Approach Navigation for a Titan Aerocapture Orbiter

Titan Explorer: The Next Step in the Exploration of a Mysterious World

“…Improvements in Titan's ephemeris based on ground-based observations coupled with Titan ephemeris data gleaned from Cassini's planned 44 flybys of Titan will result in one to two orders of magnitude improvement in the Titan ephemeris knowledge, thus significantly reducing that error component (ref. 42). Early in the Titan approach phase, uncertainties in the spacecraft state dominate the errors.…”

“…The orbit determination uncertainties include the reaction caused by the probe release mechanism and the reaction caused by the release of the orbiter truss, as well as data errors (ref. 42). Uncertainty in the ephemeris of Titan provide a large initial contributor to the navigation uncertainty.…”

“…42). A reassessment of the delivery and arrival navigation was not performed, rather the conclusions and recommendations provided (ref.…”

“…Ground-based facilities will process transmitted pictures to extract the optical observables; then the data will be combined with radiometric measurements (ref. 42). Optical navigation has to balance the needs of navigation precision with the ability to return the data.…”

“…A reassessment of the delivery and arrival navigation was not performed, rather the conclusions and recommendations provided (ref. 42), were directly incorporated into the study. The baseline navigation strategy is to use two-way coherent X-band doppler and two-way coherent X-band range measurements coupled with Delta-Differenced One-way Ranging (DDOR) and optical navigation.…”