Mars is scarred by a number of impact craters: a total of 43,000 craters with a diameter of or greater have been found. The largest confirmed of these is the Hellas impact basin, a light albedo feature clearly visible from Earth. Due to the smaller mass and size of Mars, the probability of an object colliding with the planet is about half that of Earth. Mars is located closer to the asteroid belt, so it has an increased chance of being struck by materials from that source. Mars is more likely to be struck by short-period comets, "i.e.", those that lie within the orbit of Jupiter.
Impact topography
Mars
Mars | Impact topography
Yes, Hellas impact basin Hellas impact basin Hellas impact basin. Yes, "Hellas impact basin" is one of them.
what is the location of mars in the solar system
user
Mars is the fourth planet from the Sun
assistant
is it known by any other names?
user
Yes, "Red Planet" in English
assistant
are there any volcanoes there?
user
Yes, Olympus Mons
assistant
who named it?
user
Named after observations made by Mariner 9
assistant
what was that?
user
From Nix Olympica; a volcano. Astronomers adopted the name "Olympus Mons" for the albedo feature known as Nix Olympica
assistant
was that a spaceship that made the observations?
user
It was a robotic space probe
assistant
have any other space probes landed on the planet discussed above?
user
Yes, "Mariner 4", "Viking 1", etc
assistant
did the first one land on the planet or was it just a fly by?
user
A flyby mode
assistant
how did it meet its end?
user
The gas supply in the attitude control system was exhausted, and between December 10 and 11, a total of 83 micrometeoroid hits perturbation of the spacecraft's attitude and degradation of the signal strength
assistant
what is found at the polar regions of the planet?
user
The caps at both poles consist primarily (70%) of water ice; frozen carbon dioxide layer is in northern cap and south cap has a permanent dry ice cover
assistant
are there any features resulting from impacts?
user
Yes, impact craters
assistant
are they named?
user
In spite of this, there are far fewer craters on Mars compared with the Moon, because the atmosphere of Mars provides protection against small meteors and surface modifying processes have erased some craters. Martian craters can have a morphology that suggests the ground became wet after the meteor impacted.
Mars | Impact topography
The dichotomy of Martian topography is striking: northern plains flattened by lava flows contrast with the southern highlands, pitted and cratered by ancient impacts. Research in 2008 has presented evidence regarding a theory proposed in 1980 postulating that, four billion years ago, the northern hemisphere of Mars was struck by an object one-tenth to two-thirds the size of Earth's Moon. If validated, this would make the northern hemisphere of Mars the site of an impact crater in size, or roughly the area of Europe, Asia, and Australia combined, surpassing the South Pole–Aitken basin as the largest impact crater in the Solar System.
Mars | Impact topography
Mars is scarred by a number of impact craters: a total of 43,000 craters with a diameter of or greater have been found. The largest confirmed of these is the Hellas impact basin, a light albedo feature clearly visible from Earth. Due to the smaller mass and size of Mars, the probability of an object colliding with the planet is about half that of Earth. Mars is located closer to the asteroid belt, so it has an increased chance of being struck by materials from that source. Mars is more likely to be struck by short-period comets, "i.e.", those that lie within the orbit of Jupiter.
Mars | Impact topography
Features on Mars are named from a variety of sources. Albedo features are named for classical mythology. Craters larger than 60 km are named for deceased scientists and writers and others who have contributed to the study of Mars. Craters smaller than 60 km are named for towns and villages of the world with populations of less than 100,000. Large valleys are named for the word "Mars" or "star" in various languages; small valleys are named for rivers.
LARLE crater | Nomenclature of impact craters
The dichotomy of Martian topography is striking: northern plains flattened by lava flows contrast with the southern highlands, pitted and cratered by ancient impacts. Research in 2008 has presented evidence regarding a theory proposed in 1980 postulating that, four billion years ago, the northern hemisphere of Mars was struck by an object one-tenth to two-thirds the size of the Moon. If validated, this would make the northern hemisphere of Mars the site of an impact crater 10,600 km long by 8,500 km wide, or roughly the area of Europe, Asia, and Australia combined, surpassing the South Pole–Aitken basin as the largest impact crater in the Solar System.
LARLE crater | Martian impact craters
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. There is a part of Trouvelot that displays many thin, light-toned layers; these may be evidence that a lake was present in the past. 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.
Trouvelot (Martian crater) | Description
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. 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.
Dawes (Martian crater) | Description
Complex craters have central peaks (or peak complexes), relatively flat floors, and terracing or slumping along the inner walls. Complex craters are shallower than simple craters in proportion to their widths, with depth/diameter ratios ranging from 1/5 at the simple-to-complex transition diameter (~7 km) to about 1/30 for a 100-km diameter crater. Another transition occurs at crater diameters of around 130 km as central peaks turn into concentric rings of hills to form multi-ring basins. Mars has the greatest diversity of impact crater types of any planet in the Solar System. This is partly because the presence of both rocky and volatile-rich layers in the subsurface produces a range of morphologies even among craters within the same size classes.
Geology of Mars | Impact craters
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.
Casius quadrangle | Craters
The multiple impact hypothesis is supported by correlation of segments of the dichotomy with the rims of several large impact basins. But there are large parts of the Borealis Basin outside the rims of those impact basins. If the Martian lowlands were formed by the multiple basins then their inner ejecta and rims should stand above upland elevations. The rims and ejecta blankets of the lowland impact craters are still much below the upland areas. There are also areas in the lowlands that are outside any of the impact basins, these areas must be overlain by multiple ejecta blankets and should stand at elevations similar to the original planetary surface.
Martian dichotomy | Multiple Impact Hypothesis
A single mega-impact would produce a very large, circular depression in the crust. The proposed depression has been named the Borealis Basin. However, most estimations of the shape of the lowlands area produce a shape that in places dramatically deviates from the circular shape. Additional processes could create those deviations from circularity. Also if the proposed Borealis basin is a depression created by an impact, it would be the largest impact crater known in the Solar System. An object that large could have hit Mars sometime during the process of the Solar System accretion. It is expected that an impact of such magnitude would have produced an ejecta blanket that should be found in areas around the lowland and generate enough heat to form volcanoes.
Martian dichotomy | Single Impact Hypothesis
These are found near joints and fractures that allowed deep fluid circulation which caused chemical and thermal alteration of the rocks. So, the area around martian craters may contain a variety of minerals that were produced as an indirect result of an impact. Heat from impacts results from several processes. Immediately after an impact, there is a rebound off the floor which causes hotter rocks to be uplifted to the surface. However, most of the heat comes from the kinetic energy that is produced during the impact. This enormous heat creates several useful products that may start forming early and then continue for some time.
Ore resources on Mars | Heat from impacts
Craters smaller than 60 km are named for towns and villages of the world with populations of less than 100,000. Large valleys are named for the word "Mars" or "star" in various languages; small valleys are named for rivers. Large albedo features retain many of the older names, but are often updated to reflect new knowledge of the nature of the features. For example, "Nix Olympica" (the snows of Olympus) has become "Olympus Mons" (Mount Olympus). The surface of Mars as seen from Earth is divided into two kinds of areas, with differing albedo. The paler plains covered with dust and sand rich in reddish iron oxides were once thought of as Martian "continents" and given names like Arabia Terra ("land of Arabia") or Amazonis Planitia ("Amazonian plain").
Mars | Geography and naming of surface features
Such sublimation of water or other volatiles from the dirty ice that is the bedrock causes its decomposition. The non-ice remnants form debris avalanches descending from the slopes of the crater walls. Such avalanches are often observed near and inside impact craters and termed "debris aprons". Sometimes crater walls are cut by sinuous valley-like incisions called "gullies", which resemble certain Martian surface features. In the ice sublimation hypothesis, the low-lying dark material is interpreted as a blanket of primarily non-ice debris, which originated from the degraded rims of craters and has covered a predominantly icy bedrock.
Callisto (moon) | Surface features
Mars is scarred by a number of impact craters: a total of 43,000 craters with a diameter of 5 km or greater have been found. The largest confirmed of these is the Hellas impact basin, a light albedo feature clearly visible from Earth. Due to the smaller mass of Mars, the probability of an object colliding with the planet is about half that of the Earth. Mars is located closer to the asteroid belt, so it has an increased chance of being struck by materials from that source. Mars is also more likely to be struck by short-period comets, i.e.
LARLE crater | Martian impact craters
Because of the many missions studying Mars since the 1960s, there is good coverage of its surface which contains large numbers of craters. Many of the craters on Mars differ from those on the Moon and other moons since Mars contains ice under the ground, especially in the higher latitudes. Some of the types of craters that have special shapes due to impact into ice-rich ground are pedestal craters, rampart craters, expanded craters, and LARLE craters.
Impact crater | Martian craters
During impact events, mountains can appear not only on the border of the resulting crater, but also in its center. Classical central peaks generally are not named, although some peaks within craters are named: for example, Aeolis Mons within Gale crater on Mars or the Scheria Montes within Odysseus crater on Tethys.
Mons (planetary nomenclature) | Nature of montes
Using photos from Mars Global Surveyor and HiRISE camera on NASA's Mars Reconnaissance Orbiter, scientists have found about 20 new impacts each year on Mars. Because the spacecraft have been imaging Mars almost continuously for a span of 14 years, newer images with suspected recent craters can be compared to older images to determine when the craters were formed. Since the craters were spotted in a HiRISE image from February 2006, but were not present in a Mars Global Surveyor image taken in May 2004, the impact occurred in that time frame.
Phoenicis Lacus quadrangle | Dark slope streaks
It also seems that Mars has had many ice ages in which ice was deposited, then later buried. These ice ages are caused by the frequent large changes in the tilt of the planet. The tilt of the spin axis of Mars is highly variable due to the lack of a large moon. Observations of many craters have shown that many craters are mostly full of sediments—ice could be one of the sediments. Many craters appear to be very shallow, but observations of younger craters have demonstrated that impact craters start out as sort of bowl shaped; hence a crater that today looks shallow has probably been filled with sediments.
Martian chaos terrain | Melting of buried ice
those that lie within the orbit of Jupiter. In spite of this, there are far fewer craters on Mars compared with the Moon, because the atmosphere of Mars provides protection against small meteors. Some craters have a morphology that suggests the ground became wet after the meteor impacted.
LARLE crater | Martian impact craters
There are a number of different types of craters that have been observed and studied on Mars. Many of the them are shaped by the effects of impacts into ice-rich ground.
Martian Craters | Introduction
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.
Sinus Sabaeus quadrangle | Other Craters
Impact craters were first identified on Mars by the Mariner 4 spacecraft in 1965. Early observations showed that Martian craters were generally shallower and smoother than lunar craters, indicating that Mars has a more active history of erosion and deposition than the Moon. In other aspects, Martian craters resemble lunar craters. Both are products of hypervelocity impacts and show a progression of morphology types with increasing size. Martian craters below about 7 km in diameter are called simple craters; they are bowl-shaped with sharp raised rims and have depth/diameter ratios of about 1/5. Martian craters change from simple to more complex types at diameters of roughly 5 to 8 km.
Geology of Mars | Impact craters
When a comet or asteroid collides at a high rate of speed interplanetary with the surface of Mars it creates a primary impact crater. The primary impact may also eject significant numbers of rocks which eventually fall back to make secondary craters. The secondary craters may be arranged in clusters. All of the craters in the cluster would appear to be equally eroded; indicating that they would all are of the same age. If these secondary craters formed from a single, large, nearby impact, then they would have formed at roughly the same instant in time. The image below of Denning Crater shows a cluster of secondary craters.
Sinus Sabaeus quadrangle | Other Craters
Thus viscous relaxation should have been taking place. High heat flux and high water content in the early Martian crust favored viscous relaxation. These two factors have made the crust more ductile. The basin topography of the craters would be subjected to greater stress due to self-gravitation. Such stress would drive crustal flow and therefore decay of relief. The giant impact basins are the exceptions that have not experienced viscous relaxation, as crustal thinning has made the crust too thin to sustain sub-solidus crustal flow.
Gravity of Mars | Crust redistribution by impacting and viscous relaxation
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.
Phaethontis quadrangle | Craters
Another stratigraphic principle used on planets where impact craters are well preserved is that of crater number density. The number of craters greater than a given size per unit surface area (usually million km) provides a relative age for that surface. Heavily cratered surfaces are old, and sparsely cratered surfaces are young. Old surfaces have many big craters, and young surfaces have mostly small craters or none at all. These stratigraphic concepts form the basis for the Martian geologic timescale.
Geological history of Mars | Introduction
Schaeberle is a crater in the Iapygia quadrangle of Mars, located at 24.7° S and 309.9° W. It measures approximately 159 kilometers in diameter and was named after John Martin Schaeberle, an American astronomer (1853–1924). 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.
Schaeberle (Martian crater) | Introduction
Given that it is a planet, the geography of Mars varies considerably. However, the dichotomy of Martian topography is striking: northern plains flattened by lava flows contrast with the southern highlands, pitted and cratered by ancient impacts. The surface of Mars as seen from Earth is consequently divided into two kinds of areas, with differing albedo. The paler plains covered with dust and sand rich in reddish iron oxides were once thought of as Martian 'continents' and given names like Arabia Terra ("land of Arabia") or Amazonis Planitia ("Amazonian plain"). The dark features were thought to be seas, hence their names Mare Erythraeum, Mare Sirenum and Aurorae Sinus.
Geography of Mars | Topography
Named impact craters are:
List of geological features on Iapetus | Craters
The basin floor contains thick, structurally complex sedimentary deposits that have a long geologic history of deposition, erosion, and internal deformation. The lowest elevations on the planet are located within the Hellas basin, with some areas of the basin floor lying over 8 km below datum. The two other large impact structures on the planet are the Argyre and Isidis basins. Like Hellas, Argyre (800 km in diameter) is located in the southern highlands and is surrounded by a broad ring of mountains. The mountains in the southern portion of the rim, Charitum Montes, may have been eroded by valley glaciers and ice sheets at some point in Mars's history.
Geology of Mars | Large impact basins
Degraded impact structures record variations in volcanic, fluvial, and aeolian activity. The Yuty crater is an example of a Rampart crater so called because of the rampart like edge of the ejecta. In the Yuty crater the ejecta completely covers an older crater at its side, showing that the ejected material is just a thin layer.
Geology of solar terrestrial planets | Mars
Some features on Mars seem to be in the process of being uncovered. So, the thought is that they formed, were covered over, and now are being exhumed as material is being eroded. These features are quite noticeable with craters. When a crater forms, it will destroy what's under it and leave a rim and ejecta. In the example below, only part of the crater is visible. if the crater came after the layered feature, it would have removed part of the feature.
Ismenius Lacus quadrangle | Exhumed craters
Jeans is an impact crater in the Mare Australe quadrangle of Mars, located at 69.8°S latitude and 205.9°W longitude. It is 80.2 km in diameter and was named after James Hopwood Jeans, and the name was approved in 1973 by the International Astronomical Union (IAU) Working Group for Planetary System Nomenclature (WGPSN). The pictures below show dark areas in which frost is disappearing and the dark ground beneath is being exposed. Layers are also visible—probably from the many cycles of mantle deposition.
Jeans (Martian crater) | Introduction
Escalante Crater is an impact crater in the Amenthes quadrangle of Mars. It is located at 0.2° N and 244.7° W. It is in diameter, and was named after Mexican astronomer (c. 1930) F. Escalante. 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.
Escalante (Martian crater) | Introduction
Several enormous, circular impact basins are present on Mars. The largest one that is readily visible is the Hellas basin located in the southern hemisphere. It is the second largest confirmed impact structure on the planet, centered at about 64°E longitude and 40°S latitude. The central part of the basin (Hellas Planitia) is 1,800 km in diameter and surrounded by a broad, heavily eroded annular rim structure characterized by closely spaced rugged irregular mountains (massifs), which probably represent uplifted, jostled blocks of old pre-basin crust. (See Anseris Mons, for example.) Ancient, low-relief volcanic constructs (highland paterae) are located on the northeastern and southwestern portions of the rim.
Geology of Mars | Large impact basins
Santa Fe is an impact crater in the Lunae Palus quadrangle of Mars, located at 19.5° North and 48.0° W. It is 20.5 km in diameter and was named after Santa Fe, New Mexico, USA. 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.
Santa Fe (Martian crater) | Introduction
One possible explanation for the basin's low, flat and relatively crater-free topography is that the basin was formed by a single large impact. Two simulations of a possible impact sketched a profile for the collision: low velocity— per second—oblique angle and a diameter of . Topographical data from "Mars Global Surveyor" are consistent with the models and also suggest that the elliptical crater has axes of length and , centered on , though this has been partially obscured by later volcanic eruptions that created the Tharsis bulge along its rim. There is evidence for a secondary rim as well. This would make the North Polar Basin by far the largest impact crater in the Solar System, approximately four times the diameter of the next largest craters: Utopia Planitia, which is imbedded inside the North Polar Basin, the South Pole–Aitken basin on the Moon, and Hellas Planitia on Mars's southern hemisphere.
North Polar Basin (Mars) | Formation of the Borealis Basin
Mars also has an atmosphere that plays a role in ejecta emplacement and subsequent erosion. Moreover, Mars has a rate of volcanic and tectonic activity low enough that ancient, eroded craters are still preserved, yet high enough to have resurfaced large areas of the planet, producing a diverse range of crater populations of widely differing ages. Over 42,000 impact craters greater than 5 km in diameter have been catalogued on Mars, and the number of smaller craters is probably innumerable. The density of craters on Mars is highest in the southern hemisphere, south of the dichotomy boundary. This is where most of the large craters and basins are located.
Geology of Mars | Impact craters
One rock, "Bounce Rock," found sitting on the sandy plains was found to be ejecta from an impact crater. Its chemistry was different from the bedrocks. Containing mostly pyroxene and plagioclase and no olivine, it closely resembled a part, Lithology B, of the shergottite meteorite EETA 79001, a meteorite known to have come from Mars. Bounce rock received its name by being near an airbag bounce mark.
Composition of Mars | Rock from impact
Valleys incised by such processes are geomorphically distinctive from landforms produced by fluvial processes. Denning Crater lies at the outermost stretches of a regime of hilly and cratered mottled terrain surrounding Hellas, interpreted as the reworked remnants of that impact basin's ejecta blanket. This geologic unit overlies a moderately-cratered plains unit that stretches intermittently across much of the Terra Sabaea region. This plains unit is interpreted to comprise eolian materials infilling lower areas in the cratered bedrock. Since Denning's formation, seven large craters have overprinted Denning's original features. Five of these craters themselves have been superposed by two other more recent impacts.
Denning (Martian crater) | Geology
Bouguer Crater is an impact crater in the Sinus Sabaeus quadrangle of Mars, located at 18.7° S and 332.8° W It is 107 km in diameter and was named after Pierre Bouguer, French physicist-hydrographer (1698–1758). When a comet or asteroid collides at high speed interplanetary with the surface of Mars it creates an impact crater. Layers are visible in the crater with HiRISE; these can be seen in the HiRISE image below. Layers may be formed by a number of processes. On Earth rock layers are often formed under a lake or other body of water. However, on Mars many layers may be formed by the action of groundwater.
Bouguer (Martian crater) | Introduction
Main is an impact crater on Mars, located in the Mare Australe quadrangle at 76.6°S latitude and 310.9°W longitude. It measures 109.0 kilometers in diameter and was named after Rev. Robert Main. The name was approved in 1973, by the International Astronomical Union (IAU) Working Group for Planetary System Nomenclature (WGPSN). The floor of Main shows dark portions which are caused by pressurized carbon dioxide blowing dust in the atmosphere in the spring when the temperature goes up. Some of the dust is shaped into streaks if there is a wind. Many ideas have been advanced to explain these features.
Main (Martian crater) | Introduction
They were thought to be connected with endogenic activity, but the high-resolution "Galileo" images showed that the bright, smooth plains correlate with heavily fractured and knobby terrain and do not show any signs of resurfacing. The "Galileo" images also revealed small, dark, smooth areas with overall coverage less than 10,000 km, which appear to embay the surrounding terrain. They are possible cryovolcanic deposits. Both the light and the various smooth plains are somewhat younger and less cratered than the background cratered plains. Impact crater diameters seen range from 0.1 km—a limit defined by the imaging resolution—to over 100 km, not counting the multi-ring structures.
Callisto (moon) | Surface features
Various landforms studied by the Mars Exploration Rovers are given temporary names or nicknames to identify them during exploration and investigation. However, it is hoped that the International Astronomical Union will make permanent the names of certain major features, such as the Columbia Hills, which were named after the seven astronauts who died in the Space Shuttle "Columbia" disaster.
Geography of Mars | Modern nomenclature
Using photos from Mars Global Surveyor and HiRISE camera on NASA’s Mars Reconnaissance Orbiter, scientists have found about 20 new impacts each year on Mars. Because the spacecraft have been imaging Mars almost continuously for a span of 14 years, newer images with suspected recent craters can be compared to older images to determine when the craters were formed. Since the craters were spotted in a HiRISE image from February 2006, but were not present in a Mars Global Surveyor image taken in May 2004, the impact occurred in that time frame.
Tharsis quadrangle | Dark slope streaks
Bernard is a large crater in the Memnonia quadrangle of Mars, located at 23.4° south latitude and 154.2° west longitude. It is 128 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. 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.
Bernard (crater) | Introduction
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.
Phaethontis quadrangle | Craters
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. Its rim has probably been eroded away.
Müller (Martian crater) | Introduction
Lohse is a crater in the Argyre quadrangle of Mars, located at 43.7° South and 16.8° West. It is 155.5 km in diameter and was named after Oswald Lohse, a German astronomer (1845-1915). The crater is very eroded. The uplifted area in the center contains gullies. 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.
Lohse (Martian crater) | Introduction
Chaos regions formed long ago. By counting craters (more craters in any given area means an older surface) and by studying the valleys' relations with other geological features, scientists have concluded the channels formed 2.0 to 3.8 billion years ago.
Common surface features of Mars | Chaos terrain
Complex craters have uplifted centers, and they have typically broad flat shallow crater floors, and terraced walls. At the largest sizes, one or more exterior or interior rings may appear, and the structure may be labeled an "impact basin" rather than an impact crater. Complex-crater morphology on rocky planets appears to follow a regular sequence with increasing size: small complex craters with a central topographic peak are called "central peak craters", for example Tycho; intermediate-sized craters, in which the central peak is replaced by a ring of peaks, are called "peak-ring craters", for example Schrödinger; and the largest craters contain multiple concentric topographic rings, and are called "multi-ringed basins", for example Orientale.
Impact crater | Modification and collapse
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.
Thaumasia quadrangle | Craters
Whatever its origin, the Martian dichotomy appears to be extremely old. A new theory based on the Southern Polar Giant Impact and validated by the discovery of twelve hemispherical alignments shows that exogenic theories appear to be stronger than endogenic theories and that Mars never had plate tectonics that could modify the dichotomy. Laser altimeter and radar sounding data from orbiting spacecraft have identified a large number of basin-sized structures previously hidden in visual images. Called quasi-circular depressions (QCDs), these features likely represent derelict impact craters from the period of heavy bombardment that are now covered by a veneer of younger deposits.
Geology of Mars | Hemispheric dichotomy
Von Kármán is an impact crater in the Argyre quadrangle of Mars, located at 64.6°S latitude and 58.5°W longitude. It is in diameter. It was named after Hungarian-American aeronautical engineer Theodore von Kármán. The crater contains a large field of dunes. Usually, the dunes are very dark because they contain the dark volcanic rock basalt. However, in the winter they are become covered with frost. The pictures below show the frost disappearing. Dark spots appear on dunes in the higher latitudes of Mars. Sometimes geysers form near the spots. They have two main features (dark dune spots and spider channels) that appear at the beginning of the Martian spring on dune fields covered with carbon dioxide (CO or 'dry ice'), mainly at the ridges and slopes of the dunes; by the beginning of winter, they disappear.
Von Kármán (Martian crater) | Introduction
The easily eroded nature of the Medusae Fossae Formation suggests that it is composed of weakly cemented particles, and was most likely formed by the deposition of wind-blown dust or volcanic ash. Layers are seen in parts of the formation. A resistant caprock on the top of yardangs has been observed in Viking, Mars Global Surveyor, and HiRISE photos. Very few impact craters are visible throughout the area so the surface is relatively young.
Common surface features of Mars | Medusae Fossae Formation
Onon is an impact crater on Mars, located in the Amenthes quadrangle at 16.3° N and 257.6° W. It measures 3.5 kilometer in diameter and was named after Onon, a town in Mongolia. 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. Sometimes craters expose layers that were buried. Rocks from deep underground are tossed onto the surface.
Onon (crater) | Introduction
Today, names of Martian features derive from a number of sources, but the names of the large features are derived primarily from the maps of Mars made in 1886 by the Italian astronomer Giovanni Schiaparelli. Schiaparelli named the larger features of Mars primarily using names from Greek mythology and to a lesser extent the Bible. Mars's large albedo features retain many of the older names, but are often updated to reflect new knowledge of the nature of the features. For example, 'Nix Olympica' (the snows of Olympus) has become Olympus Mons (Mount Olympus). Large Martian craters are named after important scientists and science fiction writers; smaller ones are named after towns and villages on Earth.
Geography of Mars | Modern nomenclature
The landscape polewards of around 30 degrees latitude on Mars has a distinctively different appearance to that nearer the equator, and is said to have undergone terrain softening. Softened terrain lacks the sharp ridge crests seen near the equator, and is instead smoothly rounded. This rounding is thought to be caused by high concentrations of water ice in soils. The term was coined in 1986 by Steve Squyres and Michael Carr from examining imagery from the Viking missions to Mars. Below 30 degrees of latitude, impact craters have steep walls; well-defined, sharp rims; and flat or smoothly bowl-shaped floors. Ridges on intercrater plains come to similarly well-defined, pointed crests.
Terrain softening | Introduction
In this region, are many expanded secondary craters that probably form from impacts that destabilize a subsurface layer of excess ice, which subsequently sublimates. With sublimation the ice changes directly from a solid to gaseous form. In the impact, the excess ice is broken up, resulting in an increase in surface area. Ice will sublimate much more if there is more surface area. After the ice disappears into the atmosphere, dry soil material will collapse and cause the crater diameter to become larger. Places on Mars that display expanded craters may indicate where future colonists can find water ice.
Arcadia Planitia | Expanded craters
Radau is an impact crater in the Oxia Palus quadrangle of Mars, located 17.1° N and 4.8° W. It measures 114.5 kilometers in diameter and was named for Rodolphe Radau, a French astronomer (1835–1911). 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.
Radau (crater) | Introduction
Crater deposits are mapped stratigraphically according to a morphologic degradation sequence devised by N. J. Trask (McCauley and others, 1981). This method assumes that (1) all craters of a given size range initially resemble fresh craters and (2) degrees of impact erosion are constant for all craters within a morphologically defined sequence. Although these conditions hold generally, degradation may be accelerated locally by adjacent impact events and flooding by plains materials and, rarely, may be decelerated by structural rejuvenation of topographic elements of craters. Thus, the stratigraphic significance of crater morphology is only approximate. By analogy with lunar materials, all mapped crater materials are thought to be of impact origin.
Michelangelo quadrangle | Crater materials
Montevallo is a crater on Mars, located in the Lunae Palus quadrangle at 15.4° N and 54.4° W. It measures 51.9 kilometers in diameter and was named after the town Montevallo in Alabama, United States. The name was approved by IAU's Working Group for Planetary System Nomenclature in 1988. 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.
Montevallo (crater) | Introduction
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.
Thaumasia quadrangle | Craters
In this region, are many expanded secondary craters that probably form from impacts that destabilize a subsurface layer of excess ice, which subsequently sublimates. With sublimation the ice changes directly from a solid to gaseous form. In the impact, the excess ice is broken up, resulting in an increase in surface area. Ice will sublimate much more if there is more surface area. After the ice disappears into the atmosphere, dry soil material will collapse and cause the crater diameter to become larger. Places on Mars that display expanded craters may indicate where future colonists can find water ice.
Diacria quadrangle | <a href="Expanded%20Craters">Expanded Craters</a>
One-third of the martian impact craters with ≥ 5 km diameter have discernible impact ejecta around. Layered ejecta blanket are plentiful on the surface of Mars as around 90% of ejecta are characterized as layered materials. Though impact cratering and resulted ejecta blanket are ubiquitous features in the solid bodies of the solar system, the Earth rarely preserve the signature of impact ejecta blanket due to erosion. However, to date, there are 190 identified impact craters on the surface of Earth.
Ejecta blanket | Presence
Lockyer is a crater in the Elysium quadrangle of Mars. It was named after Norman Lockyer, a British astronomer (1836-1920). Lockyer is surrounded by relatively smooth plains, where there are few craters. It is east of Elysium Mons and Hecates Tholus, two large volcanoes. It is south of the larger crater Adams and the Phlegra Montes. 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.
Lockyer (Martian crater) | Introduction
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. Sometimes craters will display layers. Craters can show us what lies deep under the surface.
Lunae Palus quadrangle | Craters
Porter is a large-scale impact crater in the Thaumasia quadrangle on the planet Mars, situated in Aonia Terra at 50.8° south and 113.9º west. The impact caused a bowl across. The name was chosen in 1973 by the International Astronomical Union in honour of the US astronomer and explorer, Russell W. Porter (1871-1949). 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.
Porter (Martian crater) | Introduction
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.
Mare Tyrrhenum quadrangle | Importance of craters
Many craters in the Arabia area of Mars contain groups of layers. Some of these layers may have resulted from climate change. The tilt of the rotational axis of Mars has repeatedly changed in the past. Some changes are large. Because of these variations of climate, at times the atmosphere of Mars would have been much thicker and contained more moisture. The amount of atmospheric dust also has increased and decreased. It is believed that these frequent changes helped to deposit material in craters and other low places. The rising of mineral-rich ground water cemented these materials. The model also predicts that after a crater is full of layered rocks, additional layers will be laid down in the area around the crater.
Groundwater on Mars | Layered terrain
This crater contains ridges that may have been produced after fractures formed with an impact. Using instruments on the Mars Reconnaissance Orbiter they found the minerals smectite, silica, zeolite, serpentine, carbonate, and chlorite that are common in impact-induced hydrothermal systems on Earth. Other evidence of post-impact hydrothermal systems on Mars from other scientists who studied other Martian craters.
Mare Tyrrhenum quadrangle | Hydrothermal features in Auki
At 75° north latitude, it is one of the highest-latitude impact craters known. The temperature is below the freezing point of water for much of the year, and the limited vegetation is slow-growing, leading to very little weathering. For this reason Haughton retains many geological features that lower-latitude craters lose to erosion. Because Haughton's geology and climatology are as close to Mars-like as can be had on Earth, Haughton and its environs have been dubbed by scientists working there as "Mars on Earth." For example, the center of the crater contains impact breccia (ejected rock which has fallen back into the impact zone and partially re-welded) that is permeated with permafrost, thus creating a close analog to what may be expected at crater sites on a cold, wet Mars.
Haughton impact crater | Description
This hypothesis is in agreement with numerical models of impacts in the 30-60° range, which are shown to produce elliptical boundary basins similar to the structure identified on Mars. Demagnetization resulting from the high heat associated with such an impact can also serve to explain the apparent lack of magnetic anomalies in the northern plains. It also explains the younger surface age of the northern plains, as determined by significantly lesser crater density. Overall, this hypothesis appears to fare better than others that have been proposed.
Tectonics of Mars | Exogenic origins
Quenisset is an impact crater on Mars, located in the Ismenius Lacus quadrangle at 34.6° N and 319.4° W. It measures 138 kilometer in diameter. Adopted by IAU's Working Group for Planetary System Nomenclature in 1973, the crater was named after French astronomer Ferdinand Quénisset.
Quenisset (crater) | Introduction
Small craters, with diameters less than 5 km, have simple bowl or flat-floored shapes. Those 5–40 km across usually have a central peak. Larger impact features, with diameters in the range 25–100 km, have central pits instead of peaks, such as Tindr crater. The largest craters with diameters over 60 km can have central domes, which are thought to result from central tectonic uplift after an impact; examples include Doh and Hár craters. A small number of very large—more than 100 km in diameter—and bright impact craters show anomalous dome geometry. These are unusually shallow and may be a transitional landform to the multi-ring structures, as with the Lofn impact feature.
Callisto (moon) | Surface features
This impact would have resulted in significant crustal melting and a general increase in the rate of crustal formation for a period of 40 million years following the impact. Such a large impact would have disturbed the mantle, altering the normal convection currents and causing upwellings which further increase the amount of melting at the impact site. Overall, such an event would actually increase the rate of cooling of the Martian interior. The lack of magnetic anomalies observed in the northern hemisphere could be explained by such an impact, as the shock waves produced might have demagnetized the crust.
North Polar Basin (Mars) | Formation of the Borealis Basin
Similar to other large craters in this region of Mars, wind-eroded features are sporadically found on the basin floor. The presence of wrinkle ridges of varying orientations within and around the Denning basin has been correlated to regional tectonic events, including the formation of the Hellas basin itself. The crater was named for British astronomer William Frederick Denning.
Denning (Martian crater) | Introduction
Crustal thinning is believed to have taken place underneath almost all the major impact craters. Crustal excavation, modification through emplacement of volcanic material and crustal flow taking place in the weak lithosphere are the possible causes. With the pre-impact crust excavated, gravitational restoration would take place through central mantle uplift, so that the mass deficit of cavity could be compensated by the mass of the uplifted denser material. Giant impact basins Utopia, Hellas, Argyre and Isidis are some of the most prominent examples. Utopia, an impact basin located in northern lowland, is filled by light and water-deposited sedimentary material and has slightly thickened crust at the center.
Gravity of Mars | Crust redistribution by impacting and viscous relaxation
Impact craters generally have a rim with ejecta around them, in contrast volcanic craters usually do not have a rim or ejecta deposits. Sometimes craters display layers. Since the collision that produces a crater is like a powerful explosion, rocks from deep underground are tossed unto the surface. Hence, craters can show us what lies deep under the surface.
Mare Acidalium quadrangle | Craters
Ring mold craters are believed to be formed from asteroid impacts into ground that has an underlying layer of ice. The impact produces an rebound of the ice layer to form a "ring-mold" shape.
Common surface features of Mars | <a href="Ring%20mold%20crater">Ring mold crater</a>s
See list of craters on Mars. Mars has two permanent polar ice caps, the northern one located at Planum Boreum and the southern one at Planum Australe.
Geography of Mars | Topography
Along crater and canyon walls, there are thousands of features that appear similar to terrestrial gullies. The gullies tend to be in the highlands of the southern hemisphere and to face the Equator; all are poleward of 30° latitude. A number of authors have suggested that their formation process involves liquid water, probably from melting ice, although others have argued for formation mechanisms involving carbon dioxide frost or the movement of dry dust. No partially degraded gullies have formed by weathering and no superimposed impact craters have been observed, indicating that these are young features, possibly still active. Other geological features, such as deltas and alluvial fans preserved in craters, are further evidence for warmer, wetter conditions at an interval or intervals in earlier Mars history.
Mars | Hydrology
The classification of impact crater-forming materials are (1) crater materials and (2) flooded crater materials, which is similar to the stratigraphic classification scheme.
Mapping of Venus | Impact crater-forming materials
These features can be seen in some of the pictures below. Close up views of these features often reveal fuzzy features that have been named "spiders."
Main (Martian crater) | Introduction
Impact cratering is a common occurrence on many Solar System bodies. Much of Enceladus's surface is covered with craters at various densities and levels of degradation. This subdivision of cratered terrains on the basis of crater density (and thus surface age) suggests that Enceladus has been resurfaced in multiple stages. "Cassini" observations provided a much closer look at the crater distribution and size, showing that many of Enceladus's craters are heavily degraded through viscous relaxation and fracturing. Viscous relaxation allows gravity, over geologic time scales, to deform craters and other topographic features formed in water ice, reducing the amount of topography over time.
Enceladus | Impact craters
Studies of impact crater densities on the Martian surface have delineated three broad periods in the planet's geologic history. The periods were named after places on Mars that have large-scale surface features, such as large craters or widespread lava flows, that date back to these time periods. The absolute ages given here are only approximate. From oldest to youngest, the time periods are: The date of the Hesperian/Amazonian boundary is particularly uncertain and could range anywhere from 3.0 to 1.5 Gya. Basically, the Hesperian is thought of as a transitional period between the end of heavy bombardment and the cold, dry Mars seen today.
Geological history of Mars | Crater density timescale
Linear ridge networks are found in various places on Mars in and around craters. Ridges often appear as mostly straight segments that intersect in a lattice-like manner. They are hundreds of meters long, tens of meters high, and several meters wide. It is thought that impacts created fractures in the surface, these fractures later acted as channels for fluids. Fluids cemented the structures. With the passage of time, surrounding material was eroded away, thereby leaving hard ridges behind. Since the ridges occur in locations with clay, these formations could serve as a marker for clay which requires water for its formation.
Common surface features of Mars | Linear Ridge Networks
Once inside the crater, shade and dust preserve the snow. The snow changes to ice. The many concentric lines are created by the many cycles of snow accumulation. Generally snow accumulates whenever the axial tilt reaches 35 degrees.
Common surface features of Mars | <a href="Concentric%20crater%20fill">Concentric crater fill</a>
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. Sometimes craters will display layers in their walls. Since the collision that produces a crater is like a powerful explosion, rocks from deep underground are tossed unto the surface. Hence, craters are useful for showing us what lies deep under the surface.
Ismenius Lacus quadrangle | Other craters
This is a partial list of craters on Mars. There are hundreds of thousands of impact craters on Mars, but only some of them have names. This list here only contains named Martian craters starting with the letter H – N "(see also lists for and )". Large Martian craters (greater than 60 kilometers in diameter) are named after famous scientists and science fiction authors; smaller ones (less than 60 km in diameter) get their names from towns on Earth. Craters cannot be named for living people, and small crater names are not intended to be commemorative – that is, a small crater isn't named after a specific town on Earth, but rather its name comes at random from a pool of terrestrial place names, with some exceptions made for craters near landing sites.
List of craters on Mars: H–N | Introduction
While estimates of the mass ejected by a large, Borealis-size impact vary, simulations suggest that a body approximately 0.02 Mars masses (~0.002 Earth Masses) in size is capable of producing a sizable debris disk in Martian orbit, on the order of 5x10 kg, with a significant fraction of the material remaining close to Mars. This figure lies within the estimated mass range necessary to form the two moons, as other data suggests that only 1% of the mass of an accretion disk successfully forms moons. There are several other large impact basins on Mars that could have ejected enough debris to form the moons.
North Polar Basin (Mars) | Potential formation of Phobos and Deimos via Borealis impact
Burton is an impact crater in the Memnonia quadrangle of Mars, located at 13.9°S latitude and 156.3°W longitude. It is 123.0 km in diameter and was named after British astronomer Charles E. Burton; the name was approved in 1973. It has a central peak. 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.
Burton (crater) | Introduction
Gledhill is an impact crater in the Hellas quadrangle of Mars, located at 53.2°S latitude and 87.1°E longitude. It is 78.5 km in diameter. It was named after British astronomer Joseph Gledhill, and the name was approved in 1973 by the International Astronomical Union (IAU) Working Group for Planetary System Nomenclature (WGPSN). 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.
Gledhill (crater) | Introduction
Such conditions necessarily require the widespread presence of crater lakes across a large proportion of the surface, for which there is independent mineralogical, sedimentological and geomorphological evidence.
Mars | Hydrology
About 60 percent of the mapped area consists of tracts of planar surfaces having a variety of small-scale textures. These tracts range in size from a few square kilometers within craters to areas larger than 10,000 km that surround and separate large craters: the so-called “intercrater plains”. The origin of the plains material is uncertain. Strom and others, Trask and Strom, Strom (1977), and Leake (1982) presented arguments in favor of volcanism, whereas Wilhelms and Oberbeck and others (1977) argued for an impact-related origin through processes similar to those responsible for the lunar Cayley Plains (fluidized ejecta sheets or ballistically deposited secondary-crater ejecta).
Bach quadrangle | Plains materials
Persbo is an impact crater in the Elysium quadrangle of Mars. It measures 19.5 kilometer in diameter and was named after Persbo, Sweden. It is just south of the Cerberus Fossae, and is adjacent to the Athabasca Valles, which issue from one of the fossae. 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.
Persbo (crater) | Introduction
Renaudot is an impact crater in the Casius quadrangle on Mars at 42.4° N and 297.4° W and measures 64 kilometers in diameter. Its name was approved in 1973, and it was named after Gabrielle Renaudot Flammarion. Along its wall are evidence of old glaciers. The floor bears a field of dunes.
Renaudot (crater) | Introduction
An impact of Planet V onto Mars, forming the Borealis Basin has recently been proposed as an explanation for the Late Heavy Bombardment. Debris from this impact would have a different size distribution than the asteroid belt with a smaller fraction of large bodies and would result in a lower number of giant impact basins relative to craters.
Planet V | Alternate version
Although better remembered for mapping the Moon, Johann Heinrich Mädler and Wilhelm Beer were the first areographers. They began by establishing that most of Mars's surface features were permanent and by more precisely determining the planet's rotation period. In 1840, Mädler combined ten years of observations and drew the first map of Mars. Rather than giving names to the various markings, Beer and Mädler simply designated them with letters; Meridian Bay (Sinus Meridiani) was thus feature ""a"". Today, features on Mars are named from a variety of sources. Albedo features are named for classical mythology. Craters larger than 60 km are named for deceased scientists and writers and others who have contributed to the study of Mars.
Mars | Geography and naming of surface features