Japan's SLIM probe to attempt historic Moon landing in January
Japan is preparing for its first-ever lunar landing with the Smart Lander for Investigating Moon (SLIM) probe in January. In the latest, SLIM, also called "Moon Sniper" has reached the lunar orbit. It aims to achieve an "unprecedentedly high precision landing" and will touch down within 100 meters of a specific site on the lunar surface. If successful, Japan will join the US, Russia, China, and India as the fifth nation to land a probe on the Moon.
SLIM's entry into lunar orbit
The Japan Aerospace Exploration Agency (JAXA) confirmed that SLIM entered the Moon's orbit on December 25 without any issues. The spacecraft is currently in an elliptical lunar orbit that takes 6.4 hours to orbit the Moon. The probe comes within 600km of the lunar surface at its closest point (perilune) and reaches 4,000km at its farthest point from the Moon (apolune). SLIM's target landing site is a small crater named Shioli in the lunar equatorial region.
Lunar landing schedule
Leading up to mid-January 2024, SLIM's apolune point will be lowered, and it will be adjusted to a circular orbit at an altitude of about 600km, per JAXA. The perilune point will then be reduced and preparations for a lunar touchdown will begin. On January 19, the perilune point will be 15km. The probe's descent toward the Moon will begin around 8:30pm IST on January 20, with landing expected 20 minutes later.
SLIM can change its shape to move on the Moon
To accomplish its lunar landing feat, SLIM is equipped with a unique spherical probe, developed in partnership with a toy company. This probe, slightly larger than a tennis ball, can change its shape to move on the lunar surface. Previous lunar probes have landed "a few or 10+ kilometers" away from the intended landing site. As opposed, SLIM's margin of error is under 100 meters, a level of accuracy once thought impossible.
Why high-precision landings are important for space exploration
With SLIM, "humans will make a qualitative shift toward being able to land where we want and not just where it is easy to land, as had been the case before," per JAXA. "By achieving this, it will become possible to land on planets even more resource-scarce than the Moon." Post-landing, SLIM will deploy two mini probes. These probes will image the lunar touchdown site, help monitor SLIM's status, and provide an "independent communication system for direct communication with Earth."
Backup launch date for SLIM and previous missions
SLIM is also expected to make sampling lunar permafrost easier, potentially revealing more about water resources on the Moon. If the landing does not happen in January, JAXA has a backup date around February 16, 2024. This is not the first lunar landing attempt for Japan. In April, Japanese startup iSpace aimed to become the first private company to land on the Moon. Although the spacecraft made it to lunar orbit, it crashed while attempting to land on the Moon.
