Lockheed Martin is to resume Atlas launches on 10 September, but the maiden flight of its Atlas III booster has been pushed back into 2000.
Atlas launches were halted in May following the loss of Boeing's first Delta III, caused by the failure of a Pratt & Whitney RL10 upper stage engine similar to that used in the Atlas family.
The Delta III investigation has isolated the cause of the RL10 failure to a brazing process that left voids in combustion chamber structural jacket splice joints, possibly in combination with higher than expected flight loads (Flight International, 11-17 August).
The Lockheed Martin-led International Launch Services (ILS) venture that operates the Atlas commercially says three RL10s have been inspected and cleared, allowing launches to resume. The EchoStar V communications satellite is to be launched on an Atlas IIAS on 10September, followed on 30September by an Atlas IIA launch of the UHF Follow-On F10 and in October by the EOS Terra-1 on an Atlas IIAS.
ILS plans two more Atlas launches by year-end, for a total of eight compared with the 12 originally planned. The company has yet to find a replacement payload for the first Atlas III and has delayed the launch until next year. The original payload, Loral's Telstar 7, was switched to an Ariane launch when the Atlas family was grounded.
Boeing, meanwhile, has yet to clear the Delta III for flight, although it still plans a December launch of the ICO 4 communications satellite. The booster will not be stacked on the pad until 30 days before the scheduled launch date, the company says.
Source: Flight International
