NASA / JPL-Caltech
Small satellites play a major role in space exploration.
CubeSats are small, only about twice the size of a Rubik's cube. As the name suggests, they are cube-shaped, 4 inches on each side and weigh about 3 kilos. But with the miniaturization of electronics, it has become possible to pack a sophisticated mission into a small package.
CubeSats has been around since 1999. Two professors, Jordi Puig-Suari of California Polytechnic State University and Bob Twiggs of Stanford University, wanted to standardize the design specifications for what they called "picosatellites." It would make it easier for groups of students all over the world to collaborate. In addition, they were cheap enough for students to create one.
"I saw a flyer on a bus stop that said," Want to build a satellite? "" says Hannah Goldberg. At the time, in 1999, she was a graduate of the University of Michigan. The flyer caught her attention and she decided that building satellites was exactly what she wanted to do.
Today Goldberg works at GomSpace, a Danish satellite company that manufactures CubeSats for the European Space Agency.
"In the early days of CubeSats, they had a bad reputation," says Goldberg. "People didn't think you could do much science or much technical benefit with them."
And in the beginning, it was probably true After all, they were originally intended as a tool for students to learn the principles of aerospace engineering. If they broke into space for a few months, no big deal.
But with the advent of smartphones, Goldberg says, engineers began to become real good at packing a bunch of electronics in a small space. CubeSats began to become more sophisticated and the cost of electronics that could be used in space decreased. Researchers began to pay attention.
Still, they were careful about writing an assignment that relied on a CubeSat, "says Barbara Cohen, a planetary scientist at NASA's Goddard Space Flight Center.
" We want to get science out of it, "says Cohen. take something out of space for three months to become space debris. "
But now she thinks CubeSats is ready for prime time.
"It's a miniature spaceship," she says. "That's actually how we think about it."
Cohen is the lead investigator for a mission called Lunar Flashlight. It is actually what is called a 6-U CubeSat, essentially six CubeSat fixed together. The end product is about the same size as a family-sized cereal box.
"The Lunar flashlight is designed to look for exposed water frost in the moon's permanently shaded regions," she says.
The deep craters at the Moon's southern pole never see the sunlight and the temperature drops to about 35 degrees above absolutely zero. The spaceship shines a laser into these craters and measures the type of light reflected back. It helps researchers determine if there is an icy frost in the bottom of the crater.
Finding water would be a blessing for future attempts to maintain human habitats on the moon. "It would be a resource to live off the land if we could find enough of that," says Cohen.
One of the reasons CubeSats can be so small and light is that they do not need a rocket engine to propel them into space. They can take a ride on other missile rockets. But Cohen, even if you get a lift from someone else, if you go to the moon or some other place off Earth's orbit, you still need some kind of propulsion system to change course.
"About a third of our satellite is dedicated to our propulsion system," she says.
Lunar flashlight uses a fairly standard thruster system for its propulsion, but there are many ways to drive through space.
"We are using a sunroof as our main propulsion system," said Tiffany Russell Lockett, NASA's Marshall Space Flight Center engineer. She is working on a CubeSat mission called NEA Scout on its way to an asteroid. "A sun sail is a large, thin film reflective surface," says Lockett. "Think of it as a sailboat or a large dragon. But instead of using wind to power itself, it uses sunlight. "
The sail is folded for launch, a process made by hand that takes weeks. The sail is unmatched larger than a highway sign, which completely dwarfs the small box that it came out from.
One of the reasons why researchers like CubeSat missions is that they are cheap compared to large science satellites like the Hubble Space Telescope, so you can have them all for yourself.
" Hubble is shared by hundreds of people every year, "says astronomer Evgenya Shkolnik of Arizona State University, who has used the telescope to study stars." And even though our team has a large program, what is considered a large program at Hubble, it is still only a week's time. "
Shkolnik studies the radiation environment around stars that have planets orbiting them. Understanding that environment will be crucial to If exoplanets have an atmosphere, to do that, she must point a telescope at the stars for as long as possible. That's why she works on a CubeSat called SPARCS, Star-Planet Activity Research CubeSat.
"This way, if you build what you need for a very clear experiment, you can have a whole year to do an experiment really well," Shkolnik says.
She believes that more researchers will turn to miniature satellites in the future.