Eberswalde (crater)

The Martian crater Eberswalde

Planet	Mars
Coordinates
Diameter	65.3 km
Depth	approx 800 m
Discoverer	Michael C. Malin and Ken Edgett
Eponym	Eberswalde, Brandenburg, Germany

Eberswalde, formerly known as Holden NE, is a partially buried impact crater in Margaritifer Terra, Mars. Eberswalde Crater lies just to the north of Holden Crater, a large crater that may have been a lake. 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. It was one of the final four proposed landing sites for the Mars rover Mars Science Laboratory mission. This extraterrestrial geological feature lies situated within the Margaritifer Sinus quadrangle (MC-19) region of Mars. It is currently considered a potential landing site for the Mars 2020 rover.

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

Mars Science Laboratory

Several sites in the Margaritifer Sinus quadrangle have been proposed as areas to send NASA's next major Mars rover, the Mars Science Laboratory (MSL). Eberswalde Crater was shortlisted as one of the final four proposed landing sites for the Curiosity rover, part of the MSL mission. It was voted a close second after Gale Crater by a team of scientists.

MRO discovered iron/magnesium smectites here. This mineral requires water to form.

Eberswalde Delta

The delta, seen by MGS

The crater contains inverted relief, an exhumed delta 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. Eberswalde delta has six lobes and is about 100 meters thick.

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. 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.

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.

See also

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

External links

• HiRISE image of Eberswalde Delta (warning: large images)
• MSSS page about the discovery
• [1] Lakes on Mars - Nathalie Cabrol (SETI Talks)