CubeSat: Little Satellite, Big Deal
MADDIE SOFIA, BYLINE: You're listening to SHORT WAVE from NPR.
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EMILY KWONG, HOST:
Hey. SHORT WAVE reporter Emily Kwong here, occasional backup host when Maddie is out on the volleyball circuit. I have science correspondent Joe Palca with me today to talk about satellites - but not just any satellites, a special nanosatellite called a CubeSat.
JOE PALCA, BYLINE: Yep. It's a tiny satellite. It's...
PALCA: It's about the size of a standard-sized Rubik's Cube. And you can join them together to make larger CubeSats, if that's what you have in mind. You can make them all the way up to about the size of - what do they call it? - a family-sized box of Cheerios is how someone described it to me.
KWONG: First of all, love Cheerios - so much deliciousness in such a tiny package.
KWONG: And second, a CubeSat sounds pretty small for something that has to operate in space. These are satellites, right?
PALCA: Yes. And in the past, they were fairly limited, and they were kind of things that you could - oh, maybe try this or try that. But they were sort of throwaways. And suddenly, in the last maybe five, six, seven years - maybe even longer than that now - gotten very sophisticated. And they've also been going into deep space, which is what's really got me amused.
KWONG: Wow. OK, so today we're going to meet some scientists who are doing cool things with CubeSats. And we'll talk about how these tiny satellites are starting to play a big part in exploring space.
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KWONG: OK, Joe, we're talking CubeSats. Where should we start?
PALCA: Well, let me start by introducing you to Hannah Goldberg. She's a systems engineer at a company that makes CubeSats. But in 1999, she was an undergraduate at the University of Michigan, majoring in engineering. And she saw this flyer...
HANNAH GOLDBERG: On a bus stop that said, want to build a satellite? And so I joined a group and ended up making a small satellite as part of a larger NASA program.
PALCA: Hannah says that this class that she took was a way for students to build a simple kind of satellite. Now, this was pre-CubeSat. But clearly, it would be valuable to have young aerospace engineers have a chance to build something that was really intended to go into space. And that hunger led to something called the CubeSat, which was an idea from two engineers - one at Cal Poly San Luis Obispo and the other at Stanford University - to build this standardized platform for building space hardware.
KWONG: OK, Joe, so let's get into this a little more. We've got this standardized platform now for CubeSats. What makes a CubeSat a CubeSat?
PALCA: Well, there's a manual, and it just spells out all the details - I mean, how big it'll be, 10 centimeters or 4 inches on a side. It has to have this kind of screws. It has to have this kind of weight. It has to have all kinds of specific things. And then there are different form factors. So it turns out that the basic CubeSat is called a 1U. But there's also 2U and a 3U. And the 6U is the one that's the cereal-box size.
KWONG: And what can you put inside?
PALCA: Well, a ham sandwich or...
PALCA: No, you can put anything you like. But that's the brilliant part - you can put any kind of scientific communications technology kind of hardware in them, and you know that it's exactly going to fit, and it's going to go into space that way.
KWONG: OK. So when I think of CubeSats, they're like the Legos of satellites. They're modular. They're customizable. They're small.
PALCA: And small is really key here because one of the things that makes the CubeSat program work is the people who build CubeSats don't actually worry about how they're going to get into space; they hitch a ride with somebody else who's already going into space. That's the real money-saver because getting into space is expensive.
KWONG: All right. So how did the aerospace field respond to all these low-cost CubeSats hitching a ride into space and embarking on this research?
PALCA: Well, I think at first they were kind of dismissive.
GOLDBERG: In the beginning, the early days of CubeSats, they kind of had a bad reputation in more of the classical aerospace. So people didn't think you could do much science or much engineering benefit with them.
KWONG: So how did CubeSat technology evolve to the point where it earned respect among scientists?
PALCA: Well, there's an example of the technology that made it possible probably in your pocket right now.
KWONG: Gum wrappers?
PALCA: Yes. No, actually, gum wrappers is a great idea. But no, I was thinking more of cellphone, mobile phone.
PALCA: This is the evolution of the ability to miniaturize electronics down to very small footprints, very little weight. And suddenly, when - you know, when you had an impossibly small space to squeeze all your stuff into, well, it was possible now. So that's why people started paying attention to what you could put into a CubeSat.
KWONG: Gotcha. Yeah, I've read there are hundreds of CubeSats that have been launched over the years, and I want to know about a few missions that have caught your attention.
PALCA: Well, what really got me started on this story was the 2018 CubeSat known as MarCO. Actually, there were two...
KWONG: Polo. Just kidding. Sorry. Go on.
PALCA: (Laughter) OK. OK, you'll be a lot of fun in space.
PALCA: Actually, there were two of them. So you remember InSight? That was the mission that's currently sitting on the surface of Mars. Well, somebody had this idea that maybe they could build CubeSats that would act as relay stations that would send signals back. As InSight was landing on Mars, it didn't have a strong enough radio antenna...
PALCA: ...To send the signal all the way back to Earth, so it sent it back to these MarCO satellites, which sent it back to Earth. And so for the first time ever, there was real-time telemetry as InSight came to the ground. It was all possible because this little tiny satellite was sent into deep space. So suddenly, you're not just thinking about CubeSats in Earth orbit; you're thinking about CubeSats in deep space. And so I think that's really cool.
KWONG: Very neat. And when you say relaying telemetry, MarCO was playing a role in telling people down on Earth what was happening on Mars with the InSight mission. Is that what it is?
PALCA: Right. InSight's saying, hey, I've just deployed my parachute...
PALCA: ...Or I've just got my retrorockets on or I'm this far above the ground. And all that information was coming back to Earth through MarCO.
KWONG: Through this CubeSat.
KWONG: Very neat. So the world of space exploration is clearly seeing these CubeSats as useful.
PALCA: Yes. A CubeSat can be very handy.
BARBARA COHEN: It's a miniature spacecraft. That's actually the way we think about it.
PALCA: That was Barbara Cohen. She's a planetary scientist at NASA's Goddard Space Flight Center. She's part of a team that's using one of these 6U CubeSats about the size of a cereal box that is for a mission called Lunar Flashlight.
KWONG: I'm assuming this mission has something to do with the moon.
PALCA: No, it has to do with the Luna moth. No, you're right.
PALCA: It is the moon lunar one. Yep, that's true.
COHEN: Lunar Flashlight is designed to look for exposed water frost in the permanently shadowed regions of the moon.
PALCA: So once Lunar Flashlight is in orbit around the moon, the spacecraft will shine a laser into those regions, which are at the South Pole, of deep craters that never see the sun.
COHEN: So those are places that never see the sun. So those are very, very cold regions. They are as low as 35 Kelvin. That's colder than the surface of Pluto.
PALCA: They want to know what kind of stuff is down there. Maybe there's water or methane or mercury, and they want to know how it got there. And Lunar Flashlight is going to help tell them. But to do its work, once it's deployed, it actually has to adjust its orbit.
KWONG: Yeah, how does something the size of a cereal box change orbit in space?
PALCA: Well, again, this is the problem. You have to use almost a third of the mass of this CubeSat for fuel. So changing direction is the real expensive part of flying around in space in terms of weight because the fuel is very heavy. But there's one more CubeSat mission I want to tell you about that has a really cool, lightweight propulsion system called a solar sail.
KWONG: Oh, I already love the sound of this mission. Tell me about it.
PALCA: OK, instead, I'll let Tiffany Russell Lockett explain. This is actually her first CubeSat mission. She's an engineer at NASA's Marshall Space Flight Center.
TIFFANY RUSSELL LOCKETT: A solar sail is a large, thin film, reflective surface - think of, like, a sailboat or a large kite. But instead of using wind to propel itself, it uses sunlight.
KWONG: Oh, that's pretty brilliant. And that's how they're able to get the CubeSat to change directions. I mean, but how does sunlight propel this CubeSat?
PALCA: Well, the sun is always pushing out photons, and that causes solar radiation pressure, and that pressure is constantly pushing against anything that happens to get in its way - in this case, the lightweight material of the solar sail. And it acts like a sail, and that's how you get thrust. And the sail, by the way, is square in shape. And about each side of this sail is about the length of a school bus. And if you want to see a really amazing video, go watch as this thing - they've unfurled it a couple of times. And oh, my goodness - it's huge because it packs into this tiny little space and unfurls to this huge thing about the size of a tennis court - actually, more properly, half a tennis court.
KWONG: This whole solar sail is packed inside this CubeSat?
KWONG: Amazing. And what's the mission for this solar sail CubeSat?
PALCA: Well, this one is going to head to a near-Earth asteroid and take pictures. And they want to learn more about this asteroid's shape, its size and how it rotates, what color it is, what it's made of. And to do that...
LOCKETT: We're planning on getting to within a kilometer of the asteroid for our closest flyby. And then we'll just keep going after that.
KWONG: So this CubeSat will fly off into the sunset on the power of the sun?
PALCA: Well, metaphorically. I don't think we have sunsets in space. There's nothing for the sun to set over. But I take your point.
KWONG: (Laughter) Joe, when are these missions likely to happen?
PALCA: Well, that's an interesting question because the two last ones I mentioned - this Lunar Flashlight and the asteroid one - are supposed to go on this project called Artemis 1, which is a rocket that's going to carry a capsule that's going to go around the moon and come back, and that's been delayed and delayed and delayed. So the cool thing is you get a free ride into space if you're a CubeSat; the bad thing is you've got to wait till your driver's ready to go.
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KWONG: Science correspondent Joe Palca, thank you so much for coming on the show.
PALCA: You're welcome. It's what I'm paid for.
KWONG: That's right (laughter). It's what you're paid for. Me, too.
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KWONG: This episode was produced by Rebecca Ramirez, edited by Andrea Kissack and fact-checked by Emily Vaughn. Special thanks to Natasha Branch for engineering. I'm Emily Kwong, and this is SHORT WAVE from NPR.
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