On Friday, October 7, CAPSTONE team members successfully executed an operation to stop the spacecraft’s spin. This clears a major hurdle in returning the spacecraft to normal operations.
Following a planned trajectory correction maneuver on September 8, CAPSTONE suffered an issue that put the spacecraft in safe mode. It was soon discovered that the spacecraft was spinning beyond the capacity of the onboard reaction wheels to control and counter. According to data from the spacecraft, the most likely cause was a valve-related issue in one of the spacecraft’s eight thrusters. The partially open valve meant the faulty thruster generated thrust whenever the propulsion system was pressurized. After extensively reviewing telemetry and simulation data, the mission team conducted multiple tests on the spacecraft in order to formulate a plan to stop the spacecraft’s spin despite this issue.
On Friday morning, recovery commands were executed. It appears that the maneuver was successful, according to initial telemetry from CAPSTONE and observation data, which indicate the spacecraft has stopped its spin and regained full 3-axis attitude control. This means CAPSTONE’s position can be controlled without unplanned rotation. CAPSTONE has now oriented its solar arrays to the Sun to maximize power generation. It has also adjusted the pointing of its antennas to provide a better data connection to Earth.
The risks of this anomaly and recovery process were substantial, and the team worked extensively and collaboratively to mitigate these risks. Over the coming days, the team will continue to monitor the spacecraft’s status and make any needed adjustments to procedures in order to account for and mitigate the effects of the partially open thruster valve. In order to reduce risk for future maneuvers, the mission team also will strive to design possible fixes for this valve-related issue.
CAPSTONE remains on track to insert into its targeted near rectilinear halo orbit at the Moon on November 13.
CAPSTONE – short for Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment – is owned by Advanced Space on behalf of NASA. The spacecraft was designed and built by Terran Orbital. Operations are performed jointly by teams at Advanced Space and Terran Orbital.
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