Lunar cubesats encounter technical problems

WASHINGTON — A NASA-funded lunar cubesat has recovered from a communications failure while engineers are developing backup plans for another cubesat that suffered a propulsion problem.

NASA announced on February 8 that controllers have restored the ability to send commands to the cubesat Cislunar Autonomous Positioning System Technology Operations and Navigation Experiment (CAPSTONE). That cubesat, operated by NASA’s Colorado-based Advanced Space, has been orbiting the moon since November in a nearly rectilinear halo orbit, the same orbit planned for the Lunar Gateway.

The spacecraft had not been able to receive commands since January 26, although it was functioning and transmitting telemetry back to Earth. The onboard computer was reset on 6 February when triggered by a loss of command timer, restoring two-way communications. NASA did not reveal what prevented the spacecraft from receiving commands.

Aside from the communication problem, CAPSTONE has worked well since it reached 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 each orbit.

In addition to testing the stability of the nearly straight halo orbit, satellite operators have attempted to test their autonomous positioning system with another spacecraft in lunar orbit, NASA’s Lunar Reconnaissance Orbiter (LRO). On that January 18 crosslink test, the LRO received a signal from CAPSTONE, but CAPSTONE did not collect range measurements from the returned signal needed for navigation measurements. Additional crosslinking tests are planned.

The CAPSTONE team has worked on a number of issues since the spacecraft launched in June, including a communications outage shortly after its Lunar Photon stage separated and an attitude control issue caused by a faulty thruster in September. The spacecraft’s engineers were able to overcome these problems, leading to a successful orbital insertion in November.

“We’ve learned a lot from just one small 12U cube on its way to the moon that is informing other programs,” said Brad Cheetham, executive director of Advanced Space, during a panel at the Federal Aviation Administration’s Commercial Space Transportation Conference Feb. 9.

Another lunar cubesat, however, is still struggling with a propulsion problem. NASA’s Lunar Flashlight cubesat was launched on December 9 as a secondary payload in the Falcon 9 launch of a commercial lunar module by the Japanese company ispace. A month later, NASA reported that cubesat’s thrusters were underperforming, which threatened the spacecraft’s ability to enter a nearly straight halo orbit.

NASA said on February 8 that efforts to correct the problem, including using a fully functional thruster to adjust its trajectory, had been unsuccessful. NASA said a booster suffered a “rapid loss of performance” after a series of maneuvers, leading engineers to conclude that the spacecraft lacks the capability to enter lunar orbit.

The mission team will try an alternative approach to achieving the mission’s scientific objectives, which involve flying over the moon’s south pole and using lasers to look for evidence of water ice deposits there. Engineers will attempt to maneuver the spacecraft into a very high Earth orbit that will allow flybys of the moon’s south pole once a month. These overflights can start as early as June.

Other Lunar Flashlight systems are working well, NASA said. This included recent testing of its laser reflectometer instrument.

Leave a Reply

Your email address will not be published. Required fields are marked *