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Tom and Jerry Start with a Racket
Friedrichshafen, March 17, 2002/02011

- Rockot launcher lifts off from the Russian cosmodrome Plesetzk - The scientific Grace satellites investigate the Earth's gravity field - New Astrium concept allows flexible and cost-effective missions

Friedrichshafen/Plesetzk - One day delayed, but textbook launch from the Russian cosmodrome Plesetzk. On Sunday, March 17, 2002, at 10:21 a.m. (CET), the Grace satellites were launched by a Rockot (Russian word for racket) launcher. For five years, the research satellites built by Astrium GmbH (Friedrichshafen) for NASA/JPL are scheduled to investigate the Earth's gravity field from a polar orbit at a height of approx. 500 kilometres. The name Grace stands for Gravity Recovery and Climate Experiment.

About 90 minutes after their launch from the cosmodrome, which lies about 800 kilometres north of Moscow, both Grace satellites separated from the launcher's upper stage. Subsequently, the two research satellites dubbed Tom and Jerry by the Astrium space engineers "established contact " to the ground station in Weilheim/Germany.

"The successful start of the Grace mission underlines our new approach for a more flexible and cost-effective design of the satellite missions by standardisation and new management and test methods", stated Alfred Setzer, Astrium director for Earth Observation and Science to journalists in the German Space Operation Control Centre GSOC in Oberpfaffenhofen. "With contract awarding by NASA/JPL, we were able to further open the gateway to the export markets".

The Grace twins will circle the Earth at a distance of 220 kilometres from one another. With a size of approx. 3 x 2 x 1 metres and a mass of 480 kilograms, both satellites will constantly and precisely (several thousands of millimetres) measure the distance between them. As this distance changes under the influence of the Earth's gravitational field, this method allows the measuring of our planet. During the five-year mission, the measurements will provide an updated model of the terrestrial gravity field every thirty days. In addition, each satellite is to provide daily up to 200 temperature distribution and water vapour concentration profiles in the atmosphere and ionosphere.

From the temporal variations in the gravity field, the geo-scientists can gain a better understanding of the dynamic processes within the Earth's interior, on the deep and surface ocean currents and on the changes of the ice coverage at the poles, in Greenland and in the mountains. Grace is the first mission to measure which quantities of water, ice and matter are moving. By these measurements, the scientists hope to obtain a completely new picture about the processes in and on Earth.

Grace (Gravity Recovery and Climate Experiment) is a joint project of the U.S. space agency Nasa and the German Aerospace Centre (DLR). DLR's German Space Operation Control Centre GSOC in Oberpfaffenhofen is responsible for satellite operation and data reception and NASA/JPL for mission management. The satellites were built by Astrium GmbH in Friedrichshafen. The launch into Earth's orbit was performed by the German-Russian company Eurockot, a holding company of Astrium. Scientific data evaluation will be carried out by the geological research centre (GFZ) in Potsdam and the Centre for Space Research at the University of Texas in Austin, USA.

Note to editors: This text and others as well as high resolution photos are available for download under www.astrium-grace.de.

M. Pikelj

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