existing worldwide network of Landsat ground receiving stations. A highly stable
spacecraft would permit a simple algorithm to be employed in the ground data
reduction for correlating the stereo records in order to produce digital terrain
elevation data. MAPSAT is not an approved program and has no funding beyond the
feasibility study. It is hoped that an eventual commercial operator will consider
the MAPSAT concept.
Shuttle Remote Sensing Missions
For the last ten years the largest NASA program has been the development of the
Space Transportation System (STS). The major advantage of this system is that
its principal component, the Shuttle Orbiter vehicle can be returned to Earth
and reused on successive missions. The back of the vehicle opens up to a cargo
bay in which manned modules and instrument pallets can be installed and operated
while the Shuttle is on sortie missions in Space. Initial launches of the Shuttle
are due east from Kennedy Space Center (KSC) in Florida, permitting remote sensor
coverage from latitudes 28.5? north to 28.509 South. Because of range safety con-
ditions, the maximum orbit inclination available from KSC is 57? which permits
coverage of most of the world's populated areas. Polar orbits for the Shuttle
will not be available until 1985 when the Western test range at Vandenberg Air
Force Base should become operational. Shuttle missions launched from KSC are
designated as STS followed by the sequential flight number. Missions launched
from Vandenberg will be designated as V followed by sequential flight number.
Five successful Shuttle flights have been completed, and the system has been de-
clared operational.
A number of STS missions will have remote sensing as part of their payload. The
second Shuttle mission, STS-2, which operated from a 275 km orbit at 40.39 incli-
nation in November 1981, carried the Earth observation payload package called
OSTA-1, developed by the NASA Office of Space and Terrestrial Applications. The
instruments were:
SMIRR - Shuttle multispectral infrared radiometer
MAPS - Measurement of air pollution from satellites
OCE - Ocean color experiment
FILE - Feature identification and location experiment
SIR-A - Shuttle imaging radar
All of the instruments operated successfully with the data from SIR-A being of
greatest interest.* This instrument was a modification of the SEASAT radar with
a 479 look angle, 56 km swath, 40m resolution, and optical recording of the data
on film.
STS-7, scheduled for April 1983 will be the first flight of the Shuttle Pallet
Satellite (SPAS-01). This is a small structure which will be the first payload
to be launched into an independent orbit and subsequently be recovered and re-
turned to Earth by the Shuttle. Among other experiments it will carry a Modular
Opto-Electronic Multispectral Scanner (MOMS) which will have two linear array
detectors operating in the visible and near infrared wavelengths with a 20m pixel
and 140 km swath. Data will be stored by an on-board tape recorder for post-
flight analysis. STS-7 will be at 296 km altitude and 28.59 inclination.
A major Shuttle payload is Spacelab, which is a joint venture between the
European Space Agency (ESA) and NASA. It is presently scheduled for launch on
STS-9 in October 1983 at 250 km altitude and 579 inclination. The payload will
consist of both manned experiment modules and pallets for other instruments.
*A complete description of the experiments and their results is given in
SCIENCE, Vol. 218, 3 December 1982, pp. 993-1033.
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