Galileo Gravity Results and the Internal Structure of Io
Abstract
Doppler data generated with the Galileo spacecraft's radio carrier wave were used to measure Io's external gravitational field. The resulting triaxial field is consistent with the assumption that Io is in tidal and rotational equilibrium. The inescapable conclusion is that it has a large metallic core. If the core is a eutectic mixture of iron and iron sulfide, it comprises 20.2 ± 7.4 percent of the satellite's total mass with a radius that is about 52 percent of Io's mean radius of 1821.3 kilometers; if the core is pure iron, it comprises 10.5 ± 3.7 percent of the total mass with a radius of about 36 percent of the mean radius.
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References
1
ANDERSON J.D., EXPT GRAVITATION: 163 (1974).
2
ANDERSON J.D., JUPITER: 113 (1976).
3
ANDERSON J.D., GRAVITATION AND CELESTIAL MECHANICS INVESTIGATIONS WITH GALILEO, SPACE SCIENCE REVIEWS 60, 591 (1992).
4
BURNS J.A., SATELLITES (1986).
5
CAMPBELL J.K., GRAVITY-FIELD OF THE JOVIAN SYSTEM FROM PIONEER AND VOYAGER TRACKING DATA, ASTRONOMICAL JOURNAL 90, 364 (1985).
6
COHEN E.R., THE 1986 ADJUSTMENT OF THE FUNDAMENTAL PHYSICAL CONSTANTS, REVIEWS OF MODERN PHYSICS 59, 1121 (1987).
7
DAVIES M.E., CELESTIAL MECH 53, 377 (1992).
8
DERMOTT S.F., TIDAL DISSIPATION IN THE SOLID CORES OF THE MAJOR PLANETS, ICARUS 37, 310 (1979).
9
HOWARD H.T., GALILEO RADIO SCIENCE INVESTIGATIONS, SPACE SCIENCE REVIEWS 60, 565 (1992).
10
HUBBARD W.B., POSSIBLE FLYBY MEASUREMENTS OF GALILEAN SATELLITE INTERIOR STRUCTURE, ICARUS 33, 336 (1978).
11
JOHNSON T.V., SPACE SCIENCE REVIEWS VOLUME ON GALILEO MISSION OVERVIEW, SPACE SCIENCE REVIEWS 60, 3 (1992).
12
KAULA W.M., INTRO PLANETARY PHYS (1968).
13
KAULA W.M., THEORY SATELLITE GEO (1966).
14
MORRISON D, SATELLITES JUPITER (1982).
15
MOYER T.D., 321527 JET PROP LAB (1971).
16
NULL G.W., GRAVITY FIELD OF JUPITER AND ITS SATELLITES FROM PIONEER-10 AND PIONEER-11 TRACKING DATA, ASTRONOMICAL JOURNAL 81, 1153 (1976).
17
NULL G.W., GRAVITY FIELD OF JUPITER FROM PIONEER 11 TRACKING DATA, SCIENCE 188, 476 (1975).
18
SEGATZ M, TIDAL DISSIPATION, SURFACE HEAT-FLOW, AND FIGURE OF VISCOELASTIC MODELS OF IO, ICARUS 75, 187 (1988).
19
SEIDELMANN P.K., ASTRONOMICAL ALMAN S (1992).
20
TAPLEY B.D., RECENT ADV DYNAMICAL: 396 (1973).
21
WIENBRUCH M, PLANET SPACE SCI 43, 1045 (1995).
22
WOO R, SPACECRAFT RADIO SCATTERING OBSERVATIONS OF THE POWER SPECTRUM OF ELECTRON-DENSITY FLUCTUATIONS IN THE SOLAR-WIND, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS 84, 7288 (1979).
23
ZHARKOV V.N., MODELS, FIGURES, AND GRAVITATIONAL MOMENTS OF THE GALILEAN SATELLITES OF JUPITER AND ICY SATELLITES OF SATURN, ICARUS 61, 92 (1985).
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Science
Volume 272 | Issue 5262
3 May 1996
3 May 1996
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© 1996 American Association for the Advancement of Science.
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Published in print: 3 May 1996
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