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NASA Expanding Tests of Star Wars-Inspired "Droids"
ISS018-E-005214: SPHERES

This close-up view shows three bowling-ball-sized free-flying satellites called Synchronized Position Hold, Engage, Reorient, Experimental Satellites (SPHERES) in the Destiny laboratory of the International Space Station. Image Credit: NASA.

You won’t find any light sabers on the International Space Station, but you will find a trio of “droids” that look a lot like what any self-respecting science fiction fan remembers as a Star Wars “remote.”

That’s the tricky little device that Luke Skywalker used to hone his light-saber skills before he went up against Darth Vader and the rest of the evil empire.

But instead of being used for light-saber practice, the droids on the space station are being used to test automated rendezvous and formation flying in zero-gravity. And soon, there may be a host of other things the droids will be used to test as their capabilities and uses are expanded and made available for National Laboratory and other uses.

Known officially as Synchronized Position, Hold, Engage and Reorient Experimental Satellites, or SPHERES, the droids have been on the station since 2006. Astronauts have conducted more than 20 experiment sessions with them, and are on tap to conduct many more. Each SPHERES droid is self-contained with power, propulsion, computing and navigation equipment. Together, they are testing techniques that could lead to advancements in automated dockings, satellite servicing, spacecraft assembly and emergency repairs.

Those techniques can be tested in computer simulations on Earth, but the space station is the only place they can be tested under sustained microgravity conditions. So far, the tests have all occurred in the safety of the station’s interior, but in the future upgraded SPHERES satellites may venture outside the station as well.


MIT undergrads flight-test a prototype droid onboard NASA's KC-135 reduced gravity aircraft. Image Credit: NASA.

In 1999, Massachusetts Institute of Technology (MIT) professor David Miller showed the movie Star Wars to his students on their first day of class. After the scene where Skywalker spars with a floating droid “remote,” Miller stood up and pointed: "I want you to build me some of those."

So they did. With support from the Department of Defense and NASA, Miller's undergraduates built five working droids. Three of them are on the station now.

“What is happening,” explained Miller, SPHERES’ principal investigator, “is that DARPA, who owns the facility on orbit, is transferring it to NASA.”

NASA, in turn, plans to make the capability available to other U.S. government agencies, schools, commercial concerns and students to expand the pool of ideas for how to test and use these bowling ball-sized droids.

Someone who has first-hand microgravity experience with the droids is Greg Chamitoff, who spent six months on the station as a member of the Expedition 17 and 18 crews, and was a co-investigator for the original SPHERES experiment.

“It was really incredible to be able to watch the SPHERES fly around in real-time following the logic of my algorithms right in front of me,” Chamitoff said. “As free-flying robots, these SPHERES are pretty amazing. There’s no other test bed where you can do this kind of research and development in 3-D. You can simulate it in a computer, but to do it in zero-G, and 3-D, that’s a unique capability.”

Additional videos from MIT
MIT Students on SPHERES
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“The algorithm I was testing was for real-time path-planning optimization while avoiding moving obstacles. One SPHERE was trying to visit a series of way-points as efficiently as possible, while another SPHERE was the moving obstacle and was actively trying to get in the way. This type of trajectory planning will be necessary for future robots to be able to navigate in their environment while trying to accomplish useful tasks,” Chamitoff explained.

NASA Administrator Charlie Bolden recently was at MIT to help kickoff the Summer of Innovation, which is designed to engage more students in science, technology, engineering and mathematics. Part of that program will be SPHERES-Zero-Robotics activities this August that will give middle school students a chance to program the droids for action on the space station.

SPHERES has been used by many organizations, including other government agencies and graduate student research groups, since 2006. This past December, two teams of Idaho high school students got to share the excitement with Astronaut Jeff Williams on the station in a SPHERES-Zero-Robotics pathfinder experiment that set the stage for this summer’s middle school activities.

ISS022-E-006355: Astronaut Jeffrey Williams with SPHERES

Expedition 22 Commander Jeff Williams performs a check of the SPHERES Beacon/Beacon Tester aboard the International Space Station. Image Credit: NASA.

> View Zero Robotics video

NASA and the Defense Advanced Research Projects Agency (DARPA) recently issued a call for ideas on how to use SPHERES. These ideas are being integrated into a new educational program called International Space Station Spheres Integrated Research Experiments, or InSPIRE. The new program is designed to use SPHERES to test advanced space technologies and facilitate student and public participation in the development process through the power of crowd-sourcing -- a concept in which many people in a community can contribute ideas or concepts. Proposals were due June 2.

"The continued expansion of capabilities will lead to an increased knowledge of navigation systems and stimulate a large number of next generation spacecraft developers," said Jason Crusan, chief technologist for Space Operations at NASA Headquarters in Washington.

Miller says that, when his team designed the SPHERES droids, all of their uses couldn’t be imagined up front. So, they built an “expansion port:” into each droid where additional sensors and appendages can be added, such as cameras and wireless power transfer systems.

“Look at wind tunnels and the role they played in aviation,” Miller said. “SPHERES is analogous to that in microgravity. We’re testing inside the station now because it is more tolerant to failure. The next plan is to go outside, sending SPHERES out through the Kibo airlock to fly away from station and be retrievable.”

For more information about the InSPIRE program and solicitation and to learn how students and teachers can get involved, visit:


For more information about SPHERES, visit:


For more information about the space station, visit:


For more information about the MIT SPHERES team, visit:


For more information about the 2010 Summer of Innovation SPHERES Zero Robotics competition, visit: