Misplaced Pages

#986013

73-575: Arabia contains many interesting features. There are some good examples of pedestal craters in the area. A pedestal crater has its ejecta above the surrounding terrain, often forming a steep cliff. The ejecta forms a resistant layer that protects the underlying material from erosion. Mounds and buttes on the floor of some craters display many layers. The layers may have formed by volcanic processes, by wind, or by underwater deposition. Dark slope streaks have been observed in Tikhonravov Basin,

146-438: A resolution of 1 microradian , or 0.3 meter at a height of 300 km. (For comparison purposes, satellite images on Google Mars are available to 1 meter. ) It can image in three color bands, 400–600 nm ( blue – green or B–G), 550–850 nm ( red ) and 800–1,000 nm ( near infrared or NIR). HiRISE incorporates a 0.5-meter primary mirror, the largest optical telescope ever sent beyond Earth's orbit. The mass of

219-459: A color strip down the middle only. The HiRISE camera is designed to view surface features of Mars in greater detail than has previously been possible. It has provided a closer look at fresh Martian craters, revealing alluvial fans , viscous flow features and ponded regions of pitted materials containing breccia clast . This allows for the study of the age of Martian features, looking for landing sites for future Mars landers, and in general, seeing

292-580: A darker lag. In other areas, dust is deposited to produce a bright surface. The selective removal and deposition of dust is most conspicuous around impact craters and other obstacles where a variety of streaks (wind tails) and blotches are formed. Dark slope streaks are relatively small features. (See A in Photo Gallery.) They differ from larger albedo features in being produced by gravity rather than wind, although wind may contribute to their initial formation. (See B in Photo Gallery.) The cause of

365-462: A darker substrate. The role that water and other volatiles plays, if any, in streak formation is still debated. Slope streaks are particularly intriguing because they are one of the few geological phenomena that can be observed occurring on Mars in the present day. Dark slope streaks are albedo features. They appear to the eye as a brightness difference between the streak and the lighter-toned background slope. Usually no topographic relief

438-404: A dry, powdery snow with little cohesion between individual snow crystals. The process produces a very shallow trough (slough) on the surface of the snow, which from a distance appears slightly darker in tone than the rest of the slope. Other models involve water, either in the form of spring discharges, wet debris flows , or seasonal percolation of chloride -rich brines . Using data from

511-510: A great source of water for future colonists on Mars In places large fractures break up surfaces. Sometimes straight edges are formed and large cubes are created by the fractures. For mapping purposes, the United States Geological Survey divides the surface of Mars into thirty " quadrangles ", each named for a prominent physiographic feature within that quadrangle. The quadrangles can be seen and explored via

584-488: A higher population of old dark streaks. Areas with abundant slope streaks also contain an apparently distinct class of avalanche scars. The scars resemble slope streaks in morphology and size. (See G in Photo Gallery) They are typically several meters deep and hundreds of meters long. They begin at a single point (sometimes a small, barely resolved impact crater) high on a slope. The edges radiate downslope in

657-457: A large eroded crater. The streaks appear on steep slopes and change over time. At first they are dark, then turn a lighter color, probably by the deposition of fine, light colored dust from the atmosphere. These streaks are thought by some to form by dust moving downslope in a way similar to snow avalanches on Earth. Arabia Terra was named in 1879 after a corresponding albedo feature on a map by Giovanni Schiaparelli , who named it in turn after

730-572: A lot of dust. It has been suggested that streaks could form when accumulations of dry ice start subliming right after sunrise. Nighttime CO 2 frost is widespread in low latitudes. Researchers have proposed a number of mechanisms for dark slope streak formation. The most widely held view is that the streaks are the result of dust avalanches produced by dry granular flow on oversteepened slopes. Dust avalanches resemble loose snow avalanches on Earth. Loose snow avalanches occur when snow accumulates under cold, nearly windless conditions, producing

803-435: A more likely explanation for the origin of the volcanic activity than putative subduction. Rapid ascent of magma through the thin crust and a consequent relative absence of degassing may explain the more explosive eruption style associated with these paterae relative to that of the shield volcanoes. The eruptions would have contributed to the layered deposits of Arabia Terra, which are among the fine-grained deposits widespread in

SECTION 10

#1732773332987

876-776: A new cycle of streak formation. A recent study published in Icarus found that they last about 40 years. The researchers looked at a region in Lycus Sulci with Viking images and with CTX images from the Mars Reconnaissance Orbiter. The ones first observed with Viking have all gone, but have been replaced with new ones. Dark slope streaks occur in association with or superficially resemble a number of other small-scale, slope-related features on Mars. These include bright slope streaks, avalanche scars, and recurring slope lineae. Water tracks are features that occur in

949-575: A new streak appeared in the aureole of Olympus Mons . A follow-up image from HiRISE showed that a new crater at the top of the streak. The researchers concluded that the impact triggered the new slope streak. Another streak connected with an impact was found in the Arabia quadrangle. Research, published in January 2012 in Icarus, found that dark streaks were initiated by airblasts from meteorites traveling at supersonic speeds. The team of scientists

1022-634: A single point ( apex ) high on the slope. The apex is often associated with an isolated small ridge, knob, or other area of local steepening. In high-resolution images, a tiny impact crater is sometimes visible at the apex. Slope streaks widen downslope from the apex in a triangular fashion, usually reaching their maximum widths short of the halfway point of their lengths. A single slope streak can split into two separate streaks around an obstacle or form an anastamosing (braided) pattern. (See D and E in Photo Gallery.) Slope streaks commonly develop multiple fingers (digitation) at their downslope ends. Images from

1095-557: A time. One study that used HiRISE pictures found over 17,000 km of ancient river valleys in Arabia Terra. Many ancient river valleys have been determined to be relatively recent, according to research published in 2016 in the Journal of Geophysical Research: Planets. These valleys carried water into lake basins. One lake, nicknamed "Heart Lake," had a volume similar to Lake Ontario . The climate of Mars may have been such in

1168-525: A triangular fashion. In about half of the documented examples, a low-lying mound of debris is visible at the downslope end. Originally called "meters-thick avalanche scars," these features were thought to be distinct from slope streaks. However, higher-resolution images from the HiRISE instrument on MRO suggest that meters-thick avalanche scars and slope streaks are related and part of a continuum of active mass wasting features formed by dust avalanches. In

1241-531: A type of terrain called the Medusae Fossae formation. The formation is coated with dust and contains wind-carved ridges called yardangs. These yardangs have steep slopes thickly covered with dust, so when the sonic boom of the airblast arrived from the impacts dust started to move down the slope. 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

1314-490: A typical maximum size of 11.2 gigabits. These images are released to the general public on the HiRISE website via a new format called JPEG 2000 . To facilitate the mapping of potential landing sites, HiRISE can produce stereo pairs of images from which the topography can be measured to an accuracy of 0.25 meter. HiRISE images are available to the public, are named according to the following rules: The target code refers to

1387-404: Is a region of maze-like ridges 3–5 meters high. Some ridges may consist of an ice core, so they may be sources of water for future colonists. 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

1460-472: Is involved in dark slope streak formation. Dark slope streaks do not appear to correlate with elevation or areas of specific bedrock geology. They occur on a wide range of slope textures, including surfaces that are smooth, featureless, and presumably young, as well as older, heavily cratered slopes. However, they are always associated with areas of high surface roughness, high albedo, and low thermal inertia , properties that indicate steep slopes covered with

1533-453: Is limited by the onboard computer's 28 Gbit ( 3.5 GB ) memory capacity. The nominal maximum size of red images (compressed to 8 bits per pixel) is about 20,000 × 126,000 pixels, or 2520 megapixels and 4,000 × 126,000 pixels (504 megapixels) for the narrower images of the B–G and NIR bands. A single uncompressed image uses up to 28   Gbit. However, these images are transmitted compressed, with

SECTION 20

#1732773332987

1606-440: Is suggested to initiate the fracture process since ribbed upper plains are common when debris aprons come together or near the edge of debris aprons—such sites would generate compressional stresses. Cracks exposed more surfaces, and consequently more ice in the material sublimates into the planet's thin atmosphere. Eventually, small cracks become large canyons or troughs. This unit also degrades into brain terrain . Brain terrain

1679-637: 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. Water here could have supported past life in these locations. Clay may also preserve fossils or other traces of past life. Pingos are believed to be present on Mars. They are mounds that contain cracks. They contain pure water ice, so they would be

1752-468: Is visible to distinguish the streak from its surroundings, except in the very highest resolution (<1 m/pixel) images. In many cases, the original surface texture of the slope is preserved and continuous across the streak, as though unaffected by events involved in dark streak formation (pictured left). The overall effect is equivalent in appearance to a partial shadow cast down the sloping surface. These observations indicate that whatever process forms

1825-547: The Arabian Peninsula . Research on the region was undertaken in 1997 and the individuality of the province better defined. An equatorial belt was noted with a crater age distinctly younger than the northern part of the province and of Noachis Terra to the south. This was interpreted as an "incipient back-arc system" provoked by the subduction of Mars lowlands under Arabia Terra during Noachian times. Regional fracture patterns were also explained in this manner, and

1898-487: The MGS Mars Orbiter Camera (MOC) in the late 1990s. The presence of new streaks showed that slope streaks are actively forming on Mars, on at least annual to decade-long timescales. A later, statistical treatment using overlapping MOC images spaced days to several years apart showed that slope streaks may form on Mars at a rate of about 70 per day. If accurate, this rate suggests that slope streaks are

1971-491: The Mars Global Surveyor (MGS) and Mars Reconnaissance Orbiter (MRO) spacecraft became available in the late 1990s and 2000s. The physical process that produces dark slope streaks is still uncertain. They are most likely caused by the mass movement of loose, fine-grained material on oversteepened slopes (i.e., dust avalanches). The avalanching disturbs and removes a bright surface layer of dust to expose

2044-643: The Mars Odyssey Neutron Spectrometer, researchers found that slope streaks in the Schiaparelli basin occur in areas predicted to yield between 7.0 and 9.0 weight percent Water Equivalent Hydrogen (WEH) in contrast to typical background values of less than 4% WEH. This relationship suggests a connection between high WEH percentages and the occurrence of dark slope streaks. However, any process that requires voluminous amounts of water (e.g., spring discharges) seems unlikely because of

2117-481: The University of Arizona 's Lunar and Planetary Laboratory by Ball Aerospace & Technologies Corp. It consists of a 0.5   m (19.7 in) aperture reflecting telescope , the largest so far of any deep space mission, which allows it to take pictures of Mars with resolutions of 0.3   m/pixel (1   ft/pixel), resolving objects below a meter across. HiRISE has imaged Mars exploration rovers on

2190-524: The HiWish program. The first is a context image from CTX to show where the HiRISE is looking. The following group of images show some significant images taken by the instrument. Some of these hint at possible sources of water for future colonists. The following set of pictures show first a full image of a scene and then enlargements from parts of it. A program called HiView can be used to produce more detailed views. Some pictures are in color. HiRISE takes

2263-572: The High Resolution Imaging Science Experiment ( HiRISE ) on MRO have shown that many slope streaks have relief , contrary to earlier descriptions in which no topographic distinction could be seen between the streaked and adjacent, non-streaked surface. The streaked surface is typically about 1 m lower than the non-streaked surface. This relief is only visible in maximum resolution images under optimal viewing conditions. Dark slope streaks are most common in

Arabia Terra - Misplaced Pages Continue

2336-513: The Martian surface in far greater detail than has previously been done from orbit. By doing so, it is allowing better studies of Martian channels and valleys, volcanic landforms, possible former lakes and oceans, sand dune fields such as Hagal and Nili Patera , and other surface landforms as they exist on the Martian surface. The general public is allowed to request sites for the HiRISE camera to capture (see HiWish ). For this reason, and due to

2409-1084: The area show how the impact site appeared to the Mars Odyssey Thermal Emission Imaging System infrared instrument before and after the impact. In the 2011 novel The Martian by Andy Weir, the protagonist encounters a dust storm in Arabia Terra while traveling from Acidalia Planitia to Schiaparelli crater . Many places on Mars show rocks arranged in layers. Rock can form layers in a variety of ways. Volcanoes, wind, or water can produce layers. Layers may be formed by groundwater rising up depositing minerals and cementing sediments. The hardened layers are consequently more protected from erosion. This process may occur instead of layers forming under lakes. A detailed discussion of layering with many Martian examples can be found in Sedimentary Geology of Mars. Many places on Mars show channels of different sizes. Many of these channels probably carried water, at least for

2482-499: The camera and prepare it for taking pictures of Mars. On March 10, 2006, MRO achieved Martian orbit and primed HiRISE to acquire some initial images of Mars. The instrument had two opportunities to take pictures of Mars (the first was on March 24, 2006) before MRO entered aerobraking, during which time the camera was turned off for six months. It was turned on successfully on September 27, and took its first high-resolution pictures of Mars on September 29. On October 6, 2006 HiRISE took

2555-431: The cluster is about 22 meters (72 feet) in diameter with close to the area of a basketball court. As the meteorite traveled through the Martian atmosphere it probably broke up; hence a tight group of impact craters resulted. Dark slope streaks have been seen for some time, and many ideas have been advanced to explain them. This research may have finally solved this mystery. Dust devils have even been observed to start

2628-425: The darkening is uncertain. The particle sizes involved are believed to be very small ( sand , silt , and clay -sized particles). No clasts large enough to be imaged are present, and the underlying bedrock slope is never exposed ( i.e., dust is avalanching on a surface of dust). Apparently, other optical, mechanical, or chemical properties are involved in producing the darker tone. Dark slope streaks commonly share

2701-552: The degradation can be reversed by heating the ADCs. On October 3, 2007, HiRISE was turned toward Earth , and took a picture of it and the Moon . In the full-resolution color image, Earth was 90 pixels across and the Moon was 24 pixels across from a distance of 142 million km. On May 25, 2008, HiRISE imaged NASA's Mars Phoenix Lander parachuting down to the surface of Mars. It was

2774-537: The equatorial regions of Mars, particularly in Tharsis , Arabia Terra , and Amazonis Planitia (pictured left). They occur between latitudes 39°N and 28°S. At their northern limits, they appear preferentially on warmer, south facing slopes. Curiously, slope streaks are also associated with areas that reach peak temperatures of 275K (2 °C), a temperature close to the triple point of water on Mars. This relationship has led some researchers to suggest that liquid water

2847-541: The equatorial regions of Mars. Total eruptive volumes of at least 4,600–7,200 km per caldera complex (over its history) were inferred. A meteorite impacted in Arabia Terra some time between 30 June 2002 and 5 October 2003. A single small crater of about 22.6 meters (about 74 feet) in diameter is surrounded by light and dark-toned ejecta – indicating that this impact excavated to a depth where light colored strata exists. The crater occurs near 20.6 degrees north latitude, 356.8 degrees west longitude, in Arabia Terra. Images of

2920-489: The first image of Victoria Crater , a site which was also under study by the Opportunity rover . In February 2007 seven detectors showed signs of degradation, with one IR channel almost completely degraded, and one other showing advanced signs of degradation. The problems seemed to disappear when higher temperatures were used to take pictures with the camera. As of March, the degradation appeared to have stabilized, but

2993-472: The first time that one spacecraft imaged the final descent of another spacecraft onto a planetary body. By 2010, HiRISE had imaged only about one percent of Mars's surface and by 2016 the coverage was around 2.4%. It was designed to capture smaller areas at high resolution—other instruments scan much more area to find things like fresh impact craters. MRO's Context Camera (CTX) captured two fresh impact craters (>130 meter each) formed on Mars in late 2021,

Arabia Terra - Misplaced Pages Continue

3066-464: The flow of briney fluids emerging from seeps at certain times of the Martian year. Unlike RSLs, dark slope streaks appear to occur sporadically throughout the Martian year, and their triggering seems unrelated to season or large regional events. Water tracks are little-studied slope features common in permafrost -dominated terrains in the arctic and Antarctic regions of Earth. They are zones of enhanced soil moisture that route water downslope over

3139-523: The formation of dark slope streaks. A team of researchers found an increase in dark slope streaks after S1222, a marsquake that was detected by the Insight lander. Slope streaks are one of the few geomorphic features forming on the surface of present-day Mars. New streaks were first identified by comparing images from the Viking Orbiters of the 1970s to images of the same locations taken by

3212-444: The former are younger than the latter. It is likely that bright slope streaks form from old dark slope streaks that have transitioned past a partially faded stage. This supposition is supported by geographical evidence indicating that bright slope streaks are slightly more common in regions where the formation rate of new dark slope streaks is low. In other words, areas with relatively many bright streaks tend to be less active and contain

3285-462: The future could be characterised by HiRISE color. On April 1, 2010, NASA released the first images under the HiWish program in which the public suggested places for HiRISE to photograph. One of the eight locations was Aureum Chaos. The first image below gives a wide view of the area. The next two images are from the HiRISE image. The following three images are among the first images taken under

3358-439: The group of meteorites shook dust loose enough to start dust avalanches that formed the many dark streaks. At first it was thought that the shaking of the ground from the impact caused the dust avalanches, but if that was the case the dark streaks would have been arranged symmetrically around the impacts, rather than being concentrated into curved shapes. The crater cluster lies near the equator 510 miles) south of Olympus Mons, on

3431-481: The images below. To see the features described in the caption and text, it may be necessary to enlarge the image by clicking on it. HiRISE High Resolution Imaging Science Experiment is a camera on board the Mars Reconnaissance Orbiter which has been orbiting and studying Mars since 2006. The 65 kg (143 lb), US$ 40 million instrument was built under the direction of

3504-401: The instrument is 64.2 kg. Red color images are at 20,048 pixels wide (6 km in a 300 km orbit), and blue-green and NIR are at 4,048 pixels wide (1.2 km). These are gathered by 14 CCD sensors, 2048 × 128 pixels . HiRISE's onboard computer reads out these lines in time with the orbiter's ground speed , meaning the images are potentially unlimited in height. Practically this

3577-502: The interactive image map below. Dark slope streak Dark slope streaks are narrow, avalanche -like features common on dust-covered slopes in the equatorial regions of Mars . They form in relatively steep terrain , such as along escarpments and crater walls. Although first recognized in Viking Orbiter images from the late 1970s, dark slope streaks were not studied in detail until higher-resolution images from

3650-567: The large Hesperian-age shield volcanoes of Tharsis or Elysium . Eden Patera, for example, is an irregular, 55 by 85 km depression up to 1.8 km deep, surrounded by ridged basaltic plains. It contains three linked interior depressions, demarcated by arcuate scarps, that have terraces suggestive of lava lake drainage and faults suggestive of collapse. The features indicative of impact origin that would be expected in an impact crater of comparable diameter and depth are absent. The authors regard crustal thinning due to regional extension to be

3723-565: The largest discovered by MRO. These seismic events were also detected by Interior Exploration using Seismic Investigations, Geodesy and Heat Transport (InSight) . The crater in Amazonis Planitia was discovered independently by both missions, while the crater in Tempe Terra was first observed by Insight and then searched for with CTX images. This identification further allowed development of new techniques by which ice deposits in

SECTION 50

#1732773332987

3796-399: The last three decades. This imbalance is unlikely to have persisted for geologically significant periods of time. One possible solution to the imbalance is that streaks last for centuries, but are wiped clean en masse after extremely rare but fierce dust storms (storms of a magnitude not observed on Mars since Viking). After the storm subsides, a thick layer of fresh dust is deposited to begin

3869-430: The latitudinal position of the center of the planned observation relative to the start of orbit. The start of orbit is located at the equator on the descending side (night side) of the orbit. A target code of 0000 refers to the start of orbit. The target code increases in value along the orbit track ranging from 0000 to 3595. This convention allows the file name ordering to be time sequential. The first three digits refers to

3942-529: The literature but are not discussed here. Bright slope streaks are streaks that have a lighter tone (about 2%) than their surroundings. (See F in Photo Gallery.) They are much rarer than dark slope streaks, but both types of streaks have similar morphologies and occur in the same regions of Mars. Evidence suggests that bright slope streaks are older than dark slope streaks. New bright slope streaks have never been observed, and dark slope streaks can be seen overlying bright slope streaks in some images, indicating that

4015-517: The mid-latitudes. It was first investigated in the Deuteronilus Mensae ( Ismenius Lacus quadrangle ) region, but it occurs in other places as well. The remnants consist of sets of dipping layers in craters and along mesas. Some regions of the upper plains unit display large fractures and troughs with raised rims; such regions are called ribbed upper plains. Fractures are believed to have started with small cracks from stresses. Stress

4088-456: The most dynamic geologic features observed on the surface of Mars. Dark slope streaks fade and disappear at a much slower rate than new ones appear. Most streaks identified in Viking images are still visible after decades, although a few have vanished. Researchers infer that streaks appear at a rate 10 times faster than they disappear, and that the number of slope streaks on Mars has increased in

4161-634: The overall thermodynamic instability of liquid water on Mars. Another model proposes that dark slope streaks are produced by ground-hugging density currents of dry dust lubricated by carbon dioxide (CO 2 ) gas. In this scenario, a small initial slump at the surface releases CO 2 gas adsorbed onto subsurface grains. This release produces a gas-supported dust flow that moves as a tenuous density current downslope. This mechanism may help explain slope streaks that are unusually long. Some observations suggest that dark slope streaks can be triggered by impacts. Pictures acquired by CTX in 2007 and 2010 showed

4234-426: The past that water ran on its surface. It has been known for some time that Mars undergoes many large changes in its tilt or obliquity because its two small moons lack the gravity to stabilize it, as the Moon stabilizes Earth; at times the tilt has even been greater than 80 degrees Parts of northern Arabia Terra contains the upper plains unit. The Upper Plains Unit is the remnants of a 50–100 meter thick mantling in

4307-443: The polar regions of Earth. They resemble dark slope streaks and recurring slope lineae, but have not yet been described on Mars. Many of the slope features on Mars may originate through a continuum of processes with dry mass wasting and minor fluvial (water-related) activity occupying opposite endpoints. Gullies are another feature common on slopes in the mid-latitude southern hemisphere of Mars They have received much attention in

4380-560: The rotational instability of the planet as a cause was not supported. It contains extension tectonic features A 2013 study proposed that a number of craters within Arabia Terra, including Eden Patera , Euphrates Patera , Siloe Patera , and possibly Semeykin crater , Ismenia Patera , Oxus Patera and Oxus Cavus , represent calderas formed by massive explosive volcanic eruptions (supervolcanoes) of Late Noachian to Early Hesperian age. Termed "plains-style caldera complexes", these very low relief volcanic features appear to be older than

4453-493: The same slope with other slope streaks of varying tones. The darkest streaks are presumed to be youngest; they have margins that are more sharply defined than streaks that are not as dark. This relationship suggests that streaks lighten and become more diffuse with age, probably because they become covered with fresh dust falling from the atmosphere. Faded dark slope streaks should not be confused with bright slope streaks (discussed below). Dust storms are common on Mars. At times

SECTION 60

#1732773332987

4526-508: The southern hemisphere between latitudes 48°S to 32°S. Repeat HiRISE images show that the markings appear and grow incrementally during warm seasons and fade in cold seasons. RSLs bear only a superficial resemblance to dark slope streaks. They are much smaller in width and have a different pattern of geographic occurrence and slope properties than dark slope streaks. RSLs seem to occur on bedrock slopes with seasonally high surface temperatures of 250–300K (-23–27 °C). These location may favor

4599-454: 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. The largest crater in

4672-541: The streaks, it affects only the very thinnest layer at the surface. Slope streaks are only about 10% darker than their surroundings but often appear black in images because the contrast has been enhanced ( stretched ). Albedo features cover the Martian surface at a wide variety of scales. They make up the classical light and dark marking seen on Mars through telescopes. (See Classical albedo features on Mars .) The markings are caused by differing proportions of dust covering

4745-476: The summer of 2011, a paper appeared in Science describing a new class of slope features with characteristics that suggest formation by seasonal releases of liquid water. (See H and I in Photo Gallery.) Called "recurring slope lineae" (RSL) , the features received a considerable amount of media attention. RSLs are narrow (0.5 to 5 meters) dark markings that preferentially occur on steep, equator-facing slopes in

4818-605: The surface, including the Opportunity rover and the ongoing Curiosity mission . In the late 1980s, Alan Delamere of Ball Aerospace & Technologies began planning the kind of high-resolution imaging needed to support sample return and surface exploration of Mars. In early 2001 he teamed up with Alfred McEwen of the University of Arizona to propose such a camera for the Mars Reconnaissance Orbiter (MRO), and NASA formally accepted it November 9, 2001. Ball Aerospace

4891-401: The surface. Martian dust is bright reddish ochre in color, while the bedrock and soil ( regolith ) is dark gray (the color of unaltered basalt ). Thus, dusty areas on Mars appear bright (high albedo), and surfaces with a high percentage of rocks and rock fragments are generally dark (low albedo). Most albedo features on Mars are caused by winds, which clear some areas of dust, leaving behind

4964-784: The top of the permanently frozen ground just below the surface ( ice table ). Although water tracks have not been specifically identified on Mars, several researchers have noted their morphological and spectroscopic similarity to Martian slope streaks. Like dark slope streaks, water tracks are narrow, sublinear features elongated in the downslope direction. They typically display a slight darkness relative to their surroundings and show little or no detectable relief. During peak flow conditions, they appear as damp, darkened, patches of soil that are generally less than 60 m wide and several hundred meters long. The dark surface discoloration vanishes in frozen water tracks during winter, rendering them nearly undetectable. Dark streaks and related features appear in

5037-479: The underlying cause remained unknown. Subsequent experiments with the Engineering Model (EM) at Ball Aerospace provided definitive evidence for the cause: contamination in the analog-to-digital converters (ADCs) which results in flipping bits to create the apparent noise or bad data in the images, combined with design flaws leading to delivery of poor analog waveforms to the ADCs. Further work showed that

5110-412: The unprecedented access of pictures to the general public, shortly after they have been received and processed, the camera has been termed "The People's Camera". The pictures can be viewed online, downloaded, or with the free HiView software. HiRISE was designed to be a high resolution camera from the beginning. It consists of a large mirror, as well as a large CCD camera. Because of this, it achieves

5183-704: The whole planet is enveloped in a dust storm, as shown in the pictures below. At moderate resolutions (20–50 m/pixel), dark slope streaks appear as thin, parallel filaments aligned downslope along crater rims and escarpments. They are often straight but may also be curved or sigmoid in shape. (See C in Photo Gallery.) Closer up, dark slope streaks typically have elongated, fan-like shapes (pictured right). They range from about 20 to 200 meters in width and are generally several hundred meters to over 1,000 meters long. Dark slope streaks exceeding 2 kilometers in length are uncommon; most terminate on slope and do not extend further out on to level terrain. A streak commonly starts at

5256-533: Was given the responsibility to build the camera and they delivered HiRISE to NASA on December 6, 2004 for integration with the rest of the spacecraft. It was prepared for launch on board the MRO on August 12, 2005, to the cheers of the HiRISE team who were present. During the cruise phase of MRO, HiRISE took multiple test shots including several of the Moon and the Jewel Box cluster. These images helped to calibrate

5329-520: Was led by Kaylan Burleigh, an undergraduate at the University of Arizona. After counting some 65,000 dark streaks around the impact site of a group of 5 new craters, patterns emerged. The number of streaks was greatest closer to the impact site. So, the impact somehow probably caused the streaks. Also, the distribution of the streaks formed a pattern with two wings extending from the impact site. The curved wings resembled scimitars, curved knives. This pattern suggests that an interaction of airblasts from

#986013