Japan's Moon Lander SLIM's Solar Panels Fail To Generate Electricity After Touchdown
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[Update] Japan's Moon Lander SLIM Regains Power, Snaps Photos
Japan's first moon lander, SLIM phoned home on Sunday (Jan. 28) and engineers quickly resumed operations, according to JAXA. "We immediately started scientific observations with MBC, and have successfully obtained first light," the agency said in a statement on X, with "first light" referring to the first use of an instrument to take images. MBC, the Multi-Band Camera, is designed to scour the lunar surface for the composition of olivine through analyzing the light signatures, or spectra, of reflected sunlight, according to the Planetary Society.
SLIM which is currently upside-down on the moon's surface, successfully landed on Jan. 19. However the small spacecraft's solar panels were in the shadow and its batteries ran out, severing contact with mission operators.
The spacecraft's landing site is Shioli Crater, a zone filled with old impact rubble within the Mare Nectaris or Sea of Nectar. The mission's landing area is roughly 322 kilometers south of Mare Tranquillitatis (the Sea of Tranquility). The Sea of Tranquility is an approximately equatorial landing site where the first moon astronauts from Apollo 11 touched down in 1969.
SLIM sent back photos of its landing zone on Sunday and JAXA is now "sorting out rocks of interest, assigning a nickname to each of them, with intent of communicating their relative sizes smoothly by the names," officials added in a press release.
The nicknames in the image appear to be invoking size by dog breed, ranging from diminutive "toy poodle" to the large and powerful "St. Bernard."
Even better science might be possible soon: "Preparation is underway to promptly conduct 10-band high-resolution spectroscopic observations, once the solar illumination condition improves and SLIM recovers by the power generated by the solar array," the press release added.
The mission is designed to operate for a single lunar day (two weeks) as long as sunshine is available.
SLIM isn't designed to survive the two-week-long cold and dark lunar night, but its design is robust enough that it may wake up again from that hibernation next month to do even more science; that's according to remarks from Hitoshi Kuninaka, director general of Japan's Institute of Space and Astronautical Science (ISAS), reported by National Public Radio on Jan. 22.
The spacecraft had an engine failure during descent that placed it upside down, but otherwise the mission met its goal of getting very close, to within 100 meters, of its target landing site. But SLIM's unexpected orientation left it unable to receive power via its solar panels in the hours after landing.
JAXA officials had said during landing that they were holding out hope that the lander would call home again, once the sun reached the stricken lander on the surface. They turned out to be right.
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SLIM ('Smart Lander for Investigating Moon'), has touched down on the moon's surface. The spacecraft which reached lunar orbit on Christmas Day(Dec. 25), performed a crucial engine burn on Jan. 14, circularizing its orbit at the 600-kilometer altitude and setting the stage for descent-and-landing operations. Another burn earlier on Jan 19, which took SLIM's orbit down to about 15 km above the lunar surface, culminated in the landing try, which began at about 1500 UTC; and reportedly lasted up to 20 minutes. Not clear yet if it achieved its target point of landing 100 meters within the Shioli Crater.
Japanese Aerospace Exploration Agency, JAXA, on Sept. 6, launched a H-2A rocket carrying the SLIM and XRISM('X-Ray Imaging and Spectroscopy Mission') space telescope, from Tanegashima Space Center at 2342 UTC. Both spacecraft were deployed on schedule, sequentially less than an hour after liftoff.
At liftoff, SLIM which measures 2.4 m high, 2.7 m long and 1.7 m wide, weighed about 700 kilograms, but roughly 70% of that weight was propellant.
Both spacecraft deployed into Earth orbit, where XRISM remains. But SLIM left our planet's gravity well on Sept. 30, and began its journey on the long, circuitous and energy-efficient route to the moon.
The moon lander carries two miniprobes. LEV-1 ("Lunar Excursion Vehicle" 1) and LEV-2 deployed as planned after touchdown, and LEV-1 was known to be operating on the lunar surface. According to JAXA, those two little craft will help the mission team monitor the status of the larger lander, take photos of the landing site and provide an "Independent communication system for direct communication with Earth."
SLIM "aims to achieve a lightweight probe system on a small scale and use the pinpoint landing technology necessary for future lunar probes," JAXA officials wrote in a mission description. "The project will aim to cut weight for higher-function observational equipment and to land on resource-scarce planets, with an eye towards future solar system research probes."
During descent on Jan. 19, SLIM hit its various milestones, and the lander communicated with its handlers all the way through, and beyond, its historic touchdown.
However, JAXA couldn't immediately confirm SLIM's status after landing. About an hour later, the agency gave an update via a press conference, explaining the spacecraft's power problems.
SLIM's solar panels failed to generate electricity on the surface of the moon, leaving the lander's future in serious doubt.
It's unclear why the solar cells aren't working, officials said. But it's unlikely they were damaged during the touchdown, because SLIM's other hardware appears to be fine and functional. It's possible that the lander isn't oriented toward the sun as expected, according to JAXA.
Early Monday morning (Jan. 21), JAXA said the lander has not been declared dead, and its handlers are working toward a possible recovery.
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," the team said in a separate X post on Monday. "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."
SLIM successfully beamed home technical data and imagery collected during Friday's descent and landing, the team added in another Monday X post.
Meanwhile on our Earth orbit, XRISM which is a collaboration involving JAXA, NASA and the European Space Agency (ESA) will study the universe in high-energy X-ray light.
"X-ray astronomy enables us to study the most energetic phenomena in the universe," Matteo Guainazzi, ESA project scientist for XRISM, said in a statement. "It holds the key to answering important questions in modern astrophysics: how the largest structures in the universe evolve, how the matter we are ultimately composed of was distributed through the cosmos, and how galaxies are shaped by massive black holes at their centers."
The observatory will focus particularly on the super-hot gas surrounding galaxy clusters.
"JAXA has designed XRISM to detect X-ray light from this gas to help astronomers measure the total mass of these systems," ESA officials wrote in the statement. "This will reveal information about the formation and evolution of the universe."
Also studying the heavens from Earth orbit, are NASA's Chandra X-Ray Observatory and ESA's XMM-Newton, both of which launched in 1999, as well as NASA's NuSTAR, which lifted off in 2012.
WATCH the launch, landing and news conference about SLIM