Radar Terminal Descent Sensor Performance During Mars Science Laboratory Landing

The Mars Science Laboratory landing architecture relies on unprecedented onboard ground-relative navigation accuracy, which is provided by the Terminal Descent Sensor. The Terminal Descent Sensor is a Ka-band landing radar that was developed specifically for the Mars Science Laboratory. It employs six narrow-beam antennas to provide high-precision line-of-sight range and velocity measurements over a challenging operational envelope that encompasses the dynamics of terminal descent, the uncertain surface properties at the landing site, and the space environment. Telemetry from landing shows that the radar generally performed very well, with measurement characteristics that match high-fidelity simulations quite closely. Two features in the radar telemetry were not predicted, although they did not adversely affect the landing. These were 1) sporadic velocity errors during the sky-crane phase that were likely caused by the motion of surface material kicked up by the thruster plumes of the descent vehicle and ...