Radar altimeter for surface analysis in planetary applications

A new-concept radar altimeter for the ESA-NASA joint mission named Rosetta has been studied. The goal of that mission is to approach and land on a comet nucleus, take a sample of the comet nucleus, and bring it to the Earth. The success of the mission is strongly related to a safe landing on a suitable site. A radar altimeter should perform the main operations during the landing phase giving information not only about attitude and surface roughness but also about the surface composition and the presence and nature of subsurface discontinuities. Surface composition means the type of material giving rise to the observed echo. A comet model, an EM model of the received echo, the radar altimeter operational mode, and optimum system design criteria are discussed in terms of transmitted frequency, pulse repetition frequency and signal bandwidth.<>