PARIS - The Astra 5A commercial telecommunications satellite is out of control after an unexplained failure Jan. 15 and is drifting eastward along the geostationary orbital arc, with ground controllers pessimistic about their ability to re-establish sufficient communications to guide it into a graveyard orbit, industry officials said Thursday.

Officials said Astra 5A used a large portion of its remaining fuel during the hours following the initial loss of attitude control Jan. 15. They described several chaotic hours during which Astra 5A's sun sensors, which help keep the spacecraft oriented toward the sun so it can recharge its batteries, failed in turn

The satellite subsequently went into an uncontrolled spin on its axis, which ground teams attempted to stop by firing its on-board motors. Most of Astra 5A's remaining on-board fuel was depleted in the attempt, and even then the situation could not be salvaged.

With its solar arrays only intermittently pointed toward the sun, the satellite's batteries were soon depleted, and controllers were unable to send commands to reorient Astra 5A, which now has left its orbital slot at 31.5 degrees east longitude and is moving eastward, officials said.

Astra 5A's owner, SES of Luxembourg, has informed owners of neighboring satellites of the event, and there is a possibility that one or more satellites will need to perform a collision-avoidance maneuver.