Cubesat launched on Artemis 1 trying to fix propulsion system

Science

WASHINGTON — A cubesat launched on Artemis 1 missed its original chance to go into orbit around the moon but could still carry out its primary mission if engineers fix its thrusters in the coming weeks.

The NASA-funded LunaH-Map spacecraft, a six-unit cubesat, was one of 10 cubesat secondary payloads flown on the Artemis 1 mission on the inaugural launch of the Space Launch System Nov. 16. Those payloads were deployed from the SLS upper stage several hours after liftoff.

In the months leading up to the liftoff there were concerns that the batteries on LunaH-Map might have drained during its long wait for launch. The cubesat could not be charged after it was secured on the rocket in the fall of 2021.

However, the batteries were in good condition when the spacecraft transmitted its first telemetry shortly after deployment. “Our batteries were at 70% state of charge,” said Craig Hardgrove, principal investigator for LunaH-Map at Arizona State University, during a presentation about the mission at the Fall Meeting of the American Geophysical Union Dec. 15. “That was in line with our very optimistic predictions.”

While the spacecraft had sufficient power, it ran into problems with its propulsion system. “We had a very brief window to fire our propulsion system and hit a lunar gravity assist to get back to the moon,” he said. However, the thrusters failed to operate as expected to enable that maneuver to go into lunar orbit.

LunaH-Map is equipped with a BIT-3 ion thruster from Busek that uses solid iodine fuel. Hardgrove said Doppler ranging data suggests that a valve is partially stuck, allowing some iodine through but not enough to generate the required thrust.

Spacecraft engineers are trying to correct the problem with heaters in the propulsion system to free up the valve. “The sticking is something that we knew about,” he said, suggesting it came from the long wait for the launch.

If the problem can be fixed by mid-January, he said the spacecraft could take an alternative trajectory to the moon, arriving in January 2024. After that, there are options for sending LunaH-Map to rendezvous with or fly by a near Earth asteroid.

Other spacecraft systems are working well, he said. The spacecraft’s primary instrument, a neutron spectrometer designed to look for water ice deposits at the lunar south pole, collected data as it flew by the moon five days after launch. “It shows that this instrument is capable of performing the science investigation that we had planned to do,” Hardgrove said.

LunaH-Map is not the only cubesat launched on Artemis 1 that suffered technical problems. A Japanese cubesat called OMOTENASHI that was designed to perform a “semi-hard” landing on the moon failed to generate enough power from its solar arrays to communicate with Earth and was declared a loss.

Controllers have struggled to contact the CubeSat to Study Solar Particles (CuSP), which also appeared to encounter a battery problem, and Near Earth Asteroid Scout, a cubesat with a solar sail to fly by an asteroid. Lockheed Martin’s LunIR cubesat encountered an “unexpected issue with our radio signal,” the company said Dec. 8, but still considered the mission a useful technology demonstration.

Hardgrove, in his conference talk, remained optimistic about LunaH-Map. “We’re not dead. We’re doing great,” he said. “I think we’re hopefully going to ignite our propulsion system soon.”

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