Featured Images June 2013
(см. новую статью В.Р. Алексеева о криовулканизме Патомского нагорья на Земле)
Cryo-volcanic “Mount Doom” on Titan
Image and caption contributed by Rosaly Lopes, Jet Propulsion Laboratory, California Institute of Technology, California, USA, Randy Kirk, US Geological Survey, Astrogeology Science Center, Flagstaff, Arizona, USA and Mary Bourke, Geography, Trinity College, Dublin, Ireland.
Data from the Cassini mission have revealed that Titan is a planetary body where the interior, the surface, and atmospheric processes interact to create and modify landforms (Loppes et al, 2010). In terms of recent surface processes, Titan is one of the most earth-like bodies in our solar system. Landforms include the largest area of aeolian dunefields in our solar system (e.g., Radebaugh et al., 2008), lakes (e.g., Stofan et al., 2006), fluvial channels (e.g., Langhans et al., 2012), mountains (e.g., Radebaugh et al., 2007), and features that have been interpreted as volcanic (e.g., Lopes et al., 2007).
Image 1: The RADAR (SAR) images in black and white over a false-color mosaic of VIMS data. The globe at upper left shows the location of the map on Titan (arrow). The white lines show the approximate boundaries of the perspective view in Image 2.
Images from the SAR swaths in the T25 and T28 flybys show a region which is bright at radar wavelengths, except for the dune field that appear as linear, radar-dark features in the middle of the image (Image 1). At the top of the image is a mountain, Erebor Mons, interpreted to be cryovolcanic in origin. SAR data from these two flybys were used to produce the DEM (Image 2). The region near bottom center of the map, formerly known as Sotra Facula (centered at 39.8W, 12.5 S) was thus named because it appears bright at visible wavelengths.
Image 2: A perspective view looking at Doom Mons and Sotra Patera from the north-northeast This Cassini image is a combination of RADAR data (SAR images and a Digital Topographic Model or DTM produced from two SAR swaths) and VIMS data showing compositional differences in false color. The DEM data has a vertical exaggeration of 10:1. A movie showing the whole region can be seen at: http://photojournal.jpl.nasa.gov/catalog/PIA13695
One of the tallest peaks on Titan, Doom Mons, is ~70 km in diameter and 1.45 +/- 0.2 km high. It lies adjacent to the deepest depression so far found on Titan, Sotra Patera, which is an elongated pit ~30 km in diameter and 1.7 +/-0.2 km deep. These features, and the surrounding flow-like features around them (Mohini Fluctus), have been interpreted as cryovolcanic features(Lopes et al, 2013). Volcanism that occurs on the outer solar system’s satellites, sometimes known as cryovolcanism, includes the eruption of water-melts from the interiors of icy satellites onto their surfaces. (Kargel, 1995) (see also December 2008Image of the Month). In Image 2 Doom Mons and Sotra Patera are shown in a false colour composition map derived from VIMS data where shades of green and yellow indicate the candidate cryovolcanic materials and the dune fields are in shades of blue signifying a different composition.
The topography of cryo-volcanic features is of great importance for understanding the rheology and, by inference, the chemical composition, of cryomagmas on Titan. Therefore, accurate topographical measurements of cryo-volcanic regions will be a focus of future investigations. Cryo-volcanism may be an important resurfacing mechanism on Titan and present-day cryo-volcanic activity is feasible, though it has not been observed.
Kargel, J. S. (1995), Cryovolcanism on the icy satellites, Earth Moon Planets, 67, 101–113
Lopes, R.M.C., et al. 2007. Cryovolcanic features on Titan’s surface as revealed by the Cassini Titan Radar Mapper. Icarus186, 395-412.
Lopes, R.M.C., et al., (2010). Distribution and Interplay of Geologic Processes on Titan from Cassini RADAR Data. Icarus, 205, 540-588, doi:10.1016/j.icarus.2009.08.010
Lopes, R.M.C., et al. (2013) Cryovolcanism on Titan: New results from Cassini RADAR and VIMS. Journal of Geophysical Research (Planets), vol. 118, 1-20, doi:10.1002/jgre.20062.
Radebaugh, J., et al., (2008). Dunes on Titan observed by Cassini Radar. Icarus, 194(2), 690-703.
Radebaugh, J., et al., (2007) Mountains on Titan observed by Cassini Radar. Icarus, 192(1), 77-91.
Stofan, E.R., et al, (2007). The lakes of Titan. Nature, 445(7123), 61-64.
Langhans, M.H., et al (2012) Titan's fluvial valleys: Morphology, distribution, and spectral properties. Planetary and Space Science, 60(1), 34-51.
Comments to Dr. Mary Bourke