HR: 1400h
AN: P33A-04    [Abstracts]
TI: High-Resolution Observations of Enceladus' Endogenic Thermal Radiation in 2008
AU: * Spencer, J
EM: spencer@boulder.swri.edu
AF: Southwest Research Institute, 1050 Walnut St., Suite 300, Boulder, CO 80302, United States
AU: Howett, C
EM: carly@boulder.swri.edu
AF: Southwest Research Institute, 1050 Walnut St., Suite 300, Boulder, CO 80302, United States
AU: Pearl, J
EM: John.C.Pearl@nasa.gov
AF: NASA-Goddard Spaceflight Center, Code 693, Greenbelt, MD 20771, United States
AU: Segura, M
EM: marcia.segura@gsfc.nasa.gov
AF: NASA-Goddard Spaceflight Center, Code 693, Greenbelt, MD 20771, United States
AU: Cassini CIRS Team,
EM: John.C.Pearl@nasa.gov
AB: Cassini's four close flybys of Enceladus in 2008 provided unprecedented views of the active "tiger stripe" fractures in the moon's south polar region. The Composite Infrared Spectrometer (CIRS) instrument obtained spectral maps of the endogenic thermal emission from the tiger stripes at wavelengths from 7 to 1000 microns, with spatial resolution of up to 1 km. Observations of the short-wavelength radiation (7--16 μm) confirmed that the tiger stripe fractures are warm along their entire lengths, with large amplitude but smooth flux variations along strike. Surface temperatures as high as 167 K were seen in the most thermally active part of the tiger stripe Damascus Sulcus, near the source of two of the plume dust jets. Low spatial resolution observations constrain the time variability of the thermal emission over timescales of several years. Longer-wavelength observations (16--1000 μm) constrain the total heat flow from the south polar region. Our current best estimates of the total heat flow are 13.6 ± 1.4 GW, from observations in March 2008, and 17.5 ^+2.1_-1.9 GW, from observations in October 2008. These values are based on direct observations of the radiated power, and are more reliable than the ∼ 6 GW published previously (Spencer et al. 2006, Science 311, 1401), which was inferred from extrapolation of short-wavelength data. The observed heat flow is an order of magnitude higher than predictions of steady-state tidal heating models (Meyer and Wisdom 2007, Icarus 188, 353).
DE: 5418 Heat flow
DE: 5462 Polar regions
DE: 5475 Tectonics (8149)
DE: 5480 Volcanism (6063, 8148, 8450)
DE: 6280 Saturnian satellites
SC: Planetary Sciences [P]
MN: 2009 Joint Assembly