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It's Alive! LightSail Spacecraft Restored After Being Silenced by Software Issue


After going silent for a few days, The Planetary Society’s LightSail™ spacecraft has resumed transmitting. A suspected software glitch had caused the satellite to stop sending telemetry back to Earth. The communication issue now out of the way, the LightSail team will soon determine when to attempt deployment of the spacecraft’s Mylar® solar sails.

“Our LightSail called home! It’s alive!” The Planetary Society’s CEO Bill Nye (The Science Guy) said in a statement on the organization’s website. “Our LightSail spacecraft has rebooted itself, just as our engineers predicted. Everyone is delighted. We were ready for three more weeks of anxiety.”

According to Nye’s statement, the LightSail team has coded a software patch and has it ready to upload. “After we are confident in the data packets regarding our orbit, we will make decisions about uploading the patch and deploying our sails — and we’ll make those decisions very soon,” Nye said. “This has been a rollercoaster for us down here on Earth, all the while our capable little spacecraft has been on orbit going about its business.”

In a lengthy May 26 blog post, the Planetary Society’s Jason Davis said the LightSail mission had “paused, while engineers wait out a suspected software glitch that has silenced the solar sailing spacecraft.” Following its successful May 20 launch, LightSail sent about 140 data packets back to Earth, Davis said. Over the Memorial Day weekend, however, the spacecraft's automated telemetry went silent.

Telemetry data are sent on 437.435 MHz (AX.25, 9600 bps FSK). Davis said a lot of radio amateurs have been helping to track LightSail and sent in data packets.

According to Davis, the LightSail team believes that “a vulnerability” that controls the primary avionics board was the problem. As he explained, the CubeSat’s onboard Linux-based flight software writes beacon packets to a spreadsheet file — beacon.csv — which, when it reaches a certain size, can cause the flight system to crash. A patch was devised to address the problem in later software revisions, but LightSail’s software did not include the update, and before the fix could be uploaded, the satellite went silent.




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