ADEOS-2, one of the largest satellites of its kind, has been collecting data on global warming and other climate-change phenomena since its launch 10 months ago, using five state-of-the-art Japanese, US and French sensors.
The satellite, known as Midori-2 in Japanese, stopped sending signals on Saturday due to a suspected glitch in its electrical circuits.
"We reached a conclusion today that there is an extremely slight possibility that we will be able to restore operations of Midori-2," the Japan Aerospace Exploration Agency (JAXA) said in statement.
The national space agency said that it had been unable to restore communications with the satellite and that analyses of the craft's condition gave little hope for its recovery.
JAXA apologised for the loss to its US and French counterparts NASA (National Aeronautics and Space Administration) and CNES (Centre National d'Etudes Spatiales) as well as the Japanese Ministry of Environment, which have sensors mounted on the ill-fated craft.
ADEOS-2 -- Advanced Earth Observation Satellite -- followed the fate of its predecessor ADEOS-1, which was similarly written off 10 months after its launch in 1996 after its solar panel broke down due to a design fault.
Developed at a cost of 70 billion yen (640 million dollars) with an expected lifespan of three years, ADEOS-2 has been orbiting the earth over the two poles 14 times a day at an altitude of about 800 kilometers (500 miles).
A JAXA spokesman Thursday said ADEOS-2 and another Japanese satellite Kodama might have been affected by recent solar flares, one of them the largest in three decades.
Kodama, a communications satellite, stopped relaying data after its sensor developed problems early Wednesday after the massive flare on Tuesday, according to the spokesman Junichi Moriuma.
ADEOS-2 may have been hit by an earlier, smaller flare, he added.