The first launch of the Lockheed Martin-built Atlas IIIA booster was achieved successfully at Cape Canaveral on 25 May.
The booster, powered by a Russian RD-180 engine and with a single Centaur upper- stage engine, put the Alcatel Space-built Eutelsat W4 communications satellite into an initial orbit, heading for its geostationary position at 36°E.
The commercial launch by International Launch Services (ILS) was the first time a US booster lifted off with a Russian engine.
The vehicle's first stage was originally the USA's first intercontinental ballistic missile. The four previous launches, cancelled because of a combination of weather and technical problems, cost an estimated $1 billion, says Lockheed Martin.
The RD-180 engine is built by the joint Russian-US company, RD AMROSS, operated by Pratt & Whitney and NPO Energomash. The engine will be the workhorse of the new Atlas V Evolved Expendable Launch Vehicle. With 75% commonality between the Atlas IIIA and the Atlas V, the flight was a valuable test for many Atlas V parts.
The throttleable, high performance, 800,000lb-thrust (3,556kN) RD-180 burns liquid oxygen and RP-1 propellants. It gives such increased performance over the traditional Rocketdyne-built Atlas powerplant that the Centaur upper stage of the Atlas II needs only one liquid oxygen-liquid hydrogen cryogenic engine compared with the two on the traditional Atlas-Centaur- based models, currently flown as the Atlas IIA.
The performance of the Atlas IIIA booster also exceeds that of the Atlas IIAS, which is also powered by four solid rocket boosters. The Atlas IIIA can place 4.1 tonnes into geostationary transfer orbit. The new booster could be flying until 2005, with up to 18 missions. An Atlas IIIB with two Centaur stage engines could put 4.5 tonnes into GTO.
Source: Flight International