Dr Jacob Bleacher on the Artemis Program
Read the full transcript of our Science Focus Podcast interview with Dr Jacob Bleacher on the next mission to the Moon - listen to the full episode at the bottom of the page.
Jacob Bleacher [00:04:24] My name is Jacob Bleacher. I'm the chief exploration scientist for human exploration at NASA.
Jacob Bleacher [00:04:30] And my job is to work with a handful of other people and make sure that the architecture we're building, basically the plan and the hardware that we're building to explore space with human crews is done in a way that can meet the types of science goals that we have; that can be from elsewhere in NASA, from our international partners and commercial partners.
Jacob Bleacher [00:04:56] Basically, anyone that wants to use our human exploration system, our job is to make sure that we build a system that can meet those goals. That's kind of what I do. And we're looking forward to exploring the Moon.
Alexander McNamara [00:05:09] Can you explain what the Moon project is for us then?
Jacob Bleacher [00:05:12] Sure. So right now, we are working on the Artemis programme, which is our programme that will enable us to send the first woman and next man back to the lunar surface. We're looking at the South Pole of the Moon, and Artemis will be a group of programmes that bring together a landing system, an orbiter around the Moon and other systems that we need to explore the surface of the Moon.
Alexander McNamara [00:05:40] So that's quite a lot of things to sort of combine all at one go so getting to the Moon and staying there, working on there essentially.
Jacob Bleacher [00:05:49] Right, that's right. And there are a lot of systems that we need to think about and understand what do they need to be able to do to work together to keep our crew safe, healthy and enable them to explore the Moon and collect the types of data that we're sending them there to get?
Alexander McNamara [00:06:05] So I guess the first thing to sort of understand is why is it why are we going back to the Moon now? Why do we need to land a woman and man on the Moon at this point? You know, 50 years on from Apollo.
Jacob Bleacher [00:06:17] Yeah, that's a great question, use the phrase back to the Moon. I like to think of it as a continuation of going to the Moon.
Jacob Bleacher [00:06:24] We landed on the Moon with our astronauts during the Apollo programme, but those were short missions, several days, and they explored different parts of the Moon. And we learnt some of the baseline data we need to understand how to explore the Moon.
Jacob Bleacher [00:06:39] Since then, we sent some robotic explorers that have orbited the Moon and some countries have even sent landers to the Moon. We're focussing now on sending humans to the surface so that we can begin to understand how to live on the Moon, live in deep space. And this is really a stepping stone for us to start preparing to explore deep space and looking outward towards destinations like Mars.
Jacob Bleacher [00:07:05] So the time is right now. We've learnt what we needed to learn to be able to identify the right places to go. And we want to take advantage of the resources that are there so that we can not just go to put flags down and walk around and bring a few rocks back, but really have a presence on the lunar surface.
Alexander McNamara [00:07:24] So what sort of things are on the Moon that we'll be able to make use of?
Jacob Bleacher [00:07:28] So the Moon we've learnt over the last several decades is diverse in the types of materials that are there. And we might be able to take advantage of that, for instance, in the last decade or so, we've learnt that there's actually more water on the surface of the Moon than we had previously thought.
Jacob Bleacher [00:07:46] So on the south polar region and the north polar region, there are locations where we think there are deposits of volatiles and volatiles means materials that if they are heated up or warmed up, they may become volatile or gas. So on the surface of the Moon, water is one of those.
Jacob Bleacher [00:08:04] But that water is trapped there on the surface of the Moon in the poles because the Moon, unlike the Earth, has an axis that's basically straight up and down. The Earth's axis is tilted. And that's what gives us our seasons as we go around the Sun. But at the Moon, because we don't have a tilted axis, the holes in the ground craters, big holes that are created from collisions with rocks from outer space. Those bottoms of those craters don't ever see the sunlight.
Jacob Bleacher [00:08:36] So they're not exposed to the solar wind. And so ices and water that can be trapped on the lunar surface and moved into those craters basically gets stuck there. They're mixed in with the dirt, the regolith of the Moon. And if that is true, if that material is there, as we believe it to be, that's a resource that we could potentially use.
Alexander McNamara [00:08:56] And this is the same kind of water that we have on Earth?
Jacob Bleacher [00:09:00] That's right. Now, it might be mixed with some other things and we need to learn about it. We need to learn what, what might be mixed with the water, how much of it is there, how easy it is for us to get to it. These are all things that we need to learn, that we really need to get onto the surface of the Moon to collect data and learn about.
Jacob Bleacher [00:09:18] So that's that's one of the goals we have now. I mentioned the tilt of the Moon, the axis being not tilted very much at all. The other aspect to that is when you have a low area in a hole or a crater where water and ice can be trapped, the opposite is true on high topography, like the rims of the craters or mountain peaks, there are places where we think we have almost continuous daylight.
Jacob Bleacher [00:09:43] So those locations are ideal for us to take advantage of because they can provide us with solar power. So there are some places we think that are fairly easily accessible that we could have daylight for 80, 85 per cent of the time on the lunar surface. And that's a that's really the first resource we're gonna go tap into to make sure we can power the systems we set down.
Alexander McNamara [00:10:04] So basically, everything is there that you need. You've got water and you've got light, you just need to be able to get people there.
Jacob Bleacher [00:10:12] Yeah. Right. It's like if you do a drive across country or, you know, to visit some folks far away from you. Right. You don't load up a whole bunch of gas cans on the back of your vehicle. You stop. Right. You stop at a gas station and you stop somewhere. And you have to fuel yourself up to. Right. You might buy a soft drink or an iced tea or something.
Jacob Bleacher [00:10:31] We want to look at the Moon as a place that we can go and live. It's not a place where we have to bring all of the resources with us. And that's a big step towards being able to stay there and have more of a permanent presence.
Alexander McNamara [00:10:45] I guess we need to be able to put people there to sort of test that and is it something that we can't do with lunar rovers or, you know, robotics?
Jacob Bleacher [00:10:57] Well, in fact, our astronaut explorers and our robotic explorers are going to do this hand in hand. It's really is a synergistic approach working together.
Jacob Bleacher [00:11:07] So as we're building the systems right now that we'll be able to carry our astronauts to the surface. We're also planning to send robotic landers and rovers to the surface to help collect some of that reconnaissance data that we need.
Jacob Bleacher [00:11:21] We've had an orbiter in space, the Lunar Reconnaissance Orbiter, that has collected images and other data that help us understand where the water might be and where the locations are that we want to land and traverse from.
Jacob Bleacher [00:11:35] The rovers that we're gonna send will help us understand where the ice might be, where it's most accessible. Some of the questions I mentioned a little bit earlier, they're going to be collecting that type of data.
Jacob Bleacher [00:11:49] We'll also send some landers that maybe they don't rove around, but they collect data at a specific site that helps us better understand the environment and the types of materials on the surface, the types of rocks that we're going to be encountering.
Jacob Bleacher [00:12:01] All of that is critical information that helps us build our systems in an optimised manner to make sure that we can do the job we were asking our astronauts to do for us.
Alexander McNamara [00:12:13] And you say that job is the Artemis programme. And so that I guess essentially what you've done so far as you've you've done the reconnaissance and you've had a look and you know where to land and what resources will be there. What's the next step in that journey?
Jacob Bleacher [00:12:28] Right. So the next step is really starting to understand how do we survive in deep space away from the Earth? If you have ambitious goals, as we do for going on to Mars or exploring elsewhere in the Solar System, it's really difficult to take that big leap the whole way there.
Jacob Bleacher [00:12:46] The Moon is a great proving ground for us. One, it's very scientifically valid. There's great data there that will help us understand not only the Moon but our Earth-Moon system, what the Earth was experiencing through the time periods where life was gaining a foothold here.
Jacob Bleacher [00:13:03] On Earth, we have an atmosphere and flowing water and plate tectonics and those basically have erased much of the data that we have about the early Earth. But on the Moon, because there is no atmosphere and there's not flowing water on the surface, we preserve all those bits of evidence.
Jacob Bleacher [00:13:20] There's evidence about how the Sun has evolved. There's evidence about the impact history that both the Earth and the Moon experienced. All of that data is there on the Moon for us to go collect to make those observations. And as we understand more about the science of the history of the Moon and the history of the Earth, we learn more about how to survive in those harsh environments.
Jacob Bleacher [00:13:45] So that's what we would refer to that as, buying down the risk for trying to send people farther out into deep space. What is it like to actually live away from the Earth for long periods of time? We can learn that incrementally and prepare ourselves so that we're as effective as we can be when we go to farther away targets.
Alexander McNamara [00:14:06] So it's kind of like using going to the Moon to conduct experiments in that time, that in itself is an experiment to push on further.
Jacob Bleacher [00:14:15] That's right. Yep. So it's a test ground for us to get ready for what we're gonna be asking future generations.
Alexander McNamara [00:14:23] So does that differ to what we did in the previous generation of Moon exploration when they went to, the Apollo programme, when they went to land on the Moon, were they doing it purely to say that it could be done or were they doing research missions and scientific missions there too?
Jacob Bleacher [00:14:39] It's a combination, just like it is today. You know, exploration and science go hand-in-hand. They're part of the same thing.
[00:14:49] I'd like to say that science is your tool box for survival when you're exploring. Right. Learn about the environment that you're in. And so it was the same during the Apollo generation as it is now and this Artemis programme.
Jacob Bleacher [00:15:00] But, you know, they didn't have a programme ahead of them that learnt any of those lessons. So they were starting from scratch at that point. And so those landings were a tremendous advance for humankind. And it took a tremendous amount of collaboration between the teams that worked on it. And they learnt a lot about the Moon.
Jacob Bleacher [00:15:20] And since that time, we haven't sent people back. But we as I mentioned earlier, we've sent other vehicles to the Moon, orbiters and landers that have collected additional information. So we're really, you know, standing on the shoulders of the generations ahead of us that learnt that early information. It's because of that that we're in a position to be able to now take this next big leap to go to the Moon and to stay there.
Alexander McNamara [00:15:46] And I guess you've you know, you've learnt from what they did 50 years ago, too, that, you know, the current Artemis programme. What are the main differences between getting to the Moon then and getting to the Moon, and, as you say, staying there, now?
Jacob Bleacher [00:16:04] Right. So there are some key differences in the architecture of the systems that we're building now. During the Apollo programme they launched and went to the Moon. They went into orbit around the Moon. And then they had a landing module that went down and carried two astronauts while the command module stayed in orbit with one astronaut.
Jacob Bleacher [00:16:23] So we're looking at that system and we have a system now that we're developing something called the Gateway. So the Gateway is going to stay in orbit around the Moon, just like the command module did for Apollo, except that the Gateway is basically going to be a reusable depot.
Jacob Bleacher [00:16:41] Some place that our astronauts and our systems can go to stay for short periods of time, or long periods of time, and they can use the resources at the Gateway, so it's not all on the system, the human landing system or the vehicles that are carrying the crew to the Gateway, the Orion spacecraft. They can dock there. They can take advantage of the power generated at the Gateway. So it really becomes more like a depot that we can reuse as we prepare to then shuttle crew members down to the lunar surface.
Jacob Bleacher [00:17:13] So the Gateway is a big difference for us. It's also a platform where we can conduct some of the research about surviving in deep space. So it'll be in an orbit that carries it up to 70 thousand kilometres away from the from the lunar surface. So really far away, they really are out there in deep space. And that's the environment that astronauts will be flying through on their way to Mars in the future. So the Gateway gives us a great place to interact with the lunar surface, as well as prepare for and collect the data for that trip to Mars.
Alexander McNamara [00:17:47] So it's kind of like a space station, similar, I guess, to the the way the International Space Station is around the Earth, it's one that's around the Moon in that respect.
Jacob Bleacher [00:17:58] So it's different than the space station in many ways. The space station is a much larger platform and it's a research platform in low Earth orbit. It was a critical step for us to learn about spending longer periods of time in low gravity environments. And the ISS, International Space Station, is a critical part for us to continue this learning process in preparation for going to the Moon and Mars. So it's a part of that pathway.
Jacob Bleacher [00:18:21] But the Gateway will be a place where several different types of vehicles will be docking. The Orion I mentioned earlier is our crew capsule that will be launched on the Space Launch System and that will carry us, our crew members, out to the Gateway. Meanwhile, a different vehicle, the Human Landing System, or HLS, will also launch and be connected with the Gateway.
Jacob Bleacher [00:18:44] So the crew can then spend some time in the Gateway. They can also go into the human landing system and then ferry themselves down to the lunar surface and then back up. So, you know, it is a location out in space, but it has some different tasks that we're assigning to it than ISS has had to have.
Alexander McNamara [00:19:02] And you say it's in deep space as compared to the ISS. What sort of effect are you sort of anticipating that would have on the astronauts that are there as compared to the ones that are in low Earth orbit?
Jacob Bleacher [00:19:15] Yes, so. So out in deep space, they're not protected from the solar wind the way that crew members are on the ISS inside the magnetic field of the of the Earth. In that orbit, they will pass through that protective envelope at some point in time, but they will also be exposed to that deep space environment.
Jacob Bleacher [00:19:34] So now we can collect data with instruments out there and understand, you know, for instance, what happens when a solar event occurs. A lot of high energy comes out of the Sun. It's coming towards us. We're almost certainly going to experience the type of events on our way to Mars. So we have to start to understand that risk, and how do we deal with it? How do you build a, you know, a safe place for the astronauts to go? How do you monitor those situations so that you're well-prepared for that by the time that they get there?
Jacob Bleacher [00:20:09] We can also look, for instance, at aspects about the Gateway, you know, are they experiencing the collection of potentially leaked gases from some of these vehicles? And do those gases stay around the Gateway? Is it creating its own atmosphere or not? So there's a lot that we can learn there as well as what is it like for the crew members to spend periods of time in orbit and then going down to the surface, either back to the Earth or down to the Moon?
Jacob Bleacher [00:20:38] It's one thing we have to think about as the trip to Mars is several months, so the astronauts that take that first trip are going to spend several months in weightlessness and then they're going to be asked to land on the surface of the Moon and start doing jobs right away, or, or maybe not. How long do they need to be prepared to be able to handle that?
Jacob Bleacher [00:20:57] And we can start testing all of these things between the International Space Station and the Gateway and going to the Moon and coming back to Earth in this, in this architecture that we're developing.
Alexander McNamara [00:21:08] I guess when you think of it like that, every every step of the way has to be considered a lot more than you would think normal things in daily life, because obviously it's such a big mission. Going to the Moon, going beyond the Moon. But how on Earth do you sort of like make sure you capture as much as you can? Is that the reason that you're doing this?
Jacob Bleacher [00:21:32] Yeah, that's exactly right. And that's why I say, you know, when we look at Apollo and Artemis, you know, this is all part of the same path. This is the same path of exploration. And you incrementally learn how to operate in these environments.
Jacob Bleacher [00:21:45] And, you know, it's hard to take big leaps, but you want to test as much as you can and model and collect data about the environments. You know, we've been sending vehicles to Mars to understand what that environment is like. That helps us prepare for going there.
Jacob Bleacher [00:22:04] As I mentioned, we've sent numerous spacecraft to the Moon to collect data and make sure we know where the best spots for us to go are. These are all part of that pathway. And so, you know, it's sometimes you look at some of the things we do and you'll see videos of something blowing up or, you know, quote unquote, not being successful. Right. But really, you're learning, right. You're learning how you want to build those systems so that that doesn't happen. And those are, you know, tough lessons to learn, but that's how we advance.
Alexander McNamara [00:22:37] I mean, I guess there's a lot of people say, you know, it's in the news all the time. There are lots of ways, not just, you know, the major space agencies, the national space agencies that are launching ships into space and, there's a lot more commercial enterprises now that are also launching satellites. How much of a role do they have to play in the Artemis programme?
Jacob Bleacher [00:23:00] Yeah, that's a great point. So the Artemis programme for us. We're going to the Moon, and we want to start to establish some of the infrastructure that we need that will help us then continue to build on that exploration through partnership with our commercial entities here in the United States, as well as our international partnerships with other space agencies.
Jacob Bleacher [00:23:21] So this really is an endeavour that's going to include humankind. NASA's leading the way here, but we're going to look to those partnerships to be a critical place for this. And that's why I said you asked me to introduce myself at the beginning, my job. You know, I'm I work as a scientist in human exploration, and my job is to be able to look out to scientists and other folks who want to send things to the Moon. There are things they want to do. There are goals that they have. And so we want to be able to develop that plan in a way that enables them to do those things.
Alexander McNamara [00:23:55] So what sort of things would they be looking at? So I can understand them on a purely science perspective. It be like we need to go find the geology of the Moon, find that there's water there and, and have that space station there, but what would these commercial interests be? What would they be looking to get out of having people there on the surface of the Moon?
Jacob Bleacher [00:24:15] Sure, there. You know, that's one of the things that really creates innovation. You know, we don't necessarily try to dictate why folks would want to go to the Moon or what they'd want to do. Oftentimes, exploration is motivated just because we're, you know, humans want to explore. We want to know what's out there.
Jacob Bleacher [00:24:33] And that may involve tourism. That may involve actually bringing material back or characterising things there. The companies and agencies that are the ones that can show they can do these jobs. I mean, the technology that you have to come up with to do this is is impressive. And so, you know, that's just, you know, imagine you've seen pictures of of NASA spacecraft doing things, right? That is the reason we have the emblem. Right. We're doing this. Look what we're doing. Just think about any corporation that would potentially want to have their name showing that they can do that as well.
Jacob Bleacher [00:25:08] And so, you know, our we don't really see the vision of what the what, we don't try to limit what the vision might be for those innovators who are going to contribute. What we do know is that everyone seems to be excited and wants to be a part of it.
Jacob Bleacher [00:25:24] And so we're trying to make sure that, you know, we use the history of NASA and the strengths that we have and that we also partner with as many as we can to make sure we're we're looking at that or tapping into that full breadth of innovation that is brought by partners.
Alexander McNamara [00:25:42] I guess that that that's sort of it feels like now is a good time for this mission to happen as well, because you sort of see to see the technology and the desire to do it there. Is that, was that factored in or is it just a you know, now is the time to do it because we can do it?
Jacob Bleacher [00:25:58] You know, it's the path, right? I think it's kind of everything that you just said. We've been on a path, and for the last 20 years now, we're just about 20 years of having the International Space Station staffed continuously. We've learnt a lot from that low Earth orbit. And you may have seen recently that the company SpaceX delivered some crew members to the International Space Station.
Jacob Bleacher [00:26:23] So we're really looking at a transition to where our corporations, our companies are now taking part in getting cargo and crew up to low Earth orbit. And so the commercial sector is taking a bigger and bigger role in low Earth orbit, which enables us, our space agency, to begin looking beyond that.
Jacob Bleacher [00:26:42] So we continue to try to push the edge of where where we're sending astronauts and we partner and they come along with us. So I think, you know, it's a combination of everything you said. This is the right time to do it because we can do it, and the partnerships we have are helping us to realise that.
Alexander McNamara [00:27:01] So just on touching on one thing that you said that which was talking about the astronauts themselves, now, obviously taking people to the Moon is quite an extraordinary thing to do. You know, we've only, there's only been a handful of people in human existence that have ever been there. And what's so, you know, what does the generation of people that are coming that are going to be the ones landing on the Moon? Is there mindset that they have to have that's different because it is obviously such a long way away, and then the idea is that it will take you even further to Mars?
Jacob Bleacher [00:27:30] Yeah. You know, I think it goes back to that point that, you know, humankind is inherently focussed to explore. Humans have always asked, you know, what's over the mountain, what's on the other side of the river. Right? And you know what's, what's on the Moon. And we've gone there just enough to tease ourselves. You know, we've gotten just a little bit of the tip of the iceberg, but we know there's so much more to be learnt there and there's so much more to be discovered.
Jacob Bleacher [00:28:00] And again, that is a stepping stone for us to understand the history of the Solar System, collect information about understanding our place in the Universe. And that's that's kind of the springboard to help propel us out to other places like Mars. So, you know, I think this generation that's going to be coming up and my hope is that we'll put ourselves in a position where they see that as the normal. Right? This is where, this is what we do. And they're going to be ready to grasp that and go forward.
Alexander McNamara [00:28:35] So I guess it must be quite, it must be happening quite soon then to sort of catch onto that momentum. When do you expect these sort of things happen? When will we have a base on the Moon and people landing?
Jacob Bleacher [00:28:47] Right. Our goal is to land our astronauts on the surface of the Moon by 2024 and then we'll be following that, we expect with about a mission, a crude mission to the surface every year after that. So once a year and slowly, then what we'll do is build up the hardware, the infrastructure on the Moon.
Jacob Bleacher [00:29:07] So we'll be looking for and returning to the same place over and over. And each time we'll leave a little bit more there and we'll build onto it. And that that will be the time when we can really look to partnerships to deliver more capability that is built into that overall infrastructure and then support a more rigorous and larger exploration programme on the surface of the Moon.
Alexander McNamara [00:29:31] So if you use the analogy of driving in a car and you don't have the gas in the back of the car and you know that, obviously you still need to get stuff there. And so it sounds like if you're going to build a Moon base, that's quite a lot of things to take from Earth to the orbiter and then subsequently down to the Moon. How are you doing that? Because, you know, the Moon is a long way away and you need a big spaceship, surely?
Jacob Bleacher [00:29:59] Yep, yep. So we're looking at, you know, the first the first people to go to the South Pole of the Moon, you know, it's not going to be the full size Winnebago with everything that you can imagine having. Right. It's going to be a mission that, that's you know, if you think about Apollo, you see the the videos and the pictures of the astronauts. You know, that wasn't a luxurious, huge space they were in. But it's you know, it's what you have. It's the what you have available to get you there.
Jacob Bleacher [00:30:31] So the first mission is certainly going to have the least amount of capability. But then as we'll continue to build it up and they'll get more and more. There may be bigger rovers. There may be habitats that the astronauts can land and then go to as opposed to staying in their lander. So initially, the first landings, they'll stay with the vehicle that they landed in, they'll explore around there and then they'll build up that capability after that.
Jacob Bleacher [00:30:58] So that's kind of how that will work. And so that's part of what we're discussing now is what do we actually need just to get there and then what is it that we'd like to be able to do after that? And so how do we get the elements there that make that a plan, a reality? Maybe we have to send some robotic landers as well that carry some additional hardware that the astronauts could leave and go get more or something like that. So those are the types of conversations that we're having now to try and build that plan that you're asking about.
Alexander McNamara [00:31:32] So it's it seems like it's building up to actually having quite a substantial spot on the Moon and 2024 is, what, four years away? It's quite it's quite a short time. I imagine there's going to be a ramping up of excitement about this, which is why I think it's great that we're talking now about it, because obviously it's going to be a big thing.
Alexander McNamara [00:31:53] But, you know, I'm thinking about people like me and I'm seeing this incredible thing happening. You say build a base there and then presumably at some point farther off into Mars as well. Do you see and I do know in our lifetime the ability for people to be able to go to the Moon for whatever reason? You say there's a lot more commercial reasons. You know, you can't ask why they're doing it and that sort of thing. But could a person like me ever land on the Moon at some point in the not too distant future?
Jacob Bleacher [00:32:23] Well, you know, to me, that's what's exciting about this, is that you're even asking that question right? You know, at no point in human history has that really been a viable question, maybe right around the time that, that Apollo was happening. But then year after year of not going back, you know that, that's not really something that we were thinking about five years ago.
Jacob Bleacher [00:32:43] So the fact that we can even ask that question right now is just wonderful to me. You know, we're we're on a good path here. And I can't tell what's going to happen in the future. But that's the plan that we have, is working towards being able to extend humankind beyond the surface of the Earth. We've done it with aeroplanes. We've done it with ships. Right. And now we're talking about it in low earth orbit. And the Moon is right out there. It's still far away, but it's not as far away as Mars. And that's what we're we're really talking about.
Jacob Bleacher [00:33:18] I mentioned earlier that as we you know, we get a stronger commercial participation as we move farther away from the Earth, that enables us to kind of push the envelope, getting astronauts back to the Moon, and then eventually we'll be looking out towards Mars. The hope is that we bring humankind with us behind and that they can can hopefully realise the kind of question that you're asking right now. So to me, it's just wonderful that you even asked me that question.
Alexander McNamara [00:33:48] Well, that's what I'm here for. So that's great. I guess this is one thing which I would just love to ask you, which is would you go to the Moon if you had the chance?
Jacob Bleacher [00:33:59] We'll tell you what they said, hey, we need you to go to the Moon. I go. That's it. I can't imagine anything more exciting than that. I've talked to a few of the people that have been there before. You know, it's I can only imagine.
This podcast was supported by brilliant.org, helping people build quantitative skills in maths, science, and computer science with fun and challenging interactive explorations.
Listen to more episodes of the Science Focus Podcast:
- Elisa Raffaella Ferrè: What happens to the brain in space?
- Everything You Wanted To Know About… Physics with Jim Al-Khalili
- Dr Erin Macdonald: Is there science in Star Trek?
- Kevin Fong: What happened to Apollo 13?
- Kathryn D. Sullivan: What is it really like to walk in space?
- Mark McCaughrean: How do you launch a successful space mission?