Venus
Infrared Map I
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 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.
Last Update: 2005-Nov-29
This is the Web Edition of "A Trip Into Space", a Coimbra-based electronic book on space science. Both the texts and the photos are by courtesy of National Aeronautics and Space Administration.
Venus 
