Venus Nightside through the Near Infrared Mapping Spectrometer
Original Caption Released with Image:
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 Infrared 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 thick clouds. This cloud layer is at about 30 degrees Fahrenheit, at a
pressure about 1/2 Earth's atmospheric pressure. 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 filaments 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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