Citation
Abstract
During the Mariner Venus/Mercury 1973 (MVM’73) mission, the S/X dualfrequency doppler calibrations (for plasma and ionospheric charged-particle dynamics) have been demonstrated to improve post-flight radio metric doppler reductions: the error of one Mercury I encounter position estimate was reduced by 500 km (~ 80%). This demonstration used tracking data acquired from March 16-29, 1974. The Sun-Earth-probe angle (SEP) was greater than 30 deg during this time. As the SEP decreases, S/X calibrations indicate dramatic increases in plasma dynamics. Simultaneously, the noises of the S and X dopplers and the S/X calibrations increase by 2 orders of magnitude as the SEP decreases from 30 to 3 deg. When these calibrations are used to support Mariner 10 navigation, unreasonable results are obtained. The calibrations, their noise characteristics, and their impact on Mariner 10 navigation are herein outlined. One possible cause for this behavior is that multi-pathing of radio signals to Mariner 10 produces phase scintillations of the S-band uplink transmission in excess of 1/2 rad/s (3.5 cm of integrated phase change per second). This probably exceeds the linear performance region of the second-order phase-locked loops.
Details
- Volume
- 42-25
- Published
- February 15, 1975
- Pages
- 47–55
- File Size
- 636.0 KB