CubeSats to the Moon (Mars and Saturn, Too)

The next generation of planetary explorers.

Artist's concept of the Interplanetary NanoSpacecraft Pathfinder In Relevant Environment (INSPIRE) CubeSat. ( NASA/JPL)
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CubeSats would also make good add-ons to larger missions. They could ride along on the mothership, then be deployed to do jobs too dangerous for the main spacecraft, like flying kamikaze into a comet’s tail or into the plume of a volcano on Jupiter’s moon Io. CubeSats could even be linked together at their destination to form a single, more capable spacecraft. The California Technical Institute is developing a self-assembling space telescope made up of six CubeSats and another hexagonal-shaped nanosatellite.

That’s another thing about CubeSats: The affordability of these spacecraft is drawing more—and more diverse—engineering talent to the field. What had long been the exclusive domain of NASA, big aerospace companies, and a few well-funded universities is now within reach of schools like St. Louis University in Missouri and Salish Kootenai College in Montana; students can be involved with developing a working spacecraft through every stage, from concept to launch. Countries that have never before made space headlines, like Colombia, Hungary, Estonia, and Peru, also are putting up their first satellites—all CubeSats.

Small startup companies are getting in on the action too. Pumpkin, Inc., based in San Francisco, sells a CubeSat Kit that lets engineers add their own payload and systems to a small, standardized bus. Raptor Space Services in Mountain View, California, is working on a vehicle to carry CubeSats from the International Space Station to higher orbits.

“[Small satellites] are probably the most exciting area of the space business right now,” says Robert Hoyt, who started Seattle-based Tethers Unlimited in 1994, just as the CubeSat revolution was about to begin. With grants from NASA and the Department of Defense, the company is developing tools to boost the capabilities of CubeSats, including a foldable, high-output solar power array and a deployable dish antenna that greatly increases communications range—both of which can be stowed in CubeSat-size compartments until they’re deployed.

New methods of financing space projects are helping to expand the number of players in the field. Ben Longmier, an aerospace engineering professor at the University of Michigan, recently led a couple of Kickstarter campaigns to fund development of his CubeSat propulsion system, a plasma thruster fueled by water and other propellants. While the initial campaign failed to meet its fundraising goal, it gained the project a lot of exposure, and the second time around Longmier and his team raised almost twice their $50,000 goal.

The CubeSat revolution will need many such creative minds to pull off cheap planetary exploration. The challenge with sending shoebox-size spacecraft into deep space is how to fit all the necessary equipment for propulsion, long-range communications, radiation protection, data processing, and power—and still have room for cameras and spectrometers.

In the DIY culture of CubeSat builders, simple (read “cheap”) is good. “Why spend a million dollars when you can use a toaster oven?” says Ali Roland, who worked as an undergraduate on St. Louis University’s Close Orbital Propellant Plume Element Recognition (COPPER) satellite. Roland and others use a toaster oven to “bake” CubeSats before launch to prevent the chemical outgassing that can interfere with instruments in space. But given all the pitfalls of operating in space, success is far from guaranteed. COPPER was launched in November (along with Vermont Tech’s Lunar CubeSat) as a first step toward developing automatic imaging systems that could help CubeSats recognize and dock with one another. Unfortunately, right after launch, the team lost contact with their spacecraft.

At JPL, Staehle is well aware of the time and money that go into preventing such failures on NASA planetary missions. Yet he hopes CubeSats will create new ways of approaching familiar problems. His favorite potential application is a low-tech sample return from Phobos, the larger of Mars’ two moons. Because the moon’s gravity is relatively weak, there’s no need for rocket thrust to escape the surface. Staehle proposes using a simple spring. One CubeSat would land on the surface, scoop up sediment in a small container, and spring the container into orbit, where another CubeSat would catch it and retrieve it for return to Earth, in a kind of robotic alley-oop. Staehle says the idea started as a joke at his CubeSat project’s weekly meeting: “Somebody said, ‘Well, you can’t do a Phobos sample return with CubeSats,’ and everyone laughed in agreement. Then somebody said, ‘Well wait a minute, let’s look at this.’ In the space of 10 minutes, the whole idea came together at a very conceptual level.”

Another JPL-led project, the Lunar Flashlight, would search for ices in lunar polar craters by using its solar sail (which is primarily for propulsion) as a mirror to shine sunlight into shaded regions, then scan the area with a spectrometer.

Each CubeSat project seems to come up with another invention. An MIT team is working on an inflatable radio antenna that transmits 10 times faster and seven times farther than existing CubeSat antennas. Others at MIT are working on a penny-size thruster that shoots ionized particles out of hundreds of microscopic metallic tips. It would generate very little thrust in the short term, but plenty over a multi-year cruise to the outer solar system.

The main challenge for small spacecraft today is proving that they can be trusted on long-range, high-stakes missions. “You can do a fair amount of testing on the ground,” says Hoyt, “but nobody’s really going to trust it until it’s flown.”

That proof, in turn, depends on launch opportunities. Many tests of interplanetary-grade technology can be conducted in low Earth orbit, and NASA’s Educational Launch of Nanosatellites (ELaNa) program, part of the agency’s broader CubeSat initiative, finds free rides for academic CubeSats on rockets that are already going to orbit. For other tests—say, confirming that your CubeSat’s avionics are adequately protected from deep-space radiation—you have to go further. Russ Cox, a space entrepreneur who organizes an annual conference on sending CubeSats to the moon, says, “If we are going to be doing anything in deep space, we are going to learn how to do it at the moon first.”

Here’s where the flight opportunities start to get rare. NASA’s new Space Launch System, still under construction, is slated to carry 12 CubeSats, including the Lunar Flashlight, on its first test flight to the moon. But that launch won’t happen until 2017 at the earliest. Meanwhile, the agency is considering awarding a few million dollars in prize money for CubeSat missions to the moon and beyond.

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