Arecibo radar observations of Martian surface characteristics near the equator
1978; Elsevier BV; Volume: 33; Issue: 1 Linguagem: Inglês
10.1016/0019-1035(78)90027-1
ISSN1090-2643
AutoresR. A. Simpson, G. L. Tyler, D. B. Campbell,
Tópico(s)Spaceflight effects on biology
ResumoMars radar observations at 12.6-cm wavelength indicate that many of what were potential Viking landing sites along the planet's equator are rougher than interpretations of Mariner 9 images suggested. Root mean square surface slopes are typically 5° in the region bounded by 160 and 200°W, 0 and 12°S. From Tharsis Montes west to 160°W, radar-scattering characteristics suggest extreme roughness on small scales, perhaps exceeding 10° in rms magnitude. East of Tharsis and north of Valles Marineris the surface is smooth, with values of rms slope as low as 1°; the elevation of this plateau was too high for a Viking landing. Study of spectral shapes indicates the Hagfors scattering law remains the best descriptor of quasi-specular surface scattering properties in an average sense; widespread variations in the surface argue against its indiscriminate use, however. Backscattering at moderate (25–40°) incidence angles was studied qualitatively and was found to be significantly above the level predicted by a strictly quasi-specular (e.g., Hagfors) process; it also is variable over the surface.
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