Gravity field of the Jovian system from Pioneer and Voyager tracking data

Abstract

Analysis of the Doppler-tracking data and star-satellite imaging from the Voyager 1 and Voyager 2 spacecraft, combined with a reanalysis of the Pioneer 10 and Pioneer 11 Doppler tracking has yielded improved values for the Galilean satellite masses, and the rotational pole, mass, and harmonic coeffi-cients of Jupiter. The present results are consistent with those previously published for Pioneer 10 and Pioneer 11 (Null 1976). Mass results are expressed as the product GM, the universal gravitational constant G times the mass in grams M of the body, in units of (km 3 s -2). The Galilean satellite masses are (5961 + 10) for lo, (3201 + 10) for Europa, (9887 + 3) for Ganymede, and (7181 + 3) for Callisto (All error estimates presented in this paper are standard errors and are our evaluation of real as opposed to formal errors). The mass of the Jupiter system is (126 712 767 + 100). A mass for Amalthea could not be reliably estimated. The second, third, fourth, and sixth zonal harmonic coefficients of Jupiter are J 2 = (14736 + 1)X IO" 6 , J 3 = (1.4 + 5)X lO" 6 , / 4 = (-587 + 5)X lO" 6 , and J 6 = (31 + 20)X 10" 6 , at an equatorial radius of 71 398 km. The sectorial harmonics are C 2 2 = (—0.03 + 0.05) X10 -6 , S 2 2 = (— 0.007 + 0.05) X10 -6 . The right ascension and declination of the pole of Jupiter relative to the mean Earth equator and equinox of 1950.0 is 268Î001 + 0°005 and 64?504 + 0.°001, respectively.