TIM FURNISS / LONDON
PAS 7 faces write-off as Boeing confronts solar array issue
The Space Systems/Loral (SSL)-built PanAmSat 7 (PAS 7) communications satellite has been declared a total loss in orbit following a power problem. The loss comes as Boeing Satellite Systems (BSS) is warning customers of a degraded power generation problem affecting its new 702 spacecraft buses.
PAS 7 is expected to be written off at a cost of $253 million after losing over 25% electrical power on 6 September, although the satellite is expected to "continue to meet customer needs for the foreseeable future", says SSL. PAS 7 was launched in 1998 and was expected to be operational until 2013. A total constructive loss policy allows for full payment after a 20% loss of operational capability.
Eleven FS-1300 spacecraft buses built by SSL and still in orbit, including PAS 7, are also facing potential short-circuits in delaminated solar arrays, as a result of imperfectly manufactured units supplied by Dutch company Fokker, SSL admitted last year.
Sirius Satellite Radio is already experiencing the problem, having "a minor issue" with solar arrays on its two SSL-built satellites. Delivery of another SSL-built satellite, the DirecTV5 communications satellite to Baikonur, Kazakhstan, for its International Launch Services flight aboard a Proton booster on 11 October, has been delayed due to a "technical issue", says SSL.
Meanwhile, BSS is advising customers of a potential "long-term issue" in solar array output on the Boeing 702 spacecraft bus. Six satellites already in orbit are affected, including Sirius Satellite Radio competitor XM Radio.
The latest BSS trouble follows major spacecraft control processor and battery cell faults on 601 and 601HP satellite models (Flight International, 5-11 December 2000).
The 702 arrays have exhibited a faster than expected power performance degradation during their early operational life.
The innovative angled reflector panels along both sides of the 702 arrays form shallow troughs that concentrate the sun's energy on to the solar cells. This allows the craft to use up to 16kW of energy, which would be expected to naturally degrade to 15kW over an operational lifetime of 15 years. The satellites in orbit are expected to be operating on 12kW after 12 years, reducing operational capability.
Boeing concedes that these generators are not concentrating as much solar energy as predicted because they are losing their optical quality, becoming "foggy" due to an as yet unknown cause.
Future 702s will be equipped with conventional solar arrays, while satellites awaiting launch will be retrofitted, the company says.
Source: Flight International
