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No. 37: Jan-Feb 1985

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Why aren't the martian craters worn down?

The preceding, almost-Lowellian vision of a watery Mars is quite different from what the Mariner and Viking spacecraft tell us about the planet's present condition. Wind rather than water is now the main erosional force. The sand dunes and drifts, the wind-shadows behind rocks, and the sand-blasted surfaces all attest to the desertification of Mars. Ronald Greeley, of Arizona State University, and his colleagues have simulated Martian winds in a special wind tunnel at NASA's Ames Research Center. Using spacecraft-measured wind velocities and patterns, they tried to duplicate the Martian erosional environment. The results were a surprise. They implied that the Martian surface should be worn down by wind-driven sand and dust at rates up to 2 centimeters per century. But at that rate, the Martian craters, which are estimated to be hundreds of millions of years old, would have been worn level long ago. The researchers are now wondering what is wrong with their simulation. They venture that the Martian sand may not be "normal," or perhaps the eroding particles do not travel as fast as they figured.

(Anonymous; "The Windblown Planet Mars," Sky and Telescope, 68:507, 1984.)

Comment. Another interpretation is that Mars has not been desert-like for as long as presently believed.

Reference. The subject of Martian crater obliteration is discussed further in AME20 in our Catalog: The Moon and the Planets. Ordering information here.

From Science Frontiers #37, JAN-FEB 1985. 1985-2000 William R. Corliss

Science Frontiers Sourcebook Project Reviewed in:


  • "A sourcebook of unexplained phenomena is therefore a valuable addition to a collection of scientific literature. William R. Corliss has provided this in the past with his source books of scientific anomalies in several subjects, and now he has provided it for astronomy. He has done an excellent job of collecting and editing a large amount of material, taken in part from scientific journals and in part from scientific reporting in the popular or semi-scientific press." -- "The Mysterious Universe: A Handbook of Astronomical Anomalies", reviwed by Thomas Gold, Cornell University, in Icarus, vol.41, 1980

  • "An interesting, systematic presentation of unusual weather [..] This book is recommended for a general audience" --"Corliss, William R., Tornados, Dark Days, Anomalous Precipitation, and Related Weather Phenomena, Sourcebook Project, 1983.", revieweed in Choice, September 1983
  • "..the science is necessarily somewhat speculative, but Corliss's symthesis is based on reputable sources." -- "Corliss, William R. (Compiler). Lightning, Auroras, Nocturnal Lights, and Related Luminous Phenomena" reviwed by Joseph M. Moran, Univ. of Wisconsin in Science Books and Films, Sep/Oct 1983

  • "Before opening the book, I set certain standards that a volume which treads into dangerous grounds grounds like this must meet. The author scrupulously met, or even exceeded those standards. Each phenomenon is exhaustively documented, with references to scientific journals [..] and extensive quotations" -- "Book Review: The moon and planets: a catalog of astronomical anomalies", The Sourcebook Project, 1985., Corliss, W. R., Journal of the Royal Astronomical Society of Canada, Vol. 81, no. 1 (1987), p. 24., 02/1987