Planetary Radio: Space Exploration, Astronomy and Science - Is This How to Land People on Mars?

Episode Date: September 28, 2009

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Hello again, podcast listeners. Matt Kaplan, back with a couple of important messages for those of you who made a generous contribution to Planetary Radio. This will take a minute, bear with me. First off, you did it! Our show is safe for the time being, for the immediate future, and it really is thanks to you. Times are still hard, so we will continue to welcome support from those of you who have not yet donated, which you can do at planetary.org slash radio. Now, there are some of you who may be wondering where your Planetary Radio t-shirt is. There are two reasons you may not have received it for your $50 or greater contribution. I learned a couple of days ago that we've run out of shirts. Not that we started out with all that many, but our call for help was more successful than some thought it would be. Not me, of course. I always knew you folks would come through. Never fear. More shirts are now on order. There's another problem, though, that's a bit more serious. We know that some of you made your donation to Planetary Radio

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And if your donation was for $50 or more, we'll put you on the list for a stunningly attractive T-shirt. You have my personal apology for any inconvenience. If you choose not to write to us, believe me, your donation, your gift, is still going to be put to very good use by the Society, but we know that if you intended to put it toward the radio show, that's probably where you'd still like it to go. We are sorry. We were new at this. We won't make the same mistake again. Again, if you think your donation might have been misdirected,

let us know by writing to planetaryradio at planetary.org, the same address we use for the Space Trivia Contest. Thank you, one and all. Here's this week's show. How to Land People on Mars, this week on Planetary Radio. Hi, everyone. Welcome to Public Radio's travel show that takes you to the final frontier. I'm Matt Kaplan of the Planetary Society.

You know how we media people love to exaggerate. No one really knows yet if an inflatable heat shield will be the solution for landing humans on the Red Planet. But it looks like the best idea so far. The first test in space of an inflatable reentry vehicle was a big success. We'll talk to the leaders of this project. Bill Nye, the science and planetary guy, says the discovery of water on the Moon is terrific, but not a good reason to send people there. Emily Lakdawalla will tell us why the miracle of adaptive optics for Earth-bound telescopes

has its limitations. And Bruce Betts will help me give away a Blu-ray copy of The Universe, the exciting series now airing on the History Channel. We'll leave the water on the Moon to Bill, but that's not the only place in the solar system where there's news of the wet. Mars Reconnaissance Orbiter scientists have positively identified the material at the bottom of a new Martian crater as water ice. In fact, it appears to be in several craters formed in just the last few months. This means an impact mission, much like the LCROSS lunar impact coming on October 9, could reveal much about the ice that seems to be nearly everywhere on Mars if you're willing to dig for it.

And as the Phoenix lander showed us, you may not have to dig far. By the time you hear this, the Messenger spacecraft will probably have made its third and final flyby of Mercury. The probe goes into orbit next year. Here's Bill. Hey, hey, Bill Nye, the planetary guy here, vice president of the Planetary Society. You can probably hear everybody's very excited because we found water on the moon. We took the Deep Impact spacecraft, which went by a comet, redirected it, renamed it the Epoxy mission, and on a calibration run going over the lunar surface, the surface

of the moon, people discovered a film or the presence of water, water and hydroxyl groups. These are the molecules that have an oxygen and hydrogen hooked together hanging off the side. Because, you know, H2O could also be written H-O-H, if you're with me. Well, anyway, they then alerted people that worked from the Indian Space Research Organization that worked on the Chandran spacecraft. And they used the Moon Mineralogy Mapper, the M3, and it has an infrared spectrometer.

And they found there's a cycle. That is to say there's a hydration cycle. There's like a water cycle in a weird way, weird by Earthling standards, on the Moon. Now, this goes way back. People have been hoping to find water on the moon. Well, they did, but it's a tiny, tiny film. There's not like there's ice cubes lying around, and there's a day-night cycle that somehow changes this hydroxyl bonding. It's fascinating. Now I'll just say this was using good scientific instruments to do basic research and make a remarkable discovery. This does not, for me,

mean we need to send astronauts or cosmonauts or taikonauts to the moon to look for the water. In less than two weeks, the LCROSS spacecraft is going to be driven into the moon. It'll knock some of the moon's regolith up into space, some rocks, and we'll sniff around and see if we find more evidence of water. It's an exciting time on the moon, but we don't need to spend that much money to make these discoveries. Well, thanks for listening. I hope you will consider becoming a Planetary Society member if you're not, because we direct space policy. We do what we can to tell the U.S. Congress and NASA what we should be doing in space

so that we could, dare I say it, change the world. Starting this week with water on the moon. I've got to fly, Bill Nye the Planetary Guy. Gotta love that sound if you're a regular in these parts. It was a Black Brant 9 rocket taking off from Wallops Island, Virginia, last August 17. Tucked tightly into the nose of that rocket was the Inflatable Reentry Vehicle Experiment, or IRVI. Four minutes later and 200 kilometers up, IRVI was released and ballooned into a giant mushroom. That mushroom then demonstrated that we may finally be on track toward a system that can get really big landers to the surface of Mars. Better than listening to me talk about it is

watching the video. We've got the link at planetary.org slash radio. We've also got the three leaders of this experiment. Mary Beth Wask is the project manager. Steve Hughes is IRVI's lead engineer. And Neil Cheatwood is both the IRVI principal investigator and chief scientist for NASA's hypersonics project at the Langley Research Center in Virginia. That's where I recently caught all three of them. First off, folks, I want to congratulate you on that extremely successful test, at least from everything that I've read a few weeks ago. And we're going to get into how this thing works. My goodness, an inflatable reentry shield. But

first of all, Neil Cheatwood, if I could start with you, have you maybe come up with a way to safely get big things, like big things containing humans, down to the surface of Mars? Well, it's certainly a first step along that way. You know, our challenge is when we go to Mars, we have to deal with a very thin atmosphere. I like to call it a poor excuse for an atmosphere. It's too thick to ignore, but it's too thin to really get the drag that we can at Earth or at, say, a Titan or Venus or someplace like that. Our challenge is, you know, we're limited to the size of our launch vehicles. So we

basically try to get as big an aeroshell, an entry vehicle, as we can in these launch vehicles, but we're limited to what size we can go. Yeah, you can't go bigger than the diameter of the rocket, right, or the top stage or whatever's getting you there. That's exactly right, at least the way we're doing it now. And so the idea behind this is, okay, we need more area. How do we do that? Well, our approach is we deploy something bigger. So it's like an umbrella concept where, you know, you carry around your umbrella, it's

thin until you open it, and then it gets very large in area. And that's what we need. The more area we've got, the more drag force we produce, and the more drag force we produce, the more stuff we can slow down. It's interesting because we've had Rob Manning of JPL on this show, who is another expert on getting things down to Mars, and he's talked about that sweet spot, or the opposite of a sweet spot, just the way that you have. That, you know, if only Mars was either thicker or vacuum, we'd have an easier time. We'd know how to do this. Looking at this inflatable shield, it looks like a fairly simple concept.

I'm sure it was far more complex to make it work right. Well, conceptually, I think it is a fairly simple concept. The real challenge is there is some significant engineering that goes into it. We need to, you know, when we slow down, we're going to generate heat, and we're going to have aerodynamic loads. So we have to design a system that will handle the structural loading, so that's our underneath element. And then the outside has got to be able to take whatever heating we generate.

Now, since we're large in diameter, we can actually, for a given amount of stuff, a given mass, we can reduce the amount of heat we would see over a smaller diameter entry shield, but we still got to deal with it. And really, what we're showing here is the development in materials over the last 30 or 40 years, since they first started looking at inflatables has come to a point that we can actually do this. Mary Beth Wesk, you're the project manager for IRVI. I assume that that means that you had oversight of all the testing and actual design and construction of this test vehicle? Yeah, that's correct.

A team of about 10 engineers and technicians here at Langley work together to review the design, implement it, and do all the testing both here at Langley, also at ILC Dover, and then ultimately at Wallace Island. Can you describe it a little bit? I mean, we're going to highly recommend that people take a look at the website, as I said, where they can also see the amazing footage of the test itself and some animation that shows how IRVI works. But how big is it, how heavy is it, and what's it made of? I'll add to Steve. Steve, that would be Steve Hughes, the lead engineer for the project.

The aeroshell had to pack inside the sounding rocket payload, and it's a fairly small payload envelope. It's about 19 inches maximum diameter. We had to put our electronics and instrumentation and radios and all the inflation system had to fit inside the aeroshell. So we basically had an annulus about 11 inches in diameter on the minimum side and 16 1⁄2 inches on the maximum side, and it was roughly 4 feet, 4 1⁄2 feet long. So we packed into a pretty small package. The density ended up being on the order of that of wood, so it was packed in very tightly.

And then we deployed to 10 feet in diameter, so it's a pretty sizable increase, about a factor of 8 to 10 increase in diameter. And the animation that's on the website really does show that, as Neil said, it opens up like an umbrella. Mary Beth, it looked like sort of like a scuba tank inside there to provide the gas. That's true. We had a nitrogen tank inside that inflated the air shell once we completed our separation and also separated from our restraint bag. It's interesting you say that it's a scuba tank because it's actually a tank that's similar to what a fireman wears on his back. And it's a two-stage regulator system, just exactly like you'd have for a scuba cylinder. You'd knock the high-pressure gas down from the bottle to a manageable pressure, and then you regulate it down to a very, very low pressure for the inflatable, because the inflatable does not require a very large pressure to maintain its structural integrity through the load.

Neil, so much work has gone into coming up with materials that would stand up to the kind of heat that reentry generates over the years. But none of those previous researchers had to also come up with a shield that was flexible, that could be packed away into such a small container. What actually faces downward as this thing plunges through the atmosphere? Yeah, I think you're referring to the various rigid ablative materials that we typically are developing here at NASA or in the industry. And yeah, what we did was we actually, for IRBEE, we took basically off-the-shelf items. I mean, I don't know that the average person thinks they're off-the-shelf, but our structure,

the inner part, is made of Kevlar. And then we've got Kapton films outside of that that prevent the hot gases from getting to the Kevlar. And on the outer layer is a material called Nextel, which is just a high-temperature fabric. So it's an open weave, actually. It's not sealed to the gases, and so that's why we had to add the Kapton behind it. Stay with us. There's more to tell about the inflatable reentry vehicle experiment when Planetary Radio continues in a minute.

Hey, hey, Bill Nye the Science Guy here. I hope you're enjoying Planetary Radio. We put a lot of work into this show and all our other great Planetary Society projects. I've been a member since the disco era. Now I'm the Society's Vice President. And you may well ask, why do we go to all this trouble? Simple. We believe in the PB&J,

the passion, beauty, and joy of space exploration. You probably do too, or you wouldn't be listening. Of course, you can do more than just listen. You can become part of the action, helping us fly solar sails, discover new planets, and search for extraterrestrial intelligence and life elsewhere in the universe. Here's how to find out more. You can learn more about the Planetary Society Transcription by CastingWords Report magazine. That's planetary.org slash radio. The Planetary Society, exploring new worlds. Welcome back to Planetary Radio. I'm Matt Kaplan. My guests are Neil Cheatwood, principal investigator for the IRVI, or Inflatable Reentry Vehicle Experiment, Mary Beth Wask, project manager, and Steve Hughes, its lead engineer. IRVI surpassed its goals during a test on August 17.

The mushroom-shaped vehicle successfully made it down through Earth's atmosphere after starting from more than 200 kilometers up at the edge of space. Our conversation picks up again with Neil Cheatwood. You actually did get into space, what, 130 miles up, a couple hundred kilometers roughly? So this was a pretty realistic test of what you'd have to do to come back down at least through the thick atmosphere of Earth. Yeah, the concept here for our real mission is we would deploy the aeroshell prior to entering the Mars atmosphere, or any other atmosphere for that matter.

It could be used elsewhere. And so we actually used a sounding rocket that did take us exo-atmospheric. matter. It could be used elsewhere. And so we actually used a sounding rocket that did take us exo-atmospheric. And once we separated from the launch vehicle, then we actually deployed prior to coming back into the atmosphere. By the way, we didn't have a control system or anything. So we had developed an aerodynamic database that gave us confidence that no matter what orientation it came back in, it would right itself so that it would be flying forward. Mary Beth, I was impressed when I watched the video because I looked at that crowd in the control room, and this really, I mean, it wasn't a shuttle launch, but it was a significant portion of that in terms of what it took to pull off this sounding rocket launch and then tracking IRVI as it came back down.

Yeah, that's correct. It was quite a large contingency of support. You have the team that's monitoring the payload and performance of the payload, even prior to taking off on the ground and making sure everything's working properly. You have a team that's looking at the meteorological data and making sure that we're going to meet our requirements for safety as well as for the payload. You have a team of the range safety who are looking at making sure that we're going to meet our requirements for safety as well as for the payload. You have a team of the range safety who are looking at making sure that the waterways and the air traffic is clear to ensure there's no issues there. Then you have all the ground support, all the telemetry and all the radar tracking.

So it's definitely a large group, a team of people out at the island that are working with us. Probably, I would say, maybe 30 people in the control room. We have people at the launch pad as well. Then we also have people in a facility getting the telemetry and the data back down to the different facilities for monitoring. I saw this described in some of the NASA material as a wind tunnel in the sky, but Steve, how did you do your testing on the ground to achieve what Neil mentioned, which is really pretty amazing? This thing just opens up, rights itself, and comes back down. We did extensive testing on small-scale articles. We did ballistic range shots where you fire an article out of a cannon to get the dynamic stability coefficients to determine

whether it will oscillate and flip over or whether it will stabilize and damp out those rates that are imparted to it when it hits the atmosphere. We did some wind tunnel testing, I think in Unitary, which is a supersonic tunnel. But mostly the database was put together from previous missions, previous experience we have here at Langley, and then pieced together and used in our post simulation, which is a trajectory simulator. And the database was applied to the post simulation, and we threw it several off-nominal cases and verified that the vehicle was stable with the computer.

We didn't really have a wind tunnel that could test this vehicle at scale, so basically the best place to do it is a dual launch. I mean, there's only so much you can do with little ground-based models and testing and simulation. Eventually you do have to shoot it into the atmosphere and see how it flies in free flight. Neil, how did it perform? I mean, was it as successful as I've already said? Yes, it actually was more successful than we had hoped for. We did have a very good aero database to tell us how it would behave through the heat pulse,

and that's where we basically defined the end of the experiment was once it got through that pulse. But we weren't real sure how it would behave at the lower supersonic speeds or transonically or even subsonically. would behave at the lower supersonic speeds or transonically or even subsonically. However, in the actual flight, we could see from the video that we got, the downlink we got, that it actually did not oscillate very much at all, whether it was supersonic or even transonic. It grew a little bit, but then damped back down subsonically. So beyond the fact that all of our instrumentation worked and that it achieved its primary objectives, we also saw that it performed aerodynamically very well through all the flight regimes, and so that was actually kind of a bonus mission.

We were hoping we could potentially eliminate another deployment sequence. You can get rid of the parachute if this aeroshell can produce enough drag for the vehicle all the way down and it stays stable through all hypersonic, supersonic, transonic, and subsonic flight regimes, you can eliminate a deployment sequence, and that's eliminating risk from your entry sequence. Yeah, it would be nice to get rid of that need for parachutes that has always been essential in the past. Neil, where do you go from here? Well, we're right now in the throes of planning the next flight.

What we want to do is we have had the ground-based testing where we've been developing new materials and new structure concepts to try to reduce the mass and increase the heating rates we can handle so that we can eventually scale this up to handle much higher masses at Mars. So we are planning that. Again, we're building on our ground-based testing, and we've got the funding to start the design work for this thing, and hopefully in 30 months we'll be launching again.

Well, wish you luck with that. Mary Beth, unfortunately, I guess we're not going to see this first IRVI test vehicle hanging in the Smithsonian. No, but if you go out to the Atlantic, you might be able to find it. But way down there. Hold your breath. Thank you very much, all of you go out to the Atlantic, you might be able to find it. But way down there. Hold your breath. Thank you very much, all of you, for joining us. And once again, congratulations on what just might be a solution to one of the most vexing problems as we continue to focus on the red planet moving forward toward, we all hope,

and I bet you hope too, a human landing there someday. That would be great. Once again, thanks very much for joining us on Planetary Radio. Thank you. We've been talking with three of the principals in the IRVI experiment, IRVI being the Inflatable Reentry Vehicle Experiment, which just, as you've heard, had a most successful test out there over the Atlantic Ocean. The principal investigator is Neil Cheatwood.

He is also the hypersonics project scientist there at Langley, joined by Mary Beth Wask, who is the project manager for IRVI, and the lead engineer, Steve Hughes. We will reenter on our own after this week's visit with Emily's Q&A. That'll be with Bruce Betts as we hear about the night sky in this week's edition of What's Up. Hi, I'm Emily Lakdawalla with questions and answers. A listener asked, I read that adaptive optics can only be used for infrared, not visible

wavelengths. Why is that? During the press briefing that heralded the new capabilities of the Hubble Space Telescope, the panel was asked how Hubble's images compare to those we can get from Earth. The surprising answer was that Earth-based telescopes can get sharper pictures than Hubble does. The Keck 2 and Gemini North telescopes on Mauna Kea and the Very Large Telescope in Chile are all equipped with adaptive optics systems that allow them to outperform Hubble. Adaptive optics uses a light source, such as a bright star, or a laser system to measure exactly how the scintillating atmosphere blurs what should be a point-like image and employs a flexible mirror whose shape is continuously deformed with tiny motors to correct for that blur. But these systems work better with infrared than visible light.

One reason is because longer infrared waves are less affected by atmospheric turbulence than shorter, visible light waves. Also, the fineness with which the correction needs to be performed goes up as wavelength goes down. For an 8-meter telescope, you need 250 motors behind your deformable mirror for infrared adaptive optics, but you'd need more than 6,000 motors for visible wavelength correction. It just gets too expensive to do adaptive optics in the visible. So while the big scopes can beat Hubble at infrared wavelengths, Hubble's got the sharper view in visible light. On top of that, Hubble can take pictures in ultraviolet wavelengths that can't even get

through the atmosphere to telescopes on the ground. Got a question about the universe? Send it to us at planetaryradio at planetary.org. And now here's Matt with more Planetary Radio. Time for What's Up on Planetary Radio. We're here live with Bruce Betts right along Colorado Boulevard. Welcome. Tell us where they are. No, tell them where we are. I have no idea where they are. Where we are is the Paseo Colorado, and we're at the World at Night exhibit, showing all sorts of really cool photographs taken around the world,

with usually some kind of famous object in the foreground and cool sky in the background. Part of International Year of Astronomy. It's going to be on display here also with the Pacific Astronomy and Telescope Conference coming up this weekend, which I'll be speaking at. But, you know, no one will know because it's already happened by the time you hear this. And what else has already happened? I got to see you in that great episode of the universe where you were very strongly featured. I think you had the first word, the last word. And, incredibly, they let you juggle.

Yes, bribery will get you everywhere. Tell us about the night sky. Well, in the night sky, we've got Jupiter still the dominant force. In the evening sky, you'll see it high in the south looking like an extremely bright star can't miss it and then in the pre-dawn Venus brightest star-like object out there but getting lower and lower over the coming weeks in the east this is pre-dawn in the east you got Mars high overhead reddish We've also got coming up both Saturn and Mercury in the first couple weeks of October. Low in the east, doing a little dance with Venus.

Venus getting lower, so Venus is the super bright one. Mercury is the next, is also bright and whitish. Saturn kind of yellowish. Mercury's going to go away quickly. Venus is going to go away quickly. Wait, wait, wait. Lou Friedman is interrupting the night. Lou Friedman's interrupting us. I'm sorry. Jody's going to go away quickly Venus is going to go away quickly Wait, wait, wait, Lou Friedman is interrupting the night Lou Friedman's interrupting us

I'm sorry Jody's going to take our picture Please come over here Everyone on the radio, smile Are we going to be in this picture? Can I keep my headphones on? Yes, please do Alright, well, all of you folks out there in Radioland

Are obviously in the picture too Yay Okay, well out there in Radioland are obviously in the picture too. Yay! Okay, well, photo accomplished. Gosh, you look great, Matt. Thank you so much. It's the hat and the headphones. Yes, I think that was it. So anywho, in the pre-dawn sky, we've got the triumvirate Venus, extremely bright. Mercury, less bright, still white, looking like Venus. And Saturn, yellowish and still kind of bright. The good news about

Saturn is it's just going to keep getting higher in the sky. It'll be visible for the next several months. Venus is ending a fabulous apparition in the next few weeks. And Mercury, as usual, just kind of poking its head up and then going away. Where do we go next? Next, we, wait, I want to try to scare everyone here. Okay, you ready? Random Space Fact! Random Space Fact!

So I enjoyed Random Space Fact coming up with this water on the moon things going on that in the over 800 pounds of Apollo samples brought back, if you somehow magically removed all the water, there would be a tablespoon. Of water, not of stones, of water. Of water. It's a dry place. It's a really dry place. Now they've discovered it's a slightly less dry, still drier than any desert place. All right, let's go on to the contest. We asked who the most isolated humans were and or how far away they were.

How did we do, Matt? Everybody understood this to be what's the farthest humans ever got from Earth. And about half the people who wrote in figured, well, we'll just take the average of all Apollo missions. Ah, but there was one Apollo mission that went where no one has gone before. And that was? Apollo 13. In their orbital trajectory to bring them on back to Earth, they went a little farther. Yeah, because it was just like, what do they call it, free return.

They just whipped right around and came right back. But they went out, not a lot, just a few thousand kilometers, I think. But our winner figured it out. That was Edward Lupin, Edward of San Diego, who we hear from every week. He said that they became the most isolated humans ever on April 15, 1970, speeding past the moon at a distance of 400,171 kilometers from Earth. And then he added this, that really is going to extremes to avoid filing a tax return. Why, yes, I think they got special dispensation. I'm not sure.

For the non-U.S. citizens out there, April 15 is a national holiday in the United States. For the federal government, not so much for the rest of us. It's kind of an inverse national holiday for everyone else when taxes are due. Let's go on to the... Well, wait. We have to say that Ed is the first winner of that first season, full first season on Blu-ray of The Universe, which you just appeared in. That is so cool. It is. It is.

And this week. Even bigger prize. Even bigger prize. On DVD, we are going to be giving away the first three seasons of The Universe from the History Channel, universe from the History Channel. Courtesy of the History Channel, the universe airing on Tuesday nights at 9 p.m. or somewhere around that time, depending on your satellite provider. Check your local listings. Check your local listings. That's it.

Now on to the next trivia contest. So, in the next trivia contest, speaking of Smackdown on the Moon, October 9th, LCROSS, one night only. Be there! LCROSS will be slamming into the moon, looking for evidence of water ice and permanently shadowed craters. What is the name of the crater they have selected for LCROSS to impact? Go to planetary.org slash radio, find out how to enter.

And you've got until Monday, October 5th at 2 p.m. Pacific time to get us that answer. Good luck going after that collector's edition collection of the universe. All right, everybody, go out there, look up the night sky, and think about pretty pictures of the night sky.

I know we are. Thank you, and good night. They surround us. We are enveloped by beauty, the beauty of the night sky. He's Bruce Betts, the director of projects for the Planetary Society. He joins us every week, right here. Well, not here at the Paseo Colorado, but here figuratively with all of you on What's Up. Next week, water on the moon. Planetary Radio is produced by the Planetary Society in Pasadena, California.

Keep looking up. Planetary Radio is produced by the Planetary Society in Pasadena, California. Keep looking up.