ISS poised for twin boost as Ariane 5 ECA takes off

Successful European launch clears way for ATV flight, while Japan prepares H2A return

European and Japanese "return to flight" launches this month are seen as major steps in guaranteeing logistic support for the International Space Station (ISS). Arianespace's most powerful booster, the Ariane 5 ECA, was successfully launched from Kourou, French Guiana on 12 February after a maiden flight failure in November 2002. Japan's H2A is to return to flight on 24 February.

The ECA booster, able to launch a payload of 9,600kg (21,100lb) - down from the originally planned 10,000kg to geosynchronous transfer orbit - carried the 3,600kg X-band communications satellite XSTAR-EUR for a joint venture between Loral Space & Communications and Spain's Hidesat.

Two technology payloads were also carried on Ariane Flight 164. The Netherlands National Aerospace Laboratory's 130kg Sloshsat mini-satellite was released after 31min, while a 3,500kg instrumented dummy spacecraft, the European Space Agency's Maqsat-B2, remained with the upper stage and sent back data on the payload environment.

The qualifying flight cleared the way for the launch of the European Space Agency's Automated Transfer Vehicle 1 (ATV), Jules Verne, to the ISS in October, aboard an Ariane 5 ES ATV booster. The ES ATV combines the Vulcain 2-powered ECA first stage with an EPS upper stage that will place the manoeuvrable ATV into an initial 300km (185 mile) -circular, 51.6¡-inclination orbit.

The ATV will supply the ISS with pressurised cargo, water, air, nitrogen, oxygen and attitude control propellant, and will be used to reboost the ISS during its six-month mission docked to the station, when it will be accessible to the crew.

Meanwhile, Japan's H2A return-to-flight mission follows the failure of the sixth launch in November 2003, with the loss of two reconnaissance satellites.

The H2A will be launched from Tanegashima carrying the MTSAT 1R multifunction satellite. This flight is seen as vital to the Japan Space Exploration Agency's participation in the ISS, as a heavyweight version of the H2A will launch the HTV automated cargo carrier, similar to the ATV.

n Arianespace is to launch the Brazilian Star One C2 communications satellite in 2007, bringing to 40 the payloads in the European launcher organisation's manifest. The basic Ariane 5G is scheduled for its next flight on 14 April carrying French military communications satellite Syracuse 3A and Indonesia's Telkom 2. The next ECA launch is scheduled for June, carrying Eumetsat's MSG 4.

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