Eberswalde (crater)

MarsGeo-Crater
name=Eberswalde crater
discoverer=Michael C. Malin and Ken Edgett
eponym=Eberswalde, Brandenburg, Germany
diameter=65.3 km
depth=approx 800 m


location=Margaritifer Terra
latitude = 24
N_or_S = S
longitude = 33
E_or_W =W

Eberswalde crater, formerly known as Holden NE crater, is a partially buried impact crater in Margaritifer Terra, Mars. The 65.3 km diameter crater, centered at 24°S, 33°W, is named after the German town of the same name, in accordance with the International Astronomical Union's rules for planetary nomenclature. [cite web|url=http://planetarynames.wr.usgs.gov/jsp/FeatureNameDetail.jsp?feature=61875|accessdate=2006-12-06|title=Gazetteer of Planetary Nomenclature] It is a proposed landing site for the future Mars rover, Mars Science Laboratory. [cite web|url=http://marsoweb.nas.nasa.gov/landingsites/msl/workshops/1st_workshop/abstracts/Schieber_1st_MSL_workshop.pdf|title=The Eberswalde deltaic complex as a high science-return target|accessdate=2006-12-06]

Landforms in the crater provide strong evidence of the prior existence of flowing water on Mars.

Eberswalde Delta

The crater contains a fossilized and exhumed delta which was formed by the flow of a liquid, most likely water. The series of valleys leading into the delta "drain" an area of approximately 4000 km². The surface area of the delta is 115 km², measuring 13 km by 11 km. The delta was discovered by Michael Malin and Kenneth Edgett of Malin Space Science Systems through imagery taken by the Mars Global Surveyor in 2003.

The delta also provides unambiguous evidence that some Martian sedimentary rocks have been deposited in a liquid. The meandering of the channels provides evidence to support this. Additional sediments were deposited on top of the delta, burying it. The deposits in the channels formed sedimentary rock. As the surrounding softer sediments were eroded away, the delta was exhumed, but inverted. [cite web|url=http://www.msss.com/mars_images/moc/2005/09/20/eberswalde|title=8 Years at Mars #6: Fossil Delta in Eberswalde Crater|accessdate=2006-12-06] [cite journal|title=Evidence for persistent flow and aqueous sedimentation on Mars|doi=10.1126/science.1090544|volume=302|author=Michael C. Malin|coauthors=Kenneth S Edgett|pages=1931–1934|journal=Science|year=2003]

Based on an estimate by Moore et. al in 2003 of flow volume to the crater at 700 m³/s, it is estimated that it would take twenty years to completely fill the crater, ignoring evaporation and infiltration. However, this is unlikely because it is hypothesized that the delta was not formed in a permanent lake but rather a series of short lacustrine episodes on the order of years. This suggests that the Martian climate at the Noachian epoch time of formation was characterized by a series of short, wet spells rather than a sustained wet climate. [cite journal|journal=Journal of Geophysical Research|author=Kevin W. Lewis|coauthors=Oded Aharonson|doi=10.1029/2005JE002558|volume=111|year=2006|title=Stratigraphic analysis of the distributary fan in Eberswalde crater using stereo imagery|pages=E06001] [cite journal|journal=Geophysical Research Letters|doi=10.1029/2003GL019002|title=Martian layered fluvial deposits: implications for Noachian climate scenarios|author=Jeffrey M. Moore|year=2003|volume=30|issue=24|coauthors=Alan D. Howard, William D. Dietrich, Paul M. Schenk|pages=E06001]

References

ee also

* Mars Science Laboratory
* Geography of Mars
* River delta - the terrestrial equivalent

External links

* [http://hirise.lpl.arizona.edu/PSP_001336_1560 HiRISE image of Eberswalde Delta] (warning: large images)
* [http://www.msss.com/mars_images/moc/2005/09/20/eberswalde MSSS page about the discovery]
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