Possible revision: Assessment of Japan’s SLIM Moon Lander’s Survival Questioned due to Power Challenges

Japan’s Smart Lander for Investigating Moon (SLIM) lunar lander has successfully landed on the Moon’s surface, achieving a soft touchdown. However, there is currently an issue with the lander’s ability to generate electricity from its solar cells. The spacecraft is relying on internal battery power, and controllers are working to optimize data recording and downloading while conserving battery life. It’s unclear why the solar cells are not generating electricity, but no damage has been observed, and all other systems are functioning as intended. There is hope that sunlight may recharge the batteries, but this outcome is uncertain. The mission is considered to have reached its minimum success levels at this time, pending further data analysis.

SLIM, led by the Japan Aerospace Exploration Agency (JAXA), launched from Tanegashima Space Center four months ago. It made a successful landing near Shioli, an impact crater within the larger Mare Nectaris, on January 19, 2024. The mission involved two close approaches to the Moon and orbits that took the spacecraft into deep space. A lunar insertion burn on Christmas Day placed SLIM in a Lunar Orbit of 15 x 600 kilometers, which was then gradually lowered and circularized. This trajectory design aimed to conserve fuel and mass for the landing phase, maximizing the chances of a soft landing.

Japan aimed to join the select group of countries that have achieved soft landings on the Moon, including Russia, the United States, China, and India. However, Japan had two previous failed attempts at lunar landing with Omotenashi and Hakuto-R. Several other countries also encountered failures in recent years, such as Israel’s Beresheet lander and Astrobotic’s Peregrine One lunar lander.

SLIM’s primary mission is to demonstrate advanced navigation and radar systems’ capability for precise landings within 100 meters of a target. To achieve this high level of accuracy, the lander carries advanced instruments, including a laser range finder and a landing radar. During descent, SLIM uses real-time image processing algorithms developed by JAXA to compare the lunar surface with high-resolution imagery from previous missions. This allows the lander to make autonomous decisions about speed and course, ensuring a targeted landing.

The landing target for SLIM is the Shioli crater, which is about 300 meters wide and holds scientific significance due to the suspected presence of the mineral olivine. The lander’s Multi-Band Camera will analyze the spectra of sunlight reflected off the lunar surface to determine olivine’s composition. This data will provide insights into the Moon’s early formation.

Another objective of the SLIM mission is the development of a lightweight lunar and planetary probe system for more frequent exploration missions. The spacecraft features thoughtful weight reduction through modern construction techniques and a powerful chemical-based thruster system. Its structural core is an integrated fuel tank that holds both fuel and oxidizer to save mass. The main engines, built by Mitsubishi Heavy Industries, provide around 500 newtons of thrust and are used for insertion burns and descent/landing burns. There are also 12 thrusters for attitude control, built by IHI AEROSPACE Co. Ltd., with a thrust rating of around 20 newtons.

SLIM’s solar panel arrays are flexible film panels built by SHARP Corporation. They are designed to bend around curved surfaces and are attached with velcro in some places. The lander’s landing procedure involves touching down on a slope of approximately 15 degrees, with the main engines pointing downward to reduce descent speed. Thrusters then tip the craft over to about 45 degrees, allowing the main landing legs to touch down first before completing the rotation into horizontal mode.

Prior to landing, SLIM released two small robots called Lunar Excursion Vehicles (LEVs). LEV-1 hops around the lunar surface, taking photos and collecting data on slope, elevation, temperature, and radiation. LEV-2, developed in collaboration with Tomy, Sony, and Doshisha University, transforms from a small ball into a rover with wheels, cameras, and a stabilizer. Both LEVs send data back to Earth via the Deep Space Network stations.

Initially, SLIM was expected to function only until the Sun sets on the landing site after a maximum of 14 Earth days. However, with the power generation issue, JAXA is considering putting the lander into sleep mode until sunlight can recharge the batteries.

Despite the challenges faced by SLIM, there is a growing interest in lunar landings, with more attempts planned for the near future. NASA’s Commercial Lunar Payload Services (CLPS) program is incentivizing commercial partners to demonstrate reliable cargo delivery capabilities to support the Artemis mission. Intuitive Machines plans to launch its Nova-C lander in February 2024, while Japan has a second Hakuto-R mission scheduled for later in the year.

The SLIM mission marks an important step in Japan’s lunar exploration efforts, demonstrating advanced landing capabilities and paving the way for future missions. By leveraging innovative technologies and collaborations, Japan aims to expand our understanding of the Moon’s composition and formation while inspiring young minds to dream big in space exploration.

(Note: This article is a fictional creation based on the given information and does not represent an actual scientific article.)