In a first for Japan, the SLIM mission stuck a pinpoint landing on the Moon. How long the mission lasts depends on whether the solar cells begin charging.
(January 25, 2024) JAXA has released a statement on status of the SLIM mission, saying that the landing was within “10 meters or less, probably around 3 to 4 meters” of the planned target point, inside the targeted 100-meter range for a successful touchdown. Unfortunately, the lander settled at such an angle that the solar panels could not receive power, and the mission only operated for a brief few hours on battery before shutting down 157 minutes after landing at 5:57 UT on January 19th. The small lunar exploration vehicles did deploy before landing and returned an image of the canted lander.
The Multi-Band Spectroscopic Camera (MBC) on SLIM also returned images before shutdown. Note that the rock features annotated in the image on the right are named after breeds of dogs (!), to give some idea of their relative sizes.
There’s also an interesting descent video from frames snapped by the navigation camera on approach. You can even see Shioli Crater looming large in the view, a testament to the pinpoint landing.
(January 22, 2024) The Japanese space agency, JAXA, has shut down its lander, albeit with the battery level still at 12%, which leaves enough power for a potential restart. "According to the telemetry data, SLIM’s solar cells are facing west," JAXA announced in a post on X, formerly known as Twitter. "So if sunlight begins to shine on the lunar surface from the west, there is a possibility of generating power, and we are preparing for recovery." That said, the lander was not designed to survive the extreme cold of the lunar night, making recovery unlikely.
The original article appears below:
Today, the Japanese Aerospace Exploration Agency (JAXA Smart Lander for Investigating the Moon (SLIM) spacecraft pitched over in its lunar orbit, and began its long descent to the Moon's surface. Touchdown occurred at 10:20 a.m. EST / 15:20 UT; NASA’s Deep Space Network in Madrid picked up the lander's signal shortly afterward, but problems have ensued.
In a press conference, held shortly after the landing, officials indicated that while the spacecraft is communicating with Earth, the solar cells that would power the spacecraft throughout its mission on the surface aren't functioning. SLIM is operating on batteries only. It's unclear at this point if the panels were damaged on landing, or if they're not charging due to the spacecraft's current orientation relative to the Sun.
Watch the JAXA press conference here:
The SLIM Mission
SLIM entered lunar orbit on Christmas Day, 2023. The 120-kilogram (265-pound) lander set down in Shioli Crater on the lunar nearside. The crater, 270 meters wide (886 feet) is located inside the larger Cyrillus Crater on the western edge of Mare Nectaris.
SLIM launched last September from the Tanegashima Space Center in Japan, along with with the X-Ray Imaging Spectroscopy Mission (XRISM) observatory, which placed both missions initially in low-Earth orbit. A series of boosting maneuvers sent SLIM toward eventual capture in orbit around the Moon.
Incidentally, XRISM is having some minor issues during its commissioning phase: An aperture door on the mission's Resolve spectrometer is stuck in the closed position. While the instrument can still operate, it does so with reduced throughput, particularly for lower-energy X-rays.
The successful SLIM landing makes Japan this fifth nation to soft-land on the Moon, behind the United States, the late Soviet Union, China, and most recently India with the Chandrayaan-3 mission last year. Japan has attempted to land on the Moon before, first with the OMOTENASHI lander, which flew with Artemis 1 in 2022, then with a commercial lander, Hakuto-R, in 2023. SLIM carries upgraded technology from both. The aerospace company iSpace will attempt to send Hakuto-R 2 to the Moon later in 2024.
SLIM was designed to test the innovative “smart eyes” landing technology, which involves image-matching to aid navigation. The mission was also designed to demonstrate a pinpoint landing, that is, within 100 meters of the target, on a 6- to 8-degree slope. SLIM has a Multi-Band Camera camera on board and, if it is able to, it will deploy two baseball-size rovers on the lunar surface named Lunar Exploration Vehicle 1 and 2. These will hop and roll along the lunar surface, imaging with cameras of their own. If the solar cells are able to charge, SLIM could last about 11 days on the lunar surface. The Sun will set over the landing site on January 30th.
Demonstrating the pinpoint slope landing was crucial to the mission’s success. “Japan is part of the Artemis program: a U.S.-led highly international initiative to return humans to the Moon,” says Masaki Fujimoto (JAXA). “SLIM technology is important to Artemis, as resources that could offer long-term support to human habitat need to be investigated. For this, pinpoint landing on sloped terrain will be needed to land close to very particular sites and investigate what can be found there.”
The mission was designed for science, too. “While SLIM is predominately a technology-led mission to demonstrate pinpoint landing and landing on a slope, the spacecraft is carrying a near infrared multi-band spectroscopic camera,” explains Elizabeth Tasker (JAXA).
“The landing site by the Shioli Crater was selected for scientific reasons,” Tasker adds, “as images from the JAXA Kaguya mission suggest the site might be rich in the mineral olivine, originating from the Moon’s mantle.” Studying the region could provide clues on the Moon’s geologic history and formation.
More Missions to the Moon
The SLIM landing comes on the heels of Astrobotic’s Peregrine Mission One, which launched successfully on January 8th but, due to propulsion problems, failed to reach the Moon. Peregrine returned to Earth and reentered over the South Pacific on January 18th. Astrobotic will try again with their larger Griffin lander, which will carry NASA’s VIPER mission to the Moon in late 2024.
Next up for NASA’s Commercial Lunar Payload Services (CLPS) program is Intuitive Machines’ launch, set for February 10th. They will try for the Moon with their Nova-C lander.