12 July 2019: Lightsail 2 Mission Manager's Log

07/10/2019 Image

Over the past two days, the flight team has developed and tested attitude determination and control subsystem flight software updates to address problems seen in flight and in lab-based testing using BenchSat. Software patches have been transmitted to the spacecraft, and version 8 of the ADCS flight software was activated on board last night. This version corrected several identified errors in the ADCS software, including torque rod initialization, eclipse entry/exit prediction based upon the on-board trajectory propagation, and scaling of sun sensor readings so that they can be properly utilized by the attitude determination software. Also, software was installed that allows attitude determination sensor readings to be included in telemetry, but not utilized in attitude determination calculations. A correction was also made to the longitude reported in telemetry.

Parameters in the ADCS gains file were updated, which should allow proper torque rod commanding. The new gains file will be uplinked later today, and the attitude control performance in detumble mode will be assessed.

Additional testing using BenchSat is ongoing to demonstrate proper sun sensor voting (a process that eliminates spurious sun sensor measurements), and to assess whether torque rod activation is being properly phased so that the magnetic fields introduced by the torquers do not interfere with the ambient magnetic field measurements using the magnetometers.

The team is working toward having all identified ADCS issues addressed by the end of shift on Sunday, July 15. If the on-orbit performance shows that the corrective actions have been successful, the team will then move on to assess ADCS Mode 2, which controls the spacecraft orientation relative to the Sun direction using a combination of the momentum wheel and torque rods.