HELSINKI — Japan’s SLIM robotic spacecraft entered lunar orbit Dec. 25, establishing a moon landing attempt scheduled for Jan. 19.
SLIM accomplished a roughly three-minute-long lunar orbit insertion burn at 2:51 a.m. Eastern (0751 UTC), the Japan Aerospace Exploration Agency (JAXA) announced Christmas Day.
SLIM is now in a 600 x 4,000-kilometer polar lunar orbit, as planned. The spacecraft is currently in a standard condition, JAXA stated. It would soon begin regularly lowering its orbit in preparation for landing.
The landing attempt is scheduled to start at 10:00 a.m. Eastern (1500 UTC) Jan. 19, landing around 20 minutes later. The lander will aim to set down inside a 100 meters of its goal point on the slope of the mid-latitude Shioli crater.
SLIM launched Sept. 6 on a H-2A rocket from Japan’s Tanegashima Space Center together with the XRISM space telescope. SLIM spacecraft entered low Earth orbit and started a series of orbit-raising maneuvers as a part of its circuitous voyage to the moon.
It made a translunar injection burn Sept. 30, making a lunar flyby Oct. 4. This set the spacecraft on a protracted, looping, propellant-saving journey to the moon, resulting in lunar orbit insertion on Christmas Day.
SLIM will next regularly lower its apolune, or farthest point from the moon, and enter a circular orbit at an roughly 600-kilometer-altitude in mid-January, in response to JAXA.
Perilune will then be lowered, reaching a 15-km-altitude orbit Jan. 19 Japan time, ready for the Jan. 19 landing. SLIM will begin to decelerate from a speed of around 1,700 meters per second at that time.
Five crushable, 3D-printed aluminum lattice landing legs will help the lander absorb the of impact of touch down and choose the sloped rim of the 300-meters-wide Shioli crater.
A successful SLIM landing would make Japan the fifth country to soft land on the moon. In August India became the fourth nation to realize the feat with its high latitude Chandrayaan-3 mission landing.
The major objective of SLIM is to exhibit a highly-accurate lunar soft-landing with a light-weight architecture. It would use a vision-based navigation system and carries observational data from Japan’s SELENE orbiter launched in 2007. This method might be used to discover its landing zone during its autonomous descent and landing. It also carries a laser range finder for the ultimate stages of descent.
Beyond the landing attempt itself, the spacecraft is designed to spend the rest of the lunar day on the surface conducting experiments. SLIM carries a Multi-Band Camera (MBC) to evaluate the composition of Shioli crater by analyzing the spectra of sunlight reflected off its surface. Teams are particularly on the lookout for the presence of the mineral olivine, which can have been ejected from beneath the moon’s crust.
SLIM can be carrying a pair of small, progressive rovers. Lunar Tour Vehicle 1 (LEV-1) uses a hopping mechanism, while LEV-2 is a baseball-sized, spherical rover. Each carry cameras and science payloads.
The mission could lead on to lower cost exploration efforts in the longer term, in response to JAXA. The accuracy of landings might be useful for accessing areas of high scientific interest as an alternative of more general, safer landing zones.
The spacecraft has a dry mass of 200 kilograms and 700-730 kg wet mass at launch. The expected development cost was 18 billion yen ($120 million).