Everything dies, including our technology. But when we’ve hurtled a few thousands pounds of robotic instrumentation to another planet, it gets a little difficult to shut it down and clean up. What do we do when a mission has reached the end of its useful life?
This episode is sponsored by: Swinburne Astronomy.
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Announcer: This episode of Astronomy Cast is brought to you by Swinburne Astronomy Online, the world’s longest running online astronomy degree program. Visit Astronomy.SWIN.edu.au for more information.
Fraser Cain: Astronomy Cast episode 342, Sunsetting Spacecraft. Welcome to Astronomy Cast, our weekly fact-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 and the director of CosmoQuest. Hey Pamela, how you doing?
Pamela Gay: I’m doing well. How are you doing, Fraser?
Fraser Cain: Good. I know I’m sounding like a broken record but I would like to plug –
Pamela Gay: Okay.
Fraser Cain: — the Hang-Out-a-Thon.
Pamela Gay: Yes, April 26, 27. I’m actually gonna start posting blogs about that today. So last week, for those of you listening to the audio recording, you’ll have multiple things to catch up on where I’m gonna talk about the history of CosmoQuest and what it is exactly that we’re looking for funding for.
So hopefully many of you out there have jobs. If you don’t, we hope you find them quickly. And if you want to consider getting your employer involved to help sponsor us, we’re looking for corporate sponsors; we’re looking for clubs to donate money.
Right now I just got back from the National Science Teachers Association meeting in Boston where all of us who do astronomy education at one level or another were pretty much walking up to each other and going, “Are you okay? Are you gonna make it?” And it was like we were talking to a bunch of other terminally ill individuals.
Because, well, NASA’s budget for doing citizen science, for doing education, for doing communications, all of those fabulous things is currently less than what one individual reportedly spent for a commercial ticket to go around the moon someday in the future on unproven technology. We need help and we’re hoping that you’ll help us define the future of astronomy citizen science, education and communication with your – your business, your friends’ contributions.
Fraser Cain: So what’s the date again? That –
Pamela Gay: April 26, 27. We’re going live at 10:00 am Central, 8:00 am Pacific, 4:00 pm London and we’re going live for 36 straight hours.
Fraser Cain: Nice. Not – I mean, it’s gonna be pain and suffering but in the cause of raising funds for CosmoQuest and astronomy research so, okay, great. One last reminder is that if we’ve timed everything right, you’re listening to this on April 14-ish.
Pamela Gay: Yes.
Fraser Cain: And if so, tomorrow on April 15 is gonna be a total eclipse of the moon that should be visible in all of North America. So if you want a good time we highly recommend that you do that. Head outside on April 15 around – well, it depends on what time it is.
Pamela Gay: But if you don’t know what time it’s going to be where you are, Fraser has an app for that. And I just needed a reason to say he has an app for that.
Fraser Cain: I have an app for that, yeah, so it’s The Phases of the Moon app, which I’m holding up to the video but you can’t see it. So anyway, check it out. It turns – let’s see, it should turn red – oh no, not in that one, the pro version. Anyway [inaudible] [00:03:30] and if it turns red on the pro version for the [inaudible] really cool.
Pamela Gay: So go ahead, get that pro version and get yourself outside and enjoy the lack of moon?
Fraser Cain: Yeah. Yeah, we’re gonna have – I mean, it’s been a long time since we’ve had a really nice lunar eclipse. So this is gonna be great. Anyway, people don’t stick around for our jabber. Let’s get on with the show.
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Fraser Cain: So everything dies including our technology. But when we’ve hurdled a few thousand pounds of robotic instrumentation to another planet it’s a little difficult to shut it down and clean up. So what do we do when a mission has reached the end of its useful life? What do we do, Pamela?
Now, let’s provide some examples of some spacecraft that have been – that have reached the end of their utility?
Pamela Gay: Well, I think my favorite case of end of lifing a spacecraft is Galileo. The Galileo Probe orbiting Saturn, they wanted to make sure that it didn’t accidentally crash land on one of the water-rich worlds out there, one of the moons that just might potentially have life.
And so they crashed it rather harshly into the surface of Jupiter and continued to take data from it until Jupiter’s atmosphere had completely destroyed it.
Fraser Cain: Right. But this is – it’s funny that they did. Have they not – when they launched this mission – I guess they didn’t know necessarily the extent of the liquid water on the moons of Jupiter when they launched Galileo. See, I hadn’t really considered that it was a potential host for life. And then they launched the spacecraft with its, you know, I guess not a very clean environment. I mean, there’s absolutely gonna be bacteria all over Galileo.
And as we know that hardy bacteria can last for thousands – hundreds of thousands of years under really extreme environments and come back to life. And so, yeah, if you crashed Galileo into a nice warm, wet environment, that bacteria could get rolling.
Pamela Gay: And on surfaces like the surface of Europa, while Europa is very, very cold it’s getting squished and unsquished in a very systematic way by Jupiter so that its core is molten. And the heat from that is causing there to be liquid oceans between the icy surface and that hot core.
And you can envision a spacecraft with sufficient kinetic energy hitting that surface. And hitting it in one of the areas that perhaps is already weak, there’s the chance that it’s gonna go through. And instead of sending smallpox blankets to Europa, we’re sending, well, bacteria-rich more equivalent of smallpox spacecraft and killing off whatever life might be there. And that would be horrendous.
Fraser Cain: And this same strategy is probably gonna be in place for Cassini because there now have – it’s come to light that there is probably a water-rich environment in Enceladus and some of the other moons potentially.
Pamela Gay: And Titan has the methane ecosystem.
Fraser Cain: Although with Titan they crashed – they landed Huygens on Titan and it’s there breeding its nasty bacteria all over the surface of Titan.
Pamela Gay: But that doesn’t mean they wanna make things worse.
Fraser Cain: Right, right. So it’s the same, because once Cassini reaches the end of its lifetime they will crash it into Saturn and hopefully get the same kind of death as it falls into the planet.
Pamela Gay: And this is why I’m bringing this up now is we’re looking at a number of different NASA missions due to budgetary cutbacks getting end of lifed. And some missions you can end of life in easier, less hazardous [inaudible] [00:08:08] spacecraft ways than others.
The Wide Field Infrared Survey Telescope that was up, survey explorer WISE, a few years ago when it hit the end of its natural funding cycle they essentially put it to sleep. But it was very much a sleeping beauty scenario where it got boosted to a higher orbit waiting for the kiss of signal that would wake it back up and allow it to be used again. And they’re waking that telescope back up and putting it back to use.
So it’s possible for some missions to get put to sleep with the chance of possibly waking up again in the future. And others like Cassini, the only thing you can really do is kill them brutally.
Fraser Cain: Okay. So let’s talk about a few scenarios then. So let’s see close to home first. Let’s talk about the kinds of spacecraft that get launched into a low-earth orbit, something like the same altitude as maybe the International Space Station or maybe even the International Space Station. So what gets done with spacecraft like that?
Pamela Gay: So low-earth orbit things are either quick experiments, pretty much all the CanSats and smaller are in low to excruciatingly lower orbit. These, in some cases, are spacecraft that are spy satellites that go over the same part of the planet every four days that just have nicely resonating 90-minute orbits that [inaudible] [00:09:48] into a 24-hour period.
These are not weather satellites. They are generally not communication satellites. They’re things that are either looking down or running experiments. And they’re happy there until they’re not because there’s a fair amount of – well, there’s still particles same atmosphere easily makes people over think it. There’s very thin parts of our atmosphere still up at the 300-mile mark. And that frictionally slows spacecraft that aren’t constantly boosting themselves up. And so things in low-earth orbit are eventually going to come down.
Fraser Cain: Right. So the atmosphere is gonna take care of this problem for us.
Pamela Gay: For the most part. The problem is the atmosphere doesn’t always take care of it enough so there are cases of when Skylab landed, well, Skylab didn’t so much land as it went through the atmosphere, shredded itself and chunks of it scattered itself across Australia. It wasn’t exactly the best thing we have done to the nation of Australia in the name of space exploration but that’s what happened.
There was the case of Operation Burnt Frost which is one of those fabulous military code words for we had a nonfunctioning U.S. satellite that had hydrazine fuel onboard which is highly toxic. It got blasted apart to make sure that there were hopefully no pieces big enough to make it all the way through the atmosphere and do something destructive on the surface of the planet. So we like to destroy things thoroughly when they come down from low-earth orbit so that chunks don’t kill people.
Fraser Cain: Right. And same thing with Mere, right, that –
Pamela Gay: Purposely put into the ocean.
Fraser Cain: Yeah, and so, I mean, we’re really fortunate, right. With Mere they had a spacecraft attached to it and they could de-orbit it when and where they wanted. But for a lot of these spacecraft, they don’t have any kind of de-orbiting technology on them. You literally just have to wait for them to run out of fuel to boost their orbit. The atmosphere finally drags them back into the atmosphere and wherever they re-enter is where they re-enter. And in most cases most of it breaks up but some of the chunks make it through.
And we went through this with a bunch of spacecraft over the last couple of years. I remember where all these lives watches for when, was it fuse came back and –
Pamela Gay: Every few months it seems like there’s a new Twitter storm of activity of, do we know if it’s down? Do we know? Do we know? And, I mean, the reality is that basically NORAD can’t see it eventually so we know it’s no longer up there.
Fraser Cain: And they’re calculating the odds that it’s gonna hit and kill a person because there is a chance because there are big chunks. And some of them survive the re-entry and crash to the earth. Most of the time they just fall into the Pacific Ocean but sometimes – okay.
So we dealt with, I guess, the spacecraft that we put into low-earth orbit in that we don’t really have to deal with them. We let the atmosphere deal with them.
Pamela Gay: Bye-bye.
Fraser Cain: But if we’re feeling careful, we’ll put some kind of re-entry rocket on it and de-orbit it faster. I’m assuming that’s what’s gonna happen with the International Space Station at some point, right?
Pamela Gay: Yeah, that’s the plan.
Fraser Cain: Yeah because, I mean, it’s coming back down. It’s big.
Pamela Gay: And, yeah, so let’s just see how long we can keep that sucker up there and that will be easier. And there’s always the cool potential with manned things like that – and the Soviets actually did this with some of their spacecraft and the Chinese have made noises about potentially doing this in the future – that you take part of the old station and put it into whatever’s the next great thing that you build. So, that’s kinda the ultimate in recycling. Oh, we’ve got solar panels already. Don’t need to carry any new ones up. Hey, this particular part of the station doesn’t smell too bad. We’ll clean it up a bit and keep things going.
Fraser Cain: So we’ve got those. The Hubble Space Telescope is another example of a spacecraft that we’re gonna have to figure out what we’re gonna do. And during a previous mission they figured that part out.
Pamela Gay: So, yeah, there was the long debate of, do we burn it up, do we boost it higher? And so there is now attached to it both the ability to grab it and the ability to move it. So there’s hope that destruction will not lead to death of humans.
Fraser Cain: Right, okay. So let’s talk about some other spacecraft then. So we talked about the low-earth orbit, so what about a little bit of a higher orbit? We’ve got something that maybe is 500 kilometers, 1,000 kilometers, something that’s not gonna get dragged down into the atmosphere, you know, stuff that’s on poor orbits. Some of the navigational satellites are at this sort of mid-range altitude. What do we do about them when they reach the end of their life?
Pamela Gay: They pretty much get to die in place, them and everything higher than them. Occasionally they will move things to new orbits before they completely die. And this is simply so that you can park a new spacecraft in a preferred orbit.
You can imagine if we’d left everything that gets put into geosynchronous orbit in place, you’d end up with eventually a solid band of spacecraft around the earth’s equator several – many, many thousands of miles up. We’re a long way from that happening but there’s still prefer places to be if you want to make sure your signal is perfect for some metropolitan area, that your weather is ideally getting that range of the planet that you want to be able to predict.
So they do tend to move those things into what are called parking orbits where they’re pretty much out of the way and can peacefully stay. [Inaudible] [00:15:26] there’s actually many different nations that are working on plans to build things that we’ll grapple on and either retrieve, bring back down to earth or destroy these dead satellites so they’re clustering – cluttering up the earth’s orbits.
Fraser Cain: Right. And this is one of the concerns, right, is this idea that we’re enclosing the earth in this shield of metal, right.
Pamela Gay: Yeah.
Fraser Cain: We’re not worried about the stuff that’s at the low-earth orbit because it’s all just gonna get brought back in with the atmosphere.
Pamela Gay: Yeah.
Fraser Cain: It’s that next level out where you’ve got these spacecraft and they’re gonna be crashing into each other and shredding each other and making smaller and smaller debris particles. And eventually you might get this mist of dust-sized particles of spacecraft going at 25,000 kilometers per hour. And it will just make any attempts to kinda move through it, like moving through, I don’t know, some kinda grinder.
Pamela Gay: Well, it’s really kind of terrifying to think of the day when it’s possible economically to put CanSats into higher orbits. Because right now all of these little anything from bucket- to circuit board-sized spacecraft, they’re all going into extremely low orbits where they’re gonna eventually be heated up, melted, destroyed by the earth’s atmosphere. That’s good.
And the reason I say that this is good is because NORAD, which is one of the primary facilities that tracks space junk, they can’t detect and track things that are really smaller than a can of soda. And so these circuit board spacecraft we can’t see at all. You really need to be bucket-sized to be reliably tracked.
And so if you can launch a couple hundred of these easily on one big rocket, you’re literally going to end up with swarms of amateur telescopes, amateur communication satellites, research devices making it impossible to get the big things up there safely. And already we’re moving the International Space Station on a regular basis to get it out of the way of this piece of junk or that piece of junk.
I know the mistakes my students make in the classroom when they build robots. Not imagine that they’re building robotic spacecraft and those mistakes are being allowed to orbit the planet.
Fraser Cain: And the miniaturization is gonna keep going and you’re gonna end up like right now, as you said, [inaudible] [00:17:53] are now big. We’re onto eighth of a [inaudible] like just what looks like little – they just look like circuit boards, circuit board [inaudible] and the next thing is there’re gonna be fragments. I mean, you’re gonna have entire satellites that are completely miniaturized, whatever’s the minimum size to get a camera and communications.
And you can imagine these grid mesh networks communicating with each other around space. So the spacecraft keep getting smaller and you’re launching like buckshot into orbit.
Pamela Gay: Yes, yes.
Fraser Cain: And so I totally agree with you that this is of interest. So spacecraft designers, how do you plan to get your microsatellites back down and crash them into the earth’s atmosphere? Okay. So we’ve got that. GPS sorta the next layer, same kinda problem –
Pamela Gay: Yeah, it’s from –
Fraser Cain: — but it’s a bigger space so –
Pamela Gay: Well, from there it’s basically all the way up. You either put them in a parking orbit so something else can take over the orbit you’re in or you just kind of let them die in place and peaceably keep orbiting the earth until something goes and grabs them and goes, bad rocket, go over here.
Fraser Cain: Now what about when we get to some planets or some other objects like the moon? Like we’ve got NASA’s LRO is at the moon right now. LADEE’s at the moon. What’s the plan for them?
Pamela Gay: So we don’t normally think about it but the moon does have enough of an atmosphere to do bad things to spacecraft. And these science spacecraft that we have that are taking amazing beautiful high-resolution images are only orbiting a few tens of kilometers above the surface. And that’s enough for them to be experiencing drag such that if you let go and ignore them they’re not going to keep orbiting the moon forever.
Fraser Cain: Yeah, and they’re getting awful title forces between the moon and the earth and nothing is – you can literally not have anything stable around the moon for any long period of time. They’re all coming down.
Pamela Gay: Right. And this actually allows us some pretty awesome scientific moments. The inspiration for this particular episode was the recent press release about, well; it’s the month of April in the year 2014 and LADEE’s going to land catastrophically this month. This is – the way they phrased it is, this is not a landing you can walk away from.
Fraser Cain: It sounds like all of my Kerbal space program landings on the moon in the Kerbal Space Program.
Pamela Gay: Right, right.
Fraser Cain: No one’s walking away from any of my landings.
Fraser Cain: So LADEE is working on detecting the lunar atmospheric dust and environment. And the closer it gets the better the data it’s getting in some ways. And so they’re working really hard to make sure that they can boost it over mountains when they need to. And people forget how extreme the topography of the moon is. There are kilometer-deep craters, kilometers-high ridges. It’s a dynamic surface. This is why Galileo with its little tiny telescope was able to make out that the moon is not smooth.
And so they’re hoping that it will get lots of data until it’s very close to the surface but there’s always the random chance that it’s gonna smack into something on one of its low orbits. But the lower it gets the more data it gets and it’s really kind of awesome.
Fraser Cain: We’ve had situations where we’ve landed a mission on an asteroid, right, with the NEAR mission.
Pamela Gay: Yes, NEAR-Shoemaker Mission. This one was really awesome because it wasn’t fully planned out ahead of time that this was how it was going to end of life. And they basically were able to get all the way down to the surface of the asteroid [inaudible] [00:21:48] and just kind of gently plant themselves there.
And that is awesome on so many levels because, first of all, asteroids are tiny. Orbiting these things is an insert word that you use to describe finding a needle in a haystack. It’s a challenge because they don’t have that much gravity. You have to match your orbital velocity around the sun to theirs before you can transfer into an orbit around them.
They’re rotating and just trying to match your orbital speed, the rotation speed, all of these different things together and touch down softly. Well, they managed it with this little spacecraft and this is why we have such good data on this particular asteroid.
Fraser Cain: Yeah, just amazing. So we talked about Galileo, we’ve talked about what Cassini’s gonna be doing. Now what about those – the rovers and the orbiters at Mars?
Pamela Gay: And here’s another one of these great cases of we aren’t recycling so well. We are slowly littering the surface of Mars with dead spacecraft. There’s a bunch of great comics all over the internet about aliens walking across the surface and just seeing everywhere they look these dead rovers kind of everywhere. And we periodically have crashed other things that weren’t quite meant to crash on Mars.
And so Mars is a place where I can imagine 500 years from now little historic signs all over the surface saying, in the crater head you can see the wreckage of, and little – the more equivalent of velvet ropes marking off where we’ve left things to die, Poor Spirit –
Fraser Cain: So just to be clear, they’re just crashing them and that’s that and they’re not doing any attempt to decontaminate them. They’re just [inaudible] [00:23:43] –
Pamela Gay: Well, we do with Mars things try and get them clean ahead of time. So Mars is one where we have put an effort in to hopefully have a few less extreme files. But things like Mars Spirit rover just kinda got stuck in a sand dune and died there. And you can imagine that over the years the sand will perhaps blow up over it and it will become a sand dune. And just like people have unburied entire towns and cities in the desert of the Middle East, someday archeologists will be unburying rovers in sand dunes on Mars.
Fraser Cain: It’s a good point that they’ll be totally hidden under sand and dust within a few hundred years.
Pamela Gay: Mars Phoenix already is during the winters.
Fraser Cain: Yeah. Now, what about some of those spacecraft that are sort of on these one-way trips out of the solar system, the Pioneers, the Voyagers, New Horizons?
Pamela Gay: They just –
Fraser Cain: Any [inaudible] [00:24:41] sunset them?
Pamela Gay: So their sunset mission is kind of to go off and be the ambassadors of human kind. So it’s sort of like the elderly statesman who, in his final years, you send him off to be an ambassador in a nation that you’re not too worried about screwing up the politics.
Fraser Cain: Aren’t we really just letting them run out of power and dying in cold space?
Pamela Gay: Yeah, but they have friendly messages painted on them or carved on them or records –
Fraser Cain: Oh great, yeah. Please take your aging senator, throw him out into space cold a freeze solid but with a message painted on him, fire him off [inaudible] –
Pamela Gay: Yes.
Fraser Cain: I’m sure some people may wanna do that with their senators.
Pamela Gay: I can well imagine them like Sharpeed with the –
Fraser Cain: Yeah, exactly. You can have them, we don’t want them.
Pamela Gay: Here’s the Pulsar map.
Fraser Cain: Right. But, I mean, there – I mean –
Pamela Gay: There are silent ambassadors.
Fraser Cain: Yeah, they will gather every piece of data they can out of the spacecraft until the very end.
Pamela Gay: Yes. And luckily these are spacecraft that were built before we really seriously ran out of nuclear fuel cells for the radiothermic generators. And so they can last for an extremely long time. We’re still periodically getting data back from the Voyagers and it will be interesting to see what happens as they get – well, they’re already beyond the sun influencing part of our solar system.
Fraser Cain: And you know what the saddest way to sunset a mission is to run out of budget to keep operating it. But the spacecraft itself is still fine [inaudible] [00:26:10] –
Pamela Gay: And this could happen with Cassini.
Fraser Cain: Um-hum. There’s no way it’s gonna happen to Cassini. Like, I know it could happen – I promise you I’m gonna go talk to the prime minister of the Canadians to take over. Don’t you worry. The Canadians and the Europeans, we got this. But there’s a lot of spacecraft that are currently in the same concern right now that there are missions [inaudible] –
Pamela Gay: Cassini messenger.
Fraser Cain: Messenger, yeah. There are spacecraft right now that because of budget shortfalls, the solution is gonna be just turning off the switch [inaudible] –
Pamela Gay: The way this is phrased is, they’re under senior review. And what that means is the funding for education public outreach and communication of the missions science is zeroed for the most part. They can keep maintaining their websites but they’re under review and in a – only spend the money that’s necessary to keep your mission operating budgetary situation. And not all missions come out the other side of senior review. Some come out with extensions; some come out with parking orbits like WISE did. And others come out with; we’re gonna crash you into the surface of whatever world it is you’re orbiting. Goodbye. You’ve served us well. You’re now dead.
Fraser Cain: So has that – are there missions that have actually just – for budgetary reasons they’ve just shut the mission down and they’re not – and they just – even though it was a perfectly operational mission they’ve just stopped receiving data from it?
Pamela Gay: But they did that to WISE. That’s exactly what happened to WISE. And right now to look at the things that undergoing senior review, we have – Chandra is approaching senior review, [inaudible] [00:27:46] orbiter has been in and out multiple times. I’ve lost track of its current state. Messenger’s under senior review, Dawn. It hurts to look at the number of things that could be taken away from us because they’ve completed their initial mission. They were engineered so that they could keep going and –
Fraser Cain: Yeah, yeah, when you feel that the engineers are like, we need this – or the mission plan was like, we need this to run for three months. And the engineers are, like, winking at each other like, “Yep, no problem. It’ll only go for three months.” And they’re like three years, twelve years, no problem. We got this.
Pamela Gay: Right, yes.
Fraser Cain: You look at how long Spirit and Opportunity – and Opportunity’s still going. It was a three-month mission. It’s lasted, what’ll it be, ten years now? Crazy, right, just how long these missions have lasted. So the engineers are building these spacecraft. They’re capable of delivering a science for a decade plus and yet the budgets for the ongoing maintenance of these missions isn’t set aside and isn’t earmarked to last.
Pamela Gay: Well, and the problem that we’re looking at is two-fold. The more missions we have living longer and longer, each of them have their own sustainability costs. You have to pay mission engineers; you have to pay for the communication time. You have money going to the scientists doing research with the data that’s coming down. As you end up with more and more spacecraft you have more and more of these costs that start to build up.
So, okay fine. So in the perfect universe of the continually growing NASA budget, we could handle that and some of the costs go down overtime. You’re also faced with the but, but, but now we wanna go to Europa, now we want to go to Neptune and Uranus. We wanna see the outer solar system. Well, you need to find the money to do that. And then the reality is we don’t have that growing NASA budget.
Like I said at the beginning of the show, right now it conferences – it’s like we’re terminally ill patients wondering how much longer we have to survive because congress keeps cutting back our funding. And with flat costs on operating spacecraft the only thing left to kill is the human salaries or the spacecraft, and it’s usually both.
Fraser Cain: Right. Well, on that sad note, thanks a lot Pamela.
Pamela Gay: Thank you, Fraser.
Fraser Cain: We’ll talk to you next week.
Pamela Gay: Okay. Bye-bye.
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