NASA Ends Lunar Flashlight Mission Following Propulsion System Failure

NASA's Jet Propulsion Laboratory (JPL) has announced the termination of the Lunar Flashlight mission, just five months after its launch.

The cubesat, designed to enter a polar orbit around the moon, encountered propulsion system issues that prevented it from achieving its intended trajectory.

Engineers at NASA had been working for several months to identify and resolve the problem, which was suspected to be debris obstructing the propellant lines. The blockage caused a reduction in propellant reaching the thrusters, resulting in insufficient thrust to enter the planned orbit.

In an attempt to clear the obstructions, NASA made a final effort on May 5 by increasing fuel pump pressures and manipulating valves outside of operational limits. This technique yielded inconsistent results, with some instances of increased thrust observed. Unfortunately, these efforts proved inadequate to maintain the spacecraft near the moon, leading JPL to conclude the mission.

While placing the cubesat into a near-rectilinear halo orbit was no longer feasible, mission planners had hoped to redirect it into a distant Earth orbit that would allow for monthly flybys of the moon. However, this objective could not be achieved due to the propulsion system's limitations.

Despite the propulsion problem, other systems on Lunar Flashlight continue to function. The spacecraft will conduct a flyby of Earth on May 17 at an altitude of 65,000 kilometers before venturing further into deep space.

The cause of debris entering the propulsion system remains unclear. Daniel Cavender, the former project manager for the cubesat's propulsion system at NASA and current director of Rubicon Space Systems, explained that the design constraints of the 6U cubesat limited the engineers' ability to incorporate filters into the system. He acknowledged a process error at some point, which compromised the system's cleanliness. Ground tests of thrusters with debris in their propellant lines yielded data consistent with the cubesat's observations.

Lunar Flashlight showcased technological advancements and successfully tested various systems. These included the Sphinx flight computer, capable of low-power operation in deep space's radiation environment, and the Iris upgraded radio.

"Lunar Flashlight was highly successful from the standpoint of being a testbed for new systems that had never flown in space before." - Christopher Baker, Program Executive For Small Spacecraft Technology in NASA's Space Technology Mission Directorate

The mission also encompassed a scientific objective of searching for water ice in the moon's permanently shadowed craters using a laser reflectometer instrument. Although the spacecraft cannot fulfill its scientific goals, it did validate the instrument's functionality and provided valuable in-flight performance data. 

Originally planned for the Artemis 1 mission, which was to be launched by the Space Launch System (SLS) rocket, Lunar Flashlight encountered delays due to a propulsion system redesign. Consequently, NASA included it as a secondary payload on the Falcon 9 launch of the HAKUTO-R M1 lander by the Japanese company ispace, which took place less than a month after Artemis 1.

Several other cubesats launched on Artemis 1 also faced technical challenges that hindered their mission objectives. 

NASA is currently considering options for the future of the cubesat based on its remaining capabilities.