Japan’s space agency “checking status“ of Moon lander

This artist's illustration shows the SLIM spacecraft descending toward the Moon and ejecting two deployable robots onto the lunar surface. — Enlarge / This artist’s illustration shows the SLIM spacecraft descending toward the Moon and ejecting two deployable robots onto the lunar surface.

The Japanese space agency’s first lunar lander appeared to reach the Moon’s surface Friday, but officials were still “checking the status” of the spacecraft more than an hour after it touched down.

Japan’s robotic Smart Lander for Investigating Moon (SLIM) mission began a 20-minute final descent using two hydrazine-fueled engines to drop out of orbit. After holding to hover at 500 meters and then 50 meters altitude, SLIM pulsed its engines to fine-tune its vertical descent before touching down at 10:20 am EST (15:20 UTC).

The Japan Aerospace Exploration Agency (JAXA), which manages the SLIM mission, streamed the landing live on YouTube. But the stream of updates stopped after SLIM’s landing, and the webcast hosts did not provide any update on the status of the spacecraft before ending live coverage about 10 minutes later.

JAXA officials will hold a press conference later Friday. The SLIM spacecraft targeted a landing adjacent to a nearly 900-foot (270-meter) crater named Shioli in a region called the Sea of Nectar on the near side of the Moon.

SLIM launched September 6 on top of a Japanese H-IIA rocket, riding to orbit alongside an X-ray astronomy telescope. The spacecraft took a long route to get to the Moon, trading time for fuel to preserve propellant for Friday’s landing attempt. SLIM entered orbit around the Moon on December 25, then completed several maneuvers to settle into a low-altitude orbit in preparation for the descent to the surface.

If successful, the landing of SLIM would make Japan the fifth country to soft-land a spacecraft on the Moon, following the Soviet Union, the United States, China, and India. But landing on the Moon is a hazardous thing to do. Three commercial landers similar in scale to SLIM failed to safely reach the lunar surface over the last five years.

One of those was developed by a Japanese company called ispace. Most recently, the US company Astrobotic attempted to send its Peregrine lander to the Moon, but a propellant leak cut short the mission. After looping more than 200,000 miles into space, Peregrine reentered Earth’s atmosphere Wednesday, where it was expected to burn up 10 days after its launch.

A Russian lander crashed into the Moon in August, and India’s first lunar lander failed in 2019. India tried again last year and made history when Chandrayaan 3 safely landed.

Japan’s mission is a pure technology demonstrator to test our new guidance algorithms and sensors, rather than pursuing scientific objectives. The technologies riding to the Moon on SLIM could be used on future spacecraft bound for the Moon. SLIM cost the Japanese government approximately 18 billion yen ($121 million) to design, develop, and build, according to JAXA.

The 20-minute descent on Friday was the the riskiest part of the entire mission. The spacecraft is modest in size, measuring nearly 8 feet (2.4 meters) tall and nearly 9 feet (2.7 meters) across. Without propellant in its tanks, SLIM has a mass of roughly 660 pounds (200 kilograms).

“The start of the deceleration to the landing on the Moon’s surface is expected to be a breathless, numbing 20 minutes of terror!” said Kushiki Kenji, sub-project manager for the SLIM mission, before the landing.

https://arstechnica.com/?p=1997302