Cassini-Huygens bistatic experiment from Titan's surface

After a successful entry and descent on Titan, on 14 January 2005, the probe remarkably survived the landing and continued radioing from the surface to the overflying Cassini, until the orbiter set below Titan’s local horizon.

The inter probe-satellite Huygens to Cassini sinal provided, other than the communications functionality, an unanticipated bistatic radio scattering experiment from Titan’s surface. This the our knowledge the furthest bistatic link experiment established between two spacecrat to date.

In the paper we summarize the high-quality measurements of the 2098 MHz (14.3 cm) postlanding radio signal, focusing on the variations observed in signal strength. The mechanism that creates this pattern is physically interpreted as multipath interference between the direct signal and the signal reflected on Titan’s surface.

A roughness property of pebble sizes in the order of 10cm is finally derived. It should be noted that this measurement is in a completely new direction from the after-landing cameras fixed view, complementing the surface knowledge of the Huygens landing area.