WASHINGTON — Engineers are resolving thruster issues on a cubesat launched last month to search for water ice on the moon, the latest in a series of technical issues among small satellites recently launched to the moon and beyond .
In a Jan. 12 update, NASA’s Jet Propulsion Laboratory said three of the Lunar Flashlight cubesat’s four thrusters were underperforming or producing less thrust than expected. One explanation, JPL said, was that there were obstructions in the lines supplying propellant to the thrusters, reducing the amount of propellant reaching the thrusters and therefore the thrust they produce.
Spacecraft controllers plan to run thrusters for longer periods, hoping this will help clear obstacles. If thruster performance cannot be restored, project officials are considering alternative approaches that would allow the spacecraft to reach the moon and complete its mission. The spacecraft will have to begin daily maneuvers in February to be able to enter orbit around the moon in about four months.
The lunar flashlight is designed to enter a near-rectilinear halo orbit, similar to that used by the CAPSTONE cubesat that arrived on the moon in November and the future lunar gateway. The orbit will take the cubesat 15 kilometers above the surface to the south pole, where it will use lasers to search for water ice that may exist on the surface.
The cubesat’s propulsion system uses a “green” thruster called Advanced Spacecraft Energetic Non-Toxic (ASCENT), formerly known as AF-M315E. The thruster was successfully demonstrated during NASA’s Green Thruster Infusion mission launched in 2019, but Lunar Flashlight is the first time ASCENT has been used in a mission beyond Earth orbit.
A change in the propulsion systems of the lunar flashlight during its development into a system provided by the Georgia Institute of Technology caused the cubesat to miss its original launch opportunity as a secondary payload during the space launch system’s inaugural mission, Artemis 1. The cubesats were due to be delivered to NASA for installation on the rocket by fall 2021, and Lunar Flashlight’s propulsion system was not ready in time. NASA instead provided a rideshare launch opportunity, eventually launching the spacecraft on a Falcon 9 on Dec. 11 with Japanese company ispace’s Hakuto-R lunar lander.
Artemis 1 was launched on November 16 with 10 cubesat secondary payloads. More than half of them encountered significant problems during the launch. An example is LunaH-Map, a NASA-funded cubesat also designed to orbit to search for water ice. He suffered from a problem with a stuck valve in his electric thruster that compromised his ability to enter lunar orbit.
The mission’s lead investigator, Craig Hardgrove, said in mid-December that engineers believed heating the valve would allow it to open and restore the thruster to normal operation. The mission has until mid-January to fix the thruster to allow the spacecraft to orbit the moon, after which he said he would look into opportunities to perform an asteroid flyby instead. .
Several other cubesats reported problems or failed to communicate with Earth at all. There is no obvious technical problem linking the issues with the cubesats.