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REMOTE. SENSING FOR PLANETARY TOPOGRAPHIC MAPPING
By
SHERMAN S.C. WU
United States Geological Survey
Flagstaff, Arizona 86001 USA
ABSTRACT.- Remote sensing data from devices using a broad spectrum of
wavelengths have been applied to planetary topographic mapping. A global
topographic map of Mars has been compiled by the synthesis of remotely
sensed data from various scientific experiments on board the Mariner 9
spacecraft and from Earth-based radar observations. Contour lines on Mars
maps are also compiled by photogrammetric methods, using pictures from both
Mariner 9 and Viking missions.
A global topographic map of the Moon is also being compiled using
. topographic information derived from various remote sensing data which
include: Apollo and Lunar Orbiter photographs, laser altimeter data, lunar
radar sounders, and Earth-based observations.
By using radar altimeter data transmitted from the Pioneer Venus
spacecraft, a preliminary global topographic map of Venus has been
compiled. For the compilation of more detailed maps of Venus, the
technology of using side-looking radar stereo images is under development.
I. INTRODUCTION
Remote-sensing data play an important role in planetary topographic
mapping. Topographic maps of planetary bodies are compiled by the synthesis of
remotely sensed data, imaging or nonimaging, transmitted by spacecraft or
received from various sensors.
A global topographic map of Mars was compiled between 1971 and 1975 by
combining measurements obtained by various remote sensing devices (Wu, 1975,
1978). They include the ultraviolet spectrometer (UVS), the infrared
radiometer (IRR), and the infrared interferometer spectrometer (IRIS) on board
the Mariner 9 spacecraft, with Earth-based radar oppositions of Mars. The Mars
topographic datum, the 0-elevation reference surface, is defined by its gravity
field (Wu, 1981b), which was established from gravity data obtained by radio
tracking of Mariner 9. With almost 60,000 Mars pictures transmitted back to
Earth by the two Viking spacecraft, Mars is currently being systematically
mapped in great detail. :
By using topographic data derived from Apollo and Lunar Orbiter
photographs, laser altimetry, and Earth-based observations, a global
topographic map of the Moon is being compiled (Wu, 198la). Using radar
altimetry data obtained by the Pioneer Venus spacecraft, a preliminary global
topographic map of Venus has been compiled (Masursky, et al., 1980). Future
topographic maps of Venus will probably be compiled from synthetic aperture
radar (SAR) images, using methods similar to those of conventional
photogrammetry. The methods and equipment for mapping using side-looking radar
stereo images are now under development (Wu and Schafer, 1980a, Wu, et al.,
1980b)
Techniques for the interpretation of remote sensing data and map
compilation are discussed in this paper.
II. INTERPRETATION OF REMOTE SENSING DATA
Remote sensing devices on board the spacecraft of the Mariner 9 mission
provided broad topographic and thermal coverage, and measurements of parameters
