WASHINGTON — The cube satellite launched on Artemis 1 missed its original opportunity to enter lunar orbit but could still carry out its primary mission if engineers fix its engines in the coming weeks.
The NASA-funded LunaH-Map spacecraft, a six-cubic module, was one of 10 cube sub-payloads flown on the Artemis 1 mission at the Space Launch System’s inaugural launch on November 16. These payloads were deployed from the SLS’s upper stage several hours after liftoff.
In the months leading up to launch, there were concerns that the batteries on LunaH-Map might have run out during its long wait for launch. The cubes cannot be shipped after they are installed on the rocket in the fall of 2021.
However, the batteries were in good condition when the spacecraft sent its first telemetry shortly after its deployment. “Our batteries were at about 70% charged,” said Craig Hardgrove, principal investigator for LunaH-Map at Arizona State University, during a presentation about the mission at the American Geophysical Union fall meeting on Dec. 15. In line with our very optimistic expectations.”
While the spacecraft had sufficient power, it had problems with its propulsion system. “We had a very short window to fire up our propulsion system and hit the lunar gravity assist to get back to the moon,” he said. However, the thrusters failed to work as expected to enable that maneuver to go into lunar orbit.
The LunaH-Map is equipped with a BIT-3 ion engine from Busek using solid iodine propellant. Hardgrove said the Doppler measurement data indicated the valve was partially stuck, letting some iodine through but not enough to generate the required thrust.
Spacecraft engineers are trying to correct a problem with heaters in the thrust release valve. “Stickness is something we knew about,” he said, indicating that it came from the long wait for launch.
If the problem can be resolved by mid-January, he said the spacecraft could take an alternate trajectory to the moon, arriving in January 2024. After that, there are options to send a LunaH-Map to rendezvous with or fly by a near-terrestrial asteroid.
He said other spacecraft systems are working fine. The spacecraft’s primary instrument, a neutron spectrometer designed to search for water ice deposits at the moon’s south pole, collected the data during its flyby of the moon five days after launch. “It shows that this tool is capable of the scientific investigation we planned to do,” Hardgrove said.
LunaH-Map isn’t the only cube launched on Artemis 1 that has experienced technical problems. A Japanese vehicle 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 had difficulty connecting to the CubeSat for Studying Solar Particles (CuSP), which also appears to have battery trouble, and the Near Earth Asteroid Scout, a cube with a solar sail to fly alongside an asteroid. Lockheed Martin’s LunIR cubesat encountered an “unexpected problem with our radio signal,” the company reported Dec. 8, but still viewed the mission as a useful technical demonstration.
Hardgrove, speaking at the conference, remained optimistic about LunaH-Map. “We’re not dead. We’re doing a great job,” he said. “I think we hope to fire up our payment system soon.”
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