Tim Furniss/LONDON
The European Space Agency's (ESA) Artemis advanced mobile and data relay telecommunications and navigation satellite has officially been returned to the Arianespace manifest and is set for an Ariane 5 launch with another satellite between June and August. The signing of the launch contract by ESA and Arianespace on 15 February ends more than four years of uncertainties regarding the launch of the Alenia Spazio-built spacecraft.
The 3,100kg (6,800lb) geostationary (GEO) satellite was to have been launched in 1996 by an Ariane 5, but the maiden flight failure of that vehicle the same year delayed its launch. Artemis was then switched to Japan's H-2 booster when that country became a project partner, with the launch reset for 1999. Technical problems with the H-2, however, prevented the launch. When Japan announced development of an improved H-2A booster, the satellite was manifested for launch on that vehicle in 2000. With the H-2A now unlikely to make its maiden flight until 2002, also due to technical problems, the satellite has been placed back into Arianespace's hands.
The satellite is stored at ESA's Technology Centre in the Netherlands following the completion of testing. It will leave for Arianespace's Kourou, French Guiana, launch site next month.
Artemis is the most advanced telecommunications satellite ever developed by ESA and will provide mobile communication and navigation services, plus data relay capability allowing satellite-to-satellite communications. For the first time on a European satellite, Artemis will use an ion propulsion system to maintain its 21.5°E orbit.
The spacecraft also features an innovative communication link that uses laser transmission instead of a traditional radio frequency (RF) link. Artemis' Semiconductor Laser Inter-Satellite Link Experiment (SILEX) will transfer data from satellites in low Earth orbit, with an initial demonstration to involve France's Spot 4 commercial Earth remote sensing satellite. "This will be the first data relay application demonstrated by Europe," says Peter Lo Galbo, ESA's head of telecommunications. The data relay function was seen originally as a precursor to a fleet of European Data Relay Satellites (DRS), yet to receive the go-ahead.
The RF transmission system in the satellite's data relay payload will serve the International Space Station and ESA's Envisat environmental polar platform, which is due for an Ariane 5 launch in July.
Artemis also employs an L-band mobile communications payload, capable of handling 662 voice channels simultaneously for use by compact terminals with antennas as small as 40cm x 20cm.
The spacecraft will also be a key element in the European Geostationary Navigation Overlay System (EGNOS), broadcasting global positioning system correction signals from its position on the equator over central Africa from 2004. Artemis will form the EGNOS space segment along with two Inmarsat-3 satellites.
Source: Flight International
