has been red-shifted.

Pamela: Exactly. So we're essentially studying the birth of stars all throughout the history of the universe, in a lot of ways. Because nearby it allows us to look at star forming regions and look INTO the star forming regions.

Fraser: And see these stars as they're just getting going, they're not bright hot stars, they're just getting going… they're warmer than the background.

Pamela: Exactly. And we're able to see the detailed temperature flows, in some ways… how is the material flowing through these nests of star formation. But then as we look out to the beginning moments of the universe, we're seeing star formation that the stars already emerging from their gas and dust and giving off violent amounts of ultraviolet radiation, but by the time that ultraviolet has been stretched and stretched and stretched and stretched on its journey from the first moments of the universe to today, it's all back out into the infrared.

Fraser: So then Herschel… it's got the detectors to see this infrared… you say it's got a mirror that's four times larger than any telescope that's looking in this spectrum?

Pamela: It has a 3 1/2 meter mirror, and it also has high-resolution spectrometers, so it's able to start saying, aha… right there I see carbon monoxide, right there I see water. And so we're able to start tearing apart what are all of the different molecules found, what are all the individual elements that are starting to turn up in all of these different gas clouds.

Fraser: And this is part of the situation where different molecules will release electrons… or photons–sorry–at a very specific wavelength, right, and then you can see them and then you know that those photons coming at me are evidence of alcohol, or…

Pamela: Formaldehyde…

Fraser: Or formaldehyde, or… yeah… exactly. So you can see those individual molecules.

Pamela: There's all sorts of amazing stuff out there, and the key to seeing it is to first get above the atmosphere, and then to get yourself good and cold and keep yourself that way. And this is one of the things that makes getting Herschel where it is something of… not a challenge, but a waiting process for scientists. They had to take Herschel and stick it out on the other side of the sun-earth system… so you go sun… earth… and then you go out past that to L2, and it's out in the L2 gravitational point where you're constantly living in Earth's shadow that they decided to stick this little mission.

Fraser: Is there anything else out in L2?

Pamela: Well, we're working on slowly filling it up. It's where James Webb is going to go live, I believe it's where WMAP lives… it's a good place to stick things you want to keep cold.

Fraser: Because the earth acts as a sun shade?

Pamela: And it's also constant temperature. If you think about it, something that's going in and out of the earth's shadow all the time is going to have all sorts of temperature fluctuations. And an instrument that is sensitive to… well, the color of temperature is one way to think of it. Having all those temperature fluctuations is going to make any sort of accuracy very difficult. One of the problems of infrared telescopes is they can see themselves if they get warm. If the tube of your telescope gets hot, it's going to be the brightest thing in your field of view, and that's just a really bad idea. So, they keep these telescopes in the shade… they keep these telescopes where they can be completely thermally controlled by not having to constantly go in and out of the sun's light.

Fraser: I think it's kind of amazing, when you think about it, we already know that space is incredibly cold… you know, just a few degrees above absolute zero. And then, they cool them further because that's not cold enough!

Pamela: It's also a matter of they have to cool off the detectors because… well, electronics get warm. Anyone who's sat on the sofa with their Apple laptop on their lap… you might want to grab a pillow before you burn yourself… electronics get warm. Telescopes get warm. And so you do have to use cryogenics to cool them off. You do have to launch them with a reserve of cooling liquids and in some ways that is a curse because it limits how long these missions can last. Hubble–we can keep using Hubble as long as the little gyroscopes are happy to keep spinning, as long as the detectors are able to send us back data. Some of the instruments on Hubble do get cooled, but not all of them. Once you start looking at the universe in the infrared, well now you're limited by how much cryogenics you can carry up with you and so Herschel, we have planned to be able to use for 3 1/2 years, and if we're lucky we'll be able to get it all the way out to 4 1/2 years. We think that the cryogenics were built well enough that they'll be able to keep going and last a whole lot longer. But if the cryostat evaporates faster than that, as happened with one of Hubble's instruments, it will have a shortened mission and a shortened amount of science that it's able to do.

Fraser: Right, right… and this isn't one of those situations like with Spirit and Opportunity where they just keep going and going and going… yeah, they've got a very set lifespan. This is more like the Phoenix lander, where it lasts one winter and then it's a goner. But, then even when it runs out of the cryonics, it's still a useful telescope… it's still going to be able to see… just not the really cold stuff anymore.

Pamela: Well, unfortunately, the way it's been calibrated, it actually has a set life… it's not like Spitzer that has a warm mission plan.

Fraser: That's what I thought… ok, ok, so it's done…

Pamela: Right. So Spitzer, they have a warm mission for Spitzer, and there's actually a really fabulous video podcast… the IR-relevant, IRrelevant video series has a great one on Spitzer's warm mission, but with Herschel, it's limited to 3 1/2 to hopefully 4 1/2 years…

Fraser: I predict they'll figure out something to do with it… something… who knows what it could be, but I'm sure they'll figure out something. They'll be bouncing lasers off of it to calculate the distance to L2 or something… I don't know…

Pamela: I think this is one of those times where they may just figure out how to recalibrate the instruments, but probably not. They'll probably move the dollars on to the next big cool mission that gets launched.

Fraser: And one of the things that we haven't really mentioned is this is not from NASA…

Pamela: No, this is the European Space Agency. This is a program that as you explore data on it, yeah a couple of the instruments were built by NASA in part, but I love all the press releases are from Cardiff because I'm a Dr. Who fan, and who doesn't love Torchwood… that has absolutely nothing to do with the mission but I just get a giggle every time I read press releases where all of the scientists are from Cardiff. So, you have a strong UK contingent, you have the European Space Agency that launched it. They launched it from French New Guinea, and the launch images are fabulous and there are these giant birds that are flying all around in the video, and it looks like it's being swarmed by pterodactyls if you use your imagination.

Fraser: Which I choose to… so it's launched on an Ariane rocket…

Pamela: And it co-launched with Planck. This was one of those great missions where we got two satellites for the cost of one rocket.

Fraser: We haven't even talked about Planck yet… we'll talk about Planck. And then it made the long slow journey out to L2.

Pamela: 60 days…

Fraser: 60 days, yeah… so we've done an episode on the Lagrange points, L2 is, as you said, on the opposite side of the earth. This is a point where the gravitational forces are perfectly in balance and it requires a minimum amount of fuel to keep it in that position. But it's not… it's fairly stable… it's sort of like perching a car at the top of a mountain, you know, as long as you keep the car at the top of the mountain it's not going to go anywhere. But if it gets a little one way or the other, maybe a big gust of wind and it starts to roll off the mountain, then it's off and away. So, when a spacecraft is in the L2 point, it needs to keep firing its thrusters to remain in that position, right?

Pamela: And more than that, it's not sitting exactly in the center of L2, it's actually in… forgive me, I'm going to mispronounce this… a Lissajous orbit that is centered on the L2 Lagrange point. So it's orbiting around the L2 point which is more like you can imagine yourself attached to a piece of string, bouncing around the top of the Matterhorn… well, a really big rope bouncing around the top of the Matterhorn.

Fraser: Right. Don't let go!

Pamela: Exactly. So it's out there, it's orbiting, but it has to have control thrusters anyways to be able to maintain its mission. It uses gyroscopes to do its pointing, but still… It has to be able to get where it needs to go and stay there.

Fraser: So it launched May 2009…

Pamela: Yes.

Fraser: And here we are, as we're recording this in early 2010, so what have they found so far?

Pamela: The first thing they did, of course, was take pretty pictures… because that's what you do when you have a brand new telescope is you take pretty pictures. And what's amazing is by looking at nearby big bright pretty stuff, they're already doing amazing science. They looked at a star-forming region in the constellation Aquila, and they were able to see through the dark, optically opaque gas and dust and make out the most amazing filament structures around the new-forming stars… where they can see knots that are significantly hotter and individual points where stars are just starting to collapse and heat up. Looking at these images, you can start to see how things are fragmenting, how materials are flowing in the texture of this image. It's really quite amazing. Then they turned it outward, looking at the Virgo cluster. They have this really fabulous pair of images–one stolen ruthlessly from the Sloan Digital Sky Survey and then a comparison image that was taken in the infrared with Herschel–and what they're able to show very well is that as you look out from these giant elliptical galaxies that are so bright in optical light… they go away almost entirely in the infrared… they just don't have that much gas and dust. Whereas small spiral galaxies, rich in star formation, pop out as these bright sources of infrared light. Suddenly we're able to say Aha! You! You have gas and dust… and you–you are dead… you shall star-form no more… just by looking at things in a completely different color of light.

Fraser: Right, this is where these galaxies have already used up all of their gas and dust and so they're just going to age and die and just turn redder and redder, while others still have a little bit of dust left over. Herschel lets them see these stockpiles of dust.

Pamela: And it also lets us see the dust that we might not have noticed otherwise. In galaxy clusters there's a lot of galaxy-on-galaxy violence that takes place. There's what we call galaxy harassment, ram-pressure stripping, all of these horribly violent words get used, and what it boils down to is through varieties of different types of interactions between galaxies and the galaxies and the stuff between galaxies, you end up knocking gas and dust out of systems. In this Herschel image of the Virgo cluster, you can see extended emission from a long dust trail streaming out behind another galaxy, and so we're able to see where the dust is that's been removed from the optically luminous galaxies.

Fraser: We'll link to some of the pictures in the Show Notes, but the pictures coming out of Herschel are just beautiful. They're sort of in that same class as the Hubble… all the really beautiful nebulae… the Eagle Nebula, the Pillars of Creation… Some of the pictures are just amazing. No, it's all fake, right? It's all fake colors, right?

Pamela: We ignore that part.

Fraser: We ignore the fact that these aren't the real colors that you're seeing with infrared eyes, but these pictures are just great. The picture of the nebula in Aquila, there's a picture of the Southern Cross… the nebula in the Southern Cross, and one of M51… these were all released in December for some of the first science that came out from Herschel, and they're just beautiful pictures. And that's what really…. that's why that telescope was launched… was for me to be able to display beautiful pictures on Universe Today…. I believe is the reason… we should check into that, though.

Pamela: But beyond just doing the pretty pictures, there's also the occasional… you look at it and go "that's a lot of dots," those are nicely colored dots, but that's a lot of dots. One of the things that Herschel is participating in is the Great Observatory Origins Deep Survey–GOODS. This is a project that's taking many of the best observatories around the planet and around on the planet and peering at this one small area on the sky, roughly the size of the moon, that has nothing nearby in it. There's no Milky Way-based stars, there's no nearby large galaxies. This is an otherwise completely empty area on the sky. At the time of this release, they'd used Herschel for about 14 hours on this one section of the sky, which is nowhere near as much observing as they're going to do by the time they're done. In just that small 14-hour window, they were able to make out what looks like… looking at Christmas lights in a snowstorm is the best way I know how to explain it. It's just dots and dots and dots and dots and dots of all the shades between blue and red, except for green because there's nothing green in the sky… at least not that the human eye perceives. These dots are galaxies all the way back to the first moments of the universe in the process of forming stars and sitting there glowing and evolving through time. So we're now able to–in a single image–look back, hopefully to the beginning. We need to start sorting out what are the nearby red galaxies, and what are the galaxies that appear red because they're at the very limits of what we're able to see. But, this is the first time that we're able to start resolving this color of light in the background of the sky.

Fraser: Are they able to see right to the background radiation? Or not quite…

Pamela: This we still have to sort out. To be able to say I have definitively seen back to the first moments of the universe you need to look at something… and these are just little fuzzy blobs on the sky. But, you need to look at the little fuzzy blob on the sky and find some way to figure out how far back in time it is, how far away it is in distance. They have spectrometers… we have other methods as well to get at that. The press releases are coming… they're not here yet… I'm sure over the next 3 1/2 to 4 1/2 years we're going to be seeing "and Herschel has confirmed…" galaxy at red shift "large number" looking back further and further into time.

Fraser: Right, and so what we're doing at this point is we are just shy of a year into this mission, and I think with Herschel, not a lot of really official news has come out yet just because these things take time. The scientists have to schedule their time, Herschel takes their readings, they take it back, they work on their journal articles, and then they start to publish. We're in that in-between time while they're still crunching the numbers and waiting to publish, so…

Pamela: Well, and it's still very much a baby mission. It launched May 14, and then it took it 60 days to get to the Lagrange point, and then once it was there it had to calibrate all of the instruments. So, we're still…. in terms of when they were able to start doing science, the science images only started coming out late June. So, we're just 6 months into the mission, and they're already starting to say this is what we can see.

Fraser: That sounds great.

Pamela: There's a lot of good things to come.

Fraser: Yeah, absolutely. We've got another 2 1/2 years of life in the spacecraft, and the news is just getting rolling. This is the time that I would recommend that you subscribe to Universe Today, and we'll be releasing all of the news as it comes out. Well, thanks a lot Pamela! I think this is great! It's really exciting that we can kind of get in at the ground floor and give people some perspective so that when they see news that comes out about Herschel, they can go oh yeah, right, that's that infrared telescope and it's only got a couple of years left, and really put that news into perspective and know what they're looking at. And like I said, the first pictures that have come out are amazing, they're beautiful… they're the kinds of things that you would frame up and put on your wall. They're just these beautiful colors of gradations of colors… it's quite amazing…

Pamela: And the thing that many of us are waiting for on the science side is all of the really ugly spectra…

Fraser: And numbers, and graphs…. I don't like to put that in the site…

Pamela: But those are the things that are going to tell us what molecules are in space and that's cool.

Fraser: Just one last thing… what would you say is like the biggest question that could be answered by Herschel?

Pamela: Herschel has the potential to look at the atmospheres of exoplanets and say I see the components that are created only through life.

Fraser: It has the potential…

Pamela: It has the potential… we need to find the right planet–it needs to be a planet that transits its star, and if those conditions are met, then we have the chance to be able to pull out molecules in that planet's atmosphere. And that would be very cool.

Fraser: That would be amazing. There's a bunch of missions that are zeroing in on that, and hopefully when James Webb finally shows up, we'll really have the tools at our disposal to find life.

Pamela: And in general, this is a chemistry mission. We talk about the pretty pictures, but this mission does chemistry.

Fraser: Yeah, but chemistry can tell you so much.

Pamela: Yes.

Fraser: Cool. Well thanks a lot Pamela! We'll talk to you next week.

Pamela: OK, bye-bye.