Spacecraft Position Determination with the Electra UHF Transceiver

In June 2022, the Electra Relay Operations teambegan conducting radiometric phase and power data collectionduring relay overflights of the InSight Lander by the ExoMarsTrace Gas Orbiter (TGO). This mode of the Electra radio haspotential applications for both navigation and radio science, butis relatively untested in flight. Here, we present both one-way(non-coherent) and two-way (coherent) Doppler observationsconducted during 32 TGO relay overflights. Then we explorethe ability to find the surface position of the lander with eachdata set and compare this against other methods.Looking forward to Mars Sample Return, the capability to doone-way Doppler tracking would be essential for monitoring thelaunch performance of the Mars Ascent Vehicle anddetermining the final trajectory of the Orbiting Samplecontainer. Testing these positioning capabilities now will help usto prepare for that anticipated need.