spacetoday.net: Proton failure strands satellite in LEO

Posted: Tue, Nov 26, 2002, 10:19 AM ET (1519 GMT)
Proton launch of Astra 1K (ILS)

A failure of the upper stage of a Proton launched Monday evening has stranded a European communications satellite in a low parking orbit that is expected to decay by the weekend. The Proton K lifted off from Baikonur on schedule at 6:04 pm EST (2304 GMT) on a mission to place the Astra 1K spacecraft into geosynchronous orbit for European satellite operator SES Astra. The Proton's lower stages worked as planned and the Block DM upper stage fired once to place it and the spacecraft into a 175-kilometer circular orbit. However, the second Block DM burn, which would have placed the spacecraft into an elliptical geosynchronous transfer orbit, did not occur, and the spacecraft separated from the upper stage while still in the temporary parking orbit. The cause of the Block DM failure is unknown. The spacecraft's low orbit means that it can survive until about Saturday before reentering; Russian reports indicate spacecraft controllers are studying using the spacecraft's thrusters to raise its orbit to avoid an immediate reentry, although the thrusters are not powerful enough to boost the spacecraft into a usable orbit. The Astra 1K, built by Alcatel Space, was to provide Ku-band communications services from 19.2 degrees east longitude. At a launch mass of 5,250 kilograms, the Spacebus 4000-series spacecraft was the heaviest commercial communications satellite launched. All Proton launches have been suspended while the investigation into the failure continues; officials with International Launch Services said they will work to return the Block DM upper stage to flight as soon as possible. The failure could hasten the retirement of the Proton K in favor of the modernized Proton M, which uses a different upper stage, the Breeze M. A version of the Energia-built Block DM stage is also used on the Sea Launch Zenit 3SL booster.