[ Update June.1.15: The LightSail spacecraft may unfurl its solar sail this week: LightSail Team Prepares for Possible Tuesday Sail Deployment – The Planetary Society.
This afternoon, mission managers gave the go-ahead for a manual solar sail deployment as early as Tuesday, June 2 at 11:44 a.m. EDT (15:44 UTC), providing the spacecraft completes an arduous set of Monday preparations. Since waking up Saturday after eight days of silence, the spacecraft has been busy sending telemetry back to Earth, snapping test images and preparing itself for sail deployment.
The Planetary Society‘s LightSail went silent not long after it reached orbit due to a software problem (see earlier post). As hoped for, it has finally rebooted and resumed sending out signals, though 2-way communications have yet to be established: Contact! LightSail Phones Home after 8-Day Silence – Jason Davis/The Planetary Society
The Planetary Society’s LightSail test spacecraft reported for duty this afternoon, heralding the end of an uneasy silence caused by a suspected software glitch. At 5:21 p.m. EDT (21:21 UTC), an automated radio chirp was received and decoded at the spacecraft’s Cal Poly San Luis Obispo ground station. Another came in eight minutes later at 5:29 p.m. The real-time clock on board the spacecraft, which does not reset after a software reboot, read 908,125 seconds—approximately ten-and-a-half days since LightSail’s May 20 launch.
You can see LightSail’s phone-home packet here.
“Based upon the on-board timers contained within the beacon (and comparing them to beacons following deployment), it appears that a reboot occurred within the past day,” wrote Georgia Tech professor David Spencer, LightSail’s mission manager. “Due to uncertainty in the orbit state (TLEs), our ability to reliably track the spacecraft is marginal at this point. Cal Poly is coordinating with international colleagues to arrange their support in acquiring beacon telemetry,” he said.
LightSail is not out of the woods yet. Its exact position remains fuzzy, complicating two-way communication. Today’s contact marks the first time engineers can compare the spacecraft’s signal with orbital models called two-line element sets, or TLEs. There are ten TLEs associated with the ULTRASat fleet that joined LightSail for a free ride to orbit courtesy of a United Launch Alliance Altas V rocket. Which TLE represents LightSail is unknown, but the each radio chirp’s doppler shift helps narrow down the possibilities.
Here’s an official statement from the Society:
Solar Sail Spacecraft Contact Restored After Software Glitch Paused Communications
Pasadena, Ca. (May 30, 2015) — After a successful launch into orbit aboard a United Launch Alliance Atlas V rocket out of Cape Canaveral, The Planetary Society’s LightSail™ spacecraft went silent after two days of communications. The solar sailing spacecraft test mission, a precursor to a 2016 mission, has now resumed contact after a suspected software glitch affected communications. The LightSail team will soon determine when to attempt deployment of the spacecraft’s Mylar® solar sails.
Bill Nye (The Science Guy), CEO at The Planetary Society, issued the following statement:
“Our LightSail called home! It’s alive! Our LightSail spacecraft has rebooted itself, just as our engineers predicted. Everyone is delighted. We were ready for three more weeks of anxiety. In this meantime, the team has coded a software patch 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. 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 the coming two days, we will have more news, and I am hopeful now that it will be very good.”
For in-depth coverage of LightSail’s test and 2016 missions, follow embedded reporter, Jason Davis at planetary.org/blogs/jason-davis.