Slim Makes a Precision Landing on the Moon

Japan is now the fifth nation to make a soft lunar landing. Its Smart Lander for Investigating Moon (Slim) successfully landed on the moon, but its solar panel failed to generate power, posing a challenge.

According to the Japan Aerospace Exploration Agency (JAXS), communication was established with Slim, but because it now needs to conserve power, its priority is data acquisition—the analysis of which will take place at a later date. The space agency hopes the solar panels will restore function and generate power, which could happen after a shift in the sunlight’s angle. However, it takes 30 days for the solar angle to change on the moon. 

An important goal for Slim was to achieve a pinpoint landing, attempting to land within 100 meters (328 feet), compared with the several kilometers normal for spacecraft. All indications are that Slim hit the landing within the 100-meter accuracy.

The vehicle is 2.4m x 1.7m x 2.7m and features two main engines, 12 thrusters, solar cells, antennas, radar, and cameras. It weighs 700 kg (1,540 lbs.). It also has a unique vision-based navigation system that recognizes where it is flying, matching its camera’s images with satellite photos of the moon. Slim also has a 2-step landing method whereby the rear touches the ground first, and the entire body gently collapses forward before stabilizing. 

Once landed, Slim was to deploy two mini probes, a hopping vehicle the size of a microwave oven, and a baseball-sized wheeled rover to take pictures of the craft. The agency has not yet confirmed whether this took place.