PARIS — Satellite fleet operator Thaicom of Thailand on April 22 said its Thaicom 5 satellite suffered a four-hour service outage April 21 due to an apparent electrostatic discharge and that the satellite has been returned to full service.

The company said Thaicom 5, a Thales Alenia Space-built Spacebus 3000A model launched in May 2006, automatically placed itself into safe mode, pointing itself toward the sun to maintain electrical power, when the outage occurred mid-afternoon Thailand time. Thaicom 5 operates at 78.5 degrees east longitude in geostationary orbit.

“Thaicom 5 is not damaged in any way,” Thaicom said in a statement, adding that an “electrostatic discharge cannot be predicted in advance, and its occurrence is quite rare.”

An electrostatic discharge was also cited for the in-orbit failure of the Galaxy 15 satellite owned by Intelsat of Luxembourg and Washington. In that case, the satellite remained electrically active, with its broadcast payload continuing to function, even as it could not respond to ground commands and began an eight-month, uncontrolled drift along the geostationary arc. It has since been brought back under control.