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PHOTO CAPTION                 P-37221   GLL-V9 NIMS

This image is a false-color version of a near-infrared map
of lower-level clouds on the night side of Venus, obtained by
the Near Intrared Mapping Spectrometer aboard the Galileo
spacecraft as it approached the planet February 10, 1990.
Taken from an altitude of about 60,000 miles above the
planet, at an infrared wavelength of 2.3 microns (about three
times the longest wavelength visible to the human eye) the
map shows the turbulent, cloudy middle atmosphere some 30-33
miles above the surface, 6-10 miles below the visible
cloudtops. The image shows the radiant heat from the lower
atmosphere (about 400 degrees Fahrenheit) shining through the
sulfuric acid clouds, which appear as much as 10 times darker
than the bright gaps between clouds. The colors indicate
relative cloud transparency; white and red show thin cloud
regions, while black and blue represent relatively thin
clouds. This cloud layer is at about 170 degrees Fahrenheit,
at a pressure about 1/2 Earth's atmospheric pressure. About
2/3 of the dark hemisphere is visible, centered on longitude
350 West, with bright slivers of daylit high clouds visible
at top and bottom left. Near the equator, the clouds appear
fluffy and blocky; farther north, they are stretched out into
East-West filiments by winds estimated at more than 150 mph,
while the poles are capped by thick clouds at this altitude.
The Near Infrared Mapping Spectrometer (NIMS) on the Galileo
spacecraft is a combined mapping (imaging) and spectral
instrument. It can sense 408 contiguous wavelengths from 0.7
microns (deep red) to 5.2 microns, and can construct a map or
image by mechanical scanning. It can spectroscopically
analyze atmospheres and surfaces and construct thermal and
chemical maps. Designed and operated by scientists and
engineers at the Jet Propulsion Laboratory, NIMS involves 15
scientists in the U.S., England, and France.

The Galileo project is managed for NASA's Office of Space
Science and Applications by JPL; its mission is to study the
planet Jupiter and its satellites and magnetosphere after
multiple gravity-assist flybys at Venus and the Earth.

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