Bernard crater based on day-time THEMIS image
|Eponym||P. Bernard, a French atmospheric scientist|
Bernard Crater is a large crater in the Memnonia quadrangle of Mars, located at 23.6° south latitude and 154.3° west longitude. It is 131.0 km in diameter and was named after P. Bernard, a French atmospheric scientist. The floor of the crater contains large cracks, which may be due to erosion.
West side of Bernard Crater, as seen by CTX camera (on Mars Reconnaissance Orbiter).
Close-up of part of floor of Bernard Crater showing troughs and dust devil tracks, as seen by CTX camera (on Mars Reconnaissance Orbiter).
Troughs on the floor of Bernard Crater showing many boulders, as seen by HiRISE under HiWish program
Troughs on the floor of Bernard Crater, as seen by HiRISE under HiWish program
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Impact craters generally have a rim with ejecta around them, in contrast volcanic craters usually do not have a rim or ejecta deposits. As craters get larger (greater than 10 km in diameter) they usually have a central peak. The peak is caused by a rebound of the crater floor following the impact. If one measures the diameter of a crater, the original depth can be estimated with various ratios. Because of this relationship, researchers have found that many Martian craters contain a great deal of material; much of it is believed to be ice deposited when the climate was different. Sometimes craters expose layers that were buried. Rocks from deep underground are tossed onto the surface. Hence, craters can show us what lies deep under the surface.
Why are Craters important?
The density of impact craters is used to determine the surface ages of Mars and other solar system bodies. The older the surface, the more craters present. Crater shapes can reveal the presence of ground ice.
The area around craters may be rich in minerals. On Mars, heat from the impact melts ice in the ground. Water from the melting ice dissolves minerals, and then deposits them in cracks or faults that were produced with the impact. This process, called hydrothermal alteration, is a major way in which ore deposits are produced. The area around Martian craters may be rich in useful ores for the future colonization of Mars. Studies on the earth have documented that cracks are produced and that secondary minerals veins are deposited in the cracks. Images from satellites orbiting Mars have detected cracks near impact craters. Great amounts of heat are produced during impacts. The area around a large impact may take hundreds of thousands of years to cool. Many craters once contained lakes. Because some crater floors show deltas, we know that water had to be present for some time. Dozens of deltas have been spotted on Mars. Deltas form when sediment is washed in from a stream entering a quiet body of water. It takes a bit of time to form a delta, so the presence of a delta is exciting; it means water was there for a time, maybe for many years. Primitive organisms may have developed in such lakes; hence, some craters may be prime targets for the search for evidence of life on the Red Planet.
- Impact crater
- List of craters on Mars
- Water on Mars
- Climate of Mars
- Ore genesis
- Ore resources on Mars
- Hydrothermal circulation
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