LightSail Signal Heard

Artists impression of LightSail

Artists impression of LightSail

On the Planetary Society’s website Jason Davis @JasonRDavis reports LightSail is again transmitting on 437.435 MHz, AX.25, 9600 bps FSK.

Jason writes: The Planetary Society’s LightSail test spacecraft reported for duty this afternoon [May 30], 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.

LightSail is not out of the woods yet. Its exact position remains fuzzy, complicating two-way communication. Today’s [May 30] 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 each radio chirp’s Doppler shift helps narrow down the possibilities.

Read Jason’s full post at

LightSail Transmissions Stopped