Tim Furniss/LONDON

Three more Hughes HS-601-based communications satellites have experienced malfunctions in geostationary orbit, following the loss of the $165 million Galaxy 4 on 19 May, which put out of action 90% of the pagers used in the USA.

Like the Galaxy 4, the latest victims, the Galaxy 7 and Panamsat 5, are operated by the PanAmSat company which merged its activities with a Hughes subsidiary last year. The other satellite is the Hughes-owned DirecTv's DBS 1.

Also like the Galaxy 4, the satellites experienced faults on control processors. In the case of the Galaxy 4, the back-up system also failed, but the Galaxy 7, DBS 1 and PAS 5, an HS-601 high-power version, are still functional.

Hughes is unable to comment on the PAS 5 situation, but says the cause of the malfunctions on the other satellites had not been determined and that "no common or generic cause has been found yet".

The launch of the Galaxy 10 aboard the first Delta III, which is scheduled for 3 August, could be delayed if checks to the spacecraft are required (see box below).

Meanwhile, the PAS 6 satellite, built by Space Systems Loral and launched in 1997, has experienced solar panel deployment problems. The Lockheed Martin Echostar 4 may be written off after a solar panel deployment failure.

Source: Flight International