Mission controllers are still trying to get in contact with the Hitomi spacecraft.

Akihiro Ikeshita/JAXA

Japan's damaged x-ray satellite: Space scientists looking for clues

At a press conference in Tokyo today, officials of the Japan Aerospace Exploration Agency (JAXA) said that because of the difficulty of gathering information from the wayward Hitomi x-ray observatory they couldn't say how long it might take to figure out what has gone wrong. A joint JAXA-NASA mission, Hitomi was launched 17 February and was still undergoing commissioning when normal communications were lost on 26 March. Originally called ASTRO-H, Hitomi carries a suite of instruments designed to detect x-rays and gamma rays emanating from black holes, swirling gases in galaxy clusters, and supernova remnants. 

Ground stations have intermittently picked up signals apparently from the spacecraft on four occasions, raising hopes that the main body of the craft might be intact. But the last of those glimpses of life was on 29 March. Ground visual and radar observations indicate that the craft has split into at least two pieces and is likely spinning. "At the moment, there is no evidence of a collision with space debris," said Saku Tsuneta, director general of JAXA's Institute of Space and Astronautical Science in Sagamihara near Tokyo.

Speculation about possible causes of an onboard explosion centers on a rupture of the helium tank for an x-ray detector cooling system, fuel leakage from the attitude control engines, and a battery malfunction. Takashi Kubota, JAXA program manager, said they are now analyzing the last transmissions of data received from the craft for clues as to what might have happened. He said the agency and its partners are striving to re-establish communications with the satellite as a first priority. They have 20 windows of opportunity to communicate each day and are sending commands hoping something gets through. At the same time they are gathering whatever clues they can from other sources about the attitude and condition of the craft. The agency has even asked the National Astronomical Observatory of Japan to train its 8.2-meter Subaru Telescope, located atop Mauna Kea in Hawaii, on Hitomi. 

Tsuneta said that given the capabilities of the various instruments on the craft, "Astronomical researchers worldwide had extremely high hopes for this satellite, I think they would like it to be recovered no matter what it takes."