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NASA Astronaut Dreams Up Space Inventions
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NASA Astronaut Dreams Up Space Inventions


NASA Astronaut Dreams Up Space Inventions
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My next guest spent nearly six months aboard the International Space Station. And while he was in space, when he had some spare time, he spent his off duty time inventing space gadgets - like making time-lapse movies of the space station, doing experiments on his own, and one of his space creations is a zero gravity coffee mug modeled after a fuel tank. How does the coffee stay in the cup without gravity? Well, let's ask the inventor.

Don Pettit is a NASA astronaut. He joins us by phone from Houston. Welcome to SCIENCE FRIDAY.

Mr. DON PETTIT (Astronaut): It's a pleasure to be here, Ira.

FLATOW: Were you always one of these gadgeteer-type guys?

Mr. PETTIT: I, yeah, I'm always one of these kind of science, stick your nose in a book and play in the workshop kind of guys.

FLATOW: So while you were up there and you had spare time, did you just bring projects with you or did you use parts you found up there?

Mr. PETTIT: Generally you use parts, what you find up there. And I do want to say that, that on Space Station we have, we have programmatic science - and this is well-planned, well thought-out science. And we spend a lot of our time doing that, but we do have off-duty time. You can't work 24 hours a day. And in your off-duty time you can look out the window or read books or do what - you know, cruise email. I wanted to spend my time doing what I call science of opportunity, where I would take things that I could find on orbit, little nuts and bolts and screw rings or food and make a science project out of it.

FLATOW: Describe your zero-gravity coffee cup, and there's a video of the cup working on our Web site at So while you're describing it, people can look at it if they can. Tell us what you did there.

Mr. PETTIT: Okay, well, this was spawned from just the human desire to be able to drink your coffee and your tea from a cup, and that's what we do here on Earth, and it seems like many social activities hinge around having a cup of coffee in your hand.

And on orbit we have to drink all our fluids from bags. So we'll have a bag of tea with the tea bag in the bag, and we'll sip this through a straw, and that's to keep from making a mess as this stuff floats out and get stuck all over everything.

And what I did was I took a sheet of plastic film, and folded it, cut it and folded it up so it looked like a cross-section an airplane wing with a flat bottom and an open top, and if you squirt your coffee or tea inside of this cup now, the shape of this cup will control the free interface, the surface of what the coffee and tea looks like, and it also, it'll keep it from sloshing out, and it'll also make it climb up the side that has the narrow apex, the narrow angle, all the way up to the lip, and you can just casually sip your coffee.

FLATOW: Wow. And did you actually drink this coffee cup - out of the coffee cup?

Mr. PETTIT: Oh, yes - yes, I did, and I made two of these, and then one of my crewmates, this was on Thanksgiving Day, we for the first time were able to perform a toast like human beings do on Earth, where we filled our cups with tea, and we made one toast to future space explorers, and then we did one toast for Thanksgiving and our families, who were obviously not there, and then we did one toast just because we could.

FLATOW: Yeah. Can we see this cup in the Air and Space Museum now, or where…

Mr. PETTIT: The cups actually came back, and they're sitting on a shelf next to my desk, collecting dust right now.

FLATOW: Ah. Well, come on. You've got to put it on exhibit, where we can see them. They're famous.

(Soundbite of laughter)

Mr. PETTIT: Who knows what'll happen to them.

(Soundbite of laughter)

FLATOW: We're talking with Don Petit, who is a NASA astronaut, who spent some time up there in the International Space Station. Were people jealous that you didn't make more for the other folks up there?

Mr. PETTIT: I think they were looking at us with, you know, wondering exactly what we were up to, and when they saw how cool these cups were, they were probably jealous. And I facetiously say that in a thousand years from now nobody will even know that I existed, but I offer that in a thousand years people living and working in space will all be drinking their coffee at the end of the day out of cups of my design.

FLATOW: There you go. You should patent that as fast you can. We're going to take a break and come back and talk with Don Petit about his gadgets.

To go to our Web site, you can see the coffee cup and his other gadgets we'll be talking about. So take this break, time to do that, and we'll be right back after this break.

(Soundbite of music)

FLATOW: I'm Ira Flatow. This is SCIENCE FRIDAY from NPR News.

(Soundbite of music)

FLATOW: You're listening to SCIENCE FRIDAY from NPR News. I'm Ira Flatow, and we're talking this hour about life in space with NASA astronaut Don Petit, who is a geek after my own heart, building all these gadgets while he was up there in orbit in the International Space Station.

If you'd like to see some of these gadgets we're going to be talking about, they're on our Web site at Our number here is 1-800-989-8255. And if you'd like to tweet us a Twitter, you can tweet us @scifri. That's @-S-C-I-F-R-I.

Don, let's talk about one of the most intriguing ones that I saw that's up on our Web site, is that the video you did with candy corn up there in space, showing how soap works. Describe that for us.

Mr. PETTIT: That falls again under science of opportunity project. We, as astronauts, get to choose a few special food items that they'll put in our pantry, and I chose some candy corn, and it occurred to me after I got on orbit that I could use this for a science demonstration instead of just eating it.

So what I did was I made a sphere of water, and I stabilize it in front of the video camera so it won't float off and stick onto the wall or something, and I realize that the candy corn's made out of sugar and the pointy end will be wet by the water. It'll try to dissolve it, and so that'll get sucked into the sphere of water.

But I carefully put a little coat of oil on the fat end of the candy corn, and oil and water don't mix, and so it'll get sucked into the sphere just as far as the big end when it hits this layer of oil.

And so surface tension forces and wetting, the wet-ability of sugar, will cause these candy corns to align themselves on the outside of this sphere as I start popping more and more candy corns in.

FLATOW: So all the pointy parts of the candy corn are pointing into the middle of your sphere, and the fat ends are sticking out.

Mr. PETTIT: Correct.

FLATOW: Instead of a popcorn ball, it's a candy-corn ball, so to speak.

Mr. PETTIT: That's right, and this is an analogy to what happens with soap molecules. Soap molecules have one end that like to be in water, and we call that hydrophilic, and then they have another end that like to be in oil. We call that hydrophobic.

And so soap will act as a bridge, so to speak, between oil and water, and that's what will allow soap mixed with water and your dirty clothes to clean all the grease off of them, and it also allows you to make salad dressings and things like that.

And so we can't see these soap molecules. We know they're there, but we can't see them, and I figure the candy corn could be used as an educational analog to what happens with hydrophilic-hydrophobic ends of molecules on the outside of a sphere.

FLATOW: It's beautiful, and you took a bite out of it at the end.

Mr. PETTIT: Well, I did. Now, the most amazing thing happened at the end of this video. When you completely coat the outside of this sphere, when you completely pack it with candy corn, when - it's this kind of loose, floppy sphere, you can touch it, and it kind of oscillates around, and little drops of water will still fly off. But when you shove that last candy corn in there, it instantaneously turns into a rigid ball, and it's the most amazing thing.

And this is a surface tension equivalent to dropping the keystone in on a Roman arch, where you have all of these loose stones not held together by mortar, and if left on their own they would just fall down into a heap.

But as long as you put that cornerstone in, you can take all the supporting structure away, and these stones will just magically hang there in the form of this arch, and this is the surface-tension equivalent of a keystone in a Roman arch.

So you shove the last candy corn in there, and this sphere just turns into this rigid ball, and then you can float it all around, and at the end, of course, you can take a bite out of it.

FLATOW: It seems like you have a paper to write about this.

Mr. PETTIT: You can, and this might be an example of, in space you get to play with your food and you can call it science.

(Soundbite of laughter)

FLATOW: But no one's done this. I've never seen anybody who's done this before. You haven't even made a video before this, have you?

Mr. PETTIT: This was the first video that I had made of the candy corn, so…

FLATOW: We have like an exclusive on this video.

Mr. PETTIT: Well, an exclusive on NPR. That's a good place to start out.

FLATOW: There you go, and you've got to publish - this is such a beautiful thing to see. It's on our Web site at But you're right, it's just magical. When you pop that last candy corn in there, it just solidifies into like a baseball. It's amazing.

Mr. PETTIT: A sweet one at that.

FLATOW: There you go. 1-800-989-8255. Some of our listeners would like to know what happens in space. Jacob in Detroit. Hi, Jacob.

JACOB (Caller): Hi, how are you?

FLATOW: Hi there.

JACOB: Huge fan, and let me tell you, it is just thrilling to be on the phone with a real astronaut. That is amazing for me. I have kind of a silly question. I'd like to know what happens when you open a bottle of champagne in space.

Mr. PETTIT: Ooh, that's a good question. I don't know because we've never brought a bottle of champagne into space. However, I can say that on the KC135 airplane, it's an airplane that flies parabolic flight paths, and for 20-second to 30-second periods you get near zero-gravity periods, and you can do experiments and training there, I have opened up a bottle of club soda, and it is one of these plastic, one-liter plastic bottles that you can crack the cap, and I'll tell you, you crack the cap and throughout the whole volume of the club soda you will see bubbles start to form.

This is called a homogeneous nucleation because they form throughout the whole volume instantaneously, and when these bubbles start to form it increases the volume of this whole system inside of the bottle, and of course the bottle is one liter.

And now if you have a liter and a half of stuff in this bottle, that's called a rocket engine, and it's a good thing that we were flying with a bunch of towels because we could mop up the mess.

(Soundbite of laughter)

FLATOW: We have a tweet from JessicaFM, who wanted to know: How do you feel after all those weeks in space?

Mr. PETTIT: You feel good when you are in space. After a few weeks your body settles down into living in space, and it figures out how to push food through your progress and all of this without having hydrostatic forces and gravity to help along the way.

You feel really good, and then of course you come back to Earth, and you have to get reacquainted with Mother Earth, so to speak, and it takes a while. It takes a few days before you get your Earth legs back again.

FLATOW: That's a real definition for coming back to Earth, you know, getting in touch with reality.

Mr. PETTIT: That's right.

FLATOW: After a while. Tell us about - you had a really fascinating time lapse that you did of the auroras, as seen from orbit there.

Mr. PETTIT: Yeah, aurora is incredibly beautiful from orbit, and I like to say that if Iris, the goddess of the rainbow, had a twin sister, she would have to be the goddess of aurora.

And we can see beautiful displays of aurora down here, but in orbit, when you look out the window at Earth, you see things on a length scale of half a continent.

When we were over the center of Australia, we can see the East Coast and the West Coast at the same time, and this perspective, this unusual perspective, allows you to see structure and detail that you can't see if your feet are on the surface of Earth or you can't see if you're in an airplane.

So aurora from space is just this amazingly beautiful display, and of course being an astronaut and being up there, you want to capture it on film, but it's too faint for standard video cameras.

And so what I did was I set up one of our standard digital still cameras for time-lapse photography. I took hundreds of sequential pictures, and then later on the ground after I came back, I could assemble these pictures into movies, and they could be rendered as high-definition movies. So that's what you see on your Web site, are movies made from still images. And it's not quite how you would see it from orbit, but it's the closest thing yet in terms of preserving and sharing this view to people who don't get a chance to go into space.

FLATOW: So you're really combining science and the arts in that video, very interesting. Are there experiments that you did not get to do that you're writing down now for your next trip?

Mr. PETTIT: Oh, I have a book. I have a little notebook that I carry with me, and I'm always writing down ideas for experiments to do.

FLATOW: Give us a few of them.

Mr. PETTIT: Well, one experiment that I want to repeat from when I was on Space Station is to look at how fine particles of material bump around and form sort of fluff balls. And when I was on Space Station, I took one of our drink bags that was filled with coffee, and it was powdered coffee inside of this drink bag, and instead of filling it with water I just puffed in it and blew this thing up like a balloon so you had this balloon that contained all this powdered coffee.

And I shook it up and the powdered coffee would spread throughout the volume of the bag. And then within tens of seconds it would all come back together in clumps that would be several centimeters in diameter in the center of the bag. And I thought this was an amazing behavior for particles floating around.

FLATOW: That is amazing.

Mr. PETTIT: And it turns out I downlinked some video of this, and it just so happened one of my astronaut colleagues who's a planetary scientist was on console that day. And he has worked with planetary formation from solar clouds, and he thought that this had relevance to how planets form.

FLATOW: So you created sort of a simulation with your coffee.

Mr. PETTIT: Yes. It's a simulation on how you go from stellar grains of dust and get something that's fist-sized where self-gravitation can then draw these things together and you can build a planet.

FLATOW: Wow. And so you what, you want to do that again?

Mr. PETTIT: I want to do that again, and I would like to do it with materials that are more indicative of what planets are made out of, not powdered coffee and milk and sugar and things like that.

FLATOW: Do you think you could bring your own stuff extra up this time instead of just depending on what you can catch in the space station?

Mr. PETTIT: You know, I don't know. They're - we're working on venues for - so that folks can bring small quantities of (unintelligible) up. Currently, there's not a process for that, I think.

FLATOW: You know, this would be such a great teaching opportunity for kids in school to watch you live in the space station, do these things, you know?

Mr. PETTIT: When you go into a frontier - and going in space is a frontier -you're going into a place where your intuition does not apply. Your Earth-honed intuition does not apply there anymore. And these places, these frontier environments, wherever they are, are places that are rich in discovery. So, you just open your eyes and look at, say, how you drink your coffee or how sugar bounces around inside of a bag, and you make new discoveries.

FLATOW: Mm-hmm.

Mr. PETTIT: And this would make an opportune environment for educational outreach as well.

FLATOW: And I'm saying, you know, the space station doesn't get a lot of great press, the Hubble, the helioscope, things like that, but if you start to turn it into - the remaining life that you have on it - into a great platform for teaching kids, then you've done some great work out there. I would think the NASA should listen to those kinds of ideas.

Mr. PETTIT: Yeah, I do. And one thing I will say about the space station, it's a construction site right now. It's nearing completion but it's still a construction site.

When I was there, we had one-fourth the electrical power, one-third of the pressurized volume, one-half of the crew size. And we spent most of our time basically bailing the water out and being glorified construction waters.

And I liken it to living in your house while you're trying to build it, and you have a table saw set up where the dining room table was supposed to be and a bucket where the kitchen sink is supposed to go, but you're living there. And then you find out you have to entertain the boss. And that's kind of like trying to do science on Space Station during this construction phase.

We are rapidly reaching the point where the construction is going to be done. And we're reaching a point where we're going to have the power and the space and the volume and the facilities and the crew available to start doing some fascinating things.

FLATOW: Talking with Don Pettit, NASA astronaut, formerly onboard the International Space Station on SCIENCE FRIDAY from NPR News.

And in that - when that period comes, do you think you'll be given that opportunity to teach from space?

Mr. PETTIT: Well, I'm planning to go back to Space Station. NASA has an educational outreach office. They've got it filled with folks that are constantly working with us in the astronaut office to bring science education, and just engineering education, how do you live and work in space - and that's an independent question of actually doing science in space - and bringing to the people who really make the space program possible through paying their taxes, bring something back to them so that they could see what's going on and they can use this frontier environment that's rich in discovery. They could used these (unintelligible) to tickle your imagination and enrich your mind.

FLATOW: Let me give them one more taste of how cool stuff is up there. Give us one more example of an invention. Tell us about your barn door tracker.

Mr. PETTIT: Oh, this is one of my favorites. I'm an amateur astronomer. And in amateur astronomy, we have this thing called a barn door tracker. And it's literally a piece of plywood on a piano hinge.

And you point the hinge - you point it up to the North Star and you mount your camera on the hinge, and you have a little bolt that goes through the plywood. And you turn the bolt like a quarter of a revolution every 25 seconds. And in doing that, you counteract Earth's motion and you could put a camera on the piece of plywood and you could take amazing pictures that shows stars all at pinpoints because you counteract the motion of Earth. That's called the barn door tracker simply because it could be made from a barn door.


Mr. PETTIT: Well, if you try to look at Earth and, say, take pictures of cities at night, the exposures are long enough that if you use a handheld camera, they're all blurry.

FLATOW: Mm-hmm.

Mr. PETTIT: And cities at night are amazingly beautiful, and astronauts have been seeing them for decades. But they've been unable to take good pictures of cities at night simply because they all turn out blurry.

So what I did was I made a barn door tracker on Earth that instead of counteracting Earth's motion so you could take pictures of space from Earth, it can counteract orbital motion so you could take pictures of Earth from space. And this allowed me to counteract the orbital motion long enough to take the time exposures needed to get sharp images of cities at night.

FLATOW: Wow. That sounds terrific.

And if you want to see a lot of these inventions that Don has created, you can go to our Web site at We've got the coffee up there, we've got the great candy corn that he talked about, and we've got all kinds of stuff up there.

And Don, you are a credit to the astronaut corps.

Mr. PETTIT: Well, thank you. Please tell my boss that.

(Soundbite of laughter)

FLATOW: Do you have a schedule when you're going up next or are you just waiting your turn?

Mr. PETTIT: Well, I just got back from a space flight in November.


Mr. PETTIT: And so, I'm still in the post-flight afterglow phase, rapidly going into doing our desk job technology work.

(Soundbite of laughter)

Mr. PETTIT: And you know, it'll be a couple more years before I get back to the station.

FLATOW: All right. Good luck to you and thanks for coming on and sharing your work with us.

Mr. PETTIT: It's a…

FLATOW: That's Don Pettit, NASA astronaut. He was joining us by phone from Houston. We're going to take a break. We'll be right back. Stay with us. Don't go away.

I'm Ira Flatow. This is SCIENCE FRIDAY from NPR News.

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