Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
, 277 (5324), 355-8

The Ionosphere of Europa From Galileo Radio Occultations

Affiliations

The Ionosphere of Europa From Galileo Radio Occultations

A J Kliore et al. Science.

Abstract

The Galileo spacecraft performed six radio occultation observations of Jupiter's Galilean satellite Europa during its tour of the jovian system. In five of the six instances, these occultations revealed the presence of a tenuous ionosphere on Europa, with an average maximum electron density of nearly 10(4) per cubic centimeter near the surface and a plasma scale height of about 240 +/- 40 kilometers from the surface to 300 kilometers and of 440 +/- 60 kilometers above 300 kilometers. Such an ionosphere could be produced by solar photoionization and jovian magnetospheric particle impact in an atmosphere having a surface density of about 10(8) electrons per cubic centimeter. If this atmosphere is composed primarily of O2, then the principal ion is O2+ and the neutral atmosphere temperature implied by the 240-kilometer scale height is about 600 kelvin. If it is composed of H2O, the principal ion is H3O+ and the neutral temperature is about 340 kelvin. In either case, these temperatures are much higher than those observed on Europa's surface, and an external heating source from the jovian magnetosphere is required.

Similar articles

  • Detection of an Oxygen Atmosphere on Jupiter's Moon Europa
    DT Hall et al. Nature 373 (6516), 677-81. PMID 7854447.
    Europa, the second large satellite out from Jupiter, is roughly the size of Earth's Moon, but unlike the Moon, it has water ice on its surface. There have been suggestion …
  • Europa's Magnetic Signature: Report From Galileo's Pass on 19 December 1996
    MG Kivelson et al. Science 276 (5316), 1239-41. PMID 9157878.
    On 19 December 1996 as Galileo passed close to Jupiter's moon, Europa, the magnetometer measured substantial departures from the slowly varying background field of Jupite …
  • A Tenuous Carbon Dioxide Atmosphere on Jupiter's Moon Callisto
    RW Carlson. Science 283 (5403), 820-1. PMID 9933159.
    An off-limb scan of Callisto was conducted by the Galileo near-infrared mapping spectrometer to search for a carbon dioxide atmosphere. Airglow in the carbon dioxide nu3 …
  • The Galilean Satellites
    AP Showman et al. Science 286 (5437), 77-84. PMID 10506564. - Review
    NASA's Galileo mission to Jupiter and improved Earth-based observing capabilities have allowed major advances in our understanding of Jupiter's moons Io, Europa, Ganymede …
  • Saturn: Atmosphere, Ionosphere, and Magnetosphere
    TI Gombosi et al. Science 327 (5972), 1476-9. PMID 20299587. - Review
    The Cassini spacecraft has been in orbit around Saturn since 30 June 2004, yielding a wealth of data about the Saturn system. This review focuses on the atmosphere and ma …
See all similar articles

Cited by 1 PubMed Central articles

Publication types

LinkOut - more resources

Feedback