One NASA-funded lunar cubesat has recovered from a communications failure, while engineers are developing back-up plans for another cubesat that experienced a drive problem.
On February 8, NASA announced that controllers have resumed sending commands to the Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment (CAPSTONE) cube satellite. Operated by Colorado-based Advanced Space for NASA, the cubesat has been orbiting the moon since November in a nearly straight halo orbit, the same orbit planned for the lunar Gateway.
The spacecraft has been unable to receive commands since January 26, although it was otherwise functional and transmitting telemetry to Earth. The on-board computer rebooted on February 6 when the crew loss timer went off, restoring two-way communication. NASA has not disclosed what prevented the spacecraft from receiving commands.
Apart from the communication problem, CAPSTONE has been performing well since arriving on the Moon, completing more than 12 orbits. The spacecraft only had to perform maneuvers twice to maintain its orbit, compared to expectations that such maneuvers would be required every orbit.
In addition to testing the stability of the near-rectilinear halo orbit, the satellite operators attempted to test their autonomous positioning system with another lunar-orbiting spacecraft, NASA’s Lunar Reconnaissance Orbiter (LRO). In that cross-linking test on January 18, LRO received a signal from CAPSTONE, but CAPSTONE did not collect the range measurements from the returned signal needed for navigation measurements. Additional stitching tests are planned.
The CAPSTONE team has worked through several problems since the spacecraft’s launch in June, including a communications outage shortly after separation from its lunar photon impact stage and an orientation control problem caused by an engine malfunction in September. Spacecraft engineers were able to overcome these problems, leading to a successful launch in November.
“We’ve learned a tremendous amount just with a small, 12U cubesat on the way to the moon that is informing other programs,” said Brad Cheatham, executive director of Advanced Space, during a panel at the FAA’s Commercial Space Transportation Conference. February 9.
Another lunar cubesat is still struggling with the motion problem. NASA’s cubesat lunar lantern was launched on December 9 as an auxiliary payload during the launch of Japan’s ispace commercial Falcon 9 lunar lander. A month later, NASA reported that Cubesat’s engines were malfunctioning, threatening the spacecraft’s ability to enter a nearly straight halo orbit.
On February 8, NASA said that efforts to fix the problem, including using one fully functioning engine to correct its trajectory, were unsuccessful. NASA said that after a series of maneuvers, one engine “rapidly lost performance,” leading engineers to conclude that the spacecraft was not capable of entering lunar orbit.
The mission team will try an alternative approach to meet the mission’s science goals, which include flying over the moon’s south pole and using lasers to look for evidence of water ice deposits there. Engineers will try to put the spacecraft into a very high Earth orbit, which will allow it to fly around the South Pole of the Moon once a month. These flights can begin already in June.
According to NASA, other Lunar Flashlight systems are performing well.