Aeolis quadrangle

The Aeolis quadrangle is one of a series of 30 quadrangle maps of Mars used by the United States Geological Survey (USGS) Astrogeology Research Program. The Aeolis quadrangle is also referred to as MC-23 (Mars Chart-23).[1]

The Aeolis quadrangle covers 180° to 225° W and 0° to 30° south on Mars. It is famous because the Spirit Rover landed there (14.5718° S and 175.4785° E) on January 4, 2004 and drove around the area in Gusev crater snapping photos and analyzing rocks.

Apollo Hills panorama from the Spirit landing site

Contents

Ma'adim Vallis

A large, ancient river valley, called Ma'adim Vallis, enters at the south rim of Gusev Crater, so Gusev Crater was believed to be an ancient lake bed. However, it seems that a volcanic flow covered up the lakebed sediments.[2] Apollinaris Patera, a large volcano, lies directly north of Gusev Crater.[3]

Recent studies lead scientists to believe that the water that formed Ma'adim Vallis originated in a complex of lakes. When the largest lake spilled over the low point in its boundary, a torrential flood would have moved north, carving the sinuous Ma'adim Vallis. At the north end of Ma'adim Vallis, the flood waters would have run into Gusev Crater.[4]

Gale Crater

Gale Crater, in the northwestern part of the Aeolis quadrangle, is of special interest to geologists because it contains a 2–4 km (1.2-2.5 mile) high mound of layered sedimentary rocks. The mound extends higher than the rim of the crater, so perhaps the layering covered an area much larger than the crater.[5] These layers are a complex record of the past. The rock layers probably took millions of years to be laid down within the crater, then more time to be eroded to make them visible.[6] There is evidence that the first phase of erosion was followed by more cratering and more rock formation.[7]

Other Craters

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 in diameter) they usually have a central peak.[8] The peak is caused by a rebound of the crater floor following the impact.[9] Sometimes craters will display layers. Since the collision that produces a crater is like a powerful explosion, rocks from deep underground are tossed unto the surface. Hence, craters can show us what lies deep under the surface.

Mars Science Laboratory

The aim of the Mars Science Laboratory is to search for signs of ancient life. It is hoped that a later mission could then return samples that the laboratory identified as probably containing remains of life. To safely bring the craft down, a 12 mile wide, smooth, flat circle is needed. Geologists hope to examine places where water once ponded.[10] They would like to examine sediment layers. Gale Crater is among the top four sites for the next major Mars rover, the Mars Science Lab.[11][12]

Inverted Relief

Some places on Mars show inverted relief. In these locations, a stream bed may be a raised feature, instead of a valley. The inverted former stream channels may be caused by the deposition of large rocks or due to cementation. In either case erosion would erode the surrounding land but leave the old channel as a raised ridge because the ridge will be more resistant to erosion. An image below, taken with HiRISE shows sinuous ridges that may be old channels that have become inverted.[13]

Yardangs

Yardangs are common on Mars. They are generally visible as a series of parallel linear ridges. Their parallel nature is thought to be caused by the direction of the prevailing wind. Two HiRISE images below show a good view of yardangs in the Aeolis quadrangle.[13] Yardangs are common in the Medusae Fossae Formation on Mars.

Gallery

See also

References

  1. ^ Davies, M.E.; Batson, R.M.; Wu, S.S.C. “Geodesy and Cartography” in Kieffer, H.H.; Jakosky, B.M.; Snyder, C.W.; Matthews, M.S., Eds. Mars. University of Arizona Press: Tucson, 1992.
  2. ^ http://www.msnbc.msn.com/id/6785665/
  3. ^ U.S. department of the Interior U.S. Geological Survey, Topographic Map of the Easern Region of Mars M 15M 0/270 2AT, 1991
  4. ^ http://antwrp.gsfc.nasa.gov/apod/ap020627.html
  5. ^ http://hirise.lpl.arizona.edu/PSP_008437_1750
  6. ^ http://mars.jpl.nasa.gov/mgs/msss/camera/images/dec00_seds/slides/265L/
  7. ^ http://www.msss.com/mars_images/moc/dec00_seds/slides/265E
  8. ^ http://www.lpi.usra.edu/publications/slidesets/stones/
  9. ^ Hugh H. Kieffer (1992). Mars. University of Arizona Press. ISBN 9780816512577. http://books.google.com/books?id=NoDvAAAAMAAJ. Retrieved 7 March 2011. 
  10. ^ http://themis.asu.edu/features/ianichaos
  11. ^ http://dsc.discovery.com/news/2008/11/21/mars-landing-sites-02.html
  12. ^ http://www.space.com/missionlaunches/mars-science-laboratory-curiosity-landing-sites-100615.htm
  13. ^ a b http://hiroc.lpl.arizona.edu/images/PSP/diafotizo.php?ID=PSP_002279_1735