CAPSTONE Back Under Control

The CAPSTONE cubesat on its way to the Moon to scout a new orbit for NASA is returning to normal operations. Built, operated and owned by the private sector, the spacecraft suffered an anomaly on September 8 that caused it to spin out of control. Operators now have stopped the spinning and regained 3-axis attitude control allowing CAPSTONE to point its solar arrays towards the Sun to restore power and its antenna toward Earth to improve communications. It still will reach lunar orbit on November 13 as planned.

The 55-pound Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment (CAPSTONE) spacecraft, about the size of a microwave oven, was developed through NASA’s Small Business Innovation Research (SBIR) program. Designed and built by Terran Orbital, the spacecraft is owned by Advanced Space in Westminster, CO on behalf of NASA. The two companies operate it jointly.

Launched on a Rocket Lab Electron rocket from New Zealand on June 28, communications were briefly lost shortly after it separated from Electron on July 4. They were soon regained, however, and the spacecraft successfully made its first course change on July 7.

Then on September 8 during another trajectory change, something happened that caused the spacecraft to lose stabilization and begin spinning. After weeks of troubleshooting, operators determined that a valve on one of the eight thrusters is partially open so it produces thrust whenever the system is pressurized.

CAPSTONE will be the first spacecraft to enter a unique elongated orbit around the Moon called a Near Rectilinear Halo Orbit. NASA plans to put its Gateway space station in that orbit to support the Artemis lunar program.

The elliptical orbit will bring a spacecraft as close as 1,000 miles of one lunar pole, but 43,500 miles from the other every seven days. CAPSTONE will validate NASA’s models of requirements for power and propulsion to maintain the orbit and test navigation capabilities using another NASA satellite that’s been orbiting the Moon since 2009, the Lunar Reconnaissance Orbiter, as a reference point.

NASA praised the work of the team in a post on its Artemis blog.

The risks of this anomaly and recovery process were significant, and the team worked extensively and collaboratively to mitigate these risks. 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. The mission team also will work to design possible fixes for this valve-related issue in order to reduce risk for future maneuvers. CAPSTONE remains on track to insert into its targeted near rectilinear halo orbit at the Moon on Nov. 13.

Advanced Space said the commands were sent to CAPSTONE this morning and initial observations and data point to “a successful recovery.” They are evalauating changes to operational procedures to avoid this problem in the future while looking at potential fixes to the valve.

Advanced Space received $13.7 million from NASA to develop and manage CAPSTONE. The Rocket Lab launch cost $9.95 million.