AT&T Skynet says that its Telstar 401 satellite experienced an abrupt failure of its telemetry and communications on 11 January. It is the second in-flight loss of this spacecraft series.

The company restored services to only those 401customers whose contracts called for transfer of their transponder services, to Telstar 402R, leaving some 402R customers without services.

AT&T Skynet and the Satcom7000 series satellite's contractor Lockheed Martin Astro Space do not know what caused the sudden, catastrophic failure at 97íW in geostationary orbit (GEO), during routine station-keeping maneouvres using the craft's hydrazine arcjet thrusters.

The Telstar 401 was launched by an Atlas 2AS rocket in December 1993 and was expected to be in service until 2006. Its launch was followed by that of the 402, another series 7000 craft, on an Ariane 4 in September 1994.

This was lost 10min after separation from the booster's third stage when the firing of a pyrovalve to open a propellant line ignited some hydrazine.

AT&T sued Lockheed Martin and is believed to have received a $250 million settlement.

The planned Telstar 403, renamed the 402R, launched by an Ariane 4 in September 1995 and placed at 89íW in GEO.

Two Telstar 300 series spacecraft are also operational, but nearing the ends of their operational lives. A new Telstar 5 series is planned, with a first launch on the ILS International Launch Services Proton booster in 1998. The Telstar 5 is being built by Space Systems Loral. The Telstar 300 and 400 series satellites are part of a proposed $712 million deal in which Loral Space and Communications will buy AT&T Skynet.

There may now be changes to the financial terms of the deal. The insurance claim for a lost Telstar 401 would be worth in the region of $150 million.

Source: Flight International