Not dead yet: Japan prepares for possible recovery of SLIM moon lander

a small spacecraft hovers just above the surface of the moon, with the blackness of space in the background.
Artist's illustration showing Japan's SLIM probe landing on the moon. (Image credit: JAXA)

Japan's first successful moon lander may still have some life left in it.

The pioneering spacecraft, called SLIM ("Smart Lander for Investigating Moon"), touched down on the lunar surface on Friday (Jan. 19), making Japan the fifth nation to join the moon-landing club.

But SLIM didn't get up and running as planned. Its solar panels failed to generate electricity on the surface of the moon, leaving the lander's future in serious doubt, officials with the Japan Aerospace Exploration Agency (JAXA) announced shortly after the historic landing. 

That was pretty much all we knew about SLIM's status until early Monday morning (Jan. 21), when JAXA gave us another update. And the news was relatively encouraging: The lander has not been declared dead, and its handlers are working toward a possible recovery. 

Related: Missions to the moon: Past, present and future

When SLIM's battery power dipped to 12% capacity on the lunar surface, the lander powered down intentionally "to avoid being unable to restart for a recovery operation due to over-discharge," team members explained early Monday via the mission's account on X.

"According to the telemetry data, SLIM's solar cells are facing west. 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. #SLIM can operate with power only from the solar cells," the team said in a separate X post on Monday.

SLIM successfully beamed home technical data and imagery collected during Friday's descent and landing, the team added in another Monday X post

We should learn much more at the end of the week, when SLIM's handlers plan to offer another status update and provide an overview of the data analyses that have been performed to date, team members said.

"Although the attitude after landing did not go as planned, we are glad we could achieve so much and are happy to have landed successfully. We're also excited to analyse the data," the SLIM team said in yet another Monday-morning X post.

SLIM is a demonstrator tasked primarily with proving out the technology required for super-precise lunar landings, which explains its "Moon Sniper" nickname. The probe aimed to land within 330 feet (100 meters) of a designated spot on the rim of the moon's Shioli Crater.

The probe launched in September 2023 along with an X-ray space telescope called XRISM, which deployed into low Earth orbit and recently beamed home its first test images.

SLIM reached lunar orbit on Christmas Day and made its historic landing on Friday. JAXA has not yet announced whether the probe hit its landing target; presumably, we'll hear more about that in the coming update.

SLIM also carried two mini-rovers, called LEV-1 ("Lunar Excursion Vehicle" 1) and LEV-2. Both of these little robots deployed as planned, and LEV-1 was known to be operating on the lunar surface, JAXA officials said on Friday shortly after the landing.

The other four nations that have soft-landed a spacecraft on the moon are the Soviet Union and the United States, both of which first did so during the Cold War space race; China, which first hit the gray dirt in 2013; and India, which joined the club in August 2023 with its Chandrayaan-3 mission. 

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Mike Wall
Senior Space Writer

Michael Wall is a Senior Space Writer with and joined the team in 2010. He primarily covers exoplanets, spaceflight and military space, but has been known to dabble in the space art beat. His book about the search for alien life, "Out There," was published on Nov. 13, 2018. Before becoming a science writer, Michael worked as a herpetologist and wildlife biologist. He has a Ph.D. in evolutionary biology from the University of Sydney, Australia, a bachelor's degree from the University of Arizona, and a graduate certificate in science writing from the University of California, Santa Cruz. To find out what his latest project is, you can follow Michael on Twitter.

  • MarkSV
    So the lander is facing away from the sunlight…
    And unless they get lucky it will likely be a scrapped mission when small remaining battery life is shot…

    So go down fighting! When it’s clear the remaining mission is doomed, signal to re-ignite a landing or steering jet again for the briefest moment, kicking the craft and giving it a chance to turn / tip / tumble and, maybe, settle down with sun on panels. If the panels are on one side the odds should be > 1 in four (it doesn’t have to be perfect just with the panel side better oriented).

    Okay maybe igniting an engine again isn’t possible but I hope they are getting creative since what’s to lose at this point…
  • Pogo
    Hopefully, since the panels are on the side, that it can get a wee bit of power from sunlight reflected from the ground.
  • COLGeek
    I suspect that the engineers are looking at optimizing landing in relation to charging more now for future missions.

    Fingers crossed that this mission can be salvaged to gather more science. Good stuff regardless.