The Galileo Near-Infrared Mapping Spectrometer (NIMS) instrument is an imaging spectrometer with the following capabilities:
|Wavelength Range||0.70 - 5.2 microns|
|Number of Channels||variable, up to 408|
|Spectral Sampling||variable, up to 12nm|
|Bandpass (FWHM)||25 nm|
|Pixel Size||0.5 milliradian|
|Spatial Image Size||20 x N pixels|
The NIMS has 17 detectors and a moving diffraction grating to scan the spectrum in up to 24 steps (408 channels). The 17 detectors are spaced uniformly throughout the 0.7-5.2 micron wavelength range. A secondary mirror can step the field of view by 20 pixels so that a 20xN pixel image can be obtained, the the N dimension provided by spacecraft motion.
The 0.5 milliradian field of view
means that NIMS will resolve a 0.5 km spot at a distance of 1,000 km.
By mosaicing multiple 20 x N images, NIMS is producing images of
Jupiter, and its moons comparable to and sometimes better than
Voyager images, but with up to 408 spectral channels at each pixel. The
spectral range and spectral resolution will allows detailed compositional mapping
of minerals on the satellites and of gases in
Example mineral mapping
of NIMS data for Ganymede using Tricorder
shows two ice absorptions and the 4.25-micron absorption whose origin
appears to be CO2 in gaseous or fluid inclusions. The host
mineral for the CO2 has not yet been identified. The
4.25-micron absorption maps strongest along the equatorial region of Ganymede,
and is also seen on Callisto, and apparently on Europa. (See Carlson
et al. 1997 and McCord et al. 1997, 1998 below.)
Galileo NIMS spectral library (nominal, 408 channel)
Carlson, R.W. Smythe, K. Baines, E. Barbinas, R. Burns, S. Calcutt, W. Calvin, R. Clark, G. Danielson, A. Davies, P. Drossart, T. Encrenaz, F. Fanale, J. Granahan, G. Hansen, P. Hererra, C. Hibbitts, J. Hui, P. Irwin, T. Johnson, L. Kamp, H. Kieffer, F. Leader, R. Lopes-Gautier, D. Matson, T. McCord, R. Mehlman, A. Ocampo, G. Orton, M. Roos-Serote, M. Segura, J. Shirley, L. Soderblom, A. Stevenson, F. Taylor, A. Weir, P. Weissman, Near-Infrared Spectroscopy and Spectral Mapping of Jupiter and the Galilean Satellites: First Results from Galileo's Initial Orbit. Science, 274, 385-388, 1996.
Carlson, R.W., W.D. Smythe, R. Lopes-Gautier, A.G. Davies, L.W. Kampa, J.A. Mosher, L.A. Soderblom, F.E. Leader, R.H. Mehlman, and R.N. Clark, The Distribution of Sulfur Dioxide and Other Infrared Absorbers on the Surface of Io in 1996, Geophys. res. Letters, 24, 2479-2482, 1997.
McCord, T.B., R.W. Carlson, W.D. Smythe, G.B. Hansen, R.N. Clark, C.A. Hibbits, F.P. Fanale, J.C. Granahan, M. Segura, D.L. Matson, T.V. Johnson, P.D. Martin, G.E. Danielson, and the NIMS team, Organics and Other Molecules in the Surface of the Icy Galilean Satellites, Science, 278 1997.
McCord, T.B., G.B. Hansen, R.N. Clark, P.D. Martin, C.A. Hibbits, F.P. Fanale, J.C. Granahan, M. Segura, D.L. Matson, T.V. Johnson, R.W. Carlson, W.D. Smythe, G.E. Danielson, and the NIMS team, Non-Water-Ice Constituents in the Surface Material of the Icy Galilean Satellites from the Galileo Near-Infrared Mapping Spectrometer Investigation, J. Geophys. Res. 103, 8603-8626, 1998.
U.S. Geological Survey,
a bureau of the U.S. Department of the Interior
This page URL= http://speclab.cr.usgs.gov/spacecraft-planetary/galileo-nims/nims1.html
This page is maintained by: Dr. Roger N. Clark firstname.lastname@example.org
Last modified November 18, 1998.