Viking Bistatic Radar Observations of the Hellas Basin on Mars: Preliminary Results

Abstract

Preliminary reduction of Viking bistatic radar data gives root-mean-square surface slopes in the Hellas basin on Mars of about 4 degrees on horizontal scales averaged over 10 centimeters to 100 meters. This roughness decreases slightly with position along the ground track, south to north. The dielectric constant in this area appears to be approximately 3.1, greater than the martian average. These values are characteristic of lunar maria and are similar to those found near the Viking lander site in Chryse with the use of Earth-based radar.

Mars Global Surveyor Bistatic Radar Probing of the MPL/DS2 Target Area

“…The "Stealth" region west of Tharsis Montes has very low backscatter (Muhleman et al 1991), but the mechanisms for scattering are poorly understood and may not be relevant here. Bistatic radar measurements on Mars' permanent north polar cap yielded ε ∼ 2-3 (Simpson and Tyler 1981); there have been no previous measurements south of Hellas Planitia (ε ∼ 3.1) where methods similar to those employed here were used (Simpson et al 1979).…”

The 3–5MHz global reflectivity map of Mars by MARSIS/Mars Express: Implications for the current inventory of subsurface H2O

“…In particular, Campbell and Hawke, 2005 show that reflectivity values measured at the wavelength: λ = 70 cm can be influenced by the composition of terrains buried more than 50 m deep in some cases, demonstrating the ability of this method to probe at large depth. In the case of Mars, some measurements had also been obtained using ground based radio telescopes at λ = 3.5 to 70 cm (Simpson et al, 1992;Harmon et al, 1999) or spacecraft as Mars-3 and Mars-4 spacecraft (Krupenio et al 1977) and Viking orbiter 2 at λ = 13.1 cm (Simpson et al, 1979) but were rather limited in terms of spatial resolution and / or geographic extent. The reflectivity values obtained from these measurements have been used to estimate the dielectric constant of surface materials (Pettengill et al, 1973;Downs et al, 1973Downs et al, , 1975Simpson et al, 1982).…”

Determination of local surface properties using Mars Express bistatic radar

“…Evaluating for γ = 0° gives C ∼ 22 and an RMS roughness on the order of C −1/2 = 12°. This is large for Mars, where typical values are more like 3–5°; Simpson et al [1979] reported roughness values of 2.5–4.5° and a dielectric constant ɛ = 3.1 along a Viking Orbiter specular point track in Hellas between (47S, 296W) and (40S, 300W) at S‐band. However, RMS values larger than 10° have been observed on very rough surfaces around the Tharsis volcanoes.…”