Photometric changes on Saturn's Titan: Evidence for active cryovolcanism

Abstract

We report infrared spectrophotometric variability on the surface of Saturn's moon Titan detected in images returned by the Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini Saturn Orbiter. The changes were observed at 7°S, 138°W and occurred between October 27, 2005 and January 15, 2006. After that date the surface was unchanged until the most recent observation, March 18, 2006. We previously reported spectrophotometric variability at another location (26°S, 78°W). Cassini Synthetic Aperture RADAR (SAR) images find that the surface morphology at both locations is consistent with surface flows possibly resulting from cryovolcanic activity (Wall et al., companion paper, this issue). The VIMS‐reported time variability and SAR morphology results suggest that Titan currently exhibits intermittent surface changes consistent with present ongoing surface processes. We suggest that these processes involve material from Titan's interior being extruded or effused and deposited on the surface, as might be expected from cryovolcanism.

Distribution and interplay of geologic processes on Titan from Cassini radar data

“…Recent SAR images from T41 and T43 (Wall et al, 2009) showed possible cryovolcanic flows in the Hotei Regio region. Candidate flows that appear similar to Hotei's are seen in SAR data located on the western part of Xanadu, coinciding with a second region where photometric changes have been reported (Wall et al, 2009;Nelson et al, 2009b).…”

“…Ganesa Macula and the various cryoflows mapped overlie the featureless plains (here the undifferentiated plains unit) discussed by Stofan et al (2006). There are no examples of cryovolcanic units having contact with hummocky and mountainous terrains or mottled plains in the current data, except for a possible small cryovolcanic region on the western part of Xanadu (discussed by Wall et al, 2009 andNelson et al, 2009b). The clearest interaction between a cryovolcanic unit and another unit is in the Winia Fluctus area (Fig.…”

“…Nelson et al (2009a) noted spectral changes in the area around Hotei Regio, an arc-like feature that is bright at visible wavelengths and is unusually bright at 5 lm (Barnes et al, 2005). Spectral changes were also observed by Nelson et al (2009b) over the western part of Xanadu that may also indicate ongoing changes. Patches of what may be CO 2 ice have been identified in VIMS spectra of Tui and Hotei Regio (Hayne et al, 2008).…”

Regional geomorphology and history of Titan’s Xanadu province

“…In addition, an area at the west end of Xanadu, in the Western Eroded Plateaus (Fig. 3a), is the location of a purported VIMS photometrically variable region (Nelson et al, 2009b). It also has similar morphologies to the lobate flows seen in Hotei and Tui Regios and has been postulated to be the location of other, possibly recent volcanism (Wall et al, 2009).…”

Geomorphologic mapping of the Menrva region of Titan using Cassini RADAR data

“…The Cassini spacecraft has revealed the surface of Titan in great detail, and studies by the Cassini science team are being done to identify the processes that formed and continue to shape Titan's surface (e.g., Barnes et al, 2005Barnes et al, , 2007aBarnes et al, ,b, 2008Brown et al, 2008;Elachi et al, 2005Elachi et al, , 2006Lunine et al, 2008;McCord et al, 2008;Porco et al, 2005;Lorenz and Radebaugh, 2009;Nelson et al, 2009;Lopes et al, 2010;Wood et al, 2010). In particular, the Cassini RADAR experiment (Elachi et al, 2004) has provided detail on surface morphology over regional scales (tens to hundreds of kilometers), enabling the recognition of surface features produced by specific geologic processes.…”