Mawrth Vallis

Mawrth Vallis

Mawrth Vallis, as seen by THEMIS.
Coordinates	22°36′N 16°30′W / 22.6°N 16.5°WCoordinates: 22°36′N 16°30′W / 22.6°N 16.5°W
Length	636.0 km
Naming	Welsh word for "Mars".

Mawrth Vallis (Welsh: [maurθ]) (Mawrth means "Mars" in Welsh) is a valley on Mars in the Oxia Palus quadrangle at 22.3°N, 343.5°E with an elevation approximately two kilometers below datum. It is an ancient water outflow channel with light-colored clay-rich rocks.

Mawrth Vallis is one of the oldest valleys on Mars. It was formed in and subsequently covered by layered rocks, from beneath which it is now being exhumed.^[1]

The Mawrth Vallis region holds special interest because of the presence of phyllosilicate (clay) minerals which form only if water is available, first identified in data from the OMEGA spectrometer on the European Space Agency's Mars Express orbiter. Mars Reconnaissance Orbiter's Compact Reconnaissance Imaging Spectrometer for Mars has identified aluminium-rich and iron-rich clays, each with a unique distribution. Some of the clays recently discovered by the Mars Reconnaissance Orbiter are montmorillonite and kaolinite, and nontronite.^[2] Since some clays seem to drape over high and low areas, it is possible that volcanic ash landed in an open body of water.^[3] On Earth such clays occur in (among other environments) weathered volcanic rocks and hydrothermal systems, where volcanic activity and water interact.^[4] Mawrth Vallis was at one point considered as a landing site for the Mars Science Laboratory, which ultimately landed at Gale Crater.^[5] Clay minerals easily preserve microscopic life on Earth, so perhaps traces of ancient life may be found at Mawrth.^[6] It is considered a potential landing site for the Mars 2020 rover.^[7]

The region is well studied with more than 40 papers published in peer-reviewed publications. Near the Mawrth channel is a 200 meter high plateau with many exposed layers. Spectral studies have detected clay minerals that present as a sequence of layers.^{[8][9][10][11][12][13][14][15][16][17][18]} Clay minerals were probably deposited in the Early to Middle Noachian period. Later weathering exposed a variety of minerals such as kaolin, alunite, and jarosite. Later, volcanic matterial covered the region. This volcanic material would have protected any possible organic materials from radiation.^[19]

MSL landing site candidate

Mawrth Vallis was one of seven finalists for the MSL landing site:^[20]

• Eberswalde Crater
• Gale Crater
• Holden Crater
• Mawrth Vallis
• Miyamoto Crater
• Nili Fossae Trough
• Southern Meridiani

References

1. NASA - Layered Rocks Near Mawrth Vallis
2. Murchie, S. et al. 2009. A synthesis of Martian aqueous mineralogy after 1 Mars year of observations from the Mars Reconnaissance Orbiter. Journal of Geophysical Research: 114.
3. Bishop, J. et al. 2008. Phyllosilicate Diversity and Past Aqueous Activity Revealed at Mawrth Vallis, Mars. Science. 321:830-833.
4. Catalog Page for PIA01921
5. http://marsoweb.nas.nasa.gov/landingsites/
6. Feature Image: Mawrth Vallis. Mars Odyssey Mission THEMIS.
7. Gross, C., et al. 2016. MAWRTH VALLIS – PROPOSED LANDING SITE FOR EXOMARS 2018/2020. 47th Lunar and Planetary Science Conference (2016) 1421.pdf.
8. Poulet et al. 2005. Nature 438, 623–627.
9. Loizeau et al. 2007. JGR 112, E08S08
10. ] Bishop et al. 2008. Science 321, 830.
11. Noe Dobrea et al. 2010. JGR 115, E00D19
12. Michalski, Noe Dobrea. 2007. Geol. 35, 10.
13. Loizeau et al. 2010. Icarus 205, 396-418.
14. Farrand et al. 2009. Icarus 204, 478- 488.
15. Wray et al. 2010. Icarus 209, 416-421
16. Bishop et al. 2013. PSS 86, 130-149.
17. ] Michalski et al. 2013. Icarus 226, 816-840.
18. Michalski et al. 2010. Astrobio. 10, 687-703.
19. Gross, C. et al. 2016. MAWRTH VALLIS – PROPOSED LANDING SITE FOR EXOMARS 2018/2020. 47th Lunar and Planetary Science Conference (2016) 1421.pdf

External links

• Clay Minerals in Mawrth Vallis Region of Mars