Bistatic radar probing of planetary surfaces

Bistatic radar provides a simple, cost-effective way to obtain survey information about planetary surfaces on scales important to landers and rovers. The centimeter-scale waves interact most strongly with surface structure on similar and slightly larger scales yielding estimates of rms surface slopes ζ and material dielectric constant ε (which can be related to density). Recent experiments in the Mars north polar region show an unusually heterogeneous surface with some segments having ζ less than 0.2°. The dielectric constants appear to vary only between 1.8 within the polar cap (snow) and 3–4 outside (sand). Uplink experiments (transmissions from ground to spacecraft) have been successfully conducted using Mars Odyssey; future possibilities include spacecraft-to-spacecraft experiments.