Saturn gravity results obtained from Pioneer 11 tracking data and earth-based Saturn satellite data
Abstract
Improved gravity coefficients for Saturn, its satellites and rings are calculated on the basis of a combination of Pioneer 11 spacecraft Doppler tracking data and earth-based determinations of Saturn natural satellite apse and node rates. Solutions are first obtained separately from the coherent Doppler tracking data obtained for the interval from August 20 to September 4, surrounding the time of closest approach, with the effects of solar plasma on radio signal propagation taken into account, and from secular rates for Mimas, Enceladus, Tethys, Dione, Rhea and Titan determined from astrometric data by Kozai (1957, 1976) and Garcia (1972). Combination of the data by the use of the Pioneer solution and corresponding unadjusted covariance matrix as a priori information for a secular rate analysis results in values for the total ring mass of essentially zero at a standard error level of 1.7 x 10 to the -6th Saturn masses, a ratio of solar mass to that of the Saturn system of 3498.09 + or - 0.22, masses of Rhea, Titan and Iapetus of 4.0 + or - 0.9, 238.8 + or - 3, and 3.4 + or - 1.3 x 10 to the -6th Saturn masses, respectively, and second and fourth zonal harmonics of 16,479 + or - 18 and -937 + or - 38, respectively. The harmonic coefficients are noted to be important as boundary conditions in the modeling of the Saturn interior.
- Publication:
-
The Astronomical Journal
- Pub Date:
- March 1981
- DOI:
- 10.1086/112905
- Bibcode:
- 1981AJ.....86..456N
- Keywords:
-
- Pioneer 11 Space Probe;
- Planetary Gravitation;
- Radar Tracking;
- Saturn (Planet);
- Saturn Rings;
- Doppler Radar;
- Error Analysis;
- Ground Truth;
- Planetary Mass;
- Rhea (Astronomy);
- Satellite Sounding;
- Secular Variations;
- Titan;
- SATURN;
- GRAVITY;
- PIONEER 11;
- COMPARISONS;
- SATELLITES;
- RINGS;
- DATA;
- TRAJECTORIES;
- ANALYSIS;
- DOPPLER OBSERVATIONS;
- ACCELERATIONS;
- MASS;
- EPHEMERIS;
- PLASMAS;
- HARMONICS;
- RHEA;
- TITAN;
- IAPETUS;
- Lunar and Planetary Exploration; Saturn