Trajectory and atmospheric structure from entry probes: Demonstration of a real-time reconstruction technique using a simple direct-to-Earth radio link

The reconstruction of the trajectory and atmospheric structure associated with an entry probe has traditionally relied upon onboard accelerometer measurements. Here we outline an equivalent reconstruction technique that uses Doppler-shifted direct-to-Earth transmissions instead. A critical assumption is that the entry probe's angle of attack is zero. The technique is successfully demonstrated on the atmospheric entry of the Mars Exploration Rover Opportunity, terminating at parachute deployment. This technique can be applied in real-time, which supports mission operations and public engagement. It can also be applied to entry probes that fail during their high-risk atmospheric entry.