Tim Furniss/LONDON

Hughes has cleared the Galaxy X and Astra 2A satellites for launch after completing investigations into the failure of space control processors aboard three HS-601 model communications satellites. The failure resulted in the total loss of Galaxy IV and the loss of the primary processor systems on Galaxy VII and DirecTV DBS I in May, June and July, respectively.

The failures were caused by electrical shorts in tin-plated electrical switches which blew fuses in the processors. The company cannot rule out similar problems in other HS-601s in orbit, but believes that the probability of an incident is very low. Galaxy X was scheduled to be launched on the first Boeing Delta III booster on 24 August, while the Astra 2A launch is now planned for later this year on board a Proton. DirecTV has ordered another DBS 1 HS-601HP model replacement spacecraft from Hughes.

Meanwhile, Hughes has postponed the launch of the HS-601 model JCSAT 6 communications satellite which was scheduled for an Atlas launch from Cape Canaveral, Florida this month because two electronic units were damaged, probably during a power surge caused by a thunderstorm near the Astrotech plant at Titusville where the craft was being processed.

In addition, the launch of the Hughes-built HS-601 Ultra High Frequency F9 US Navy communications satellite scheduled for another Atlas launch from Canaveral on 15 September has been called off so that an electronic part in the craft's communications payload can be replaced, and "to complete additional testing".

Source: Flight International