NASA Solar Sail Belatedly Ejects from Mothership

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NASA said Jan. 19 that an experimental solar sail unexpectedly ejected from its host spacecraft weeks after space agency officials had written off the demonstration as a flop.

NASA’s NanoSail-D satellite was supposed to have ejected from its mothership, a small satellite called FASTSAT, back on Dec. 6. But that apparently did not happen.

Analysis of FASTSAT telemetry by engineers at NASA’s Marshall Space Flight Center in Huntsville, Ala., indicates that NanoSail-D has popped free on its own, according to a NASA announcement.

Ground-based satellite-tracking efforts confirmed the ejection, NASA officials said.

“We knew that the door opened and it was possible that NanoSail-D could eject on its own,” Mark Boudreaux, FASTSAT project manager at Marshall, said in a Jan. 19 statement. “What a pleasant surprise this morning when our flight operations team confirmed that NanoSail-D is now a free flyer.”

Engineers are not sure yet if NanoSail-D, a $12 million satellite about the size of a loaf of bread, is operating. To find out, officials are asking amateur radio operators to listen for the satellite’s signal, which can be found at 437.270 MHz.

The NanoSail-D science team is hopeful the 3.9-kilogram satellite is healthy and can complete its mission, which is a demonstration of a solar sail system. This technology could lead to further development of solar sails for future missions, officials have said.

“This is great news for our team. We’re anxious to hear the beacon which tells us that NanoSail-D is healthy and operating as planned,” said Dean Alhorn, NanoSail-D principal investigator and aerospace engineer at Marshall. “The science team is hopeful to see that NanoSail-D is operational and will be able to unfurl its solar sail.”

After ejection, a timer within NanoSail-D began a three-day countdown as the satellite orbits the Earth. Once the timer reached zero, four booms were supposed to deploy and the nanosatellite’s sail was to unfold, unfurling into an 18-square-meter polymer sail within 5 seconds.

If deployment was successful, NanoSail-D will stay in low Earth orbit between 70 and 120 days, depending on atmospheric conditions, officials said.

On Dec. 6, NASA triggered the planned ejection of NanoSail-D from FASTSAT, which was carrying several other scientific payloads as well.

At that time, the team confirmed that the door opened and data indicated a successful ejection. Upon further analysis, however, no evidence of NanoSail-D was identified in low Earth orbit. So the team concluded that NanoSail-D likely remained inside FASTSAT, which is short for Fast, Affordable Science and Technology Satellite.

NanoSail-D is not the first spacecraft to attempt to demonstrate solar-sail technology. In June 2010, Japan’s Ikaros probe deployed its solar sail, becoming the first craft to cruise through space propelled only by sunlight.