Oct 22, 2018
This last week was very busy for the mission. On Oct. 15, the spacecraft successfully executed its second Asteroid Approach Maneuver (AAM-2), which slowed its rate of approach toward Bennu by approximately 305 mph (137 m/s) and burned around 186 lbs. (84.4 kg) of fuel. There are two more AAMs scheduled over the next month to further slow and more precisely target the spacecraft’s trajectory toward Bennu. The final two maneuvers are much smaller than AAMs 1 and 2, and will use the spacecraft’s Trajectory Correction Maneuver (TCM) engines instead of its Main Engines.
On Oct. 17, the OSIRIS-REx team jettisoned the cover that protected the TAGSAM head during launch and early flight. The team used several methods to confirm that the cover ejection was successful. Directly before the deployment, the spacecraft executed its third sample mass measurement (SMM-3) spin to measure the spacecraft’s mass properties while the cover was still attached. The day after the deployment, the spacecraft executed SMM-4, which confirmed that the spacecraft’s mass had decreased by around 2.67 lbs. (1.21 kg) from the previous day. The team was also able to confirm the cover ejection through telemetry indicating changes in thermal signatures and forces on the spacecraft.
On the mission’s science side, the spacecraft also continued with its Bennu Phase Function Observation campaign this week. Bennu now appears larger than a pixel in the PolyCam imager’s field of view, and the team is looking forward to the next few weeks as the asteroid’s shape is finally revealed.