Arandas is a crater in the Mare Acidalium quadrangle of Mars, located 42.77° North and 15.17° West. It is 24.76 km (15.39 mi) in diameter and is named after the town of Arandas in Mexico.[1]
 Arandas crater, as seen by HiRISE. Click on image for a better view of North and South Walls, as well as central hills. Scale bar is 1000 meters long. | |
| Planet | Mars |
|---|---|
| Coordinates | 42°46′N 15°10′W / 42.77°N 15.17°W |
| Quadrangle | Mare Acidalium |
| Diameter | 24.76 km (15.39 mi) |
| Eponym | The town of Arandas in Mexico |
Gullies are visible in Arandas. On the basis of their form, aspects, positions, and ___location amongst an apparent interaction with features thought to be rich in water ice, many researchers believed that the processes carving the gullies involve liquid water. However, this remains a topic of active research. As soon as gullies were discovered,[2] researchers began to image many gullies over and over, looking for possible changes. By 2006, some changes were found.[3] Later, with further analysis it was determined that the changes could have occurred by dry granular flows rather than being driven by flowing water.[4][5][6] With continued observations many more changes were found in Gasa Crater and others.[7] As further observations have been made, still more changes have been noted; since the changes occur in the winter and spring, experts tend to believe that gullies were formed from dry ice. Before-and-after images demonstrated the timing of this activity coincided with seasonal carbon-dioxide frost and temperatures that would not have allowed for liquid water. When dry ice frost changes to a gas, it may lubricate dry material to flow, especially on steep slopes.[8][9][10]
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MOLA map showing Arandas crater and other nearby craters. Color indicates elevation. -
Arandas crater, as seen by CTX camera (on MRO). -
Gullies in Arandas, as seen by CTX camera. Note: this is an enlargement of the previous photo. -
Gullies in Arandas, as seen by HiRISE under HiWish program.
Impact craters generally have a rim with ejecta around them, in contrast volcanic craters usually do not have a rim or ejecta deposits. As craters get larger (greater than 10 km (6.2 mi) in diameter) they usually have a central peak.[11] The peak is caused by a rebound of the crater floor following the impact.[12] Sometimes craters expose layers that were buried. Rocks from deep underground are tossed onto the surface. Hence, craters can expose what lies deep under the surface.
See also
editReferences
edit- ^ "Arandas". planetarynames.wr.usgs.gov. International Astronomical Union. Retrieved 3 July 2015.
- ^ Malin, M., Edgett, K. 2000. "Evidence for recent groundwater seepage and surface runoff on Mars". Science 288, 2330–2335.
- ^ Malin, M., K. Edgett, L. Posiolova, S. McColley, E. Dobrea. 2006. "Present-day impact cratering rate and contemporary gully activity on Mars". Science 314, 1573_1577.
- ^ Kolb, et al. 2010. "Investigating gully flow emplacement mechanisms using apex slopes". Icarus 2008, 132-142.
- ^ McEwen, A. et al. 2007. "A closer look at water-related geological activity on Mars". Science 317, 1706-1708.
- ^ Pelletier, J., et al. 2008. "Recent bright gully deposits on Mars wet or dry flow?" Geology 36, 211-214.
- ^ NASA/Jet Propulsion Laboratory. "NASA orbiter finds new gully channel on Mars". Science Daily, 22 March 2014.
- ^ "NASA Spacecraft Observes Further Evidence of Dry Ice Gullies on Mars". Jet Propulsion Laboratory.
- ^ "Activity in Martian Gullies". HiRISE: High Resolution Imaging Science Experiment. The University of Arizona: Lunar and Planetary Laboratory. 10 July 2014. Retrieved 7 January 2021.
- ^ "Gullies on Mars Carved by Dry Ice, Not Water". Space.com. 16 July 2014.
- ^ "Stones, Wind, and Ice: A Guide to Martian Impact Craters".
- ^ Hugh H. Kieffer (1992). Mars. University of Arizona Press. ISBN 978-0-8165-1257-7. Retrieved 7 March 2011.
