High above the Earth floats a graveyard — a growing fleet of moribund communications satellites jettisoned into retirement after they broke or became obsolete. Now, they may be about to get second lives as working satellites, with local laboratories developing ways to repurpose them 22,000 miles up in space.
The laboratories are working for a Department of Defense program called Phoenix, which is built on the bold vision of recycling rather than replacing satellites.
It is a task that requires a complicated choreography of software, engineering, and deft maneuvering of robotic arms far above the Earth. Miniature “satlets,” equipped with assemblages of electronics, software, and propulsion, would hitch rides on commercial flights into space. A servicing spacecraft would pick up the satlets and stow them in a toolbelt until it approached an old antenna. There, the robotic arms of the spacecraft would be used to attach a satlet and transform a piece of space junk into a working satellite.
“There are a good number of retired spacecraft that are perfectly functioning, but either ran out of fuel or got taken over by [newer] technology,” said Seamus Tuohy, director of space systems at Draper Laboratory in Cambridge. “Getting a rather large antenna up in orbit is a rather costly thing, so when they’re up there you want to utilize them to their fullest.”
Draper is developing software that could be used to keep the satellites pointing in the right direction, building on its experience in maintaining the International Space Station in its correct alignment.
According to the Defense Department, an estimated 140 commercial satellites with salvageable antennas or other equipment sit in a so-called “graveyard orbit” and could be repurposed if the right technology were available.
That represents a big opportunity and a big technical challenge. Software, thrusters, and control equipment that would keep the refurbished satellites functioning and pointing in the right direction also need to be flexible to handle a variety of situations.
Dave Barnhart, program manager for the project at the Defense Advanced Research Projects Agency, said more than 20 companies and government laboratories are working on the project, which has $44.5 million in funding through fiscal year 2013. If the project is successful, the agency estimates it could provide a way to get satellites into space at a tenth of the cost, with hopes of doing a demonstration in which they turn a defunct satellite into a “new” one in 2015.
Draper is just one of the local teams involved in the Phoenix project.
Aurora Flight Sciences’ research and development center in Cambridge is working on development of the satlets that would be used to give the old antennas a new purpose as a functioning telecommunications satellite.
Many of the details, including the size of the satlets, are still being worked out, but the satlets’s functions would include propelling the satellite, guiding the alignment, handling data, and providing power.
Busek Co., a Natick company that develops technologies for space systems, is working on electronics and thrusters that could be used to point a satellite in a specific direction and maintain its orientation.
“When you have a spacecraft up in space, it’s floating freely and it needs to have some sort of mechanism to point it and position it,” said Douglas Spence, director of micropropulsion and flight hardware fabrication at Busek.
The challenge is not only to create a system that can precisely control the direction in which the satellite points, but to use very little fuel.
Many design issues have yet to be determined, including which technologies will be the most useful.
The local companies said cooperation will be necessary to integrate different technologies into a working system.
The project’s success also depends on the cooperation and interest of the companies that own the satellites.
Tuohy said the Defense Department has just begun the search for satellite providers willing to be guinea pigs in the initial effort to demonstrate the effectiveness of the strategy.
Darren McKnight, a member of the National Research Council committee that assessed the problem of space debris and issued a report last year, said the space junk closer to Earth is considered a hazard, but the satellites that sit much farther away have not caused much concern.
And, he said, “anytime you take something that was useless and make it useful, you turn debris back into an operational satellite that’s a wonderful thing,” McKnight said.
“Definitely, it could help us get some of these satellites that are derelict and turn them into something useful again.”