December 7, 1996

AMSAT-Deutschland e.V. (Germany)

Telecommunications Satellite AMSAT-OSCAR 13 Burned Up On Re-Entry

On December 5th, 1996, the international telecommunications satellite AMSAT OSCAR-13 burned up upon re-entering the Earth's atmosphere. AMSAT OSCAR-13 was successfully launched on June 15th, 1988, into a highly elliptical orbit on board the first test flight of the new European ARIANE 4 rocket. Over the years, AMSAT OSCAR-13 has enabled direct radio contacts among the world-wide community of nearly 2 million radio amateurs.

AMSAT OSCAR-13 had been constructed within four years by an international project group under the leadership of Dr. Karl Meinzer of AMSAT-Germany. AMSAT (Amateur Radio Satellite Corporation) is a world-wide alliance of approximately 6000 scientists, engineers, technicians and radio amateurs who voluntarily build and operate scientific and communications satellites. During its operational period, AMSAT OSCAR-13 was monitored and controlled by a group of ground stations in Germany, the United Kingdom, Australia, New Zealand and the United States of America.

Upon its re-entry, AMSAT OSCAR-13 has had a lifespan of over eight years. Originally the mission had been conceived to last only seven years. Overheating of the satellite due to air friction in the upper atmosphere resulted in the destruction of the solar panels on November 24th and the consequent interruption of all radio links. Prior to this event, the on-board monitoring system had transmitted much data relating to the satellite's behavior in the upper atmosphere to ground stations for evaluation.

The decay of the orbit was caused by the gravitational attraction of the Sun and the Moon. The elliptical orbit was stretched so that the satellite gradually approached the Earth which lies at one of the two focal points of the ellipse. This phenomenon motivated AMSAT to develop new analytical and computational methods to allow long term predictions for future satellites on similar, highly elliptical orbits.

The orbit of the next satellite, AMSAT Phase 3-D, has been calculated using these new methods and will therefore be more stable over the long term. AMSAT Phase 3-D is scheduled to be launched into space during the first half of 1997 as apparently the only satellite payload for the second test flight of the new ARIANE 5 launcher.

(AMSAT-DL Journal Editor)

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