More problems have hit Hughes HS-601 satellites - another of the spacecraft is on the brink of losing its final workable battery and is about to be written off. The incident brings to seven the number of HS-601s that have malfunctioned this year.
The latest problem satellite is the Indonesian Palapa C1, operated by PT Pasifik Satelit Nusantara. Launched in February 1996, the craft recently suffered a second battery charge controller failure and is to be "declared a total loss", says London-based loss adjuster Airclaims.
An earlier battery controller malfunction had already resulted in the loss of some transponders on the satellite during eclipse periods, when the craft depends on battery power alone, triggering a partial insurance loss claim of about $31 million.
Another HS-601-based spacecraft, the PanAmSat 4, has been operating on a back-up spacecraft control processor (SCP) since early November to maintain orbital and attitude control. This is the latest in a series of SCP anomalies to have hit the HS-601 buses. The craft was launched in 1994.
In May, PanAmSat's Galaxy 4 suffered a prime SCP failure. Because the back-up SCP had failed earlier, it was declared a total loss in-orbit, resulting in a $180 million insurance pay-out.
In June, an SCP on PanAmSat's 1992-launched Galaxy 7 failed, and in July, one of the SCPs on DirecTV's DBS 1 satellite shut down, leaving just a back-up working. The craft was launched in 1993.
Airclaims says insurers and operators are worried there may be an inherent fault in the spacecraft bus.
On top of these difficulties, two other PanAmSat High Power versions of the HS-601 have experienced separate battery faults. One is the PanAmSat 5, launched in 1997, and Airclaims believes the other is the Galaxy 8I, also launched in 1997.
Hughes, which has 39 HS-601-based spacecraft in orbit and which is building a further 30 satellites - including seven for PanAmSat - says it has "identified the problems and fixed them on future craft".
PanAmSat, which has been particularly affected by the Hughes trials, has also been affected by other failures. The Space Systems/Loral PanAmSat 6 is suffering from power shortages after a solar array was damaged by a solar storm, resulting in a $37 partial loss claim, and its Galaxy X was lost in the failure of the maiden flight of the Boeing Delta III last August. This brought a $250 million claim.
Another Indonesian satellite operator, PT Media Citra, has been hit by a battery-charging anomaly aboard the Cakrawarta 1 satellite built by the former CTA, now part of Orbital Sciences. The problem was noticed in March, resulting in a partial loss claim of about $40 million, understood to be still pending.
Despite these problems, Arianespace's V114 mission, using an Ariane 42L booster, was launched successfully from Kourou in French Guiana on 6 December, carrying Mexico's HS-601 Satmex 5 communications satellite.
The next Ariane mission will also launch an HS-601, the PanAmSat 6B, on 21 December. Thirty-eight satellites remain on Arianespace's order book, with a contract expected to be confirmed soon for the launch of the Lockheed Martin GE 7 and GE 8 satellites in 2000 an 2001.
The first Ariane 5 commercial flight, in April, will carry Indonesia's Telkom 1 and the Eutelsat W4 satellites.
Source: Flight International
