22 July 2019: Lightsail 2 Mission Manager's Log

On July 21-22, the flight team conducted additional testing of attitude control Mode 2, solar sailing mode. The team implemented filtering of the commanded momentum wheel torques to reduce jitter. Following the July 21 test, an error in flight software related to the momentum wheel maximum speed threshold was found and corrected via a software patch. The gains for the proportional-derivative control algorithm were updated to increase the expected magnitude of commanded momentum wheel torques.

Results from the July 22 test are shown below. The test was fully successful, and LightSail 2 correctly followed the desired profile, as indicated by the red line in the Figure. Three 90 degree slews were performed during the test.

The flight team is prepared for solar sail deployment on July 23. The nominal time for solar sail deployment is approximately 18:45 UTC.