TIM FURNISS / LONDON
Mission demonstrates several new technologies developed for later version of booster
Lockheed Martin's Atlas IIIB booster made its first flight on 21 February, from Pad 36B at Cape Canaveral, Florida, carrying the 4,000kg Lockheed Martin-built Echostar VII communications satellite into a geostationary transfer orbit.
The Atlas IIIB launch, by International Launch Services (ILS), paves the way for the maiden flight of the Atlas V Evolved Expendable Launch Vehicle (EELV). The Atlas IIIB demonstrated several technologies developed for the Atlas V, which will enter commercial service in early May carrying the Eutelsat Hot Bird 6 communications satellite.
Lockheed Martin-led ILS may, however, decide to delay the Atlas V launch to allow an Atlas IIIB to fly on 28 May, carrying the Asiasat 4 communications satellite.
The IIIB model is a more powerful version of the Atlas IIIA, which made its only flight in May 2000 and experienced higher than expected vibration levels during the first-stage burn due to anaerodynamic coupling problem.
The stretched first stage of the Atlas IIIB, powered by an Amross RD-180 engine, is equipped with an upgraded Centaur upper stage with two Pratt & Whitney RL-10A-4 cryogenic engines. The Atlas IIIA has one RL-10 engine.
The Atlas V will employ a new payload fairing and will use full 100% thrust on the first stage and added burn time on the Centaur second stage. It will also employ a structurally stable core stage rather than use the pressure stabilisation of previous Atlas stages. These improvements will increase the geostationary transfer orbit performance from 4.5t for the Atlas IIIB to 4.95t on the first Atlas V version. Further models will increase this to 8.65t on the Atlas V 551, with a stretched payload shroud and five solid rocket boosters.
Ariane mission V148 involving an 44L booster from Kourou, French Giuana, carrying the Intelsat 904 communications satellite, was successfully completed on 23 February.Source: Flight International