May 1982:space activities report

ATS-1 REPOSITIONED

NASA has started to relocate the geosynchronous Applications Technology Satellite-1 (ATS-1) from its present position at 149 degrees west longitude to a new position at 162 degrees east longitude.

The old location required maximum thruster use to maintain orbital position. Relocating to 162 east longitude puts the satellite into a more stable position where the power from onboard thrusters for station-keeping is reduced substantially, extending the lifetime to beyond mid-1982. This action will prolong the orbital station-keeping period to 1983 and reduce station-keeping activities to quarterly from bi-weekly. This new position also improves the satellite’s “look angle” to more westerly islands in the Pacific Basin.

ATS-1 is the oldest synchronous communications satellite still in use. Present experiments include voice transmission among 11 Pacific island nations, the Trust Territory of the Pacific, Australia, New Zealand, Hawaii and California. Other experiments provide medical care communications for Alaska, technology transmissions between Japan and Australia, and coordination of oceanic research vessels in the Pacific and Gulf regions.

ATS-1 was launched on 7 December 1966 and has been a pioneer in the use of communications satellites for health services, education, public safety, emergency communications and mobile land and maritime applications.

Tne repositioning manoeuvre is expected to take about eight months to complete. Full communications with ATS-1 will be maintained throughout with periodic adjustments of ground station antennaes to keep the satellite in view.

EUROPEAN LAUNCHER STUDY

It is generally recognised that Europe’s Ariane launcher will not be able to handle the space payload requirements of the late 1990’s. Ariane 4 will be adequate until early that decade but frequent trips into geostationary orbit will need a much larger, more versatile type of launcher.

R.G. Reichert of Dornier presented the paper "Potential Long Range Trend in European Space Launcher Developments” at last September’s IAF Congress in Rome. His study pointed out that, by the year 2000, Europe will need a launcher capable of taking 50 tonnes into low Earth orbit. The launcher should be fully reusable which, although resulting in high development costs, yields lower operating costs. An orbital transfer vehicle will also be necessary.

One vehicle studied is the “TSTO” - the Two Stage to Orbit ballistic vehicle powered by oxygen/hydrogen engines. With a lift-off mass of around 900 tonnes and a total height of 42 m, the launcher could handle a payload diameter of 8 m. The 17 m diameter first stage would return to Earth for ocean recovery and eventual reuse.

An alternative design would be to use an aerodynamic first stage, looking rather like a squat, present-day Shuttle Orbiter. Total lift-off weight would be about 1200 tonnes and the bulky liquid hydrogen would sit at the rear. Jet engines would assist in the runway landing.

UPPER ATMOSPHERE STUDIES

NASA’s Office of Space and Terrestrial Applications has selected nine experimental and 10 theoretical teams for participation in the proposed Upper Atmosphere Research Satellites (UARS) programme.

The UARS programme is designed to obtain data on the energy input, chemical composition and dynamics of the Earth’s stratosphere and mesosphere in order to determine the chemical and dynamical state of the upper atmosphere and its susceptibility to change. Interest in stratospheric chemistry has been heightened over the last decade by growing awareness of the potential for reductions in stratospheric ozone caused by emissions from high flying aircraft and by chlorofluorocarbons from aerosol spray cans, refrigeration, air conditioning and foam blowing operations.

The experimental teams will develop instruments to make direct measurements of upper atmospheric winds, measurements of solar ultraviolet irradiance, energetic particle interactions with the upper atmosphere and densities of critical chemical species as a function of altitude. The theoretical teams will develop and apply models of the upper atmosphere which, when combined with the new data, should significantly increase our understanding of upper atmospheric chemistry and dynamics and improve the capability to assess the impact of man’s activities on the delicate chemical processes in the stratosphere.

CHANGE IN VENERA/HALLEY MISSION

CNES, the French space agency, has announced changes to the 1984 Soviet Venera/Halley’s Comet probe which was scheduled to drop balloons into the upper layers of the Venusian atmosphere, writes Neville Kidger. The French say that the balloons, which were to have been made in France, have been dropped from the revised plan in favour of a craft which will land on the night side of the planet.

The project, now named VEGA, also envisages observations of Halley's Comet in March 1986 from the carrier bus spacecraft after it has carried out its ferry role for the lander probe. The French will participate in eight experiments on the flight, four each on the lander and the bus. The maximum weight allowed to the French for scientific payload is 50 kg.

The experiments consist of (on the lander): mass spectrometer, aerosol collector, ultraviolet spectrophotometer and equipment for measurements of pressure and temperature during the descent. On the comet observation bus the French are to participate in the TV imaging experiment (which will use a French-built telescope), infrared spectrometer, three- channel spectrometer and plasma wave analyser.

French-built Signe 2MS3 gamma-ray burst detectors were carried to Venus on the Venera 13 and 14 probes. Another French payload, to be flown aboard a Soviet spacecraft in 1986, is a gamma ray telescope called Gamma 1.