24 July 2019: Lightsail 2 Mission Manager's Log



The LightSail 2 flight team successfully commanded solar sail deployment on July 23, 2019. At 18:46:11 UTC (11:46:11 AM PDT), in response to a ground command the deployment motor count began to increase, initiating the deployment of the four booms that pull out the four segments of the solar sail. At 18:49:55 UTC (11:49:55 AM PDT) the deployment motor reached the specified full deployment motor count limit. The motor came to rest at a count of 135,786, compared with the full deployment motor count limit of 135,728. The motor count as a function of time during the deployment event is shown in the figure below.




One orbit after sail deployment, the flight team commanded LightSail 2 to enter the solar sailing attitude control mode, Mode 2. In this mode, the sail will turn edge-on to the Sun direction when approaching the Sun, and face-on to the Sun when receding. The flight team observed the spacecraft properly initiate a rotation to the face-on attitude relative to the Sun.

During the final tracking pass opportunity of the day, the team attempted to command downlink of image thumbnails acquired during the solar sail deployment event. The command was not received or acted upon by the spacecraft.

The plan for July 24 mission operations is to downlink image thumbnails and a selected full resolution image. The team will also observe the spacecraft’s attitude control performance in Mode 2.


Solar sail deployment complete.