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.