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GEOS-2 reactivated
Since launch, the Telecom-1A satellite has been controlled from the Toulouse Space Centre. It is operating normally in all respects. The manoeuvre to make its orbit circular was carried out on 6 August at 0256:12 GMT, by firing the MAGE-2 Apogee Boost Motor. During the day of 6 August the solar generator was deployed following Sun acquisition and switching-on. In the evening the satellite was stabilized with respect to the Earth. It is planned to actuate the payload on 21 August, when the satellite will, after drifting and orbit corrections, have reached its final position on 8W longitude. 2.12. ECS-2 ON-STATION MANOEUVRE”5’
On 23 August 1984, the European Space Operations Centre (ESOC) at Darmstadt, FRG, carried out the final manoeuvre required to halt ECS-2 at its test location at 10”E, thus ending the spacecraft’s drift phase which began after the successful firing of the apogee boost motor on 6 August (cf. item 2.11 above). The commissioning and acceptance tests of the spacecraft and its payload will take place over a period of several weeks, after which ECS-2 will be moved to its final position at 7”E prior to hand-over to the European Telecommunications Satellite Organisation, Eutelsat, for operational communications services. 2.13. GEOS-2 REACTIVATED’-
At the request of Switzerland and the FRG, ESA has reactivated its GEOS-2 spacecraft. This satellite was launched into geostationary orbit in June 1978 and completed its planned scientific mission in July 1980. In response to the continued interest shown by the scientific community, GEOS-2 operations were resumed in 1981 and continued until the end of 1983. The last year of this extension was carried out as a special project financed by the FRG and Switzerland only. In January 1984 GEOS-2 was moved from the densely occupied geostationary orbit into a higher and slightly asynchronous orbit where it now drifts at a rate of about 3.5” in longitude per day, becoming visible to the ESOC ground station at Michelstadt, FRG, for four weeks every 3’/* months. In view of (1) the wish of the scientific community to obtain data over a complete 11-year solar cycle, (2) the support of the current AMPTE (Active Magnetospheric Particle Tracer Experiment) project,(“) and (3) the good health of both spacecraft and payload, Switzerland and the FRG have agreed to finance a further one-year extension of GEOS-2 operations. c’5)ESA News Release No. 32 of 24 August 1984. ““)ESA News Release No. 33 of 24 August 1984. (“The AMPTE spacecraft, a project jointly undertaken launched successfully on 16 August 1984.
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by the US, UK and the FRG were
GEOS 1 and 2 The scientific mission of the two GEOS satellites has been to increase understanding of the Earths near environment. Both satellites were specially equipped to measure electric fields in the Earth’s magnetosphere. GEOS- 1 was launched in 1977 and, despite the fact that it did not reach its planned orbit, was able to make a substantial contribution to the International Magnetosphere Study. It was reactivated in late 1978 and early 1979 but further attempts to reactivate the satellite in January 1980 were unfruitful and its mission was declared terminated. GEOS-2 was launched in 1978 with a lifetime due to terminate in June 1980. Its missions was extended in 1980 and, after a period of hibernation, the satellite was reactivated for a fixed term in 1981. GEOS-2 has proved very useful as the reference spacecraft for the International Magnetosphere Study. It has collected magnetic attitude data of good quality and the observations carried out near the geomagnetic equator have proved particularly interesting. The information collected by this satellite has been widely used in correlations with groundbased data and also with data from other satellites. It has made a significant contribution towards identifying the composition and movement of the plasma around the Earths magnetosphere.
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On 23 August 1984, the European Space Operations Centre (ESOC) at Darmstadt, FRG, carried out the final manoeuvre required to halt ECS-2 at its test location at 10”E, thus ending the spacecraft’s drift phase which began after the successful firing of the apogee boost motor on 6 August (cf. item 2.11 above). The commissioning and acceptance tests of the spacecraft and its payload will take place over a period of several weeks, after which ECS-2 will be moved to its final position at 7”E prior to hand-over to the European Telecommunications Satellite Organisation, Eutelsat, for operational communications services. 2.13. GEOS-2 REACTIVATED’-
At the request of Switzerland and the FRG, ESA has reactivated its GEOS-2 spacecraft. This satellite was launched into geostationary orbit in June 1978 and completed its planned scientific mission in July 1980. In response to the continued interest shown by the scientific community, GEOS-2 operations were resumed in 1981 and continued until the end of 1983. The last year of this extension was carried out as a special project financed by the FRG and Switzerland only. In January 1984 GEOS-2 was moved from the densely occupied geostationary orbit into a higher and slightly asynchronous orbit where it now drifts at a rate of about 3.5” in longitude per day, becoming visible to the ESOC ground station at Michelstadt, FRG, for four weeks every 3’/* months. In view of (1) the wish of the scientific community to obtain data over a complete 11-year solar cycle, (2) the support of the current AMPTE (Active Magnetospheric Particle Tracer Experiment) project,(“) and (3) the good health of both spacecraft and payload, Switzerland and the FRG have agreed to finance a further one-year extension of GEOS-2 operations. c’5)ESA News Release No. 32 of 24 August 1984. ““)ESA News Release No. 33 of 24 August 1984. (“The AMPTE spacecraft, a project jointly undertaken launched successfully on 16 August 1984.
58
by the US, UK and the FRG were
GEOS 1 and 2 The scientific mission of the two GEOS satellites has been to increase understanding of the Earths near environment. Both satellites were specially equipped to measure electric fields in the Earth’s magnetosphere. GEOS- 1 was launched in 1977 and, despite the fact that it did not reach its planned orbit, was able to make a substantial contribution to the International Magnetosphere Study. It was reactivated in late 1978 and early 1979 but further attempts to reactivate the satellite in January 1980 were unfruitful and its mission was declared terminated. GEOS-2 was launched in 1978 with a lifetime due to terminate in June 1980. Its missions was extended in 1980 and, after a period of hibernation, the satellite was reactivated for a fixed term in 1981. GEOS-2 has proved very useful as the reference spacecraft for the International Magnetosphere Study. It has collected magnetic attitude data of good quality and the observations carried out near the geomagnetic equator have proved particularly interesting. The information collected by this satellite has been widely used in correlations with groundbased data and also with data from other satellites. It has made a significant contribution towards identifying the composition and movement of the plasma around the Earths magnetosphere.
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