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Published January 1982 | Published
Journal Article Open

Infrared observations of Phobos and Deimos from Viking

Abstract

The surface thermal properties of Phobos and Deimos have been determined from observations made with the Viking Orbiter Infrared Thermal Mapper (IRTM), at wavelengths ranging from 6 to 20 μm. The data, composed of both global and high-resolution infrared photometry of the satellite surfaces as well as eclipse observations, indicate surface material of low thermal conductivity comparable to that of the earth's moon. Values of the thermal inertia I consistent with the data for Phobos are 0.9 ≲ I ≲ 1.6 × 10^(−3) cal cm^(−2) s^(−1/2) K^(−1), and 0.6 ≲ I ≲ 2.0 × 10^(−3) cal cm^(−2) s^(−1/2) K^(−1) for Deimos. It is concluded that both satellites are covered with a vertically uniform layer of finely divided material at least several centimeters thick. Observed differences between brightness temperatures at different wavelengths on Phobos are due mainly to topographic slopes and to the presence of ∼5% by area high inertia or blocky material.

Additional Information

© 1982 American Geophysical Union. Issue online 20 September 2012; version of record online 20 September 2012; manuscript accepted 28 June 1982; manuscript revised 16 April 1982; manuscript received 16 November 1981. We thank Hugh Kieffer, Frank Palluconi, Ellis Miner, and Dave Paige for discussions and assistance, Judy Bennett for critical aid in processing the data, Fred Wieland for help in constructing the temperature maps, Stillman Chase for providing data on IRTM extra-field sensitivity, and Tom Duxbury for providing geodetic grids for Phobos. We are especially grateful to Phil Christensen for making available his results prior to publication as well as providing the necessary gain corrections to the data. Finally, we acknowledge the entire Viking Flight Team for carrying out the complex observations expertly. Contribution 3697 from the Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California 91125.

Attached Files

Published - Lunine_et_al-1982-Journal_of_Geophysical_Research-_Solid_Earth__1978-2012_.pdf

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Lunine_et_al-1982-Journal_of_Geophysical_Research-_Solid_Earth__1978-2012_.pdf

Additional details

Created:
August 19, 2023
Modified:
October 24, 2023