Citation
Abstract
When the geocentric angular separation between two spacecraft is but a few degrees, navigational advantages may be achieved by navigating one spacecraft with respect to the other. In this dual-spacecraft navigation technique, radio metric data from the two spacecraft are not treated independently, but differenced to cancel common observable modeling errors. In the circumstance of the Galileo Spacecraft flyby of Mars, the Mars Viking Lander 1 might provide a radio beacon that could be used to navigate Galileo past Mars. The Viking Lander has been operating on the Martian surface since July 20, 1976, and is expected to continue through 1990. It is intended that the navigational delivery accuracy capability of Galileo at Mars [25 km (1σ)] is going to be met with interferometric angular measurements (VLBI) and range and range-rate measurements. Like VLBI, however, dual-spacecraft differenced range has little sensitivity to transmission media modeling errors, and to tracking-station location errors. Similarly, differenced range provides angular information about the separation between the Mars Viking Lander 1 and the Galileo Spacecraft. In covariance studies, dual-spacecraft differenced range coupled with conventional range and doppler is shown to estimate the Galileo-Mars flyby distance to better than 10 km (1 a), which is favorably comparable to the projected ΔVLBI performance. For the Galileo-Mars flyby, dual-spacecraft differenced range promises to be an excellent backup to VLBI if the Mars Viking Lander remains operational.
Details
- Volume
- 42-60
- Published
- December 15, 1980
- Pages
- 47–59
- File Size
- 188.9 KB