Eberswalde, formerly known as Holden NE, is a partially buried

impact crater An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact crater ...

in Margaritifer Terra,

Mars Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, only being larger than Mercury. In the English language, Mars is named for the Roman god of war. Mars is a terrestrial planet with a thin at ...

. Eberswalde crater lies just to the north of Holden, 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 The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...

's rules for

planetary nomenclature Planetary nomenclature, like terrestrial nomenclature, is a system of uniquely identifying features on the surface of a planet or natural satellite so that the features can be easily located, described, and discussed. Since the invention of the tel ...

. It was one of the final four proposed landing sites for the Mars rover

Mars Science Laboratory Mars Science Laboratory (MSL) is a robotic space probe mission to Mars launched by NASA on November 26, 2011, which successfully landed ''Curiosity'', a Mars rover, in Gale Crater on August 6, 2012. The overall objectives include investigati ...

mission. This extraterrestrial geological feature lies situated within the Margaritifer Sinus quadrangle (MC-19) region of Mars. Although not chosen, it was considered a potential landing site for the

Mars 2020 Mars 2020 is a Mars rover mission forming part of NASA's Mars Exploration Program that includes the rover '' Perseverance'', the small robotic, coaxial helicopter '' Ingenuity'', and associated delivery vehicles. Mars 2020 was launched from ...

''Perseverance'' rover, and in the second Mars 2020 Landing Site Workshop it survived the cut and was among the top eight sites still in the running. 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 major Mars rover, the Mars Science Laboratory (MSL). Eberswalde 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 A gale is a strong wind; the word is typically used as a descriptor in nautical contexts. The U.S. National Weather Service defines a gale as sustained surface winds moving at a speed of between 34 and 47 knots (, or ).MRO discovered iron/magnesium smectites here. This mineral requires water to form.

Eberswalde Delta

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 from images acquired by the

Mars Global Surveyor ''Mars Global Surveyor'' (MGS) was an American robotic space probe developed by NASA's Jet Propulsion Laboratory and launched November 1996. MGS was a global mapping mission that examined the entire planet, from the ionosphere down through t ...

in 2003, operated Malin Space Science Systems. 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. Many craters once contained lakes. The delta in Eberswalde Crater is strong evidence that a lake once existed here.

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 A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much larger ...

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.

References

External links

HiRISE image of Eberswalde Delta
(warning: large images)
MSSS page about the discovery
* * * *

Lakes on Mars - Nathalie Cabrol (SETI Talks) {{Portal bar, Solar System Impact craters on Mars River deltas Mars 2020 Margaritifer Sinus quadrangle

Mars Science Laboratory

Eberswalde Delta

See also

References

External links