NASA relieved as tumbling CAPSTONE Moon spacecraft restored to normal operations

NASA is now relieved as the CAPSTONE spacecraft has been restored to normal operations and its uncontrolled spin has been put to an end. The spacecraft, which was launched by Rocket Lab from New Zealand on June 28, is on its way to the Moon but an anomaly sent it spinning out of control while losing communication with the ground controllers.

The issue, that is now resolved, occurred on September 8 when the mission team executed a trajectory correction manoeuvre but it caused the spacecraft to spin and controlling and countering it was beyond the capacity of the onboard reaction wheels. Short for Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment, CAPSTONE will test a non-rectilinear halo orbit (NRHO) around the Moon for NASA's Artemis Program.

NASA said that the anomaly was due to a partially-opened valve in one of CAPSTONE’s eight thrusters; whenever the propulsion system was pressurised, the thrusters produced the thrust thus pushing the probe away. “Initial telemetry from CAPSTONE and observation data points to a successful manoeuvre, indicating that the spacecraft has stopped its spin and regained full 3-axis attitude control, meaning CAPSTONE’s position is controlled without unplanned rotation,” NASA said in its statement. 

After spacecraft recovery, the mission team oriented its solar arrays with respect to the Sun and adjusted the pointing of its antennas for uninterrupted communication with Earth. NASA is in contact with the spacecraft through the Deep Space Network which comprises three huge radio antennas in the US, Australia and Spain.

"Over the coming days, the team will monitor the spacecraft status and make any needed adjustments to procedures in order to account for and mitigate the effects of the partially open thruster valve," NASA said. "The mission team also will work to design possible fixes for this valve-related issue in order to reduce the risk for future manoeuvres."

Built by Advanced Space and funded by NASA, the CAPSTONE probe will enter the NRHO on November 13 and will carry out its mission for six months. It weighs around 25kg and would come as close as 1,609 km from one lunar pole and go as far as 70,000km from the other.

Image: NASA