HELSINKI — Japan’s space agency made contact with its SLIM moon lander Sunday, despite the spacecraft not being expected to function after lunar night.
Contact with the Smart Lander for Investigating Moon (SLIM) spacecraft was reestablished on Sunday, Feb. 25, the Japan Aerospace Exploration Agency (JAXA) announced via its dedicated SLIM account on X, formerly known as Twitter, early Feb. 26.
The mission team received telemetry from SLIM around 5:00 a.m. Eastern (1000 UTC). The temperature of the communication equipment was extremely high, according to JAXA, due to the sun being high over the landing area. Communication was terminated after only a short period of time, JAXA stated.
The SLIM team is however now preparing to conduct observations with SLIM’s multiband spectroscopic camera (MBC) later in the lunar day. MBC is designed to ascertain the composition of the lunar surface and could provide insights into the moon’s history. Sunset over Shioli crater, on the rim of which SLIM landed, will occur Feb. 29.
SLIM was not designed to survive the deep cold of lunar night. Temperatures fall below minus 130 Celsius during the roughly 14-Earth-day lunar nighttime, damaging electronics. Other spacecraft have used radioisotope heater units to provide heating during lunar nights to allow prolonged operations.
The spacecraft—also referred to as “Moon Sniper” for its objective of making a precise landing—made its historic landing Jan. 19.
That feat saw the country join an exclusive club of the United States, the former Soviet Union, China and India in making successful robotic lunar soft landings. Intuitive Machines has since become the first private entity to land on the moon. The Nova-C lander, named Odysseus, likely tipped over on its side when landing, however.
SLIM’s operations on the surface have been limited due to the unintended attitude of the spacecraft after landing.
Shinichiro Sakai, SLIM project manager, provided an update to the Space Development and Utilization Subcommittee of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Feb. 26 Japan time.
Sakai reiterated that the landing was hampered by the failure of one of two engines with around 50 meters of descent remaining. This resulted in uncontrolled lateral movement and the lander ending up on its nose, and the main engine pointing upwards.
SLIM was planned to tip onto its side, cushioned by five crushable, 3D-printed aluminum lattice landing legs. Instead, with SLIM’s solar cell facing westwards, away from the sun, the spacecraft was forced to power down just over two hours after landing Jan. 19. Communication with the spacecraft was established on the night of January 28th once sufficient power was obtained from the solar cells.
Sakai said the team is currently conducting a detailed investigation into the cause of the engine malfunction. The team will also consider future countermeasures. SLIM’s precision landing technology could allow greater science returns for future missions, allowing teams to target very specific locations of interest instead of general areas.
SLIM also carried a pair of small, innovative rovers which it successfully deployed onto the moon in the final stages of descent. The 2.1-kilogram Lunar Excursion Vehicle 1 (LEV-1) uses a hopping mechanism, while LEV-2 is a 0.25-kg, baseball-sized, spherical rover.
LEV-1 transmitted directly to Earth an image of SLIM taken by LEV-2, demonstrating inter-robot radio wave data transmission and revealing the landing state of the main spacecraft. LEV-1 performed seven autonomous hops across 107 minutes, according to Sakai’s presentation.
