NASA Wants to Build Self-Assembling Spacecraft

The SPHERES orbs on the ISS. Image: NASA/ISS

In 1999, David Miller brought a copy of Star Wars: A New Hope into his MIT engineering class. He fast forwarded to the scene where Luke Skywalker is training with a lightsaber aboard the Millennium Falcon, deflecting the tiny lasers its shooting out at him.

Miller paused the movie and told his students that he wanted them to build free-flying satellites like the one Luke was training with, minus the lasers. In 2003, three Star Wars-inspired satellites called SPHERES arrived on board the International Space Station. Two months ago, Miller became NASA’s chief technologist.

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As chief technologist, Miller is NASA Administrator Charlie Bolden’s principal advisor and advocate on everything concerning technology policy and programs throughout the agency. It’s a job that goes further than an office, as I learned in a quick chat I recently had with Miller.

Locally in NASA’s Washington headquarters, Miller coordinates, tracks, and integrates all of NASA’s technological investments spanning the human, space science, aeronautical, and space technology mission directorates. Out of office he travels to field sites around the country to see NASA’s technological investments in action. He also ensures NASA is coordinating its activities with other government organizations (like DARPA), industries, and academic institutions.

NASA Chief Technologist David Miller. Image: NASA

And as you might guess, there are a lot of interesting technological developments happening with NASA at the moment. Most, though not everything, is related to the goal of landing men on Mars, and some of the more exciting technology is closely related to the free-flying robots Miller worked with for the SPHERES experiment.

Imagine a micrometeoroid smashes into a spacecraft on its way to Mars. It doesn’t destroy the vehicle, but causes enough damage to require an external repair. It would take a lot of time and energy for astronauts on board to suit up for a spacewalk, survey the damage, and fix the problem. But as Miller told me, the crew could instead send automated robots out as their proxy.

The goal of the SPHERES project—which stands for Synchronized Position Hold, Engage, Reorient, Experimental Satellites—is to test if such free-flying inspectors could speed alongside the spacecraft, surveying damage and fixing what’s broken. The name is apt: The three orbs inside the International Space Station are a test bed that NASA is using to gather data that will ultimately feed into the autonomous maneuvering systems of future spacecraft.

But most importantly, the SPHERES experiment is maturing the technology for missions that will eventually go well beyond low Earth orbit. Miller said that his vision with SPHERES was always to create a testbed to which increased capabilities could be added, a seed that could eventually support a whole bunch of different research activities. And this is exactly what’s happened with the robots over eight years. New advances will allow these spheres to be armed with smartphones to create a user interface, meaning developers can theoretically build apps to help control them.

The advances made using these versatile free floating satellites are impressive. Fitted with interferometers, they can undertake rendezvous and docking maneuvers with tumbling objects, as done under the VERTIGO test program.

Imagine a satellite knocked by debris in orbit, tumbling too dangerously for an astronaut to repair. The hope is that these free-floating satellites could match the tumbling satellite’s motion and land on it, carrying out the necessary repair remotely without endangering a man’s life. This technology can even characterize things like tumble rate and inertia properties, things Miller said are vital when dealing with a tumbling spacecraft.

Beyond their individual abilities, the potential of using SPHERES to develop craft that can fly in formation is enormous. One advanced technology related to these free-flying satellites that Miller has worked with before is electromagnetic formation flight between small spacecraft.

Traditionally, spacecraft maneuver in space using fuel; small thrust rockets positioned outside the spacecraft fire, nudging it slightly on its path to a destination or adjusting its place in orbit. The problem with this propulsive method is that eventually the fuel runs out and a perfectly good but spacecraft is left hurtling through space uncontrolled.

Among the technologies Miller has investigated is the use of electromagnets to nudge a spacecraft in flight. Harnessing, storing, and using energy from the Sun, these satellites could move relative to each other without using up limited fuel stores. They could even transfer electrical energy wirelessly between themselves. Fuel wouldn’t be the limiting factor anymore; the longevity of the hardware would dictate the length of the mission. And as the Voyager spacecraft have shown, a well-built spacecraft can last decades.

This technology becomes really interesting when you think about deep space telescopes. Imagine launching a telescope in pieces. The question at this point, Miller pointed out, is how do you take pieces that are free flowing and bring them together? Electromagnetic free-flying satellites could assemble themselves into one cohesive spacecraft after launch, the nascent stages of which has been studied at MIT.

The pieces wouldn’t have to stay assembled. If something were to break or become inoperable by a micrometeorite strike or simple wear and tear, the telescope could perhaps rearrange its pieces and recover from the setback. The same types of free-flying satellites could also make deep space repairs, arriving at the scene to make repairs without a human component.

Repair bots flying in formation and self-assembling spacecraft are one thing, but there’s one big question that remains: When will NASA develop lightsabers so astronauts can train using the SPHERES on the ISS? To that, Miller pointed out the ISS is a testbed that hosts experiments from all kinds of researchers ranging from high school students to international scientists. So anyone can take on the challenge of developing a lightsaber, and if NASA is interested enough, maybe then astronauts will finally be able to reenact that scene from Star Wars.