Note to users. If you're seeing this message, it means that your browser cannot find this page's style/presentation instructions -- or possibly that you are using a browser that does not support current Web standards. Find out more about why this message is appearing, and what you can do to make your experience of our site the best it can be.

Science 27 May 2005:
Vol. 308. no. 5726, pp. 1291 - 1293
DOI: 10.1126/science.1110422
Prev | Table of Contents | Next

Reports

Amalthea's Density Is Less Than That of Water

John D. Anderson,1* Torrence V. Johnson,1 Gerald Schubert,2,3 Sami Asmar,1 Robert A. Jacobson,1 Douglas Johnston,1 Eunice L. Lau,1 George Lewis,1 William B. Moore,2 Anthony Taylor,1{dagger} Peter C. Thomas,4 Gudrun Weinwurm5{ddagger}

Radio Doppler data from the Galileo spacecraft's encounter with Amalthea, one of Jupiter's small inner moons, on 5 November 2002 yield a mass of (2.08 ± 0.15) x 1018 kilograms. Images of Amalthea from two Voyager spacecraft in 1979 and Galileo imaging between November 1996 and June 1997 yield a volume of (2.43 ± 0.22) x 106 cubic kilometers. The satellite thus has a density of 857 ± 99 kilograms per cubic meter. We suggest that Amalthea is porous and composed of water ice, as well as rocky material, and thus formed in a cold region of the solar system, possibly not at its present location near Jupiter.

1 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099, USA.
2 Department of Earth and Space Sciences, University of California, Los Angeles, CA 90095-1567, USA.
3 Institute of Geophysics and Planetary Physics, Los Angeles, CA 90095-1567, USA.
4 Center for Radio Physics and Space Research, Cornell University, Ithaca, NY 14853-4901, USA.
5 Institute of Geodesy and Geophysics, Vienna University of Technology, A-1040 Vienna, Austria.

{dagger} Present address: Kinetx, Inc. Space Navigation and Flight Dynamics, 21 West Easy Street, Suite 108, Simi Valley, CA 93065-1694, USA.

{ddagger} Present address: Austrian Research Centers, Seibersdorf Research GmbH, 2444 Seibersdorf, Austria.

* To whom correspondence should be addressed. E-mail: john.d.anderson{at}jpl.nasa.gov

Read the Full Text


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Oxygen and Other Volatiles in the Giant Planets and their Satellites.
M. H. Wong, J. I. Lunine, S. K. Atreya, T. Johnson, P. R. Mahaffy, T. C. Owen, and T. Encrenaz (2008)
Reviews in Mineralogy and Geochemistry 68, 219-246
   Abstract »    Full Text »    PDF »


To Advertise     Find Products

Science. ISSN 0036-8075 (print), 1095-9203 (online)