Planetary Radio: Space Exploration, Astronomy and Science - Ad Astra Builds “The Martian’s” Rocket Engine

Episode Date: January 5, 2016

Mat Kaplan visits the Ad Astra Rocket Company in Texas where they are perfecting the VASIMIR electric rocket engine. Emily Lakdawalla has created a comprehensive timeline tracing missions throughout the solar system. Bill Nye salutes Planetary Society colleagues who gathered to record a Planetary Radio Extra year in review conversation. The new year’s sky is chock full of planets according to Bruce Betts.Learn more about your ad choices. Visit megaphone.fm/adchoicesSee omnystudio.com/listener for privacy information.See omnystudio.com/listener for privacy information.

The rocket engine that got the Martian to Mars, this week on Planetary Radio. Welcome to the travel show that takes you to the final frontier. I'm Matt Kaplan of the Planetary Society. We return to Houston, Texas for a visit with two leaders of Ad Astra, the company that hopes to revolutionize rocket propulsion and make the solar system a much smaller place. Bill Nye has praise for several of my Planetary Society colleagues who joined an online conversation about the year in space. There's no shortage of planets to view in the night sky,

says our regular guide, Bruce Betts, in today's What's Up segment. It all begins with our senior editor, Emily Lakdawalla. Emily, Happy New Year once again. You are the first to be heard from in this first show in the new year. We welcome it with this new creation of yours. Tell us about this timeline. I've been struggling for a long time with how to display where solar system spacecraft are, where they have been, and kind of be able to step back to display where solar system spacecraft are, where they have been,

and kind of be able to step back from all of solar system exploration to get a broad view of where we've been and where we're going. And so I came up with this idea of representing missions as little ribbons of timelines year over year over year. And it really was quite interesting putting this together to recognize how long modern missions last compared to ones just a couple of decades ago. You do have some very long lines on here. I'm looking at Mars at the moment, but then there's Cassini, it's Saturn. Did this reveal other things to you, laying it out this way, looking at everything all on one page? Well, it did.

I've been aware for a long time of the looming gap in humanity's exploration of the giant planets. But once I put things out on this timeline, I realized that there's something particularly dire coming up. In the beginning of 2018, NASA and ESA are not going to have any spacecraft returning data from any place else other than Mars. And that is really striking to me. Yeah, that is disturbing. And you talk about that. You reach pretty far into the past year as well, don't you? I do. And actually, the timelines that I've put together, I have ones that I did not even put into the blog post that go way further into the past, right to the beginning of space exploration. And it's amazing how the character has changed from

these multiple, great many short, very short missions to these long overlapping ones. And it's made me really come to understand one of the reasons that funding for NASA is so difficult is because missions last so long, they're actually victims of their own success. They have this huge portfolio of active missions that they have to maintain, even as they try to get new ones off the ground. All right. It is a fascinating December 31st, 2015 entry that Emily has posted at planetary.org. And I recommend taking a look at it. I've really never seen anything like it.

Thank you for this, Emily. And we'll be talking more throughout the year. Looking forward to it, Matt. That's Emily Lakdawalla, the senior editor and planetary evangelist for the Planetary Society. You will also be able to hear her in our hour-long discussion, another review of 2015, but this time we'll be joined by all of the colleagues we spoke to individually in our last show of 2015. That's Casey Dreyer, Jason Davis, Bruce Betts, for what I thought was a pretty rollicking

discussion, a review, at least of their highlights for the year just passed. You'll be able to find that, of course, at planetary.org slash radio. We'll link to it from this show, but it will be elsewhere, SoundCloud and lots of other places that you can find on the net. Up next is our weekly, our nearly weekly conversation with the boss, the CEO of the Planetary Society, Bill Nye, the science guy. Bill, I know you haven't heard it yet, but I did mention to you this discussion that we've recorded with four of my colleagues,

five of us at the Planetary Society. Let me just start by saying, you know, you all work for me. I guess that's true. I sort of work for you guys. Anyway, everybody, if you don't know these people, they're extraordinary. And what has contributed to the success of the Planetary Society the last two or three years especially is the remarkable work of our staff. Emily is the – I think the most knowledgeable journalist on earth about what humans do with regard to other bodies in the solar system. I think she's the number one most authoritative person. Planetary body by planetary body, I think Emily could win any contest. Then Casey Dreyer has gone

to Washington, D.C. Last year, he made eight trips to Washington. And as the old saying goes, Washington's a small town based on relationships. Politics makes strange bedfellows. Space brings together congressmen and senators that would not agree on anything else except a mission to Europa or other planetary missions, spacecraft sent to other bodies in the solar system. He's just really changed the organization. We're much more effective than ever. And then Bruce Betts, everybody. Bruce Betts studied under Bruce Murray, who was a colleague of Carl Sagan,

one of the co-founders of the Planetary Society, along with Carl Sagan. And he's just the most knowledgeable guy on planetary defense, on detecting asteroids, has run all of our science and technology projects for the last 15, 16 years at the Planetary Society. He's the man. He's the real deal. And then the newest addition, Jason Davis, who I think we'll be hearing much more from this year.

Yeah, Jason Davis is a journalist who really spent a lot of time on LightSail and did an outstanding job in helping everybody understand all the really odd and special technical problems, challenges, let's call them, for getting this odd little spacecraft, this wonderful little spacecraft on orbit, getting pushed by the sun. And we were very excited. Jason will be on top of that project. So it's really everybody who supports the Planetary Society, this is why you support it, to support these people, to pay the salaries of these people and you, Matt, of course. As the old saying goes, the strongest thing about any organization is its people. And our staff is just remarkable. So stay tuned, everybody, and turn it up loud.

They are a heck of a group. And to hear this unprecedented discussion, as I mentioned with Emily, you'll need to go to planetary.org and look for this edition of Planetary Radio Extra. We'll link to it, of course, from the show page, this show page at planetary.org slash radio. Bill, thank you. I'm sure all of those folks would agree with me.

It's a pleasure working for you. Thanks, thank you. I'm sure all of those folks would agree with me. It's a pleasure working for you. Thanks, Matt. Carry on. He's the CEO of the Planetary Society, Bill Nye the Science Guy. Now we go back to Houston, Texas to Ad Astra, not far from the Johnson Space Center, where they are attempting to build, actually have built, a revolutionary rocket engine, the one that got the Martian to Mars. They call it VASIMIR, the Variable Specific Impulse Magnetoplasma Rocket. It has not yet gone into space, except in the movies, but it's real, and it can be visited at the Texas headquarters of a company called Ad Astra Rocket. When I stopped by in mid-November,

I was greeted by Jared Squire and Mark Carter. Physicist Jared heads the research effort at Ad Astra, while nuclear engineer Mark Carter is in charge of technology development. They answer to Franklin Chang Diaz. If that name sounds familiar, it's probably because he flew on the space shuttle. He flew on it seven times. Mark Carter first took me on a tour of the facility. You can hear my amazing audio record of that tour and see photos on the show page at planetary.org slash radio. It was one of the geekiest and most exciting experiences I've ever had, and it included climbing inside the giant vacuum chamber where Ad Astra fires its electric engines. Mark, Jared, and I then sat down to talk about the future of rocket propulsion.

Mark and Jared, I have now put another checkmark on my bucket list because I'm at Ad Astra. It is a great pleasure to be here. Thanks for letting me in and for sitting down for a conversation. So I watched your terrific documentary, the one you got done with a Kickstarter campaign called Crossing the Space Frontier, and we'll put a link up to that as well. That's a very dramatic piece. It does a great job of communicating not just the science that you guys are up to here and the high-level engineering, but the motivation, the feeling that goes behind this. Is this something that you guys really believe in as just having to do with, you know, the future of humans in space, Jared? I've been doing this 20 years, and that's really the

primary motive that I've had the whole long time, is just to bring an increased capability for humanity, and the transportation is such a fundamental piece of everything we've done in history. Mark, same for you. Yeah, absolutely. It's, you know, it's a different type of logistics you have to do when you're really getting serious about colonizing or moving out into a new frontier. We're all for trying to go longer term, expand the horizons. In the video, Mike Griffin, former NASA administrator, he says rocket propulsion today works, but just barely. What does he mean by that? Well, what he really means is that rocket engines today are chemically driven

or the main ones that people think about. You're limited for how fast you can put your propellant out the back end. So general momentum conservation says that how much propellant you put out times how fast it's going out is what gives you the momentum to make a rocket work. And so you can increase the mass flow, the amount of propellant through a chemical engine, but you really can't make it go out any faster than whatever hydrogen and oxygen burns at. So that puts an upper limit on your exhaust of about 4,000 meters per second. If you want to go faster than 4,000 meters per second,

you have to have exponentially increasing amounts of fuel in order to achieve faster speeds. So what this system does that we have, electric propulsion plasma engines allow you to go to the next temperature range, which is instead of thousands of degrees, it's millions of degrees. Now your propellant is coming out at very high velocity, 10 times faster velocity, and that means that you need one-tenth the amount of propellant to achieve the same basic momentum transfer.

So all that propellant savings can be used for other payload. It can be used to eventually go faster all the way up to the speeds that you're coming out at 50 kilometers per second instead of four. So better than an order of magnitude better. Yes. It's about an order of magnitude better? Yes, it's about an order of magnitude better in its capabilities. And I think people even in von Braun's day understood that to go long distances and go fast, you would have to go to a plasma type state for

your propulsion. So how much of this also is not just stuff coming out a lot faster, but doing it for a lot longer? I mean, after all, the big chemical rockets, some of them, you know, you talk about running them for a couple of minutes and you're done. You guys and the other engines that we've talked about some on this show, so-called ion engines, which, Mark, you told me really are plasma engines, can run for months at a time. Look at the Dawn spacecraft. I mean, that's a big part of it, right, Terran?

Well, yeah, electric propulsion has been a huge improvement, and that was a great gain. The Dawn and Deep Space One, those ion engines were a great achievement. Now the push is power. If you want to increase mass and move things relevant for humans, you need to take that type of technology and expand it to more powerful engines, and that's what more powerful engines. And that's what we push on.

VASIMIR, therefore, is a big step up, even from these advanced engines that are on the Dawn spacecraft. Yeah, power level-wise, we're looking at 10 to 100 times more powerful is where we're starting. I told Andy Weir, the author of The Martian, of course, that you guys really owe him big time. I said, Franklin Chang Diaz really ought to send him a check or a box of candy or something. Because, of course, he mentions in the book, at least, his big spaceship, Hermes, has Vazimir engines. When you read the book, were you surprised? Well, I read the book after I found out that that was in there. Somebody else told me. I actually read the book after I met him and his father, so I had no idea about the book or the movie.

And he came here for a visit. Yeah, he told me. That's where I learned about it, from him directly. Yeah, they didn't mention it, of course, in the movie, but I think you got good exposure, certainly, from the book. It's the kind of publicity you can't buy. He's sort of nonchalantly in the book, and it even comes up in the movie. They talk about there's a nuclear reactor on that ship,

which I assume is providing this vast amount of electricity that is needed to push that big spaceship all the way to Mars. That's right. We've done several studies on how you would do sort of like human missions to Mars. And solar power just becomes so unwieldy when you get to the megawatt levels that you really need for taking these larger vehicles to and from Mars. So you pretty much have to go nuclear electric, and the power levels need to be about 10 megawatts. And I think that's very close to what Andy Weir's systems were doing. So he did a good job of getting the basic

you know, that's an optimum location for that type of a trajectory. He even said to me when I asked him, do you think we're going to see nuclear reactors in space? And of course, they've been in space. The main objection, of course, now being more political than technological. And he said, oh yeah, it's inevitable because you just can't find a better, more compact source of energy. I mean, Jared, do you have any problem with that? No, I think the analogy I think of is our Navy. Just imagine if we had not taken the step to nuclear, what would our Navy be like?

The energy density, that's the main thing the electric propulsion brings. It eliminates the energy density. That's the main thing the electric propulsion brings. It eliminates the energy density limit. The challenge is the power density is the challenge for electric propulsion. So it becomes what they call power limited. Chemical rockets are energy limited because they can only have so much energy in that chemical bond. But the nuclear takes that out, takes it out. And in short term, solar takes it out, which is basically effectively nuclear. You're pulling your energy from the sun. Good point. Below that level of 10 megawatts, which you might want to push people and lots of mass to Mars, right behind you is this beautiful artist's conception of a solar-powered

or VASIMR-driven spacecraft, which is also in the video that people can see. And it's got these big solar panels. I mean, in that conception, how much power is being sent into those engines that you guys are working on? Well, this is our baseline 200-kilowatt system, so 0.2 megawatts. The reason for choosing that is that's a very good sweet spot for doing tug operations around in low Earth orbit or out to the moon. Solar arrays at that size are tractable. The sun only puts out so much power. And so to get more power, you have to have more area. And

the more area you have, the more control issues you have eventually. But I think 200 to even 400 kilowatts of solar power is considered to be doable. It just needs a customer, and, hey, that's us. Well, 200 kilowatts, that's not really beyond what you guys are starting to do with this big vacuum chamber out here, right, Jared? That's why we chose this point, because we've talked to the folks that are developing these solar arrays, DSS, Deployable Space Systems, and also Orbital ATK. Both those folks out in California have developed deployable systems that can do this at these power levels. They're impressive. Give me a little bit of background about how VASMR actually works. It has similarities to another technology that fascinates me,

and that's the decades-long effort to try and achieve controlled fusion. Mark? Yeah, I'm a nuclear engineer, and I spent 20-some years working on the fusion problem. We use a lot of the same technologies and techniques that were developed in fusion starting in the 50s. So the fusion field is maybe not so well known as the space light. It's not as sexy a thing. But the energy problem has been on… I don't know. I think it's pretty damn sexy.

Okay. Well, I do too. I spent a lot of time working on it. But the great thing about this is in a fusion system, you're trying to hold the plasma for a long period of time. Confinement is an important aspect of fusion so that you get enough fusion reactions to really make it work. But whenever you try to confine plasma, it does not cooperate very well. So the great thing about our system, and we discovered this, is that the best thing to do with a plasma after you heat it up is to let it go and make it into a rocket.

do with the plasma after you heat it up is to let it go and make it into a rocket. So it's been a perfect application for many of the technologies, the radio frequency technologies, these natural harmonic waves that exist inside the plasma. We can exploit those to heat it and control it. And the instabilities that you run into by trying to confine it are pretty much eliminated. the instabilities that you run into by trying to confine it are pretty much eliminated. Jared, you said you also come out of the fusion world, right? And it is a lot of the same technology. I mean, you're pumping energy in and you're keeping the stuff from touching the sidewalls of your rocket engine, right? Because it's really hot stuff.

Actually, what we're doing is much easier than fusion. My conversation with Ad Astra's Mark Carter and Jared Squire about the VASMIR rocket engine continues in a minute. This is Planetary Radio. Hi, I'm Andy Weir, author of The Martian. Do you know how my character, Mark Watney, will make it to Mars someday? He'll get there because people like you and me and organizations like the Planetary Society never stop fighting to advance space exploration and science.

The challenges have rarely been greater than they are right now. You can learn what the Society is doing and how you can help at Planetary.org. Mark and I will thank you for taking steps to ensure humanity's bright future across the solar system and beyond. Hey, hey, Bill Nye here. I'd like to introduce you to Merck Boyan. Hello. He's been making all those fabulous videos, which hundreds of thousands of you have been watching.

That's right. We're going to put all the videos in one place, Merk. Is that right? Planetary TV. So I can watch them on my television? No. So wait a minute. Planetary TV's not on TV? That's the best thing about it. They're all going to be online. You can watch them anytime you want. Where do I watch Planetary TV then, Merck?

Well, you can watch it all at planetary.org slash TV. Welcome back to Planetary Radio. I'm Matt Kaplan, this week looking back at a terrific visit to Ad Astra Rocket Company, just outside Houston, Texas, and minutes from NASA's Johnson Space Center. Mark Carter is Ad Astra's Senior VP of Technology Development. Jared Squire is the SVP of Research. Let's talk about some of the applications, like that big one on the wall behind you there, which is there's a pretty cool animation in the film that people might want to take a look at.

Talk about space trucking. That's what this thing is doing, right? Right? It's visiting different spacecraft and doing what to them, Mark? Well, in this particular case, we were trying to deorbit. Orbital debris is up there and becoming a bigger and bigger problem all the time. You have large solar arrays, but almost everything else is pretty small by comparison to chemical engines. So this system goes up one time and can actually rendezvous with these Zenit upper stages from Russian launches.

Oh, that's what you have. It's got stored away in those racks there. That's what we use as an example because they're real targets. You can actually go engineer a mission to handle real targets that are potentially a problem. Yeah. So this system goes up and gets close. It gets in proximity with the booster. The idea here is you would implant a solid rocket booster into the nozzle

of the Zenit and then stabilize its tumbling or whatever it's doing. And then you can come back and effectively birth with your solar system or your solar powered electric propulsion system. And you do that so that you don't have a big impact docking with the solar arrays. This ZENITE thing is about the size of a school bus, okay? It's not small. So once you've got it under control, then the electric propulsion system can take over and lower it from about 800 kilometers high down to about 400 kilometers. From that height, your solid rocket booster that you implanted into the nozzle of the

Zenit, you can go ahead and plant it safely wherever you really want to put it, probably the Pacific Ocean or something like that. Just decelerate it and it comes down like everything does. And with this kind of a system, you can actually go get 19 real targets with one mission. And when you're done, your space tug comes back. If you load it up with some more trays of solid rocket boosters and replenish the propellant supply, it can go get more things. It just stays in space and continues to work, and you don't throw it away.

Just working on solar power and argon, right? Like the engines you've got out here that you're testing. Right. Yeah. We could use other – for some things you might want to use krypton or argon or even other gases. We're not super particular about what gas we use, but argon is a very good one for us. Jared, another application that is talked about, it's shown in the film, in fact, is something that the Planetary Society cares a lot about, a lot of people care about, and that's asteroid redirection and deflection. You know, when we find that big one that has our name on it, why is VASIMIR or this kind

of propulsion especially suited for that? It goes back to power. And you have a big asteroid, you need power to move it. And so you need a powerful engine to move a large mass. Having that power capability is what's key. That's what we've always been after is delivering an engine that has high power, hundreds up to megawatts. But if you have a big one in a direct target to earth, you're going to want to move it as fast as you can with all the power you have available.

I mean, it's high power by electric propulsion standards, but it's also just a lot of energy because remember, we're decoupled. Your solar power is going to keep working as long as your solar panels are functioning. Because of the propellant advantage, you can sit and push on it. It might be, I mean, chemical rockets might be gigawatts, but they burn out in tens of seconds. So your total power that you have available is limited to how much chemical energy you have in your propellant. With a system like this, you can go make much more efficient use of the propellant you have and pull power in from the solar arrays, and you can push on this thing for months. So you can go out and push and actually change the energy, the kinetics of the orbit

by pushing on it for months at a time instead of just going out and trying to hit it with something abruptly. Would you say that maybe the ultimate application for what you're hoping to achieve here is turning humanity into a multi-planet species? Yeah, that's the plan. Just like what sailing ships and steamships did to make people multi-continent. We can make it a multi-planet by that transportation is the key. My only regret today is that I'm not getting to meet your boss because I'm told he's in Washington, D.C., doing business on behalf of the company.

Tell me about him, Franklin Chang Diaz. He is the reason why we're able to do this. I don't know how else to say it. He's had this vision for many years, and he was able to see that the technologies might not have been directly available, but they were coming. What you need for that requires technologies that in the 80s were stretching it, but possible, and he saw that they were coming. And by the 90s, you started seeing the superconducting magnets appear. The high-power radio systems that we need are solid state.

All that's become just like chips in your computers. So seeing that coming in ahead of time was a stroke of genius to work on that part of it. So he has great vision for doing that sort of thing. And plus, he's also gone out and raised the private money that we needed to make this work because it's different from what the government systems have typically used. And that makes them, I think, nervous about trying to support it. He's a very stubborn guy. He doesn't give up.

He must be. So that's, I think, the main reason why we're here. Without him, we wouldn't be here. Like I say, he's tenaciously optimistic. And it rubs off. I mean, when he's here, he's just very positive. And just that brings energy to everybody involved. And he and you have been pursuing this dream for a long time.

What do you think is the outlook? I mean, obviously, it's still a struggle. You've got to find the funds and hopefully get one of these up into space at some point and test it where it's supposed to do the most good. Yeah, the funding is probably the biggest challenge now. The engineering, like I said, once we cleared the physics hurdle, you know, the no amount of money is going to change the physics, but we've crossed that. We've proven the physics works. So it's just a matter of hard, more grungy engineering at this point and funding. The funding is probably the hardest part.

So what's ahead in the next five years? I mean, I saw, we can't show it to the audience, but I saw the next engine coming together out there in the shop floor. Well, the next step in the next year or two is to put together a rocket core, which is the main part that handles the plasma and couples the power to the plasma, to get that rocket core so that it runs in thermal steady state. So it can run for thousands of hours. These propulsion systems, they need to be, you steady state. So it can run for thousands of hours. These propulsion systems, they need to be, you know, not just able to run for a long mission,

they need to come back and run multiple missions too. So our goal is to run for thousands of hours and we need to be thermal steady state. That costs a lot of money to get those tests put in place, but we have some support from NASA, plus building on all the private support we've had for the last several years, we're now getting ready to do those tests and demonstrate that. We'll also be able to look at erosion measurements and things like that, which today we have about three hours of accumulated time, 10,000 shots, but they were short shots for physics purposes.

But we can't measure the erosion, so we don't know what the answer is. Zero is not a good number to use. We're scientists. We want to know what the number really is. So we think if we run for 100 hours continuously at 100 kilowatts, we'll have a good chance to measure maybe something, and whatever we measure will tell us how to extrapolate to the long lifetimes.

The rest of it is mostly engineering. The other piece, which where we're looking, hopefully NASA will continue down a great path, is the funding of these solar arrays. The power source is critical. And ultimately, if the U.S. would take the step towards nuclear. If the U.S. doesn't do it, other countries are capable. So we have to watch out that if the U.S. doesn't, we may be following, not leading. Gentlemen, Mark Carter, Jared Squire, thank you very much for the conversation and also

for staying in this fight for the long haul. Best of luck as VASIMR continues to show its potential for achieving our dreams in space. I'll just wish you Ad Astra. Well, thank you. Thank you. Bruce Betts is with us for this week's edition of What's Up on Planetary Radio. He is the Director of Science and Technology for the Planetary Society. He's going to get us ready for a new year of stuff in the night sky. Hi. Hi. In this first week of the new year, you can check out Mercury, though it's fading and dropping fast, low in the west shortly after sunset. And then in the pre-dawn, we've got our lineup of four planets, and they're doing some

kind of interesting stuff this week. From lowest to highest, we have Saturn, Venus, Mars, Jupiter, along a line of representing roughly the ecliptic, the orbital plane they all orbit in. But on the 6th and 7th of January, you will see the Moon near Venus and Saturn, making a nice little grouping. And then Saturn and Venus are really, really close together on the morning of January 9th. And generally, we'll be getting closer together until the 9th, and then getting farther apart following the 9th. On to this week in space history, you remember that in 1610, this was the week Galileo discovered Callisto, Europa, and Io using its spiffy little telescope. How appropriate that there's Galileo references.

You will learn at the end of the segment today. Ooh, I'm so excited. On to random space fact. Well, there's an exciting new year for you. All sedate, all the time. 2016, the year of sedate random space fact. Not really. Saturn's rings are

thought to be more than 99% water ice. So they have other impurities, but they're by and large water ice. Better than the stuff coming out of taps in parts of the United States. Yeah, it helps, though, still, even with the rings, to have some type of filter. On to the trivia contest.

We asked you, last millennium, what Apollo spacecraft was named Falcon? How'd we do, Matt? Very nice response, I suspect, because people were interested in winning this copy of Randall Munroe's Thing Explainer, Complicated Stuff. In simple words, it is a signed copy of this terrific book by the guy who also, of course, created and continues the wonderful comic strip XKCD. You owe it to yourself if you're a science geek to take a look at this stuff. I got this from Rennie Christopher. He may be a first-time winner, long-time listener though. He said, Apollo 15's lunar module

was named Falcon after the Air Force Academy's mascot. All three crew members were Air Force. Despite that affiliation, the command service module was named Endeavor after a British naval ship and eventually a space shuttle that now lives in Los Angeles. How about that? Did he do OK? Yeah, very good. Bonus points for extra information. Then, Rennie, congratulations. You're getting that book by Randall Munroe and a Planetary Radio T-shirt. So, yes, very much. Congratulations.

So, yes, very much. Congratulations. He added, it's been said, you know, that Apollo 15 made it to the moon in less than 1.246 times 10 to the eighth parsecs. Still making those Star Wars references. Hoboken, New Jersey, said that Falcon landed near Hadley Rill in an area called Pallas Petridnius. Petridnius? Anyway, when you're not speaking... It's a place near Hadley Rill. Thank you. It's the Marsh of Decay when you're not doing it in Latin. You've mentioned this as a random space fact.

It carried the first rover. It did indeed, the first lunar rover. Wheels on the moon driven like a dune buggy by astronauts. And one of the rocks they picked up was the Genesis Rock, according to Mark Little in Ireland. I told you that there was a Galileo reference. Stephen Coulter, Woodville, Australia. It was here that Dave Scott dropped both a hammer and a falcon feather that proved Galileo was correct about gravity fields. That is a very cool video if you have not seen it.

Yeah, you know, we'll find it. We'll put up the link on the show page, planetary.org slash radio. All right, we can go on to the next one. Hydrogen and helium come in as the first and second most abundant elements in the Milky Way galaxy. first and second most abundant elements in the Milky Way galaxy. What comes in a distant third as the third most abundant element in the Milky Way galaxy by mass fraction, if you need that part, go to planetary.org slash radio contest. Get us your entry. I don't think it's unobtainium. There's a hint. Oh, great. Now you gave away the answer.

Well, I narrowed it down. You have until the 12th, Tuesday, January 12, 2016, to get in on this one. And our prize package, it's that big one again, a Planetary Radio t-shirt, a Year in Space desk and wall calendar set from the folks at yearinspace.com. Bruce and I contribute to that. Also, a 200-point itelescope.net account from iTelescope, the worldwide network

of telescopes. You can buy in, take pictures, look at anything you want in the northern or southern hemispheres of the sky. Okay, I got through it. Very cool prize package. All right, everybody, go out there and look up the night sky and think about bollisters. Thank you, and good night.

Well, I'm not going to think about bollisters, but I will think about Steven Peterson's note. Steven wrote, Matt, how dare Bruce say you are on the dark side? You are always in the light of the stars. Oh. Thank you, Steven. Thank you, Bruce. I know the power of the dark side. He is, when he's not a dark lord of the Sith,

the Director of Science and Technology for the Planetary Society, who joins us every week here for What's Up. I think I like the lightsaber effect better. Planetary Radio is produced by the Planetary Society in Pasadena, California, and is made possible by its high-voltage members. Danielle Gunn is our associate producer. Josh Doyle created the theme music. I'm Matt Kaplan. Clear skies.