The Data Relay Test Satellite (DRTS), also known as Kodama, went into safe mode, essentially shutting down all noncritical functions, the morning of Oct. 29, according to Tsuguhiko Katagi, JAXAs associate executive director. The satellite is still able to communicate with ground stations, Katagi told the governments Space Activities Commission.

The first sign of trouble was an abnormal data reading from the geostationary-orbiting satellites Earth sensor, Katagi said. The excessive signal noise coming from the Earth sensor assembly suggests the satellite was affected by a proton barrage, Katagi told the commission. The most likely culprit is the solar flare, Katagi said.

Forecasters at the U.S. National Oceanic and Atmospheric Administrations Space Environment Center in Boulder, Colo., warned that the flare could cause a severe geomagnetic storm, possibly disrupting operations of satellites, power grids and other sensitive electronic systems. On its World Wide Web site, the U.S. agency said the solar radiation bombardment was likely to continue for the next 48 hours.

The DRTS satellite, launched in September 2002, is designed to relay data from spacecraft in low Earth orbit including Japans Earth observing satellites and the international space station to the ground. Although the satellite burned more fuel than expected in making its way to its operating orbit, Japanese officials said it was expected to fulfill its seven-year mission.

Katagi expressed optimism that the satellite, built by Tokyo-based Mitsubishi Electric Corp., ultimately can resume operations. But Japanese officials also raised the possibility that Kodama has suffered permanent damage.

We dont know if it is a single event upset or a latch, said Masaaki Notsu, director of the Ministry of Public Management, Home Affairs, Posts and Telecommunications. If it is an event, there may be no problem in reactivating Kodama. It has been hit by a strong proton barrage, however. If there is a latchup, in this case many circuits could have been destroyed, Notsu said.

Notsu, who is responsible for developing Japans future communications satellites, also said that attempts to reactivate the satellite would start Oct. 31, when the geomagnetic storm is expected to subside.

Masahiro Kawasaki, a member of the Space Activities Commission, said it is too early to tell if the satellite can be fully recovered. Its not in our hands to know whether DRTS will become fully functional again, he said.

If the satellite cannot be recovered, it would be Japans second major space mishap in less than a week. On Oct. 25, JAXA lost contact with the Advanced Earth Observing Satellite-2, and hopes for recovering that craft are fading rapidly.

The DRTS incident also has raised questions about Japans ability to protect its satellites from solar flares. JAXA has no countermeasures to assist during a solar flare, complained one official. Its a weakness.

Junichiro Moriuma, a JAXA spokesman, confirmed that the agency had no procedures to protect the satellite, despite warnings that a strong geomagnetic storm was on the way. DRTS is a big satellite and it is difficult for us to take precautions, he said.