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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When it’s ready for launch, your typical spacecraft is transported to the launch vehicle in a special truck, or on its own airplane, or in a railway car. It usually has to be packed in something at least the size of a shed. Carl Brandon, a physics professor at Vermont Technical College, stowed his in the overhead compartment of a commercial airliner.

“It took me about two minutes to go through security,” he says. When they heard what had just gone through the X-ray machine, the TSA agents at Burlington’s airport flocked to him. “They all wanted to hear about the CubeSat,” says Brandon.

Vermont Tech’s satellite—its first ever—is one of hundreds of tiny spacecraft projects under development that may change how we explore the solar system. This particular one won’t travel far, but after being launched into Earth orbit last November, the Vermont Lunar CubeSat began testing navigational equipment that, in theory, could guide it to the moon. If all goes well, in a few years Brandon and his team will try to turn theory to reality with a slightly larger version.

Slightly larger, in this case, would mean 10 by 10 by 30 centimeters, about the size of a loaf of bread. The satellite now in orbit is a cube only 10 centimeters on a side, but it has the same kind of equipment you’d expect on a much larger spacecraft: star-tracking camera, GPS, gyroscope, accelerometer, magnetometer, solar panels, computer, and radio transceiver.

Technology you can get your arms around: Students from the University of Alabama at Huntsville check out their CubeSat on a zero-G flight in 2012. (Robert MarkowItz / NASA)
Cheap satellites need cheap rides. Under a defense department contract, Boeing is looking into a low-cost smallsat launcher that would first be carried to 40,000 feet by an F-15. ( Boeing)
The University of Michigan’s proposed CubeSat Ambipolar Thruster (CAT) would turn water into plasma propellant. (University of Michigan)
No spacecraft has seen Saturn’s ring particles from this close up. A CubeSat might get right in there among them. (Ron Miller)

Small spacecraft are nothing new—the first satellite launched by the United States in 1958, Explorer 1, weighed only about 30 pounds. But with electronics getting more compact—a trend driven largely by demand for things like smartphones—smallsats can now perform functions, such as photographing Earth from space, that used to be possible only with large, expensive spacecraft (see “Spysats for Everyone,” Sept. 2013). For some jobs, little spacecraft may even be better.

Case in point: Saturn’s rings. The $3 billion Cassini spacecraft, which has gathered the most detailed information about Saturn to date, can’t risk coming close enough to the rings to study the icy particles they’re made of. One wayward particle and boom, there goes Cassini. Some researchers have suggested sending a large spacecraft to hover above the rings and take detailed images, but the fuel requirements for such maneuvers would be enormous, says Matthew Tiscareno, who works with Cassini’s imaging team at Cornell University in New York.

That’s why he and other colleagues at Cornell propose something simpler, smaller, and about 1,000 times cheaper. A swarm of tiny spacecraft, not unlike Vermont Tech’s Lunar CubeSat, could be injected directly into Saturn’s rings, where they would orbit along with the ice particles. Those CubeSats could then release hundreds of even smaller spacecraft, called chipsats, that would “tag” individual ice particles, recording basic information about their composition, density, and motion within the rings.

In some ways, this would be the ideal way to study the rings: gathering lots of data from lots of little sources. You actually don’t want something bigger, says Tiscareno. “If you had a spacecraft the size of a Volkswagen or—you know, Cassini’s the size of a schoolbus—it would disrupt the environment that it’s trying to measure a lot more than a CubeSat would.” Not all the tiny spacecraft would likely survive bumping around inside Saturn’s rings, but even if only one in four sent back data, he says, the mission would be a success. It’s the buckshot approach to planetary science.

The first CubeSats (called picosatellites if they weigh less than a kilogram) were developed in 1999 by Jordi Puig-Suari and Bob Twiggs at California Polytechnic State and Stanford universities, respectively. The inventors wanted a project that would allow students to build functioning satellites within just a couple of school years. Later, students at Cal Poly designed a Poly-Picosatellite Orbital Deployer, or P-POD, which packs several CubeSats together for easy release in orbit. The P-POD fits inside the unused volume on rockets delivering other, larger payloads to space.

Compactness is one advantage of the CubeSat form, but the real benefit is cost. Vermont’s CubeSat cost about $50,000, several orders of magnitude less than a typical NASA spacecraft, which means that CubeSats have a much better chance than bigger satellites do of actually flying. “The new age that’s dawning right now comes at a time when billion-dollar flagship missions are not being funded at the rate that they were in the past,” says Paula Pingree, an engineer at NASA’s Jet Propulsion Laboratory in Pasadena, California, who has designed electronics and instruments for expensive missions like Cassini and now oversees several of JPL’s CubeSat projects. “The CubeSat opportunity does give us a chance to get that access to space,” she says.

Thinking small also spurs creativity, according to Robert Staehle, another seasoned JPL engineer, who has spearheaded a project to brainstorm planetary CubeSat missions. “The fact that you have this limited-size box is part of the engine of innovation,” he says. “If you can’t figure out how to get it in the size box it is, then you’re not going [to space]. And that has been a tremendous forcing function of innovation.” Cheaper, simpler spacecraft give engineers the freedom to fail. It’s okay to lose a few CubeSats if they can be easily replaced, and learning from failure is often how technology gets better faster.

Now it’s up to CubeSat aficionados to show that small satellites can take on big jobs, like planetary exploration. Among the most attractive potential missions are those that require more than one spacecraft in more than one place. Besides infiltrating Saturn’s rings, swarms of CubeSats could fan out and explore hundreds of near-Earth asteroids, or create a network to observe electrical storms on Mars or view regions on the sun not visible from Earth.

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