Titan’s labyrinth terrain

Post contributed by Michael J. Malaska, PhD, Scientist, Jet Propulsion Laboratory / California Institute of Technology, USA.

Saturn’s moon Titan is where organic chemistry and surface geomorphology intersect to create an enigmatic landscape with many features in common with Earth, but that are made of completely different materials. Much of Titan’s surface is made up of organic sedimentary materials; recent mapping shows that plains and dunes cover over 80 percent of the globe. The Cassini spacecraft’s Synthetic Aperture Radar (SAR) was able to penetrate Titan’s thick haze and reveal areas of highly dissected plateaux on the surface that are called labyrinth terrain. Image 1 shows an SAR image of an example of this type of terrain, the Sikun Labyrinth. Detailed examination of Titan’s labyrinth terrain can tell us a lot about Titan’s geological history and surface evolution.

Image 1. Top: Image of the Sikun Labyrinth in the south polar terrain of Titan. The blue arrow and number at top left indicates direction of radar illumination and incidence angle for this scene. Bottom: diagram showing how radar illumination interacts with terrain of valleys and plateaux. Image credit: Mike Malaska.

Pit chains on Enceladus

Post contributed by Dr. Emily S. Martin, Research Fellow, Center for Earth and Planetary Studies, National Air & Space Museum, Smithsonian Institution.

Pit chains are linear assemblages of circular to elliptical pits and have been observed across the solar system. Pit chains have been found on Venus, Earth, Mars, Phobos, Eros, Gaspra, Ida, and Vesta. Across the solar system, pit chains may form through a variety of mechanisms including the collapse of lava tubes, karst, venting, extensional fracturing, or dilational faulting. Saturn’s tiny icy moon Enceladus is the first body of the outer solar system on which pit chains have been identified. Enceladus is only 500 km in diameter and is best known for its warm south pole and its watery plume emanating from prominent ridges known as tiger stripes. The source of the plume is likely a global liquid water ocean beneath an icy shell.


Image 1: The morphology of pit chains across the solar system. a. Eros from NEAR. Image no. 135344864. b. Phobos. Image PIA10367. c. Albalonga Catena, Vesta. d. Venus. Right-look Magellan data near 13°S, 112°E. e. Kilauea Volcano, Hawaii centered at 19.3909°N 155.3076°W. Image taken 12/06/2014, acquired from Google Earth on 04/20/2016. f. Ida, modified from image PIA00332. g. Gaspra, modified from Galileo image PIA00332. h. Pit chains in north-eastern Iceland centered near 65.9902°N and 16.5301°W. Image taken on 7/27/2012, acquired from Google Earth 04/20/2016. i. Pit chains on Mars from the Mars Global Surveyor Mars Orbiter Camera, centered near 6.5398°S and 119.9703°W on the flank of Arsia Mons. Image PIA02874.


Unexpected variety among small inner satellites of Saturn

Post by Peter Thomas, Cornell University, Ithaca, New York

 Small satellites (< 150 km mean radius) usually resemble potatoes. Their irregular shapes are formed by a history of impact cratering without the benefit of internally-driven processes of volcanism, tectonics, or atmospheric effects (Castillo-Rogez et al., 2012).  During its 9 years orbiting Saturn, the Cassini spacecraft has shown that the small satellites orbiting close to Saturn have a variety of shapes, most of which deviate from the expected familiar battered potato appearance.  These objects are likely dominated by water ice as determined from mean densities and spectroscopy (Thomas et al., 2010; Buratti et al. 2010).  Satellites within rings have equatorial ridges (Charnoz et al. 2007; Porco et al., 2007).  Others, such as Janus and Epimetheus, the “co-orbitals” are almost lunar-like in appearance, close to the expected potato variety.

Image 1: Best available view of Helene. N1687119756, UV3 filter, phase = 97°, sub-spacecraft point is 2.7°N, 124.8°W.  North is down in this presentation.  Taken June 18, 2011.

Image 1: Best available view of Helene. N1687119756, UV3 filter, phase = 97°, sub-spacecraft point is 2.7°N, 124.8°W. North is down in this presentation. Taken June 18, 2011.


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