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Rocket Ranch - Episode 2: Some Like it Hot

Season 1Episode 2Jul 25, 2018

Even though our Sun shines bright in the sky, it is shrouded in mystery. In this episode, we'll sit down with scientists working to get us closer to the Sun than ever before.

Rocket Ranch podcast cover illustration

Rocket Ranch podcast cover illustration

Dr. Nicky Fox:Everything is driven by the Sun. It’s like the missing piece of the puzzle. We don’t know, truly, what physics is going on in that region because we’ve never been there.

Launch Countdown Sequence: EGS Program Chief Engineer, verify no constraints for launch.

EGS Chief Engineer team has no constraints.

I copy that. You are clear to launch.

Five, four, three, two, one, and lift-off.

All clear. Now passing through max Q, maximum dynamic pressure.

Welcome to space.

Joshua Santora (Host):Welcome to the Rocket Ranch. I’m Joshua Santora. Even though our sun shines bright in the sky, it is shrouded in mystery. In this episode, we’ll sit down with scientists working to get us closer to the Sun than ever before. First up, we talk with a project scientist on the Parker Solar Probe mission that will be launching soon, attempting to fly inside the Sun’s atmosphere in order to unlock its many secrets.

Dr. Nicky Fox:Um, the big mystery we’re trying to solve is why is that corona so hot?

Host:Next, we talk with a researcher working on a cryogenic coating that could get us even closer. But his goal is not to go to the Sun– it’s to store up rocket fuel in space while keeping it from boiling off– a critical breakthrough needed to help us explore farther into space.

Dr. Bob Youngquist:Liquid hydrogen– hydrogen has to be down to 20 Kelvin. I mean, you’re talking getting– you’re getting close to absolute zero when you talk liquid hydrogen.

Host:NASA’s Parker Solar Probe will be the first ever mission to travel directly into the Sun’s atmosphere, about 4 million miles from our star’s surface. With me in the booth today is Dr. Nicky Fox. She’s from the Johns Hopkins University Applied Physics Laboratory, and is also the project scientist for the Parker Solar Probe mission. Dr. Fox, we are celebrating 60 years of NASA this month. And I understand that this mission is older than NASA?

Dr. Nicky Fox:Yes, that’s right. So Parker Solar Probe was first thought of and first proposed in 1958, so it’s also going to turn 60 years as well as NASA this year. Um, but when the agencies were forming– so NASA, the National Science Foundation, and really, the Department of Defense– and you know, what do we wanna do with this newfound thing called space? Um, what do we need a big agency for that, you know, these big, grand missions that-that we really, just really want to do? And so, uh, they pulled together a committee. It was chaired by John Simpson, co-chaired by James Van Allen. Um, and they had a panel of experts, and they came up with these missions that were just big and shiny, and that’s what everybody wanted to do. One of those missions was a spacecraft to go into the Sun’s corona. So that’s where– solar probe. They wanted one to probe the Sun’s corona. And it was, you know, high priority for all this time, um, in the decadal surveys, in the NASA roadmaps. A solar probe has been there since then. Um, other countries, other agencies have tried to do it. But it’s really taken 60 years for technology to catch up with our dreams. And we’re now sitting on the verge of making this come true. And so it does predate NASA. And I wouldn’t say that we are competitive, but we are faster, hotter, and closer than anything has ever been before. In fact, I always like to call this– call the mission, “the coolest, hottest mission under the sun.”

Host:And so you talk about technology catching up, and I’m assuming that has to do with the heat involved, because we’ve been sending things out into space for decades now. So i-is that the challenge, the technology of getting close to the Sun? And how hot are we talking?

Dr. Nicky Fox:There are many different challenges with Parker Solar Probe. It isn’t just the heat. And we can talk about the heat, obviously. We’re going to 3 million-degree plasma. Um, the big mystery we’re trying to solve is why is that corona so hot? The surface of the Sun is about 6,000 degrees Centigrade, 10,000 degrees Fahrenheit. And now we’re talking about plasma that’s 3 million degrees? You walk away from a campfire, you don’t suddenly get hotter. You get colder. And so why is this bizarre thing happening? And the only way we can answer that question is to travel into this region where this plasma, this coronal material is 3 million degrees. And so obviously, we have to have materials that are specially developed. Um, they can’t melt. Uh, also, they can’t change their properties. And so we have this very highly elliptical orbit. It looks like a petal of a flower. We go very close to the Sun on one side, and then we come out around the orbit of Venus on the other side. And so we’re going super hot and then very cold. And if you think of taking any material that you know, and you heat it, and cool it, and heat it, and cool it–

Host:This is– usually doesn’t end well.

Dr. Nicky Fox:It’s either gonna become elastic, it’s gonna become brittle– whatever. It’s going to change its properties. And so these materials have to withstand these incredible changes in heat. But also, it’s miniaturization. It’s getting technology into small packages. Um, we are travelling at 430,000 miles an hour, or 118 miles a second, um, and we have to keep our heat shield between us and the Sun. And so the spacecraft is incredibly, incredibly independent. She’s a plucky little spacecraft, going out there and looking after herself. Because if we have any kind of fault, the spacecraft has to know how to correct that fault. It takes light 8 minutes to go from the Sun to the Earth. We don’t have time to joystick this spacecraft. She has to correct herself. And so if you think of the sheer technology that would have taken to do that in 1958–

Host:Sure.

Dr. Nicky Fox:You’re talking city blocks’ worth of buildings with computer power in them.

Host:Not easy to get off the ground.

Dr. Nicky Fox:Not easy to get off the ground. Um, I mean, if you think, in 1958, you wanted to talk to somebody, you went to the wall where your rotary dial phone was attached, and you made your phone call. Now we all have iPhones, and we probably do everything except make a phone call with them. Uh, you know, the whole way we communicate– I mean, it’s a last ditch attempt if you have to make a phone call now. By the time you’ve tried texting, and instant messenger, and-and Instagram, and Snapchat, and you’ve done all those things.

Host:Sure.

Dr. Nicky Fox:And so just the sheer way that w– that society has changed is dramatic. And that’s very– um, a good demonstration of what we needed to do to be able to get Parker Solar Probe into orbit.

Host:So we were talking about this for decades as a priority and just really didn’t touch it, or has it really been worked on for 60 years now?

Dr. Nicky Fox:There have been many, many incarnations of a solar probe. Um, I think there was a Russian one called Firebird. Um, you know, JPL had a-a design. Um, the Johns Hopkins Applied Physics Lab had a different design. Um, it looked kind of like a bullet. And it was gonna go super close, but it was going to go out to Jupiter, kick out of the, um, the kind of– the plane of the Sun and the Earth, and then come up and go over the pole and go down, sort of north-south, if you like, past the Sun. Um, but they were very expensive missions. They required some kind of nuclear RTG, some kind of, you know, power source. Um, and they were very, very expensive. Um, they took a long time to get into the orbit, and then they got, you know, a few hours’ worth of data, if you like. And so it really was just the ability to afford all of the technology, to come up with a mission design that would allow us to-to go where we need to go and do it for a reasonable price. So that was where the mission used to be called Solar Probe Plus, and that’s where the plus came from. Uh, we changed, and we stay in the ecliptic plane. So you put the Sun and the Earth and you stay in that sort of plane there. Um, and we don’t use any kind of RTGs– we use solar cells. And you may look at me and say, “hey, Nicky, well, duh. You’re going to the sun. Why wouldn’t you use solar power? That’s a no-brainer.” Except what happens if you leave your iPhone in the car on a beautiful Florida day? It overheats.

Host:Yeah.

Dr. Nicky Fox:And solar panels are extremely sensitive to heat. And so we have to find a way to keep them cool. Um, and so they– you know, we have them– they’re articulated, kind of on a shoulder joint, and so they can move out and they can also kind of twist around, um, so that we can maximize the amount of power and minimize it by tucking them all the way in as we get close to the Sun. Um, we also cool them with water, and again, not a very exotic material, but the best coolant, um, that-that we have. And we run, uh, water through the veins. Like the veins in your, uh, your hand, they run between each of the solar cells all the time, continually keeping those cells cool. And so, you know, it’s taken a lot to get the technology, but also to bring it in in a really good mission design that does the science we want to do.

Host:I have the benefit of sitting across the table from you, so I know the answer to this question, but did you start working on this 60 years ago? And if not, when did you do that?

Dr. Nicky Fox:I have a very good plastic surgeon. Um, uh, no, I started working on this mission in 2010. So I’m a relative newbie to the mission. Uh, there are people who’ve been working on it for a lot longer than that. Even this particular incarnation, there have been people working on it for well over a decade. So I’m-I’m a little new.

Host:And-and how has this been from a-an-a personal perspective? Because I know that we talk to people all the time, and we hear similar stories– “we’ve spent a decade or more working on this and giving our lives to this project.” So how has that been for you kind of through this process and getting ready for launch?

Dr. Nicky Fox:So I think for me, um, it’s-it’s been a very personal journey. Uh, you know, I started working on the mission late in 2010, and about six weeks after I accepted my position, my husband died, um, very suddenly, leaving me with a 1-year-old and a 3-year-old.

Host:I’m sorry to hear that.

Dr. Nicky Fox:And my life kind of fell apart. You know, I felt like I can’t take on anything. Um, you know, I’m never gonna be able to do anything. And the way this team kind of gathered around and supported me through this period, it was almost like I used Solar Probe as a grief kind of solving mission. You know, there were things I could come in, I could actually do things. I could-could make this thing work. And just the tremendous support of, you know, people that just said, “ah, do you need me to pick up your kids tonight?” Um, “do you need groceries?” Um, “what can we do to help you?” And the science team also. You know, my first science team meeting where I had to stand up and lead them, and you know, I was nervous, and one of the principal investigators just said, “hey, you know, I thought it might be nice just to come and have dinner with my wife and I. And you know, you don’t have to do anything big in the evening. It’ll be low stress for you, and we’ll just give you some food.” And just the-the sort of– the people realizing, “this person is really falling apart, and they’re really hurting, and we are going to support you through it.” So they’re like a family. I come down to Astrotech here and I walk in the door, and everyone’s like, “hey, Nicky, how’s it going?” You know, and-and it’s just such a friendly, lovely, highly professional, highly skilled, best at the– you know, in the world at what they do, but real people.

Host:Yeah.

Dr. Nicky Fox:That see someone that’s really struggling and they’ll all band together and help that person be successful. And so this mission is deeply personal for me. I put my husband’s name on the spacecraft. My children are all excited about “Daddy’s gonna orbit the Sun forever.” And you know, it’s a very personal thing.

Host:I’m sure that that extends now beyond just the trust of this personal relationship with people into a professional engineering and problem solving reality of your team.

Dr. Nicky Fox:Absolutely. I mean, when– you know, when we have an issue, a technical issue, people just deal with it. Nobody panics. They say, “okay, we’ve got a technical issue. We’re gonna do it– we’re gonna come up with a plan, we’re gonna do this, we’re gonna do the action items, we’re gonna status it, and we’re going to get through it.” Um, you know, my-my project manager, Andy Driesman, um, from the Applied Physics Lab, he, um, he always says, “you know, you work on the missions. The missions are fantastic. The technology is great. The science is awesome. But it’s the relationships you make with the people that stay with you for life.” And it’s really true.

Host:That’s awesome. So kind of getting back to Parker Solar Probe, how close are we getting to the Sun? Obviously, coming out past Venus is pretty far from the Sun, so what are our distances like here in– compared to Earth?

Dr. Nicky Fox:So, you know, I often say– people ask me, “well, how close?” ‘Cause you’re getting so excited, it must be really close.” And I say, “oh, yeah, we’re just gonna get, um, just below 4 million miles from the Sun’s surface.” And I always get people that look at me like, “oh, I thought you said you were gonna get really, really close.”

Host:‘Cause what I’d like you to say is be like, “we’re gonna just like drive right into the Sun.”

Dr. Nicky Fox:Exactly.

Host:And just like–

Dr. Nicky Fox:Exactly, exactly, and–

Host:Go out in a blaze of glory.

Dr. Nicky Fox:If I put the Sun and the Earth in, um, the– uh, either side of the football field, at the touchdown in the goal area…

Host:Okay. So American football.

Dr. Nicky Fox:And– American football. Uh, I can– I can translate. Um, um, and, uh, you know, we’d have, um, Venus about the 27 yard line of the Earth’s 27. You’d have Mercury at about the Sun’s 35. Um, some of those big coronal loops that you see come out, um, they can come out to maybe the 15 yard line. But you know, welcome to the main event– Parker Solar Probe, who’s gonna tuck and run all the way to the 4 yard line.

Host:Okay.

Dr. Nicky Fox:So in the red zone, knockin’ on the door for the touchdown. Let’s go Ravens. Um, so– um, it’s very close. Uh, you know, on a meter scale it’s 4 centimeters away. On a football field, it’s 4 yards away. It’s really close. We– you know, we tend to not think about just the sheer scales, but the Sun is 93 million miles away. So getting to 3.7 million miles is super close. And it’s in that region where all the excitement happens. And so last year, a lot of us here were treated to this amazing celestial sight when we had the total solar eclipse.

Total Solar Eclipse reports:This is the celestial event that we’ve all been waiting and anticipating for years.

Dr. Nicky Fox:And you saw that beautiful hazy atmosphere. That’s the corona. Uh, it’s basically the outer atmosphere of the Sun. Um, the reason it’s called corona is ’cause it’s Latin for crown. It does look like a crown around the Sun.

Total Solar Eclipse reports:So look now. We see the corona in Madras.

That’s gorgeous.

That’s amazing.

I mean, and that only can be seen when you have this kind of totality.

Dr. Nicky Fox:So the corona, that’s what solar scientists really live for, right?

Host:Right. That is where the origin of space weather comes from.

Dr. Nicky Fox:That’s where we’re going. And so what you are looking at is basically where Solar Probe will be orbiting.

Host:How long is it gonna take to get there?

Dr. Nicky Fox:So, uh, we are a very busy team, uh, at the very beginning. Uh, we launch on a Delta IV Heavy with a-an upper stage from right here at Kennedy Space Center. A Delta IV Heavy, the reason we need such a big launch vehicle is– and we’re tiny, by the way. The spacecraft is tiny. We look like a little hood ornament on the top of the Delta IV Heavy. Um, and we are so small and we’re so mass-constrained because we need to be thrown away from the Earth, essentially, as fast as possible with a huge amount of energy. Because we don’t want to be influenced by the Earth’s orbit around the Sun. We don’t want to be dragged around with the Earth. We want to go in towards the Sun. Just 6 weeks after launch, we will fly past the planet Venus for the first time. Uh, we use Venus for gravity assists. And a lot of people are familiar with the idea of, you know, we do sling-shots around Jupiter. Uh, New Horizons, for example, did one and took more than a year off its journey to Pluto because it was able to speed up using Jupiter. And really, we use it more like a little hand brake turn to kind of just focus, um, and turn the spacecraft in towards the Sun so we’re now going directly to the Sun. About 6 weeks after we pass Venus, we are in the corona for the first time. So it’s a very busy time as we have to commission all the instruments, get all the subsystems on, get everything working. We are travelling at 430,000 miles an hour, 118 miles a second, um, New York to Tokyo in much less than a minute.

Host:Oh-ho-ho-ho, what?

Dr. Nicky Fox:It’s blistering speeds. Um, you know, it’s-it’s sort of DC to Philadelphia in a second. You know, it’s-it’s just incredible how fast we’re moving. That’s-that’s why we’re small. Um, that’s why we need to move so fast– we need to not be in any way influenced by the Earth. We wanna go to the Sun and study the corona.

Host: So you’re hurtling towards the Sun at unbelievable speeds– how do you not burn up in the heat of the Sun, that feels hot on a Florida day from 93 million miles?

Dr. Nicky Fox:Solar Probe, when she is at her closest, um, to the Sun, will experience just a little bit less than 500 times the Sun that we see here. So essentially, 500 suns in the sky at the same time beating down on us is what Parker Solar Probe will experience. We have a wonderful heat shield. Uh, sits out the front of our spacecraft. Um, the spacecraft itself is very small– um, about a meter, um, across, about a meter and a half tall. Uh, the whole spacecraft stands about 3 meters tall. She’s very small. The heat shield sits at the-the top. Um, we lovingly call that our 8-foot frisbee because it is, uh, a big disc, and it’s very thin. It’s only 4 1/2 inches thick. Obviously, one of our biggest technology developments was coming up with that heat shield. When I tell people what it’s made with, they always sort of look at me like, “oh, I thought it would’ve been something really exotic.” It’s made out of carbon. There are two phase sheets that are very thin. Uh, they’re 8 feet in diameter, uh, very thin, and they’re made from like a graphite epoxy. So something that you would have in a nice bicycle, or your golf clubs, or a nice tennis racket. In between the, uh, the two phase sheets, there is a carbon-carbon foam. It’s about 97% air. Um, and that is a tremendous way to-to keep everything cool. And on the very front of it, we have our whiter than white, uh, plasma-sprayed. It’s a bit like a ceramic coating. It’s an alumina, um, and it’s plasma-sprayed. So we say it’s plasma-tized in that you heat it so much that it-it basically dissociates. And you fire it from a gun.

Host:Huh.

Dr. Nicky Fox:A paint gun, and coat the front of the spacecraft with that, and that’s actually going to reflect, um, a tremendous amount of the Sun’s energy before the heat shield even has to deal with it.

Host:Interesting. So I’m assuming that that end is pointed towards the Sun, and everything else kind of hides behind it.

Dr. Nicky Fox:Absolutely. Um, that-that basically creates a nice shade. Our heat shield is so good that the front side of the heat shield will be at temperatures of about 2,500 degrees Fahrenheit, 1,400 degrees Centigrade. But those instruments that are on the main body of the spacecraft, they’re a little warmer than room temperature. It’s a sort of– basically, not even a hot Florida day. It’s a– you know, it’s a pleasant Florida day.

Host: Awesome.

Dr. Nicky Fox:It’s about 80 degrees Fahrenheit that those-those instruments are working at. And so that is mind-blowing as well, uh, that you can actually manage to cool, um, the environment that much. Most of the instruments sit on that main body of the spacecraft, and they kind of look sort of sideways around the heat shield. Um, however, we have– do have a couple of brave guys that sit out in the– in the full environment. Uh, we have four sort of radio antennas. Uh, they’re electric field antennas that come out, um, and they-they are on each side of the, uh, of the heat shield. So they make a nice cross shape so we can do, um, full, uh, sweeps and get all of the-the data we want. Um, they’re very thin whips. They’re made of niobium. And, uh, they’re sort of like little tubes of niobium. Um, and they-they stick out. And then we have an instrument that I always think of as the bravest little instrument on the spacecraft, because it is not a thin tube of– it’s a big, honking instrument. And it’s, uh, it’s a Faraday cup. So we call it the Solar Probe Cup, SPC. Faraday cups have been flown for years and years. They’re very simple instruments. They measure particle populations. But getting one that can survive this incredible heat, and cool, and heat, and cool–

Host:Yeah.

Dr. Nicky Fox:It’s a really important instrument because it’s looking at exactly what is coming towards the spacecraft right now.

Host: Oh, interesting.

Dr. Nicky Fox:There’s no hid– no hiding behind the shade, no peeping around the side. It’s looking at what we’re flying into. And so it’s a very important instrument for us.

Host:One of my questions, concerns would be that you’re gonna have plasma coming around the edge of your heat shield. Are you expecting this thing to have issues with that?

Dr. Nicky Fox:So one of the things– it’s-it’s difficult to visualize. You know, I-I explain, “well, the heat shield gets really hot, and everything else is in the shade.” And people will say, “but, well, I mean, you’ve still got 3 million degree plasma all around you. Why are you not still feeling, um, the-the effects of it?” but if you think of being on the beach, here you’re sitting under an umbrella. You have, essentially, a heat shield, but you’re still incredibly hot.

Host: Sure.

Dr. Nicky Fox:Because the sand has absorbed all of the-the heat, um, and you’ve got a lot of convection, and you’ve got wind, you’ve got current things that are blowing. In space, there are no– there’s no convection. There’s no, um, there’s no real atmosphere in the same way. So space is cold, um, around you. There’s no– there’s no sort of plasma that can come around because there-there’s nothing to sort of blow it into the side of the spacecraft.

Host: Okay.

Dr. Nicky Fox:And so the-the side of the spacecraft will stay nice and-and sort of cool at this about 80-degree, um, Fahrenheit level. Um, but the-the-the way the– that we’re traveling, we will see a great deal of different temperatures on the heat shield as we get close, and then we get cold. And so we do know that the heat shield will kind of deform on orbit. It will sort of maybe puff out like a drum. It may even do a kind of a potato-chipping. So if you think of the shape of a Pringle, where, you know, maybe two sides are gonna go up and two sides are gonna go down.

Host:So is this like a melting heat shield? Is that what we’re lookin’ at here?

Dr. Nicky Fox:It’s not melting. It’s just, um, changing, you know– it’s-it’s gonna get bigger in certain points and smaller in other points as it’s getting– it’s– you know, it’s gonna get very hot, and the sh– we know the shape will change. Um, and so we have this design of the way we attach the heat shield to the spacecraft is, again, a– just a breathtaking piece of technology. Um, and we have– they’re on rather like shoulder joints, again. So you can, um, you can imagine as the thing is changing, the whole sort of attachment fixture is moving with it. It’s kind of– kind of giving in to it, and it’s never– you know, it’s not gonna just snap off. It’s going to kind of move.

Host: Sure.

Dr. Nicky Fox:As the heat shield deforms in different ways at different times and different distances from the Sun. Um, the other thing is we-we have to minimize the, uh, the amount of heat that gets conducted into the spacecraft. And so the whole, um, heat shield is, uh, attached with six carbon bolts only, um, which is amazing to me.

Host:Yeah, that’s– that sounds like not a lot for a spacecraft headed to the Sun.

Dr. Nicky Fox:Right? Um, but you know, we’ve obviously tested and tested and tested. And, uh, they’re-they’re sort of– they call them pie pan structures. They look like inverted pie pans that are on the back side of the heat shield. And you’ll see them in some of the, uh, the pictures of the– um, when you see our heat shield actually attached to the spacecraft, you can see these pie pans. Um, and then we have this just beautiful titanium welded structure that is, um, it’s like a– I don’t know, s– like a cone-shaped, um, that is attached to the main body of the spacecraft, and then, um, goes up and out, and the heat shield attaches on the top of this structure. And I can tell you that, um, I have– I’m not– it will probably surprise you– I’m not a welder. Um, but-but I have engineers who I’ve seen kind of go almost weepy at the beautiful quality of the welding of this structure. Um, it is just phenomenal. And it’s made of titanium, and, uh, that’s what holds our heat shield to the spacecraft.

Host:So people who appreciate great engineering and really cool technology, this is a moment to geek out on that.

Dr. Nicky Fox:It really is, and, uh, not only does this truss hold our heat shield in place, but it also holds the cooling system for the solar panels. So it’s an amazing piece of technology.

Host:How should people kind of relate to this mission? Because there’s a sexiness to the idea of like flying near the sun, but what are you learning to help people, and why should people be really interested in this?

Dr. Nicky Fox:So the big mysteries are really why the corona is so hot, why it’s so active. So where you see this 3 million-degree temperature, the plasma itself, the coronal material, suddenly gets so energized that it can move away from the Sun, and it sort of bathes all the planets, that it’s a– it’s a continual streaming. We call it the solar wind. And Gene Parker, for whom the mission was– is named actually predicted there would be a solar wind.

Dr. Eugene Parker:When I first stumbled across the mathematics and established the solar wind, it was 1957. I was 30 years old. C over V equals… It’s so simple. Four lines of algebra, and it sort of hit me– it’s a solar wind.

Dr. Nicky Fox:We’re essentially a boulder in the stream that is flowing from the Sun all the time.

Host:That’s a really interesting way to look at it.

Dr. Nicky Fox:And so, you know, here we are. We are now, um, we’re interacting with this solar wind. And so it gets very accelerated. It carries with it the sun’s magnetic field. It carries a lot of plasma. It carries a lot of particles. And the Earth has a magnetic field also. When those fields are in the opposite direction, um, just like like poles repel, opposite poles attract. Um, it will actually allow these two magnetic fields to kind of join. It lets all of this energy in from the solar wind. Lots of great physics happens all around the Earth. But the result is space weather. Um, so the nice part of space weather is the beautiful Northern and Southern Lights.

Host:Okay.

Dr. Nicky Fox:The Northern and Southern Lights are essentially a large current system flowing in the sky. It’s like having a big wire with a current flowing across it.

Host:A really pretty one.

Dr. Nicky Fox:Very pretty. Very dangerous one. If it happens to be flowing over a power grid at the time– all currents need to have somewhere to close. If the ground is not conducting, they will look for something else to close through. Very nice of you– you’ve actually provided a power grid for them. They can actually flow through the power grids, and cause big damage.

Host:Interesting.

Dr. Nicky Fox:Um, you know, we’ve had, uh, catastrophic failures of power grids. We’ve had burn-outs. We’ve had brown-outs. We’ve had all kinds of issues. If you lose your power grid, everything goes down now. Think how reliant we are on technology. Um, you can’t– you can’t move money– your bank is no longer working. You can’t put gas in your car. You can’t– all these things. If you lose your power, eventually you’ll have no clean water. Um, so these-these are big issues that we deal with. Of course, satellites get damaged because you let all these particles in, and they can get damaged ’cause the radiation belts pump up. Everything is driven by the Sun. We have great models that predict– you know, you see a big event on the Sun, and we predict what that’s going to do to Earth. Right now, those models have a gap in them. It’s like the missing piece of the puzzle, because we don’t know, truly, what physics is going on in that region, because we’ve never been there. And so we’ll make transformational improvements in our ability to be able to predict how the Earth is going to respond to our ever-changing Sun. And so it’s-it’s a great mission, it’s a mission of discovery, it’s a voyage into the unknown that we’re going to.There be dragons. Um, it’s amazing from the scientific point of view. But does have a big societal impact, because that star is there. It’s doing whatever it wants to do, and we have to live in the atmosphere of that sun. So it-it really does affect everybody.

Host:What NASA does is discover the unknown, which is, uh, a challenging thing to do. Dr. Fox, appreciate you, and your efforts, and your team, and your hard work. We wish you all the best. Go Parker Solar Probe, and, uh, thanks, Dr. Fox.

Dr. Nicky Fox:Coolest hottest mission under the sun.

[ music ]

Host:As Dr. Fox was talking about the coatings for the Parker Solar Probe heat shield, it reminded me– we have some similar work happening in our own applied physics lab. As it turns out, this technology is evolving really fast.

Dr. Bob Youngquist:Yeah, I got a phone call recently from one of the big aerospace companies.

Host:Okay.

Dr. Bob Youngquist:One of the-the big ones. And they contacted me and they said, “we think this technology is awesome. We wanna see it fast-tracked. We want to store liquid oxygen on the Moon. That’s our goal, and we know we can only do that with your coating.”

Host:That’s Dr. Bob Youngquist with me in the booth. He spent over 25 years solving problems and inventing solutions for Shuttle ground support. Since the Shuttle program ended in 2011, he’s been freed up to do more pure research. Today he’s here to talk with me about radiation protection. My understanding is you’re developing something that can– could potentially in the future improve the ability of a probe like that to get closer to the Sun?

Dr. Bob Youngquist:Uh, yes, yes. The, um– right now, the state-of-the-art in optical solar reflectors is based on silver and quartz. The best-best reflection of solar power that you can buy is basically a quartz layer on top of silver. And that has the astonishing result of still absorbing 6% of the Sun’s energy. That’s a lot of energy when you get close.

Host: Sure.

Dr. Bob Youngquist:And the Parker Solar Probe people couldn’t even use that because the silver would melt with how close they’re getting. I mean, the Parker Solar Probe is, um, outstanding. It’s an incredible piece of engineering. Um, and then they have a really effective and-and-and– shield that they’ve developed to help block the Sun’s radiation. But-but there’s always things you can do to improve on these things.

Host: Absolutely.

Dr. Bob Youngquist:And, um, we believe that our coatings would allow you to reflect away more of the Sun’s energy, so that your shield wouldn’t get as-as hot. And if you can keep the shield temperature down, you can get closer. The Parker Solar Probe, the heat shield gets really, really hot. You don’t wanna sit under a broiler.

Host:Okay, yeah.

Dr. Bob Youngquist:This thing’s hotter than a broiler.

Host:I don’t wanna sit on that.

Dr. Bob Youngquist:Don’t wanna sit– right. So they put about 4 inches of carbon foam in there to act as an insulator.

Host:Okay.

Dr. Bob Youngquist:And that’s great. It works. What we would rather do is radiate that heat backwards.

Host:Okay.

Dr. Bob Youngquist:And put in a silver reflector, so the infrared radiation that would normally hit us bounces off of that silver reflector and gets thrown off to the sides.

Host:I see.

Dr. Bob Youngquist:So we would rather use a radiative shield than a big thick piece of–

Host:Okay.

Dr. Bob Youngquist:Of carbon shield.

Host:Okay.

Dr. Bob Youngquist:Um, so, assuming that, and assuming we have a very good reflective surface, we believe we can get maybe ten times closer to the Sun than the Parker Solar Probe.

Host:So I think they’re getting about 4 million miles, so you’re talking about getting in the range of like–

Dr. Bob Youngquist:0.4, 0.4.

Host:So 400,000 miles, which, again–

Dr. Bob Youngquist:Yeah, from the surface of the Sun.

Host:Coming from here on Earth, 93 million miles.

Dr. Bob Youngquist:Yeah.

Host:That’s incredibly close.

Dr. Bob Youngquist:Incredibly close.

Host:So future missions could-could pull on you guys not to create great scientific instruments for their spacecraft, but to help them protect those spacecraft even better.

Dr. Bob Youngquist:That’s-that’s exactly right. In fact, I was, um, invited to go talk to the Science Mission directorate a couple of weeks ago in Washington to-to discuss this-this very thing. And, uh, they’re-they’re interested in looking, down the road, at what a, um, a future heliophysics mission to the Sun might look like. And our-our coatings are one option, you know, that could be brought to bear to help get even closer to the Sun than the Parker Solar Probe. So, so let me talk a little bit about some more applications.

Host:Yeah, that’d be awesome. I’d love to hear.

Dr. Bob Youngquist:Okay, so the original request was that we be able to take liquid oxygen to Mars.

Host:Okay.

Dr. Bob Youngquist:And we-we demonstrated theoretically and then built our coatings, we put them into a– we actually built a chamber that we could chill down to 40 Kelvin– very– almost-almost-almost absolute zero– chill things down, put our samples in there, hit them with-with light, and look and see whether they were absorbing or not.

Host:Okay.

Dr. Bob Youngquist:And so far, we’ve done quite well on those tests. The coatings are-are holding up. We need to do a little more work, but we’re demonstrating we can keep things cold in space.

Host:You kind of blew past this, but you built a chamber to test things at 40 Kelvin?

Dr. Bob Youngquist:Well, yeah, we have a cryogenics lab at the Kennedy Space Center.

Host:Okay.

Dr. Bob Youngquist:And they have something called a cryo cooler, which will take you down to about 20 Kelvin, which is liquid hydrogen temperature.

Host:Sure.

Dr. Bob Youngquist:Um, when we put heat loads on it and add structure to that surface, it comes up to maybe 40 Kelvin. So we’re really operating at about 40 Kelvin, which is very, very cold.

Host:Which is an accomplishment on its own to be able to test with that, but you guys are getting a chance to test in an actual environment your coatings, which is fantastic.

Dr. Bob Youngquist:That’s right, we have a chamber that we evacuate and chill down to very cold temperatures, we paint the walls all black.

Host:Okay.

Dr. Bob Youngquist:So if you were sitting in there, it would be as if you were sitting out in, you know, deep space.

Host:Wow.

Dr. Bob Youngquist:Very cold environment, very black environment. And then there’s a little window at the top, and we can bring in what radiation we want to-to simulate various wavelengths, sort of bringing in a simulated sun.

Host:Sure.

Dr. Bob Youngquist:Now, it’s hard to simulate the Sun exactly.

Host:Yeah, no doubt.

Dr. Bob Youngquist:Yeah, but we can– we can make ballpark simulations. So it’s– I don’t wanna– I don’t wanna say this testing replaces an actual test in space.

Host:Sure.

Dr. Bob Youngquist:But it’s-it’s a good step.

Host:Yeah.

Dr. Bob Youngquist:And the people up at the Glenn Research Center are working with us, building a higher fidelity version of that system.

Host:Cool. So you were talking about applications– I wanna get back to that.

Dr. Bob Youngquist:Yeah, so there– the people at Glenn that we’re working with, they’re very interested in taking propellants into space and storing them. There’s a lot of interest out there in taking liquid natural gas into space and preserving it, you know, liquid oxygen into space and preserving it without active cooling– being able to take this stuff on a long– a long mission. Rather than having to take nitrogen tetroxide, you actually take liquid oxygen. And liquid oxygen has much more oxygen in it than nitrogen tetroxide, which is the other material that’s often used as an oxidizer. So you gain a lot of weight advantage if you can kick liquid oxygen and not have to add a lot of cryo coolers and, you know, active cooling kind of systems. You could put a tank out in space and it would get cold. It would just emit away radiation into the background of the– of the universe and get colder, and colder, and colder. And you’d be able to store liquid oxygen in space.

Host:Which is pretty cold.

Dr. Bob Youngquist:Which is really cold. Yeah, 90 Kelvin.

Host:Okay.

Dr. Bob Youngquist:Yeah, very, very cold.

Host:Which is roughly, like, -350 Fahrenheit?

Dr. Bob Youngquist:Yeah, something like that.

Host:In that area?

Dr. Bob Youngquist:In that area, yeah.

Host:Okay.

Dr. Bob Youngquist:But right now, we can’t do that because we don’t have any coatings that reflect away enough of the Sun’s energy. So a few years back, I approached what’s called NIAC, the NASA Institute for Advanced Concepts. And they agreed to fund me to see if I could come up with a better coating. And we soon realized the answer to this problem had been achieved by the optics community in the 1960s. They-they actually– the optics community had the same problem– they couldn’t come up with a good reflective coating, and they realized the way to make a good coating is to use white scatterers. Think of snow, clouds.

Host:Okay.

Dr. Bob Youngquist:You know, these things are bright white, and they’re bright white because they don’t absorb the visible light that your eyes can see. They just bounce it all around, by little particles, and they scatter that light back at you. And they’re very, very efficient at that. They don’t absorb– essentially absorb almost nothing. And so all that light has to go somewhere, so eventually it all gets scattered back. Big snowbank, you know, a salt-salt shaker, you know, cotton fibers– all these things are white because they’re scatterers. So if you wanna make a really good reflector of energy, what you do is you say to yourself, “over what spectral band am I interested?” Do I wanna scatter ultraviolet as well? Do I wanna scatter infrared? You know, how– what do I want to scatter? You find a material that won’t absorb that energy. You know, some-some base material–

Host:Sure, makes sense.

Dr. Bob Youngquist:Grind it up into a powder.

Host:Okay.

Dr. Bob Youngquist:And maybe center it– mix a little water, make a clay.

Host:And-and– sorry– centering is heating it?

Dr. Bob Youngquist:Yeah, basically, what you did when you were in, um, 7th, 8th grade when you baked clay and put it into a kiln and you fired it up– that kind of thing.

Host:Okay.

Dr. Bob Youngquist:So you’re basically just taking this stuff, making a powder, add a little water, make a paste, squeeze it into a mold, put it in an oven, a kiln, fire it, pull it out, and you’re done– you’ve got a tile that will scatter energy over whatever band you chose.

Host:And so you could make your own shape, essentially.

Dr. Bob Youngquist:Exactly, you make your own shape, and you can make this stuff arbitrarily thick, and you can make it out of pretty much whatever material that you want.

Host:Okay.

Dr. Bob Youngquist:So we chose a material originally called barium fluoride, which is an optical material that is transparent from the ultraviolet through the visible, to the near infrared, the mid-infrared, even into the full– even where– the heat your body’s giving off goes right through this stuff.

Host:Interesting.

Dr. Bob Youngquist:Yeah, so it’s very broad-band. So you grind– we actually buy it as a powder, make these tiles out of it, and these things should theoretically– and so far, to the best of our measurements– scatter away the majority of the Sun’s energy. Theory says if you coat a tank with this stuff, at the Earth’s distance from the Sun, the tank should get well below liquid oxygen temperatures.

Host:So can I coat my house in this? Like, it’s Florida. It’s hot. Summertime is coming. Can I– can I keep my house cool with this stuff?

Dr. Bob Youngquist:You-you could. You could, but there are cheaper approaches. Yeah, here on Earth, here on Earth, the ozone layer blocks a lot of the UV.

Host:Okay.

Dr. Bob Youngquist:So you don’t have to worry about that stuff. The atmosphere won’t transmit a lot of that infrared. So people have come up with cheaper white coatings than barium fluoride.

Host:Gotcha.

Dr. Bob Youngquist:Barium fluoride is ideal for when you’re above the ozone layer and you get that really– there’s a lot of really harsh ultraviolet coming off the Sun, you know, that doesn’t make it through the ozone layer.

Host:Sure.

Dr. Bob Youngquist:And so down here on Earth, at ground level, you know, things aren’t quite as bad. It’s not quite the spectral extent of the Sun that we have to worry about– that we have to worry about in space.

Host:So if my house is on the Moon…

Dr. Bob Youngquist:Oh.

Host:Is this what I want?

Dr. Bob Youngquist:Yep, this is what you want.

Host:Okay, so this is– this is– beyond Earth, this is kind of the right solution for what we want.

Dr. Bob Youngquist:Yeah, but let me– let me talk about– I got talking to some of the people from the Jet Propulsion Lab.

Host:Okay– one of our centers out in California.

Dr. Bob Youngquist:That’s right, and I-I gave a presentation to them concerning my-my coating and its ability to get closer to the Sun, you know, than the Parker Solar Probe currently will reach. And they raised two very interesting issues, or possibilities. The first one is they would like to better test Einstein’s general theory of relativity.

Host:Okay.

Dr. Bob Youngquist:And they need a very strong gravitational field to do that.

Host:Okay.

Dr. Bob Youngquist:So they would like to get close to the Sun and park like an atomic clock, and watch and see how time passes close to the Sun–

Host:Interesting.

Dr. Bob Youngquist:And try to help continue to validate Einstein’s theories.

Host:Interesting.

Dr. Bob Youngquist:But the other topic they raised is truly fascinating. They would like mankind to begin its first interstellar missions. They would like us to build a launch, uh, not a Pioneer and a Voyager to take, you know, 100 years to get any substantial distance. They would like an actual mission that’s going so fast that it flies out of the solar system and can reach some point between the stars, between our star and say Alpha Centauri.

Host:Sure.

Dr. Bob Youngquist:So it can look back at us.

Host:Sure.

Dr. Bob Youngquist:And we can start to image our actual solar system from some distance out.

Host:Okay.

Dr. Bob Youngquist:And see what things really look like out there and what the environment is truly like. We’re just conjecturing now, but this is a mission to get out there and really do it.

Host:Okay.

Dr. Bob Youngquist:The only way right now with current technology to go that fast is to slingshot around the Sun.

Host:Oh, interesting.

Dr. Bob Youngquist:They have to get closer than–

Host:Interesting.

Dr. Bob Youngquist:Yeah, than about a million miles from the surface of the Sun.

Host:That’s– That is terribly interesting.

Dr. Bob Youngquist:Yeah.

Host:So will you see gravity assist with missions like New Horizons?

Dr. Bob Youngquist:Mm-hmm.

Host:Uh, even Parker Solar Probe is gonna do a few with Venus.

Dr. Bob Youngquist:Yup. Yes.

Host:But we’re talking about doing it off of the Sun.

Dr. Bob Youngquist:Off of the Sun itself. So you take the biggest gravitational field you have in the solar system and you’re gonna slingshot around it. You’re gonna use it as your gravity assist.

Host:Do you know– Did-did they give you a sense of how fast they’re talking, if they can pull this off, how fast they’re– that-that slingshot give them, what speed they’ll get?

Dr. Bob Youngquist:Oh, I mean, it comes to hundreds of kilometers a second. I-I-I– Don’t quote me– Well, you are gonna quote me, but–

Host:We won’t hold you to it.

Dr. Bob Youngquist:Well, we’ll just say–

Host:We won’t quote you.

Dr. Bob Youngquist:Hun-hun-hundreds of kilometers a second.

Host:Okay.

Dr. Bob Youngquist:As you–

Host:So really, really fast.

Dr. Bob Youngquist:It’s really, really fast.

Host:Okay.

Dr. Bob Youngquist:They’re– They actually give their distances, their-their speeds in terms of astronomical units. In other words, the distance from the Sun to the Earth astronomical units per year and what they want to do is leave Pluto.

Host:Sure.

Dr. Bob Youngquist:Well, flying past Pluto and still be moving at about 20 astronomical units a year.

Host:We heard from the Parker Solar Probe folks that the corona, which comes out a great distance from the Sun and is hotter than the Sun itself, so how does this kinda coating help you get even closer? ‘Cause obviously you’re talking about the ability to get closer under a million miles.

Dr. Bob Youngquist:Mm-hmm.

Host:Is the corona not an issue?

Dr. Bob Youngquist:Yeah, the-the corona under– at least the analysis that-that I’ve done– the-the corona is not a serious issue because the density of material is very, very low. There’s really very little material there. You know, the-the Sun has a photosphere that’s very dense and, you know, 6,000 degrees Kelvin. So it’s, you know, it’s hot but not incredibly hot. But you got this trans–

Host:Oh, that sounds really hot to me.

Dr. Bob Youngquist:Yeah, I know. But then you got this transition region. They call it the transition region and above that the corona starts.

Host:Okay.

Dr. Bob Youngquist:And the corona’s around-around a million degrees.

Host:Okay.

Dr. Bob Youngquist:Much, much hotter. But it’s very, very sparse.

Host:Okay.

Dr. Bob Youngquist:There’s very few particles there. In fact, the solar wind, when you go out and leave the Earth’s magnetic field the solar wind is composed of particles that have an effective temperature on the order of a million degrees, but there’s only one particle per cubic centimeter. There’s almost no particles there. You’re seeing the-the emission from the Sun of these particles that have a lot of energy but there’s not a lot of them. So the-the corona, it does extend out from the Sun and it is very high temperature but there’s very little energy content to it.

Host:I wanted to ask you, so we-we’ve talked about repelling the heat and radiation.

Dr. Bob Youngquist:Mm-hmm.

Host:Is this enough to protect humans? If I take a capsule to Mars, one of the challenges we know of is the radiation from the Sun. Can I protect myself with this?

Dr. Bob Youngquist:Okay, oh– Well, they’re different kinds of radiation.

Host:Okay.

Dr. Bob Youngquist:Yeah.

Host:That’s– Man, that’s so important to know.

Dr. Bob Youngquist:Yeah, the-the radiation that we’re trying to block is the stuff you see. It’s the– mostly the visible light coming off the Sun, the-the-the, um, visible and ultraviolet and infrared irradiance, the light that’s hitting you.

Host:Sure.

Dr. Bob Youngquist:Now the Sun also has solar wind coming off, which are particles, protons and electrons.

Host:Sure.

Dr. Bob Youngquist:And that’s a source of radiation. That’s easily blocked, unless there’s a solar flare.

Host:Right.

Dr. Bob Youngquist:If there’s a solar flare then you get a lot of particles in the high density with a lot of energy and now you have to go to a safe room.

Host:Okay.

Dr. Bob Youngquist:You have to block yourself. Our coatings don’t help with that. Now you’re talking, you know, high-high irradiant– h-high-high levels of particles with high energies.

Host:Okay.

Dr. Bob Youngquist:And then there’s galactic cosmic radiation.

Host:Which just sounds awesome to say that. Like, that just sounds really cool.

Dr. Bob Youngquist:Yeah.

Host:I’m sure it’s probably dangerous.

Dr. Bob Youngquist:Well, it v– It’s the remnants of supernova.

Host:Okay.

Dr. Bob Youngquist:And so they’re bad. And the Sun’s magnetic field gets rid of a lot of it, but the really nasty stuff still reaches the Earth. The Earth’s magnetic field blocks most of the rest, but when you’re above the Earth’s magnetic field you’re subject to being hit by galactic cosmic radiation. And these are the nuclei of things like iron, like an iron nuclei that’s coming at you so fast there’s no electrons stuck to it anymore. It’s just a-a bullet coming at you.

Host:See, that doesn’t sound cool. It just sounds scary now.

Dr. Bob Youngquist:It is sc– Yup, yeah. Galactic cosmic radiation is scary and– but that’s a whole ‘nother-‘nother world. The Nuclear Thermal Propulsion Program needs to take liquid hydrogen to Mars.

Host:Okay.

Dr. Bob Youngquist:I mean, liquid hydrogen. Hydrogen has to be down to 20 Kelvin. I mean, you’re talking getting– You’re getting close to absolute zero when you talk liquid hydrogen.

Host:Okay.

Dr. Bob Youngquist:Even with our coating, even optimally with our coating we cannot block enough of the Sun’s energy to maintain liquid hydrogen. So you have to have active cooling on board.

Host:Okay.

Dr. Bob Youngquist:But, we can make it better.

Host:Sure.

Dr. Bob Youngquist:And we can lower the heat load on these liquid hydrogen tanks with our coating.

Host:Sure.

Dr. Bob Youngquist:And the Nuclear Thermal Propulsion people have come to us and have talked to us about flexible versions of our coatings, very thin layers that could be just sprayed on, and we’re currently making significant advance in that direction with some funding from the Nuclear Thermal Propulsion agency. So that’s one direction that we’re going, is coming up with a thin versions of the coating. The performance is not as good as a very thick coating. Now–

Host:So, h-how does that work? ‘Cause you’ve talked about it’s just kinda reflecting that energy.

Dr. Bob Youngquist:Yup, yup.

Host:So do you still need a thickness there to-to really be-be effective?

Dr. Bob Youngquist:What we’re doing is no different from white paint.

Host:Okay.

Dr. Bob Youngquist:In-in the fundamental understanding.

Host:Okay, so a thicker coat covers up the darker colors.

Dr. Bob Youngquist:Yup, go-go to Home Depot, buy the best quality white paint you got, put it on the wall and paint over a black surface.

Host:Yeah.

Dr. Bob Youngquist:And you paint it and you look at it and you go, “Is that good enough?”

Host:Now it’s kinda brownish.

Dr. Bob Youngquist:Yeah, so you put another layer and it’s whiter.

Host:Okay, I got ya.

Dr. Bob Youngquist:Well it turns out the more layers you put the whiter it gets.

Host:Okay.

Dr. Bob Youngquist:There’s no– there’s never an end to that.

Host:Okay, interesting.

Dr. Bob Youngquist:If you can keep on thicker and thicker and thicker, but there’s of course a place where you have so little.

Host:Sure.

Dr. Bob Youngquist:You know, lost– you know, of light actually getting through all that white paint and being absorbed by that black under layer that you don’t care anymore. Sure, and this–

Host:And we talk about a layer, what are we talking about thickness-wise?

Dr. Bob Youngquist:Well, the spray-on coatings that we’re doing are probably 100 microns, uh, 4,000th of an inch, 5,000th of an inch.

Host:5,000th of an inch?

Dr. Bob Youngquist:Yeah, for the– for the thin ones.

Host:For-for a coat.

Dr. Bob Youngquist:Yeah, for the– for spray-on coating. For the– But that’s not– If you wanna get the really good performance we’re talking a couple of millimeters.

Host:Okay.

Dr. Bob Youngquist:Tenth of an inch.

Host:So a 10th of an inch gives you really, really–

Dr. Bob Youngquist:Yeah, good performance.

Host:–effective–

Dr. Bob Youngquist:Yeah, yeah.

Host:–resistance to Sun’s energy?

Dr. Bob Youngquist:Yeah.

Host:That’s awesome.

Dr. Bob Youngquist:With the– with the new materials that we’re look– hopefully that gets improved a little bit. We still have some optimization going on, but somewhere in that ballpark.

Host:So with fast tracking, what does that timeline look like? Are we talking like a couple years? Ten years?

Dr. Bob Youngquist:Probably– You know, the problem with doing research and-and-and development is you tend to make these long several months not much happen and then there’s this leapfrog and suddenly you have things work better, especially if you step back a bit. So I-I-I’m hesitant to say in a year we’ll have it work.

Host:Sure.

Dr. Bob Youngquist:You know, like-like the barium fluoride we started off with. We discovered and found experimentally. We can’t get water off of it very easily and so we’re actually changing to a different material right now.

Host:Okay.

Dr. Bob Youngquist:And we’re looking at other options because the barium fluoride, even though it’s great and we-we’d be really good to go to the Sun because the Sun’s heat would bake off the water it’s not the appropriate material to use to get really cold because of that. Water is-is something that absorbs some ultraviolet and some infrared and it’s not the material of choice. So we don’t want that water in there.

Host:So obviously some-some details and some hurdles along the way, what’s the– what’s the process of developing a technology like this? Obviously, like, you’ve made some really good progress, you’re learning more, you’re adapting and adjusting the-the approach, so where do you go from here?

Dr. Bob Youngquist:Well, there-there-there’s actually, uh, multiple directions that we’re going and a lot of that is based on a variety of customers that are coming to the door. Um, for example, within 10 years there are 200, uh, omre astronomical units. They circuit any substantial distances.

Host:Yeah, that’s awesome. Man, that’s so cool. Hey, is it possible to block out too much radiation? Can I– Can I create something that’s too effective? Is there a problem with doing that?

Dr. Bob Youngquist:Well-Well, like in our earlier analysis we show that as you’re flying to Mars and you’re blocking all the Sun’s– uh, substantial amounts of the Sun’s energy, there’s a possibility that the liquid oxygen can freeze.

Host:Okay.

Dr. Bob Youngquist:And people don’t want it to freeze.

Host:Sure.

Dr. Bob Youngquist:And you can’t get at it.

Host:Sure.

Dr. Bob Youngquist:So we’ve actually had people come back to us and say, “Don’t get too cold. We-we want some pressure so we can pull out that oxygen as we need it.”

Host:But it’s probably easier to just not put as many layers.

Dr. Bob Youngquist:Yeah, yeah.

Host:So that’s an easy problem probably to deal with.

Dr. Bob Youngquist:It-it is. Also, there’s other sources of heat.

Host:Okay.

Dr. Bob Youngquist:You conduct heat from other parts of your spacecraft. You can actually pick up infrared warmth from planets, from Mars or from the Earth. They give– The Earth gives off a huge amount of heat, you know, as radiating warm body. So when you’re up in orbit– When-when The Orbiter was in orbit they had a radiative heat rejection system that works when they’re facing the Sun. It does not work when they face the Earth.

Host:Interesting.

Dr. Bob Youngquist:So-so they turn and face the Earth there’s so much infrared heat coming off the Earth The Orbiter starts heating up.

Host:Interesting.

Dr. Bob Youngquist:And they can’t keep it cool inside. They have to actually turn and face away from the Earth, towards the Sun or space. So, I mean, these-these things are all kinda counterintuitive. I mean, you would think the Sun is your big source of heat, but when you’re in low Earth orbit the Earth is radiating from this huge extent.

Host:Sure.

Dr. Bob Youngquist:It’s a huge object, so the heat is coming from all directions at you. The Sun is just one point in the sky so that-that-that-that heat issue is something you really have to keep in-in mind when you’re orbiting Mars or orbiting the Earth.

Host:Yeah, that’s– It’s crazy to kinda make the mental leap from understanding the world and kinda how heat and things work around us in an atmosphere. But when you get to a vacuum of space it’s a different game.

Dr. Bob Youngquist:Yeah, e-everything is ready to– The temperatures of the planets, the temperatures, you know, of the moons– You-you work out the temperature of the moon itself and all you really need to know is that the Sun is hitting it with radiation. And you can work all the numbers and you get a really good estimate for the temperature of the moon on the side facing the Sun. The same with the Earth. You got the Earth’s temperature is heavily dictated, you know, by its interaction of the Sun. There’s a little bit of internal heat coming up from the– from the core, but for the most part the Earth’s temp– the Earth and the Moon and the planets their temperatures are set by their interaction of the Sun. And that’s all radiative.

Host:Awesome. Dr. Youngquist I appreciate your time today. This has been phenomenal. Good luck to you and your team as you guys help to shape the future of-of our life beyond Earth.

Dr. Bob Youngquist:Well, thank you so much for having me. I appreciate it.

Joshua Santora (Host):That’s our show. Thanks for stopping by the Rocket Ranch. And special thanks to our guests, our Sun scientist, Dr. Nicky Fox, and cryo coatings extraordinaire Dr. Bob Youngquist. To learn more about all things Sun you can head to nasa.gov/sun. There are also several NASA podcasts you can check to learn more about the science happening all over our centers at nasa.gov/podcasts. And shout out to our intern Madison Tuttle, sound man, Lorne Mathre, editor Frankie Martin, our producer Jessica Landa, and our production manager Amanda Griffin. Tune in next month as we hear how experts are working to insure failure isn’t an option when human lives are on the line.