It’s been a bumpy ride for a prototype solar sail spacecraft, which was put into orbit two weeks ago by the Atlas 5 rocket that carried the Air Force’s X-37B robotic space plane.
Ground controllers lost contact with the experimental spacecraft, known as LightSail, two days after launch due to a computer software problem. After more than a week of silence, a stray cosmic ray hit apparently rebooted the spacecraft. Relieved flight controllers prepared to manually deploy the spacecraft’s thin sails.
LightSail, funded by The Planetary Society, a space exploration advocacy organization, is intended to serve as a steppingstone for a full demonstration of solar sailing next year. The precursor LightSail CubeSat mission is designed to test communication systems and the spacecraft’s deployment mechanism.
Solar sailing is an alternative, chemical-free propulsion method for in-space transportation. It takes advantage of the pressure of photons from the sun striking a thin, sail-like film to generate forward motion.
Flight controllers hoped to deploy the spacecraft’s sail on Friday, following what appeared to be a successful solar panel release. Instead, they are grappling with a battery issue.
“Following solar panel deployment, it was noticed that all of the battery cells were drawing near-zero current. This indicated that the batteries were likely in a fault condition stemming from the solar panel deployment event,” mission manager David Spencer wrote in an update posted on the project’s website.
Engineers briefly considered bypassing LightSail’s battery cells and directly tapping solar power to deploy the sail, but decided to wait to see if they would be able to gather more information to better understand the spacecraft’s condition.
“LightSail’s power system can enter a variety of failsafe conditions based on the behavior of the batteries. Engineers ... are working through a complex fault tree to determine the spacecraft’s likely state, as well as options for moving forward,” wrote Planetary Society digital editor Jason Davis.
It may fall to Mother Nature, for a second time, to fix the problem.
“The spacecraft orbit is in a geometry where eclipse occurs roughly 2,100 seconds each orbit ... Over the next couple of weeks, the orbit will precess to a full-sun condition, where the entire orbit is sunlit,” Spencer wrote.
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