Home | Site Map | What's New | Image Index | Copyright | Posters | ScienceViews | Science Fiction Timelines |

PHOTO INDEX OF
PRIMARY TARGETS
ASTEROIDS
COMETS
EARTH
JUPITER
KUIPER BELT
MARS
MERCURY
METEORITES
NEPTUNE
OORT CLOUD
PLUTO
SATURN
SOLAR SYSTEM
SPACE
SUN
URANUS
VENUS
ORDER PRINTS

OTHER PHOTO INDEXES
ALL TARGETS
PHOTO CATEGORIES

SCIENCEVIEWS
AMERICAN INDIAN
AMPHIBIANS
BIRDS
BUGS
FINE ART
FOSSILS
THE ISLANDS
HISTORICAL PHOTOS
MAMMALS
OTHER
PARKS
PLANTS
RELIGIOUS
REPTILES
SCIENCEVIEWS PRINTS

Distribution of Sulfur Dioxide Frost on Io

Target Name:  Io
Spacecraft:  Galileo
Produced by:  NASA/JPL
Copyright: Public Domain
Date Released: 1998-03-26

Related Document
Download Options

NameTypeWidth x HeightSize
galio16.jpgJPEG1300 x 85058K
PIA00841.tifTIFF1300 x 850173 kilobytes

Sulfur dioxide, normally a gas at room temperatures, is known to exist on Io's surface as a frost, condensing there from the hot gases emanating from the Io volcanoes. However, the deposition patterns and relation of the frost distribution to the volcanic activity is unknown, since prior measurements lacked the spatial resolution to accurately map the surface frost.

The Galileo Near Infrared Mapping Spectrometer (NIMS) obtained relatively high spatial and spectral resolution images during the C3 orbit, and the characteristic infrared absorptions of sulfur dioxide frost appearing in the spectra were used to produce the SO2 frost map shown on the right. The comparison image on the left (from 1979 Voyager measurements) shows the same view and indicates the surface brightness as seen in visible light.

The frost map shows maximum SO2 concentration as white, lesser amounts as blue coloration, and areas with little or no SO2 as black. The resolution of this map is about 120 km (75 miles), which spans the latitude range 120 W to 270 W.

It is interesting to compare this frost distribution with regions of volcanic activity. Volcanic hotspots identified from NIMS and SSI images occur in many of the dark - low SO2 - areas, a reasonable finding since sulfur dioxide would not condense on such hot regions. The Pele region (to the lower left), N. Colchis hot spots (upper center) and S. Volund (upper right) are good examples of hot spot areas depleted in sulfur dioxide. Much of the rest of this hemisphere of Io has varying amounts of sulfur dioxide present. The most sulfur dioxide-rich area is Colchis Regio, the white area to the right of center.

Of particular interest is the dark area to the south of Colchis Regio. From the study of other NIMS images, it is seen that this region does not have any large, obvious hotspots. However, it is depleted in sulfur dioxide.

Copyright © 1995-2016 by Calvin J. Hamilton. All rights reserved.