A Terminal Descent System for Landing and Proximity Operations – Initial Validation Results

Autonomous vehicle landing and proximity operations rely on accurate range and velocity measurements for guidance, navigation, and landing. As preeminent examples, Mars Science Laboratory and Mars 2020 both deploy a “Terminal Descent Sensor” (TDS), a purpose-built, Ka-band pencil beam radar designed specifically for the challenging sky-crane landing requirements. Beyond Mars 2020, the availability of the TDS for missions is unclear due to problems of obsolescence and reproducibility; in addition, the TDS is quite large, prohibitively so for smaller missions. Remote Sensing Solutions is currently funded under a NASA Small Business Innovative Research program to continue, shrink, and extend the capability of TDS concept. In this paper we discuss the recent design, prototyping, and validation efforts of a prototype “Terminal Descent Radar” (TDR). The prototype TDR is built around unique, independent beams, pointed appropriately to allow reconstruction of a body-fixed three-dimensional velocity. The TDR includes implementation of the core firmware in the RSS commercial, off-the-shelf (COTS) digital receiver, ARENA, as well as a mix of high fidelity and a few other COTS elements. The prototype TDR has undergone initial laboratory and helicopter testing, and we discuss these results in this paper. All early indications are that the RSS TDR is performing according to expectations. We also discuss future experiment and development plans for the TDR concept.