Photo/Illutration An illustration of the Smart Lander for Investigating Moon (SLIM) probe approaching the lunar surface (Provided by JAXA)

SAGAMIHARA, Kanagawa Prefecture--Something was clearly amiss when Shinichiro Sakai, project manager for Japan’s daring moon mission, was a no-show at a news conference called in the wee hours of Jan. 20.

Instead, Hitoshi Kuninaka, head of the Institute of Space and Astronautical Science (ISAS), handled the media at the 2:10 a.m. gathering to report on progress in the Smart Lander for Investigating Moon (SLIM) probe. ISAS is an arm of the Japan Aerospace Exploration Agency (JAXA).

“The probe made a successful soft landing on the moon. It has begun transmitting signals back to Earth and is generally operating soundly,” Kuninaka said.

He added that two small robot vehicles had been released from the probe.

Kuninaka tried not to let it show, but he was gloomy because the solar panels on the probe were not operating properly.

The SLIM probe made a near-perfect soft landing on the lunar surface while calculating possible risks from cameras mounted on the spacecraft.

At mission control, technicians could only monitor the data streaming into the various displays that showed the altitude of the probe, its acceleration and revolution as well as what the engine was doing.

At 12:20 a.m., the data showed the probe’s altitude was approaching zero, meaning it was almost on the lunar surface. The engine had stopped firing short bursts of power, and another display showed the probe was in lunar landing mode.

The ISAS’s Yasuhiro Kawakatsu was providing technical explanations to media representatives gathered at JAXA’s Sagamihara campus.

“The data shows the probe landed and is stable,” Kawakatsu said.

And that was it, as far as explanations went about the lunar landing, for the next two hours or so.

The solar panels did not unfold properly, restricting power to its battery cells, because the probe tilted upon landing.

Kuninaka said project staff were trying to analyze and interpret the data pouring in.

JAXA officials switched the probe to battery mode to capture images taken during the flight to the moon until that battery ran out of juice. As Sakai was overseeing the data transfer, he stayed away from the news conference room.

When a reporter asked why JAXA officials were not happier about Japan becoming only the fifth nation to successfully land a probe on the moon, Masaki Fujimoto, ISAS’s deputy head, said: “That would be difficult under the present circumstances. If things had gone according to plan, I would be smiling now, but I need to know the condition (of the probe) as soon as possible.”

The lack of solar power generation threatens to compromise the probe’s mission to possibly just a few hours instead of several days.

There was still the possibility that a change in the sun’s position might fire up the solar panels and stir the probe back into full operation.