Lunar Flashlight

Description

NASA announced the mission was ended on 12 May 2023 due to problems with the thrusters.

Lunar Flashlight is a modified 6U CubeSat mission designed to go into a polar orbit around the Moon and search for water in the shadowed polar regions. The science objective of the mission is to find locations in permanently shadowed regions on the lunar surface where water ice is present at concentrations of 0.5 weight percent or more with an optimal mapping resolution of 1 to 2 km. Lunar Flashlight launched as a ride-on with the ispace Hakuto Mission 1, on 11 December 2022.

Spacecraft and Subsystems

The spacecraft has a mass of 14 kg and is 11.62 x 23.94 x 36.6 cm in size. A green monopropellant (AF-M315E) propulsion system with four thrusters can provide over 3000 N-s of total impulse for orbit insertion and other maneuvers. Communications are via the Iris radio system. Power is supplied by solar panels.

Lunar Flashlight science payload consists of two subsystems, the Lunar Radiometer and the Laser Projector. The Lunar Radiometer is an infrared detector coupled to a telescope with a field of view of 1.5 to 3 degrees giving a surface spot size of about 1 km. The detector is a single pixel InGaAS photodiode with a cutoff of 2.2 microns. It is nadir-pointed and will detect the signal from the Laser Projector. The Laser Projector is a set of four shortwave infrared (SWIR) lasers. Each laser emits at a different wavelength in the SWIR spectrum (1.064, 1.495, 1.85, and 1.99 microns) in sequentially pulsed mode. The wavelengths were chosen to correspond to specific features in the water-ice spectrum.

Mission Profile

Lunar Flashlight launched with the Hakuto-R M1 mission from Cape Canaveral, Florida on a Falcon 9 Full Thrust vehicle, on 11 December 2022 at 07:38:13 UT. It was put into a lunar transfer trajectory 40 minutes after launch and was deployed from the booster 13 minutes later. Communications were established with Lunar Flashlight following deployment. It was determined that 3 of the 4 thrusters were underperforming. Modified maneuvers were planned with the fourth thruster, but that also began to underperform. Obstructions in the fuel lines are the primary suspects. Attempts to clear these were only partially successful, the mission was declared over on 12 May. It flew by Earth on 17 May and went into a heliocentric orbit.

The original plan for the mission was: The spacecraft would make observations from an elliptical near-rectilinear lunar polar orbit, concentrating on permanently shadowed regions from altitudes of 12.6 to 52.4 km. The nominal mission was 2 months, but the mission could have continued until there was not enough propellant to maintain the science orbit, at which point it would be targeted to impact the Moon.

Image credit: NASA-JPL-CalTech