LOCKHEED MARTIN is to develop a new version of the Atlas II expendable booster, the first launch of which is expected in late 1998.
The two- or three-engine Atlas IIAR ("R" for re-engine) will replace the Atlas IIAS, which has nine engines: three core, four Castor IVA strap-on booster, and two RL10A-4s for the Centaur upper stage.
The number of engines will depend on the main-engine choice. The firm is replacing the three core engines, plus four Castors, with a single-stage booster, and intends to substitute a Centaur upper-stage using one RL10E.
Two Russian concerns, NPO Energomash (with its RD-180) and NK Engines (offering its NK33) join US firm Rocketdyne (proposing its MA-5D) in the main-engine contest. NPO Energomash has teamed with Pratt & Whitney, while NK Engine has formed a joint venture with Aerojet. The Atlas IIAR will have a stretched liquid-oxygen tank, as well as a throttleable main rocket engine.
The NK33 is not in production, but 50 have been flight certificated, and 72 have been assembled. Aerojet is conducting NK33 test firings at the firm's Sacramento, California, test centre.
Lockheed Martin, has virtually completed development of an improved version, of the Titan 4 space launch vehicle. Its first launch is planned for late 1996, says the company.
The rocket, called the Titan 4 B, is designed to launch 25% heavier payloads, cost less and be more reliable than its predecessor. The current Titan - the USA's most powerful expendable launch-vehicle - is capable of boosting spacecraft weighing 17,700kg into low-Earth orbit, or payloads of more than 4,540kg into geosynchronous orbit.
The Titan 4B uses new upgraded solid-rocket motors. A full-scale static-test-firing programme has qualified the motors, and the initial production unit has been delivered for flight on the first Titan 4B in late 1996.
Source: Flight International
