DPS 2001 meeting, November 2001
Session 5. Cassini and Galileo at Jupiter II
Oral, Chairs: R. Lopes, A. Simon-Miller, Tuesday, November 27, 2001, 2:00-3:20pm, Regency E

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[5.06] Io's Active Volcanism: New Results from Galileo's Near-Infrared Mapping Spectrometer (NIMS)

R.M.C. Lopes, L.W. Kamp (Jet Propulsion Laboratory/Caltech), S. Doute' (Laboratoire de Planetologie de Grenoble, France), R.W. Carlson, W.D. Smythe (Jet Propulsion Laboratory/Caltech), Galileo NIMS Team

The Galileo spacecraft made its fifth close fly-by of Io on August 6, 2001 (orbit I31). Observations by NIMS showed numerous active volcanic regions and significant changes since the spacecraft's earlier encounters with Io in 1999 and 2000. The spectral range of NIMS (0.7 to 5.2 microns) allows the instrument to map the thermal emission from Io's volcanic regions, and the surface distribution of SO2 and of other compounds. This paper focuses on thermal mapping (see Doute' et al, this volume, for spectral analysis). During I31, NIMS mapped part of Io's anti-Jovian hemisphere, from north to south pole, at spatial resolution ranging from 22 to 34 km/NIMS pixel. This observation revealed a bright eruption from about (41N, 136 W), a location not known to be active previously. This eruption may have included a plume (A. McEwen, pers.comm.). Numerous previously undetected hot spots are seen in this observation, mostly concentrated at low and mid-latitudes. A bright eruption detected during orbit C30 (May 2001) from a previously undetected hot spot (49 S, 71W) is still underway. Higher spatial resolution observations (<20 km/NIMS pixel) allow us to assess small-scale changes at several active volcanic centers, some of which were also targeted during the earlier Io fly-bys. We will present results on the thermal structure of individual volcanic centers, including Tvashtar, Amirani/Maui, Prometheus, Pele, Isum, and Gish Bar. Observations obtained during the fly-bys show that the structure of these hot spots is more complex than thought from distant observations and that hot spots are often made up of more than one volcanic center. Galileo will fly close to Io's surface again on October 16, 2001 (I32) and several regions will be targeted that have not yet been observed at high spatial resolution. We expect to also present some initial results from this later orbit.

The author(s) of this abstract have provided an email address for comments about the abstract: rlopes@lively.jpl.nasa.gov

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