Eberswalde Crater

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Location and name

Eberswalde is a crater in Margaritifer Sinus quadrangle. It used to be called Holden NE. Eberswalde Crater lies just to the north of Holden Crater which is a large crater that was a lake. Eberswalde Crater is 65.3-km in diameter, is centered at 24°S, 33°W, and is named after the town Eberswalde in Germany.[1]

Importance

Eberswalde was suggested as a landing site for both the Curiosity Rover (actually sent to Gale Crater) and for the Perseverance Rover (was sent to Jezero Crater). Eberswalde did not make the cut, but it will probably be considered for further exploration in the future.[2] [3] [4]

There is strong evidence that water once flowed in the crater. The Mars Reconnaissance Orbiter discovered iron/magnesium smectites here. Smectites are clay minerals. .[5] They can absorb water, as a result they shrink and swell depending on how much water they contain. [6] This mineral requires water to form.[7] Finding clay is significant because it forms in water with a pH close to neutral. This type of environment would support life, and clay can form well-preserved fossils.

Eberswalde Delta

The delta, seen by MGS

Of major interest to scientists is a river delta in the crater. Deltas form when water flows into a quiet body of water; hence, it is believed that Eberswalde once contained a large lake. A series of valleys leads up into the delta. Water may have come from an area (drainage basin) that was approximately 4000 square km. The delta itself has a surface area of 115 square km, and is 13 km by 11km. It was discovered by Mars Global Surveyor in 2003. It has six lobes each about 100 meters thick.[8]

So, it is thought that channels first picked up sediments from the surrounding land. They carried them along until they reached the quiet waters of the lake in the crater. The movement of the water slowed down when the water spread out in the lake. When this happens, water cannot continue to hold sediments and drops them. Eventually over time a delta develops. In the case of Eberswalde, the delta did not form at once but in a series of steps. The sediments were harder by cementing minerals. Later, some of the softer or less cemented material was eroded away. This, today we see much detail in the delta. Only the harder parts are visible.[9] [10] Some layers of the delta contain clay. Finding clay is significant because it forms in water with a pH close to neutral. This type of environment would support life, and clay can form well-preserved fossils.

Many craters once contained lakes.[11] [12] [13]

See also

References

  1. ↑ http://planetarynames.wr.usgs.gov/jsp/FeatureNameDetail.jsp?
  2. ↑ https://marsoweb.nas.nasa.gov/landingsites/msl/workshops/1st_workshop/abstracts/Schieber_1st_MSL_workshop.pdf
  3. ↑ https://marsoweb.nas.nasa.gov/landingsites/msl/workshops/1st_workshop/abstracts/Schieber_1st_MSL_workshop.pdf
  4. ↑ Hand, Eric (27 July 2011). "NASA picks Mars landing site". Nature. 475 (7357): 433.
  5. ↑ Grotzinger, J. and R. Milliken (eds.) 2012. Sedimentary Geology of Mars. SEPM
  6. ↑ https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/smectite
  7. ↑ 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.
  8. ↑ Lewis, K. and O. Aharonson. 2008. Geomorphic Aspects of the Eberswalde Delta and Potential MSL Traverses
  9. ↑ http://www.msss.com/mars_images/moc/2005/09/20/eberswalde
  10. ↑ Malin, M. and K. Edgett. 2003. Evidence for persistent flow and aqueous sedimentation on Mars. Science. 302. Volume 302. pages=1931–1934
  11. ↑ Cabrol, N. and E. Grin. 2001. The Evolution of Lacustrine Environments on Mars: Is Mars Only Hydrologically Dormant? Icarus: 149, 291-328.
  12. ↑ Fassett, C. and J. Head. 2008. Open-basin lakes on Mars: Distribution and implications for Noachian surface and subsurface hydrology. Icarus: 198, 37-56.
  13. ↑ Fassett, C. and J. Head. 2008. Open-basin lakes on Mars: Implications of valley network lakes for the nature of Noachian hydrology.

External links

  • [Pondrelli, M. 2010. Geological, geomorphological, facies and allostratigraphic maps of the Eberswalde fan delta. Planetary and Space Science. volume=59. issue=11–12. page=1166]
  • [Pondrelli, M. 2008. Evolution and depositional environments of the Eberswalde fan delta, Mars. Icarus. volume=197.]
  • [1] Lakes on Mars - Nathalie Cabrol (SETI Talks)
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