|
|
Cool Summer
| title |
Cool Summer |
| description |
Mars Global Surveyor captured this wide-angle view of the Martian North Pole in summer. It is one of more than 134,000 images in the Mars Orbiter Camera image gallery. A batch of 10,232 new images were added this week. |
|
Phobos' Stickney Crater
| title |
Phobos' Stickney Crater |
| date |
08.19.1998 |
| description |
This image of Phobos, the inner and larger of the two moons of Mars, was taken by Mars Global Surveyor in 1998. This image shows a close-up of the largest crater on Phobos, Stickney, 10 kilometers in diameter. Individual boulders are visible on the near rim of the crater, and are presumed to be ejecta blocks from the impact that formed Stickney. Some of these boulders are enormous, more than 50 meters across. Also crossing at and near the rim of Stickney are shallow, elongated depressions called grooves. This crater is nearly half the size of Phobos, and these grooves may be fractures caused by its formation. Phobos was observed by both the Mars Orbiter Camera (MOC) and Thermal Emission Spectrometer (TES). This image is one of the highest-resolution images (4 meters per pixel) ever obtained of the martian satellite. *Image Credit*: NASA, Jet Propulsion Laboratory, Malin Space Science Systems |
|
Olympus Mons, 1998
| title |
Olympus Mons, 1998 |
| date |
04.25.1998 |
| description |
Olympus Mons is a mountain of mystery. Taller than three Mount Everests and about as wide as the entire Hawaiian Island chain, this giant volcano is nearly as flat as a pancake. That is, its flanks typically only slope 20 to 50. The Mars Orbiter Camera (MOC) obtained this spectacular wide-angle view of Olympus Mons on Mars Global Surveyor's 263rd orbit, around 10:40 p.m. PDT on April 25, 1998. In the view presented here, north is to the left and east is up. The spacecraft was traveling from north to south (left to right). Although the camera looks straight down (towards the nadir) and cannot be pointed to the side, the wide angle camera has such a large field of view (it sees from horizon to horizon) that, in effect, it provides side looking views. Unlike some other MOC images, that have had to be warped to provide a view as if seen from a certain direction and altitude, this image shows what the camera saw without additional processing. It is easy to imagine that you are looking out a window at the surface of Mars from about 900 km (560 miles) up. The image was taken on a cool, crisp winter morning. The west side of the volcano (lower portion of view, above) was clear and details on the surface appear very sharp. The skies above the plains to the east of Olympus Mons (upper portion of view) were cloudy. Clouds were lapping against the lower east flanks of this 26 kilometers (16 miles) high volcano, but the summit skies were clear. When Mars Global Surveyor attains its Mapping Orbit in March 1999, the MOC wide angle camera system will be used to make daily, global maps of martian clouds and weather systems. The wide angle images will resemble weather satellite pictures of Earth, and will help the Mars science teams plan their observations and test computer-driven Mars weather prediction models. Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO. Image Note: This color picture was made using MOC red wide angle image 26301 and blue wide angle image 26302. The green channel was synthesized by averaging the red and blue bands. Color is not the true color of Mars as it would appear to the human eye (the actual colors would be more pale and contrast more subdued) *Image Credit*: NASA/JPL/Malin Space Science Systems |
|
High-Resolution MOC Image of
…
| title |
High-Resolution MOC Image of Phobos |
| date |
08.19.1998 |
| description |
This image of Phobos, the inner and larger of the two moons of Mars, was taken by the Mars Global Surveyor on August 19, 1998. This image shows a close-up of the largest crater on Phobos, Stickney, 10 kilometers (6 miles) in diameter. Individual boulders are visible on the near rim of the crater, and are presumed to be ejecta blocks from the impact that formed Stickney. Some of these boulders are enormous - more than 50 meters (160 feet) across. Also crossing at and near the rim of Stickney are shallow, elongated depressions called grooves. This crater is nearly half the size of Phobos and these grooves may be fractures caused by its formation. Phobos was observed by both the Mars Orbiter Camera (MOC) and Thermal Emission Spectrometer (TES). This image is one of the highest resolution images (4 meters or 13 feet per picture element or pixel) ever obtained of the Martian satellite. Malin Space Science Systems, Inc. and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Thermal Emission Spectrometer is operated by Arizona State University and was built by Raytheon Santa Barbara Remote Sensing. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO. *Image Credit*: Erich Karkoschka (University of Arizona Lunar & Planetary Lab) and NASA |
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Mars River Delta?
| title |
Mars River Delta? |
| description |
A high-resolution TIFF file of this image is available at http://photojournal.jpl.nasa.gov/catalog/PIA04869. Details in a fan-shaped deposit discovered by NASA's Mars Global Surveyor orbiter provide evidence that some ancient rivers on Mars flowed for a long time, not just in brief, intense floods. The apron of debris filling the middle of this picture from the spacecraft's Mars Orbiter Camera is a hardened and eroded distributory fan, a type of geological feature that includes river deltas and alluvial fans. Sediments transported through valleys by water on early Mars formed the 13-kilometer-long (8-mile) deposit in the distant past, when it was still possible for liquid water to flow across the martian surface. Mars Orbiter Camera team members published discovery of this feature in the online edition of the journal Science. What is important about it? First, it provides unequivocal evidence that some valleys on Mars experienced persistent flow over considerable periods of time, as rivers do on Earth. Second, because the fan is today a deposit of sedimentary rock, it demonstrates that some sedimentary rocks on Mars were deposited in a liquid environment. Third, the fan's general shape, the pattern of its channels, and its low slopes provide circumstantial evidence that the feature was an actual delta -- that is, a deposit made when a river or stream enters a body of water. If so, this landform is a strong indicator that some craters and basins on Mars once held lakes. Hundreds of other locations on Mars where valleys enter craters and basins have been imaged by the Mars Orbiter Camera, but none has shown landforms like those presented here. The picture is a mosaic of images acquired between August 2000 and September 2003. The area covered 14 kilometer (8.7 miles) by 19.3 kilometers (12 miles). North is up. Sunlight illuminates the scene from the left. The spacecraft's narrow-angle camera takes grayscale images, the color added is based on information from a camera on Mars Odyssey. The fan is in an unnamed crater that is 64 kilometers (40 miles) in diameter, at 24.3 degrees south latitude, 33.5 degrees west longitude. The crater lies northeast of a larger one named Holden Crater. The fan is a fossil landform. That is, it is an eroded remnant of a somewhat larger and thicker deposit. The originally loose sediment was turned to rock and then eroded over time to present the features seen today. The channels through which sediment was transported are no longer present. Instead, only their floors remain, and these have been elevated by erosion so that former channels now stand as ridges. The floors of former channels became inverted in this way because they were more resistant to the forces of erosion, indicating they either were more strongly cemented than surrounding materials, or they have more coarse grains (which are harder to remove), or both. *Image Credit*: NASA/JPL/Malin Space Science Systems |
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New Gullies on Martian Sand
…
| title |
New Gullies on Martian Sand Dune |
| description |
As part of extended-mission science investigation using the Mars Orbiter Camera on NASA's Mars Global Surveyor spacecraft, the camera team is re-imaging many locations where previous observations revealed gullies. The intent is to see if gully-forming processes are operating on Mars at the present time. The team has found one location where a new gully formed on a dune in an unnamed crater in the Hellespontus region of Mars, west of the Hellas Basin. This pair of narrow-angle images from the Mars Orbiter Camera shows the dune as it appeared on July 17, 2002, (left) and as it appeared on April 27, 2005, (right). The nearly three Earth years of intervening time amount to about 1.4 Mars years. During this period, a couple of gullies formed on the dune slip face. It is critical to recognize that the 2002 image was obtained at a time of year when the incident sunlight was coming in from a lower angle, relative to the horizon, than in the 2005 image. If the gullies had been present in 2002, their appearance would be sharper and more pronounced than they are in the 2005 image. The gullies simply did not exist on July 17, 2002. The steep walls of the gully alcove and channels suggests that the sand in this dune is somewhat cohesive, an observation common among martian sand dunes seen by the Mars Orbiter Camera over the past eight years. Image Credit: NASA/JPL/MSSS |
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Evidence of Martian Quakes
| title |
Evidence of Martian Quakes |
| description |
One of the many mysteries associated with martian geology is the origin of gullies found at latitudes poleward of 30 degrees latitude. Most of these gullies are found within craters or other depressions, and appear to be related to the bedrock. Several hypotheses have been proposed for their origin, including groundwater seepage and melting at the base of a dust-mantled snow pack. Some middle-latitude gullies are found on sand dunes. These gullies appear to be different from those found on the slopes of craters, but generally have been interpreted to form by similar processes. In the present martian environment, it is difficult to introduce water to the surface. The temperature and atmospheric pressure may permit water to exist, but the rate of heating of the ground and atmosphere, and the amount of energy available to warm the ground or melt snow, are not conducive to such processes. An alternative process of gully formation on these sand dunes involves frozen carbon dioxide trapped in the winter by windblown sand, then subliming rapidly enough for the escaping carbon-dioxide gas to make the sand flow as a gully-cutting fluid. As part of extended-mission science investigation using the Mars Orbiter Camera on NASA's Mars Global Surveyor spacecraft, the camera team is re-imaging many locations where previous observations revealed gullies. The intent is to see if gully-forming processes are operating on Mars at the present time. The team has found one location where a new gully formed on a dune in an unnamed crater in the Hellespontus region of Mars, west of the Hellas Basin. This pair of narrow-angle images from the Mars Orbiter Camera shows the dune as it appeared on July 17, 2002, (left) and as it appeared on April 27, 2005, (right). The nearly three Earth years of intervening time amount to about 1.4 Mars years. During this period, a couple of gullies formed on the dune slip face. It is critical to recognize that the 2002 image was obtained at a time of year when the incident sunlight was coming in from a lower angle, relative to the horizon, than in the 2005 image. If the gullies had been present in 2002, their appearance would be sharper and more pronounced than they are in the 2005 image. The gullies simply did not exist on July 17, 2002. The steep walls of the gully alcove and channels suggests that the sand in this dune is somewhat cohesive, an observation common among martian sand dunes seen by the Mars Orbiter Camera over the past eight years. Wider context for the dune is shown in a mosaic of two images from the Thermal Emission Imaging System on NASA's Mars Odyssey orbiter, encompassing the dark-toned sand dune field on the floor of a crater located near 49.8 degrees south latitude, 325.4 degrees west longitude. In this image, north is approximately up and sunlight illuminates the scene from the upper left. More information about this image can be found at: http://photojournal.jpl.nasa.gov/catalog/PIA04290 |
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Evidence for Recent Liquid W
…
| Title |
Evidence for Recent Liquid Water on Mars |
| Full Description |
Newton Crater is a large basin formed by an asteroid impact that probably occurred more than 3 billion years ago. It is approximately 287 kilometers (178 miles) across. The picture shown here (top) highlights the north wall of a specific, smaller crater located in the southwestern quarter of Newton Crater (above). The crater of interest was also formed by an impact, it is about 7 km (4.4 mi) across, which is about 7 times bigger than the famous Meteor Crater in northern Arizona in North America. The north wall of the small crater has many narrow gullies eroded into it. These are hypothesized to have been formed by flowing water and debris flows. Debris transported with the water created lobed and finger-like deposits at the base of the crater wall where it intersects the floor (bottom center top image). Many of the finger-like deposits have small channels indicating that a liquid, most likely water, flowed in these areas. Hundreds of individual water and debris flow events might have occurred to create the scene shown here. Each outburst of water from higher up on the crater slopes would have constituted a competition between evaporation, freezing, and gravity. The individual deposits at the ends of channels in this MOC image mosaic were used to get a rough estimate of the minimum amount of water that might be involved in each flow event. This is done first by assuming that the deposits are like debris flows on Earth. In a debris flow, no less than about 10% (and no more than 30%) of their volume is water. Second, the volume of an apron deposit is estimated by measuring the area covered in the MOC image and multiplying it by a conservative estimate of thickness, 2 meters (6.5 feet). For a flow containing only 10% water, these estimates conservatively suggest that about 2.5 million liters (660,000 gallons) of water are involved in each event, this is enough to fill about 7 community-sized swimming pools or enough to supply 20 people with their water needs for a year. The Mars Orbiter Camera (MOC) high resolution view is located near 41.1S, 159.8W and is a mosaic of three different pictures acquired between January and May 2000. The MOC scene is illuminated from the left, north is up. |
| Date |
06/22/2000 |
| NASA Center |
Jet Propulsion Laboratory |
|
Evidence for Recent Liquid W
…
| Title |
Evidence for Recent Liquid Water on Mars |
| Full Description |
Gullies eroded into the wall of a meteor impact crater in Noachis Terra. This high resolution view (top left) from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) shows channels and associated aprons of debris that are interpreted to have formed by groundwater seepage, surface runoff, and debris flow. The lack of small craters superimposed on the channels and apron deposits indicates that these features are geologically young. It is possible that these gullies indicate that liquid water is present within the martian subsurface today. The MOC image was acquired on September 28, 1999. The scene covers an area approximately 3 kilometers (1.9 miles) wide by 6.7 km (4.1 mi) high (note, the aspect ratio is 1.5 to 1.0). Sunlight illuminates this area from the upper left. The image is located near 54.8S, 342.5W. The context image (above) shows the location of the MOC image on the south-facing wall of an impact crater approximately 20 kilometers (12 miles) in diameter. The context picture was obtained by the Viking 1 orbiter in 1980 and is illuminated from the upper left. The large mound on the floor of the crater in the context view is a sand dune field. The Mars Orbiter Camera high resolution images are taken black-and-white (grayscale), the color seen here has been synthesized from the colors of Mars observed by the MOC wide angle cameras and by the Viking Orbiters in the late 1970s. A brief description of how the color was generated: The MOC narrow angle camera only takes grayscale (black and white) pictures. To create the color versions seen here, we have taken much lower resolution red and blue images acquired by the MOC's wide angle cameras, and by the Viking Orbiter cameras in the 1970s, synthesized a green image by averaging red and blue, and created a pallete of colors that represent the range of colors on Mars. We then use a relationship that correlates color and brightness to assign a color to each gray level. This is only a crude approximation of martian color. It is likely Mars would not look like this to a human observer at Mars. |
| Date |
06/22/2000 |
| NASA Center |
Jet Propulsion Laboratory |
|
High-Resolution MOC Image of
…
| Title |
High-Resolution MOC Image of Phobos |
| Description |
This image of Phobos, the inner and larger of the two moons of Mars, was taken by the Mars Global Surveyor on August 19, 1998. This image shows a close-up of the largest crater on Phobos, Stickney, 10 kilometers (6 miles) in diameter. Individual boulders are visible on the near rim of the crater, and are presumed to be ejecta blocks from the impact that formed Stickney. Some of these boulders are enormous - more than 50 meters (160 feet) across. Also crossing at and near the rim of Stickney are shallow, elongated depressions called grooves. This crater is nearly half the size of Phobos and these grooves may be fractures caused by its formation. Phobos was observed by both the Mars Orbiter Camera (MOC) and Thermal Emission Spectrometer (TES). This image is one of the highest resolution images (4 meters or 13 feet per picture element or pixel) ever obtained of the Martian satellite. Malin Space Science Systems, Inc. and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Thermal Emission Spectrometer is operated by Arizona State University and was built by Raytheon Santa Barbara Remote Sensing. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO. |
| Date |
08.19.1998 |
|
High-Resolution MOC Image of
…
| Title |
High-Resolution MOC Image of Phobos with Graphics Overlay |
| Description |
This image of Phobos, the inner and larger of the two moons of Mars, was taken by the Mars Global Surveyor on August 19, 1998. The white boxes indicate the location of the subframes or close-ups: that on the left is C and that on the right is D. Each box is 1.92 kilometers (1.19 miles) square. The image shows several new features of this lumpy moon -- features that are associated with the prominent crater seen in the upper left quarter of the image. This is the largest crater on Phobos, Stickney, 10 kilometers (6 miles) in diameter. Individual boulders are visible on the near rim of the crater (D), and are presumed to be ejecta blocks from the impact that formed Stickney. Some of these boulders are enormous - more than 50 meters (160 feet) across. Also crossing at and near the rim of Stickney are shallow, elongated depressions called grooves. This crater is nearly half the size of Phobos and these grooves may be fractures caused by its formation. The far wall of the crater shows lighter and darker streaks going down the slopes (C). Phobos was observed by both the Mars Orbiter Camera (MOC) and Thermal Emission Spectrometer (TES). This image is one of the highest resolution images (4 meters or 13 feet per picture element or pixel) ever obtained of the Martian satellite. Malin Space Science Systems, Inc. and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Thermal Emission Spectrometer is operated by Arizona State University and was built by Raytheon Santa Barbara Remote Sensing. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO. |
| Date |
08.19.1998 |
|
High-Resolution MOC Image of
…
| Title |
High-Resolution MOC Image of Phobos' Face |
| Description |
This image of Phobos, the inner and larger of the two moons of Mars, was taken by the Mars Global Surveyor on August 19, 1998. The minimum distance between the spacecraft and Phobos was 1,080 kilometers (671 miles). Phobos was observed by both the Mars Orbiter Camera (MOC) and Thermal Emission Spectrometer (TES). This image is one of the highest resolution images (4 meters or 13 feet per picture element or pixel) ever obtained of the Martian satellite. The image shows several new features of this lumpy moon -- features that are associated with the prominent crater seen in the upper left quarter of the image. This is the largest crater on Phobos, Stickney, 10 kilometers (6 miles) in diameter. Individual boulders are visible on the near rim of the crater (D), and are presumed to be ejecta blocks from the impact that formed Stickney. Some of these boulders are enormous - more than 50 meters (160 feet) across. Also crossing at and near the rim of Stickney are shallow, elongated depressions called grooves. This crater is nearly half the size of Phobos and these grooves may be fractures caused by its formation. The far wall of the crater shows lighter and darker streaks going down the slopes (C). The presence of material of different brightness on the far crater slopes and in some of the grooves shows that the satellite is heterogeneous (that is, it is made of a mixture of different types of materials). The motion of debris down slopes is guided by gravity, which is only about 1/1000th that of the Earth -- e.g., a 68-kilogram (150- pound) person would weigh only about 57 grams (2 ounces) on Phobos. Previous images from the Viking spacecraft in the 1970's were not of sufficient resolution to show the effectiveness of gravity on Phobos in moving material down slopes. Malin Space Science Systems, Inc. and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Thermal Emission Spectrometer is operated by Arizona State University and was built by Raytheon Santa Barbara Remote Sensing. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO. |
| Date |
08.19.1998 |
|
High-Resolution MOC Image of
…
| Title |
High-Resolution MOC Image of Phobos' Stickney Crater |
| Description |
This image of Phobos, the inner and larger of the two moons of Mars, was taken by the Mars Global Surveyor on August 19, 1998. This image is a close-up of the far wall of the Stickney crater, 10 kilometers (6 miles) in diameter, that is the largest crater on Phobos. This image shows lighter and darker streaks going down the slopes (C). The presence of material of different brightness on the far crater slopes and in some of the grooves shows that the satellite is heterogeneous (that is, it is made of a mixture of different types of materials). The motion of debris down slopes is guided by gravity, which is only about 1/1000th that of the Earth -- e.g., a 68-kilogram (150-pound) person would weigh only about 57 grams (2 ounces) on Phobos. Phobos was observed by both the Mars Orbiter Camera (MOC) and Thermal Emission Spectrometer (TES). This image is one of the highest resolution images (4 meters or 13 feet per picture element or pixel) ever obtained of the Martian satellite. Malin Space Science Systems, Inc. and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Thermal Emission Spectrometer is operated by Arizona State University and was built by Raytheon Santa Barbara Remote Sensing. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO. |
| Date |
08.19.1998 |
|
Wide Angle View of Arsia Mon
…
| Title |
Wide Angle View of Arsia Mons Volcano |
| Description |
Arsia Mons (above) is one of the largest volcanoes known. This shield volcano is part of an aligned trio known as the Tharsis Montes--the others are Pavonis Mons and Ascraeus Mons. Arsia Mons is rivaled only by Olympus Mons in terms of its volume. The summit of Arsia Mons is more than 9 kilometers (5.6 miles) higher than the surrounding plains. The crater--or caldera--at the volcano summit is approximately 110 km (68 mi) across. This view of Arsia Mons was taken by the red and blue wide angle cameras of the Mars Global Surveyor Mars Orbiter Camera (MOC) system. Bright water ice clouds (the whitish/bluish wisps) hang above the volcano--a common sight every martian afternoon in this region. Arsia Mons is located at 120o west longitude and 9o south latitude. Illumination is from the left. |
| Date |
09.28.1999 |
|
The Martian Prime Meridian
| title |
The Martian Prime Meridian |
| Description |
On Earth, the longitude of the Royal Observatory in Greenwich, England is defined as the 'prime meridian,' or the zero point of longitude. Locations on Earth are measured in degrees east or west from this position. The prime meridian was defined by international agreement in 1884 as the position of the large 'transit circle', a telescope in the Observatory's Meridian Building. The transit circle was built by Sir George Biddell Airy, the 7th Astronomer Royal, in 1850. (While visual observations with transits were the basis of navigation until the space age, it is interesting to note that the current definition of the prime meridian is in reference to orbiting satellites and Very Long Baseline Interferometry (VLBI) measurements of distant radio sources such as quasars. This 'International Reference Meridian' is now about 100 meters east of the Airy Transit at Greenwich.) For Mars, the prime meridian was first defined by the German astronomers W. Beer and J. H. Mädler in 1830-32. They used a small circular feature, which they designated 'a,' as a reference point to determine the rotation period of the planet. The Italian astronomer G. V. Schiaparelli, in his 1877 map of Mars, used this feature as the zero point of longitude. It was subsequently named Sinus Meridiani ('Middle Bay') by Camille Flammarion. When Mariner 9 mapped the planet at about 1 kilometer (0.62 mile) resolution in 1972, an extensive 'control net' of locations was computed by Merton Davies of the RAND Corporation. Davies designated a 0.5-kilometer-wide crater (0.3 miles wide), subsequently named 'Airy-0' (within the large crater Airy in Sinus Meridiani) as the longitude zero point. (Airy, of course, was named to commemorate the builder of the Greenwich transit.) This crater was imaged once by Mariner 9 (the 3rd picture taken on its 533rd orbit, 533B03) and once by the Viking 1 orbiter in 1978 (the 46th image on that spacecraft's 746th orbit, 746A46), and these two images were the basis of the martian longitude system for the rest of the 20th Century. The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) has attempted to take a picture of Airy-0 on every close overflight since the beginning of the MGS mapping mission. It is a measure of the difficulty of hitting such a small target that nine attempts were required, since the spacecraft did not pass directly over Airy-0 until almost the end of the MGS primary mission, on orbit 8280 (January 13, 2001). more information [ http://photojournal.jpl.nasa.gov/catalog/PIA03207 ] Photo Credit: NASA/JPL/Malin Space Science Systems |
|
Spectacular Layers Exposed i
…
| title |
Spectacular Layers Exposed in Becquerel Crater |
| Description |
Toward the end of its Primary Mapping Mission, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) acquired one of its most spectacular pictures of layered sedimentary rock exposed within the ancient crater Becquerel. Pictures such as this one from January 25, 2001, underscore the fact that you never know from one day to the next what the next MOC images will uncover. While the Primary Mission ends January 31, 2001, thousands of new pictures---revealing as-yet-unseen terrain on the red planet---may be obtained during the Extended Mission phase, scheduled to run through at least April 2002. The picture shown here reveals hundreds of light-toned layers in the 167 kilometers- (104 miles-) wide basin named for 19th Century French physicist Antoine H. Becquerel (1852-1908). These layers are interpreted to be sedimentary rocks deposited in the crater at some time in the distant past. They have since been eroded and exposed, revealing faults, dark layers between the bright layers, and a long geologic history (of unknown duration) recorded in these materials. Sets of parallel faults can be seen cutting across the layers in the left third of the image. Sunlight illuminates this scene from the top/upper right. Photo Credit: NASA/JPL/Malin Space Science Systems |
|
Pit Craters
| title |
Pit Craters |
| Description |
Among the most exciting places that the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) has photographed during its three and a half years in orbit has been this crater in central Noachis Terra. Located at 47°S, 355°W, the crater appears to have been almost completely filled, and subsequently eroded in localized pits, by unknown processes. In this one place we see elements of the two most important results of the MOC investigation--the discovery of young gullies formed by fluid erosion and the occurrence of thick sequences of layered rock attesting to a martian past of substantial geologic activity. more information [ http://photojournal.jpl.nasa.gov/catalog/PIA03205 ] Photo Credit: NASA/JPL/Malin Space Science Systems |
|
Lyot Crater
| title |
Lyot Crater |
| Description |
Martian 'fretted terrain' occurs in regions of buttes and mesas that stand at the erosional margin where northern low-lying plains meet the higher-standing cratered uplands. Found mostly in the mid-northern latitudes, some of the best examples of fretted terrain occur in Deuteronilus Mensae. Here, the interaction of the process that creates the mesas and buttes, the processes that modify these surfaces after they form, and the relationship of both of these processes with the 'near-instantaneous' event that formed the large crater Lyot, provide us places to look to decipher this small but important piece of martian geological history. Part of that effort requires us to acquire compositional information--from the Mars Global Surveyor Thermal Emission Spectrometer (TES), from the Thermal Infrared Mapping Spectrometer (THEMIS) and Gamma Ray Spectrometer (GRS) on the 2001 Mars Odyssey mission, and from color images such as these taken by Mars Global Surveyor's Mars Orbiter Camera. Subtle and not-so-subtle color variations seen in this composite of MOC images M23-01279 and M23-01280 (acquired January 19, 2001) trace both the movement of dark sand of possible volcanic origin and fresh, dark outcrops of unweathered bedrock. Photo Credit: NASA/JPL/Malin Space Science Systems |
|
Melas Chasma
| title |
Melas Chasma |
| Description |
One of the earliest observations made by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) was that the upper crust of the planet appears to be layered to considerable depth. This was especially apparent, early in the mission, in the walls of the the Valles Marineris chasms. However, layered mesas and mounds within the Valles Marineris troughs were recognized all the way back in 1972 with Mariner 9 images. The MOC image presented here shows many tens of layers of several meters (yards) thickness in the walls of a mesa in southern Melas Chasma in Valles Marineris. Erosion by mass wasting--landslides--has exposed these layers and created the dark fan-shaped deposits seen near the middle of 3 the image. The floor of Melas Chasma is dark and covered with many parallel ridges and grooves (lower 1/3 of image). In the lower left corner of the picture, a bright, circular dust devil can be seen casting a columnar shadow toward the left. This image, illuminated by sunlight from the right/lower right, covers an area 3 kilometers (1.9 miles) wide and 8.2 kilometers (5.1 miles) long. The scene is located near 10.1°S, 74.4°W and was acquired on July 11, 1999. North is toward the lower left. Photo Credit: NASA/JPL/Malin Space Science Systems |
|
Happy Face" Crater
| title |
Happy Face" Crater |
| Description |
The story of the Mars Orbiter Camera (MOC) onboard the Mars Global Surveyor (MGS) spacecraft began with a proposal to NASA in 1985. The first MOC flew on Mars Observer, a spacecraft that was lost before it reached the red planet in 1993. Now, after 14 years of effort, a MOC has finally been placed in the desired mapping orbit. The MOC team's happiness is perhaps best expressed by the planet Mars itself. On the first day of the Mapping Phase of the MGS mission--during the second week of March 1999--MOC was greeted with this view of "Happy Face Crater" (center right) smiling back at the camera from its location on the east side of Argyre Planitia. This crater is officially known as Galle Crater, and it is about 215 kilometers (134 miles) across. The picture was taken by the MOC's red and blue wide angle cameras. The bluish-white tone is caused by wintertime frost. Illumination is from the upper left. For more information and Viking Orbiter views of "Happy Face Crater," see http://www.msss.com/education/happy_face/happy_face.html [ http://www.msss.com/education/happy_face/happy_face.html ]. Photo Credit: NASA/JPL/Malin Space Science Systems |
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The Martian Northern Plains
| title |
The Martian Northern Plains |
| Description |
The martian northern plains remain nearly as mysterious today as they seemed 25 years ago during the Viking missions, even though one of those spacecraft--the Viking 2 lander--went to the northern plains. The northern plains are a lowland with fewer impact craters exposed at the surface than the heavily cratered martian southern highlands. Normally, surfaces with fewer craters are considered younger (i.e., they have had less time to accumulate craters). Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) high resolution images have shown that there really are a lot of craters in this region, but most are thinly buried beneath the plains. This low resolution view, covering an area 168 km (104 mi) by 124 km (77 km), shows a few craters at the surface (such as the one at the center of the image), and several circular features that represent craters that are mostly buried beneath the plains. This view was obtained in August 2002, sunlight illuminates the scene from the lower left. Images Credit: NASA/JPL/Malin Space Science Systems Caption by: K. S. Edgett and M. C. Malin, MSSS |
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18,812 New MGS MOC Images (E
…
| title |
18,812 New MGS MOC Images (E07-E12) Archived and Online |
| Description |
With the release this month (October 2002) of the latest installment of 18,812 images, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) passes another major milestone: more than 100,000 images have been validated and archived with the NASA Planetary Data System. The total number of archived images now available on-line is 112,218--more than twice the number of pictures acquired by the two Viking orbiters in 1976-1980. These pictures, from MOC extended mission subphases E07 through E12, were acquired August 2001 through January 2002. Every six months, after a six-month, labor-intensive archiving effort, the MOC team releases six months-worth of validated data to the NASA Planetary Data System. Mars Global Surveyor is now in its sixth year orbiting the red planet. MGS reached Mars on 12 September 1997. The first MOC images were obtained on 15 September 1997. The two pictures shown here were taken by the MOC narrow angle (high resolution) camera and "colorized" by applying the colors of Mars obtained by the MOC wide angle cameras. Both pictures show gullies on the walls of two different meteor impact craters that occur in Newton Basin in Sirenum Terra, Mars. The picture on the left, showing gullies in a crater at 42.4°S, 158.2°W, exhibits patches of wintertime frost on the crater wall, and dark-toned sand dunes on the floor. The picture on the right, from a crater at 39.0°S, 166.1°W, is one of the highest-resolution images obtained from Mars. It's resolution is 1.5 meters (5 feet) per pixel--objects the size of school buses can be resolved in the full size image. The gullies in these craters originate at a specific layer and may have formed by release of groundwater to the martian surface in geologically recent times. Photo Credit: NASA/JPL/Malin Space Science Systems |
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Strange Surfaces of Hellas P
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| title |
Strange Surfaces of Hellas Planitia |
| Description |
Sometimes Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images show things that look very bizzare. Unique among the MOC images is a suite of pictures from northwestern Hellas Planitia, such as the example shown here. The seeming familiarity of many MOC images, such as those showing earth-like sand dunes or stream-like gullies might give the impression that it is pretty easy to understand what MOC images are telling us about the geology of Mars. Indeed, much of what has been found by MOC is both interpretable and profound---layers recording the planet's early geologic history, evidence for recent groundwater emerging at the surface, dust storms and frost patterns that indicate seasonal change. Howver, many martian landforms remain unexplained and may require years of study. This picture, acquired in late October 2000, appears to be a jumble of plates or layers exposed at the surface but subsequently covered by a thin mantle to give the scene a uniform brightness. What are these materials? Perhaps time and careful study will tell. The picture is illuminated from the upper left and covers an area 2.9 by 4.1 km (1.8 by 2.5 mi) near 39.7°S, 306.7°W. Photo Credit: NASA/JPL/Malin Space Science Systems |
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Kaiser Crater
| title |
Kaiser Crater |
| Description |
As the Mars Global Surveyor Primary Mission draws to an end, the southern hemisphere of Mars is in the depths of winter. At high latitudes, it is dark most, if not all, of the day. Even at middle latitudes, the sun shines only thinly through a veil of water and carbon dioxide ice clouds, and the ground is so cold that carbon dioxide frosts have formed. Kaiser Crater (47°S, 340°W) is one such place. At a latitude comparable to Seattle, Washington, Duluth, Minnesota, or Helena, Montana, Kaiser Crater is studied primarily because of the sand dune field found within the confines of its walls (lower center of the Mars Orbiter Camera image, above). The normally dark-gray or blue-black sand can be seen in this image to be shaded with light-toned frost. Other parts of the crater are also frosted. Kaiser Crater and its dunes were the subject of an earlier presentation of results. Close-up pictures of these and other dunes in the region show details of their snow-cover, including small avalanches. The two Mars Global Surveyor Mars Orbiter Camera images that comprise this color view (M23-01751 and M23-01752) were acquired on January 26, 2001. Photo Credit: NASA/JPL/Malin Space Science Systems |
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Cydonia - "The Face
| title |
Cydonia - "The Face |
| Description |
In April 2000 we presented all the images that had been taken in the Cydonia region of Mars up until that time. This is the area where popular books, magazine articles, tabloids and other news/infotainment media have speculated that some of the hills and mesas were artificially-shaped by extraterrestrial intelligence into forms such as a pyramid, a cone, and, most publicized, a face. Owing to this continuing interest, the Mars Orbiter Camera (MOC) team has, whenever the Mars Global Surveyor spacecraft has flown over the region, commanded the MOC to take a picture. This picture shows a section of one of these, MOC image M16-00184, which shows a portion of the famed "face" landform. It covers an area 1.1 km (0.7 mi) across and 3.0 km (1.9 mi) down and is the highest-resolution view ever obtained for this feature (1.7 meters-- 5.6 feet-- per pixel).more information and images [ http://marsprogram.jpl.nasa.gov/mgs/msss/camera/images/01_31_01_releases/cydonia/index.html ] Photo Credit: NASA/JPL/Malin Space Science Systems |
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Rover Tracks Seen from Orbit
| title |
Rover Tracks Seen from Orbit |
| Description |
Wheel tracks left by NASA's Mars Exploration Rover Spirit, and even the rover itself, are visible in this image from the Mars Orbiter Camera on NASA's Mars Global Surveyor orbiter. North is up in this image. The tracks and rover are in the area south of a crater informally named "Bonneville," which is just southeast of the center of the image. The orbiter captured this image with use of an enhanced-resolution technique called compensated pitch and roll targeted observation. It took the picture on March 30, 2004, 85 martian days, or sols, after Spirit landed on Mars. The rover had driven from its landing site to the rim of Bonneville and was examining materials around the crater's rim. In this portion of the plains inside the much larger Gusev Crater, Spirit created wheel tracks darker than the undisturbed surface, as seen in the rover's own images showing the tracks (for example, http://photojournal.jpl.nasa.gov/catalog/PIA05450 [ http://photojournal.jpl.nasa.gov/catalog/PIA05450 ]). The contrast allows the tracks to show up in the image obtained from orbit. Also visible are Spirit's lander, backshell and parachute, and the scar where its heat shield hit the ground. The full image covers an area 3 kilometers (2 miles) wide, at 14.8 degrees south latitude and 184.6 degrees west longitude. Pixel size is about 1.5 meters (5 feet) by one-half meter (1.6 feet). Sunlight illuminates the scene from the upper left. Photo Credit: NASA/JPL/Malin Space Science Systems |
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Snapshot of Southern Spring
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| title |
Snapshot of Southern Spring Dust Storm Activity |
| Description |
Southern spring on Mars began with a "bang" in late June 2001 with a series of large dust storms that in some regions were still occurring each day well into September. By early July, the martian atmosphere was so hazy that opportunities for high resolution imaging of the planet were very limited. This wide angle camera view obtained by the Mars Global Surveyor Mars Orbiter Camera shows a large dust-raising event that occurred on July 8, 2001, as cold, raging winds blew off the frozen south polar cap (bottom) and rushed toward the network of troughs known as Labyrinthus Noctis near the martian equator (center). A second, smaller dust storm can be seen near the top just left of center, northwest of the Ascraeus Mons volcano (uppermost dark elliptical feature). To give a sense of scale, Ascraeus Mons is large enough to nearly cover the state of Washington, home of the famous (and much smaller) Mount St. Helens volcano. Sunlight illuminates the scene from the left, and north is toward the upper right. Image Credit: NASA/JPL/Malin Space Science Systems |
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Springtime North Polar Dust
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| title |
Springtime North Polar Dust Storms |
| Description |
As on the Earth, many severe storms brew in the martian polar regions. Here, temperature contrasts between the cold carbon dioxide ("dry ice") seasonal frost cap and the warm ground adjacent to it--combined with a flow of cool polar air evaporating off the cap--sweeps up dust and funnels it into swirling dust storms along the cap edge. The dust storms shown here were observed during the recent northern spring by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) in May 2002. The picture is a mosaic of daily global images from the MOC wide angle cameras. The north polar cap is the bright, frosty surface at the top. Images Credit: NASA/JPL/Malin Space Science Systems Caption by: K. S. Edgett and M. C. Malin, MSSS |
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Syrtis Major and Arabia Terr
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| title |
Syrtis Major and Arabia Terra |
| Description |
The Mars Global Surveyor Mars Orbiter Camera (MOC) has, in fact, three cameras. The narrow angle system obtains monochrome (black-and-white) super-high resolution views of the red planet, while the wide angle system obtains regional and global views in both the red and blue portions of the visible spectrum (to make a color image, the red and blue are averaged to obtain the green channel). The picture shown here is a composite of 9 color strips taken by the MOC on 9 successive orbits from pole-to-pole over the planet during the calibration phase of the mission in March 1999. The large, circular bright region that dominates the scene is Arabia Terra. Syrtis Major is the dark region toward the lower right. The north polar cap is visible at the top, and the bright feature at the lower right is the Hellas Basin. The color in this picture is computer-enhanced and is not shown as it would actually appear to the human eye. Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission. MSSS operates the camera from its facilities in San Diego, CA. The Jet Propulsion Laboratory's Mars Surveyor Operations Project operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO. Photo Credit: NASA/JPL/Malin Space Science Systems |
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Mars and Earth Dust Storms
| title |
Mars and Earth Dust Storms |
| Description |
seasonal meteorology [ http://www.thirdworld.org/role.html ] and the health of biological communities [ http://catbert.er.usgs.gov/african_dust/ ]. Photo Credit: NASA/JPL/Malin Space Science Systems, Spring on Mars...in either hemisphere...is a time for local and regional dust storms. These storms arise as the seasonal carbon dioxide frost cap, which can extend almost half-way to the equator, sublimes in the warming spring environment. Several factors promote these dust storms: * the atmospheric pressure is increasing as carbon dioxide frost (CO2) sublimes--higher pressure allows more dust to be suspended, and for a longer time, * the temperature contrast between the frost covered surface and immediately adjacent, recently defrosted surfaces is quite high, creating thermally-generated winds that circulate onto and off of the frost cap edge, * similar, temperature-driven winds arise as sublimation of frost covering sun-facing slopes and dark sandy surfaces deep within the polar region creates intense slope winds away from the higher-standing layered deposits and permanent cap. The roughly circular, polar orbit of the Mars Global Surveyor (MGS) spacecraft affords a view not unlike that seen by low Earth-orbiting environmental satellites. Mars is roughly 6800 km (4226 mi) in diameter, and a 370 km (230 mi) average altitude gives a diameter to altitude ratio for MGS of 18.4:1. For comparison, the SeaStar spacecraft in Earth orbit follows a very similar orbit: it's the diameter to altitude ratio is 17.5:1 (12,760 km or 7,928 mi diameter relative to a 705 km or 438 mi altitude). Each spacecraft covers the entire planet in 12 orbits. In this figure, we compare a recent dust storm on Mars with one that occurred earlier this year on Earth. The top image shows a martian north polar dust storm observed on 29 August 2000. This image is part of the Mars Orbiter Camera (MOC) daily global map--a low resolution, two-color view of Mars acquired from pole to pole every orbit. The storm is moving as a front, outward from a central "jet," and marginal "vortices" can be seen. In this image it extends about 900 km (560 mi) out from the north polar seasonal frost cap. The region on the right side of the Mars picture includes the north pole. The bottom image shows a terrestrial dust storm, seen in a SeaWiFS image [ http://seawifs.gsfc.nasa.gov/SEAWIFS/IMAGES/SEAWIFS_GALLERY.html ], acquired on 26 February 2000. This storm extends about 1800 km (1100 mi) off the coast of northwest Africa near the Earth's equator. Both images are shown at the same scale, 4 km (2.5 mi) per pixel. Dust storms play an important role in governing the climate of Mars. The rare, global storms alter the planet's total heat balance and promote variations in seasonal frost formation and dissipation, and greatly affect the distribution of water vapor. Local and regional storms, especially those in the polar regions, affect the rate at which seasonal frost evolves, and control local and regional weather patterns. On Earth, dust storms are also being recognized as contributing to environmental change, potentially influencing |
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Global Views of Mars in late
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| title |
Global Views of Mars in late Northern Summer |
| Description |
Mars Global Surveyor (MGS) orbits around the red planet 12 times a day. Each orbit goes from pole to pole. Over the course of a single day, the wide angle cameras of the Mars Orbiter Camera (MOC) system take 24 pictures--12 red and 12 blue--that are assembled to create a daily global map. Such global views are used to monitor the martian weather and observe changes in the patterns of frost and dust distribution on the surface. These two pictures are examples of what Mars looks like in late northern summer, which is also late southern winter. At this time of year, the south polar cap (bottom, white feature in each image) is very large, extending from the south pole northward to 60°S. Also at this time of year, clouds of water ice crystals are common over the four largest volcanoes in Tharsis. The picture on the right shows Tharsis, with the four volcanoes forming a triangle resembling the pattern of holes on a bowling ball. The image on the left is centered on Syrtis Major, a dark, windswept volcanic plain so large that it has been known to science since the first telescopes were turned toward Mars in the 1600s. The elliptical bright feature at lower-center in the left image is the Hellas Basin, the largest unequivocal impact basin (formed by an asteroid or comet) on the planet. Hellas is approximately 2200 km (1,370 mi) across. Image Credit: NASA/JPL/Malin Space Science Systems |
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A Mid-Summer's Dust Devil
| title |
A Mid-Summer's Dust Devil |
| Description |
One objective for the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) in the Extended Mission is to continue looking for changes and dynamic events taking place on the red planet. The feature shown here elicited gasps of exitement among the MOC Operations Staff when it was received in early April 2001. The feature is a dust devil. Dust devils are spinning, columnar vortices of wind that move across the landscape, pick up dust, and look somewhat like miniature tornadoes. Dust devils are a common occurrence in dry and desert landscapes on Earth as well as Mars. When this dust devil was spied in Amazonis Planitia on April 10th, the MOC was looking straight down. Usually when the camera is looking down the dust devil will appear as a circular, fuzzy patch with a straight shadow indicating its columnar shape. In this case, however, the dust devil is somewhat curved and kinked---its shape is best seen in the shadow it casts to the right. A thin, light-toned track has been left by the dust devil as it moved eastward across the landscape. Usually, such tracks are darker than the surroundings, in this case the light tone might indicate that the dust being removed by the passing dust devil is darker than the surface underneath the thin veneer of dust. Dust devils most typically form when the ground heats up during the day, warming the air immediately above the surface. As the warmed air nearest the surface begins to rise, it spins. The spinning column begins to move across the surface and picks up loose dust (if any is present). The dust makes the vortex visible and gives it the "dust devil" or tornado-like appearance. This dust devil occurred at an optimal time for dust devils whether on Earth or Mars---around 2 p.m. local time in the middle of Northern Hemisphere Summer. North is up, sunlight illuminates the scene from the left (west), and 500 meters is about 547 yards. The shadow cast by the dust devil goes off the edge of the image, but the length shown here (about 1.5 km) indicates that the dust devil was a bit more than 1 km (0.62 mi) in height. Images Credit: NASA/JPL/Malin Space Science Systems |
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A Mid-Northern Summer/Southe
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| title |
A Mid-Northern Summer/Southern Winter's Mars |
| Description |
MGS MOC Release No. MOC2-325, 04 April 2003 The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) began its daily global imaging campaign four years ago, on March 9, 1999. Since that time, slightly more than 2 full Martian years have elapsed, and MOC has obtained a complete daily record of the red planet's ever-changing weather patterns. Observing Mars every day over many years is critical to understanding how to forecast weather that may occur in the future, and MOC is the only U.S. instrument slated to orbit Mars until late 2006 that can provide this information. For example, the MOC team has found that many weather events repeat from one year to the next. Such knowledge is useful in considering where future spacecraft might land on Mars---a site that is known to experience a dust storm each year during the period a lander or rover will be operational might not be a good place to land. The six views of Mars shown here are a composite of the 24 daily global images acquired by MOC on February 14, 2003. At this time, it was the middle of summer in the northern hemisphere, and the middle of winter in the south. Taken together, the six views show the entire planet, its albedo (bright and dark) features, polar frosts, and cloud patterns. Water-ice clouds dominate the martian atmosphere over the tropical and sub-tropical latitudes, while orographically-generated (i.e. those associated with high-standing topography) water-ice clouds hang over each of the large volcanoes of the Tharsis and Elysium regions (see MOC2-326a, MOC2-326b, MOC326f). In the north polar region, the residual water-ice cap is fully exposed. In the southern hemisphere, the winter-time seasonal carbon dioxide frost cap can be seen, extending from the south pole (which is in darkness and not seen in these images) northward to 50°S latitude. In the deep Hellas Basin (an ancient, giant impact scar seen as the bright elliptical feature at the bottom of MOC2-326e), the winter-time cap extends northward to 31°S because the lower elevation permits carbon dioxide to freeze at slightly higher temperatures than at the high elevations elsewhere in the southern hemisphere. When these pictures were taken on February 14, 2003, dust storm activity was at a minimum and isolated to early morning hours around the edges of the north polar cap. Within a day, however, dust storm activity began to pick up in both hemispheres--as was expected from previous MOC images at this time of year in 1999 and 2001--and dust storms remained active through the rest of February and March. Images Credit: NASA/JPL/Malin Space Science Systems Caption by: B. C. Cantor, K. S. Edgett, and M. C. Malin, MSSS |
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Layers and a Dust Devil in M
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| title |
Layers and a Dust Devil in Melas Chasma |
| Description |
One of the earliest observations made by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) was that the upper crust of the planet appears to be layered to considerable depth. This was especially apparent, early in the mission, in the walls of the the Valles Marineris chasms. However, layered mesas and mounds within the Valles Marineris troughs were recognized all the way back in 1972 with Mariner 9 images. The MOC image presented here shows many tens of layers of several meters (yards) thickness in the walls of a mesa in southern Melas Chasma in Valles Marineris. Erosion by mass wasting--landslides--has exposed these layers and created the dark fan-shaped deposits seen near the middle of the image. The floor of Melas Chasma is dark and covered with many parallel ridges and grooves (lower 1/3 of image). In the lower left corner of the picture, a bright, circular dust devil can be seen casting a columnar shadow toward the left. This image, illuminated by sunlight from the right/lower right, covers an area 3 kilometers (1.9 miles) wide and 8.2 kilometers (5.1 miles) long. The scene is located near 10.1°S, 74.4°W and was acquired on July 11, 1999. North is toward the lower left. Photo Credit: NASA/JPL/Malin Space Science Systems |
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| Description |
Mars in Early Northern Spring MGS MOC Release No. MOC2-329, 04 April 2003 In April 2003, the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) operations team completed the validation and archiving of MOC data acquired between February and July 2002. This was a period that included the end of northern winter and the start of spring in that hemisphere. This composite of MOC daily global images, acquired in early May 2002, shows what the planet looked like in early northern spring. The retreating north polar seasonal carbon dioxide frost cap is seen at the top of this view. Other white features in the image are clouds of water ice crystals in the martian atmosphere. The left half of this picture shows the Tharsis region, which includes several very large volcanoes. Olympus Mons, the largest martian volcano, is as wide as the Hawaiian Island chain is long, it is the dark, somewhat circular feature at the far left. Toward the lower right, the system of deep Valles Marineris chasms can be seen. Images Credit: NASA/JPL/Malin Space Science Systems Caption by: K. S. Edgett and M. C. Malin, MSSS |
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Spallanzani Crater
| title |
Spallanzani Crater |
| Description |
Although most of the best examples of layered sedimentary rock seen on Mars are found at equatorial and sub-tropical latitudes, a few locations seen at mid- and high-latitudes suggest that layered rocks are probably more common than we can actually see from orbit. One extremely good example of these "atypical" layered rock exposures is found in the 72 km-diameter (45 miles) crater, Spallanzani (58.4°S, 273.5°W). Located southeast of Hellas Planitia, the crater is named for the 18th Century Italian biologist, Lazzaro Spallanzani (1729-1799). Picture A presents a composite of the best Viking orbiter image (VO2-504B55) of the region with 4 pictures obtained June 1999 through January 2001 by the Mars Global Surveyor Mars Orbiter Camera (MOC). Each MOC narrow angle image is 3 km across. Taken in the MOC's "survey mode," all four images were acquired at roughly 12 meters (39 ft) per pixel. Picture B zooms-in on the portion of the composite image that includes the 4 MOC images (the 100%-size view is 20 m (66 ft) per pixel). Other craters in the region near Spallanzani show features--at Viking Orbiter scale--that are reminiscent of the layering seen in Spallanzani. Exactly what these layers are made of and how they came to be where we see them today are mysteries, but it is possible that they are similar to the materials seen in the many craters and chasms of the equatorial latitudes on Mars. Images Credit: NASA/JPL/Malin Space Science Systems |
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Dust Storms of 2001
| title |
Dust Storms of 2001 |
| Description |
The wide angle cameras of the Mars Orbiter Camera (MOC) system onboard Mars Global Surveyor (MGS) are used every day to gather a global view of changes occurring in martian weather and surface frost patterns. Late in June 2001, as southern winter transitioned to spring, dust storm activity began to pick up as cold air from the south polar cap moved northward toward the warmer air at the martian equator. By early July, dust storms had popped up all over the planet, particularly throughout the southern hemisphere and in the Elysium/Amazonis regions of the northern hemisphere. Soon, the entire planet--except the south polar cap--was enshrouded in dust. Similar storms have occurred before. For example, the planet was obscured by dust when the Mariner 9, Mars 2, and Mars 3 spacecraft reached the planet in late 1971. The MGS MOC images showed the evolution of the 2001 great dust storm period. There was never a time when the entire planet was in the midst of a single storm. Several large storms would occur at the same time, and dust was kicked high into the atmosphere to cause much of the rest of the planet to be obscured. The dust storms largely subsided by late September 2001, but the atmosphere remained hazy into November of that year. The two pictures shown here come from the E05 (June 2001) and E06 (July 2001) subphases of the MGS MOC Extended Mission. The view from June shows the Tharsis volcanic region (left), Valles Marineris chasms (right) and the late winter south polar cap (bottom). The view from July shows the same regions, but most of the details are hidden by dust storms and haze. Image Credit: NASA/JPL/Malin Space Science Systems |
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| Description |
The Martian Limb MGS MOC Release No. MOC2-328, 04 April 2003 The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) red and blue wide angle cameras provide daily coverage of the planet "from limb to limb." The "limbs" are the edges of the planet as seen to the west and east of the spacecraft. Depending on weather conditions, clouds or haze can sometimes be seen above the limb. This picture was taken by the blue camera in December 2002. It is an oblique view looking westward across heavily cratered terrain at high southern latitudes. A thin line of haze, high in the martian atmosphere, can be seen above the planet's surface. The view of craters in the foreground is enhanced by the presence of bright, winter-time carbon dioxide frost. The darkness above the limb is outer space. Images Credit: NASA/JPL/Malin Space Science Systems Caption by: K. S. Edgett and M. C. Malin, MSSS |
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Highest-Resolution View of "
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| title |
Highest-Resolution View of "Face on Mars |
| Description |
A key aspect of the Mars Global Surveyor (MGS) Extended Mission is the opportunity to turn the spacecraft and point the Mars Orbiter Camera (MOC) at specific features of interest. A chance to point the spacecraft comes about ten times a week. Throughout the Primary Mission (March 1999 - January 2001), nearly all MGS operations were conducted with the spacecraft pointing "nadir"---that is, straight down. In this orientation, opportunities to hit a specific small feature of interest were in some cases rare, and in other cases non-existent. In April 1998, nearly a year before MGS reached its Primary Mission mapping orbit, several tests of the spacecraft's ability to be pointed at specific features was conducted with great success (e.g., Mars Pathfinder landing site, Viking 1 site, and Cydonia landforms). When the Mars Polar Lander was lost in December 1999, this capability was again employed to search for the missing lander. Following the lander search activities, a plan to conduct similar off-nadir observations during the MGS Extended Mission was put into place. The Extended Mission began February 1, 2001. On April 8, 2001, the first opportunity since April 1998 arose to turn the spacecraft and point the MOC at the popular "Face on Mars" feature. Viking orbiter images acquired in 1976 showed that one of thousands of buttes, mesas, ridges, and knobs in the transition zone between the cratered uplands of western Arabia Terra and the low, northern plains of Mars looked somewhat like a human face. The feature was subsequently popularized as a potential "alien artifact" in books, tabloids, radio talk shows, television, and even a major motion picture. Given the popularity of this landform, a new high-resolution view was targeted by pointing the spacecraft off-nadir on April 8, 2001. On that date at 20:54 UTC (8:54 p.m., Greenwich time zone), the MGS was rolled 24.8° to the left so that it was looking at the "face" 165 km to the side from a distance of about 450 km. The resulting image has a resolution of about 2 meters (6.6 feet) per pixel. If present on Mars, objects the size of typical passenger jet airplanes would be distinguishable in an image of this scale. An earlier picture obtained in June 2000 was combined with the new, April 2001 image, to produce a stereo ("3-D") view of the western portion of the hill ("3-D" glasses with red for left eye and blue for right eye are needed to view the anaglyph). The large "face" picture, above, covers an area about 3.6 kilometers (2.2 miles) on a side, the 3-D picture [ http://www.msss.com/mars_images/moc/extended_may2001/face/index.html ] is about 1 km (0.62 mi) wide. Sunlight illuminates the images from the left/lower left. Images Credit: NASA/JPL/Malin Space Science Systems |
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Northern Terra Meridiani's "
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| title |
Northern Terra Meridiani's "Monument Valley |
| Description |
Northern Terra Meridiani, near the intersection of the martian equator and prime meridian, is a region of vast exposures of layered rock. A thermal image from the Phobos 2 orbiter in 1989 showed these materials to be anomalously cool during the daytime, an observation very suggestive of dense, hardened materials like rock. Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images of this region show layered material exposed in cliffs, buttes, and mesas that in some ways resemble the rock outcrops of northern Arizona and southeastern Utah in North America (e.g., Monument Valley, Canyonlands, Zion National Park, Four Corners). MGS MOC Extended Mission operations have included several hundred opportunities for the spacecraft to be rolled off-nadir (i.e., at an angle other than "straight down") to take pictures that repeat earlier MOC coverage. These repeat images, because they are taken from a different angle, can be combined with the original picture to produce a stereoscopic ("3-D") view. The image shown here is a composite of two pictures, the first taken October 23, 2000, the second acquired by pointing the spacecraft off-nadir on May 15, 2001. This view shows four buttes and a pinnacle (near left-center) composed of eroded, layered rock. The four buttes are each capped by the remains of a single layer of rock that is harder than the materials beneath it. It is the presence of this caprock that has permitted these buttes to remain standing after surrounding materials were eroded away. Like the buttes of Monument Valley in the Navajo Nation on the Arizona/Utah border, these are believed to consist of sedimentary rocks, perhaps deposited in water or by wind, though some scientists have speculated that they could be made of thick accumulations of volcanic ash. The image covers an area approximately 3 km (1.9 mi) across and is illuminated by sunlight from the left. To see the image in 3-D, red (left-eye) and blue (right-eye) "3-D" glasses are required. Photo Credit: NASA/JPL/Malin Space Science Systems. |
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Changes Over a Martian Year
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| title |
Changes Over a Martian Year -- New Dark Slope Streaks in Lycus Sucli |
| Description |
Now in its Extended Mission, Mars Global Surveyor (MGS) is into its second Mars year of systematic observations of the red planet. With the Extended Mission slated to run through April 2002, the Mars Orbiter Camera (MOC) is being used, among other things, to look for changes that have occurred in the past martian year. Because Mars is farther from the Sun than Earth, its year is longer---about 687 Earth days. The two pictures shown here cover the same portion of Lycus Sulci, a rugged, ridged terrain north of the giant Olympus Mons volcano. The interval between the pictures span 92% of a martian year (August 2, 1999 to April 27, 2001). Dark streaks considered to result from the avalanching of dry, fine, bright dust are seen in both images. The disruption of the surface by the avalanching materials is thought to cause them to appear darker than their surroundings, just as the 1997 bouncing of Mars Pathfinder's airbags and the tire tracks made by the Sojourner rover left darkened markings indicating where the martian soil had been disrupted and disturbed. The arrows in the April 2001 picture indicate eight new streaks that formed on these slopes in Lycus Sulci since August 1999. These observations suggest that a new streak forms approximately once per martian year per kilometer (about 0.62 miles) along a slope. In both images, north is toward the top/upper right and sunlight illuminates each from the left. Dark (as well bright) slope streaks are most common in the dust-covered martian regions of Tharsis, Arabia, and Elysium. Additional examples of dark slope streaks can be seen in the following earlier MOC image media releases: * "Recent Movements: New Landslides in Less than 1 Martian Year," March 12, 2000 [ http://www.msss.com/mars_images/moc/lpsc2000/3_00_massmovement/ ] * "Dark Slope Streaks on Elysium Basin Buttes," July 19, 1999 [ http://www.msss.com/mars_images/moc/7_19_99_fifthMars/18_slopes/ ] Images Credit: NASA/JPL/Malin Space Science Systems |
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Mars Express Seen by Mars Gl
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Mars Express Seen by Mars Global Surveyor, This picture shows the Mars Express orbiter as a white, wavy, slanted streak centered against a vast, deep black background. The lines of the spacecraft make it appear somewhat like a jagged, three-inch worm in space. |
| Description |
This picture of the European Space Agency's Mars Express spacecraft by the Mars Orbiter Camera on NASA's Mars Global Surveyor is from the first successful imaging of any spacecraft orbiting Mars by another spacecraft orbiting Mars. The picture is a composite of two views of Mars Express that Mars Orbiter Camera acquired on April 20, 2005, from distances of about 250 and 370 kilometers (155 and 229 miles). Owing to the large distance between Mars Global Surveyor and Mars Express when the two views could be acquired and to a substantial cross-track component of apparent motion for which no correction could be made, Mars Express appears in the image as a narrow blur rather than as a well-defined spacecraft. It appears in the image to be about 1.5 meters in the small dimension and 15 meters in the long dimension, which is consistent with the viewing distance, pixel scale, and encounter geometry. The components of Mars Express when viewed from the same angle as this image can be seen in an artist's rendition http://photojournal.jpl.nasa.gov/figures/PIA07944_fig1.jpg and an annotated rendition http://photojournal.jpl.nasa.gov/figures/PIA07944_fig2.jpg of the spacecraft. Mars Express was launched on June 3, 2003, and reached Mars on Dec. 25, 2003. Mars Global Surveyor left Earth on Nov. 7, 1996, and arrived in Mars orbit on Sept. 12, 1997. JPL, a division of the California Institute of Technology, Pasadena, manages Mars Global Surveyor for NASA's Science Mission Directorate, Washingon, D.C. Credit: NASA/JPL/MSSS |
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Happy 8th Birthday, MGS
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Happy 8th Birthday, MGS |
| Description |
. The reason there is no MOC image for April 1999 is a product of the MGS spacecraft's 8-year history at Mars. MGS was certainly in orbit at the time, and it was taking data during the month of April. However, the camera did not obtain any images between 17 and 28 April because the spacecraft encountered, and then had to be recovered from, a problem. It was at this time that the spacecraft team realized that there is something obstructing the full movement of MGS's high gain antenna. A work-around was created and the mission has continued, ever since, but the down-side was that MOC did not have the opportunity in 1999 to provide detailed observations of the north polar, summertime, annular cloud. The remaining three pictures show MGS MOC views of the cloud feature, as it appeared in the subsequent 3 Mars years. Each year, the cloud appeared at about the same time or slightly earlier than in the previous year. Despite its superficial resemblance to a hurricane or cyclone on Earth, the northern summer annular cloud does not rotate. The cloud forms as different currents of air merge in the morning hours in the polar region, by afternoon, the annular cloud typically dissipates or breaks up into smaller clouds. MGS MOC has observed other repeated phenomena over the course of its 8-year mission orbiting Mars. These include dust storms that repeat, year after year, in the same location within a week or two of the time it occurred in the previous year. They also include dust devils in northern Amazonis, which start up shortly after the first day of spring, and keep occurring nearly every afternoon until a few days into the autumn season. MOC is continuing its mission to monitor the planet -- in 2006, MOC's weather observations will be used to provide guidance for the aerobraking maneuvers of the Mars Reconnaissance Orbiter (MRO). MOC images will show whether dust storms are occurring, and whether the dust suspended by these storms will impact the density of the atmosphere at the altitudes that MRO is passing through to slow the spacecraft and change its orbit to the one desired for the MRO primary mission. Location Near: 90°N Season: Northern Summer Credit: NASA/JPL/MSSS, Mars Global Surveyor (MGS) entered Mars orbit on 12 September 1997. Today, we celebrate the MGS's 8th anniversary! The 8 Earth years that MGS has been in orbit span portions of 5 martian years. One of the critical science activities that the Mars Orbiter Camera (MOC) has been engaged in for the past 8 years has been to document daily changes in the martian weather. Each day that MOC is operating, the red and blue wide angle cameras are used to build up a daily global map. These maps provide a record of the planet's changing meteorological conditions. One of the most exciting observations that the MOC wide angle cameras have made during these 8 years is that the red planet has very repeatable weather patterns. In light of weather-related problems and disruptions that occur every year on Earth, one can only imagine how nice it would be if our planet followed a similar, repeated pattern. The four pictures shown here provide an example of one of the weather phenomena that repeat each martian year. Each picture shows the north polar region of Mars during the northern summer season. Each picture is a composite of several images acquired at different visible wavelengths to give a color view of the planet. Each picture was taken about 1 Mars year apart, and each shows an annular (circular) cloud located over the same terrain each summer. The first picture, acquired in April 1999, is actually not from the MGS MOC instrument. It was obtained by the Hubble Space Telescope (HST) Wide Field Planetary Camera 2 (WFPC2) and was originally released by the Space Telescope Science Institute on 19 May 1999 [ http://hubblesite.org/newscenter/newsdesk/archive/releases/1999/22/ ] |
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Mars Global Surveyor Celebra
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| title |
Mars Global Surveyor Celebrates Discovery of Deimos |
| Description |
, University of Western Ontario (London, Ontario, Canada) for his input on the geography of Deimos and the locations of Swift and Voltaire. Credit: NASA/JPL/Malin Space Science Systems, One might say that today is Deimos' birthday. To celebrate, we present here the first and only Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image of this tiny moon. Deimos was discovered 129 years ago on 11 August 1877 (U.S. time, it was 12 August UTC), by U.S. astronomer Asaph Hall. It was the first of two major discoveries that he made that month, less than a week later, he found the other, inner martian satellite, Phobos. About a month before the 129th anniversary of its discovery, on 10 July 2006, Mars Global Surveyor was pointed away from the martian surface, out toward distant Deimos. Imaging the smaller of the two martian moons was the result of a combined effort between MGS engineers at Lockheed Martin Astronautics and MOC operations engineers at Malin Space Science Systems. When the picture was acquired, Deimos was about 22,985 kilometers (14,285 miles) from MGS. This results in an image of approximately 95 meters (about 312 feet) per pixel. Higher resolution images were obtained by the Viking orbiters in the 1970s - some of those pictures were so good that boulders could be resolved on the moon's surface. While the MOC image is at a lower resolution than the Viking data, acquiring an image of Deimos helps refine the understanding of the tiny moon's orbit and geography. The two craters, Voltaire and Swift, are presently the only craters with names on all of Deimos. Author Jonathan Swift, in his 1726 "Gulliver's Travels," had coincidentally surmised that Mars has two moons. Sunlight illuminates the scene from the upper right. MGS previously imaged the inner, larger moon, Phobos, on several occasions in 1998 and 2003. In 1998, MGS was in an elliptical orbit that permitted the spacecraft to actually fly past the moon, this was not done for Deimos because MGS hasn't been out past the orbit of Deimos since it arrived at the red planet in 1997. To review the MOC images of Phobos, visit: * Moons of Mars [ http://www.msss.com/mars_images/moc/themes/MOONS.html ] * 1998 First Phobos Encounter [ http://www.msss.com/moc_gallery/ab1_m04/images/SP247603.html ] * 1998 Second Phobos Encounter [ http://www.msss.com/moc_gallery/ab1_m04/images/SP250103.html ] * 1998 Third Phobos Encounter, first view [ http://www.msss.com/moc_gallery/ab1_m04/images/SP252603.html ] * 1998 Third Phobos Encounter, second view [ http://www.msss.com/moc_gallery/ab1_m04/images/SP252604.html ] * 1998 Fourth Phobos Encounter [ http://www.msss.com/moc_gallery/ab1_m04/images/SP255103.html ] * 2003 view of Phobos [ http://www.msss.com/moc_gallery/r03_r09/images/R06/R0600044.html ] The MGS MOC team thanks Philip J. Stooke [ http://www.ssc.uwo.ca/geography/spacemap/index.htm ] |
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Spirit Rover on 'Husband Hil
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| title |
Spirit Rover on 'Husband Hill' |
| Description |
Two Earth years ago, NASA's Mars Exploration Rover Spirit touched down in Gusev Crater. The rover marked its first Mars-year (687 Earth days) anniversary in November 2005. Shortly before Spirit's Martian anniversary, the Mars Orbiter Camera on NASA's Mars Global Surveyor acquired an image covering approximately 3 kilometers by 3 kilometers (1.9 miles by 1.9 miles) centered on the rover's location at that time in the "Columbia Hills.""Husband Hill," the tallest in the range, is just below the center of the image. The image has a resolution of about 50 centimeters (1.6 feet) per pixel. North is up, illumination is from the left. The location is near 14.8 degrees south latitude, 184.6 degrees west longitude. The image was acquired on Nov. 2, 2005. A white box indicates the location of an excerpted portion on which the location of Spirit on that date is marked. Dr. Timothy J. Parker of the Mars Exploration Rover team at the NASA's Jet Propulsion Laboratory, Pasadena, Calif., confirmed the location of the rover in the image. The region toward the bottom of the image shows the area where the rover is currently headed. The large dark patch and other similar dark patches are accumulations of windblown sand and granules. Credit: NASA/JPL-Caltech/MSSS |
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| Description |
Landslide in Kasei Valles MGS MOC Release No. MOC2-326, 04 April 2003 The Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) continues in 2003 to return excellent, high resolution images of the red planet's surface. This nearly 1.5 meters (5 ft.) per pixel view of a landslide on a 200 meter-high (219 yards-high) slope in Kasei Valles was specifically targeted for scientific investigation by rotating the MGS spacecraft about 7.8° off-nadir in January 2003. The scar left by the landslide reveals layers in the bedrock at the top the slope and shows a plethora of dark-toned, house-sized boulders that rolled down the slope and collected at the base of the landslide scar. A few meteor impact craters have formed on the landslide deposit and within the scar, indicating that this landslide occurred a very long time ago. Sunlight illuminates this scene from the left/lower left, the landslide is located near 28.3°N, 71.9°W. Images Credit: NASA/JPL/Malin Space Science Systems Caption by: K. S. Edgett and M. C. Malin, MSSS |
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Rolling Stones Make New Boul
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| title |
Rolling Stones Make New Boulder Tracks |
| Description |
When a boulder rolls down a dusty slope, it can leave behind a trail of depressions. Usually known as boulder tracks, these features have been documented and studied on Earth, the Moon, and Mars. Geologists studying the Moon and Mars can use these tracks to learn about the physical properties of the fine-grained debris encountered by the boulder as it rolled down the slope. Because of the high-resolution capability (0.5 to 12 meters, 1.6 to 39 feet, per pixel) of the Mars Orbiter Camera on NASA's Mars Global Surveyor spacecraft, dozens of boulder track sites have been identified on the red planet. A Mars Orbiter Camera image of one set of boulder tracks in a south mid-latitude crater (located near 35.8 degrees south latitude, 158.4 degrees west longitude) was obtained on Nov. 14, 2003, (left). A second image of the same site, from Dec. 4, 2004, (right) shows that more than a dozen new boulder tracks formed on the crater wall during the intervening time. Mars is an active planet, with geologic changes occurring -- at some scale -- every day. In this case, some time between mid November 2003 and early December 2004, a suite of boulders became dislodged from the crater wall, then rolled and perhaps bounced their way to the crater floor. Wider context for the site can be seen in a mosaic of Mars Orbiter Camera wide-angle images acquired in May 1999 (insert MOC2-1213a). The white box indicates the location of the later, higher-resolution views. Why the new boulders slid down the slope is unknown. This is the product of a mass movement (landsliding) process. That is, gravity is the main culprit. Whether the boulder motion was triggered by something -- a seismic event ("Marsquake") or strong winds -- is not known. Also unknown is whether all of the new boulder tracks formed at the same time, in response to a single event, or rolled downhill one at a time over the nearly 13-month period. The Mars Orbiter Camera was built and is operated by Malin Space Science Systems, San Diego, Calif. Mars Global Surveyor left Earth on Nov. 7, 1996, and began orbiting Mars on Sept. 12, 1997. JPL, a division of the California Institute of Technology, Pasadena, manages Mars Global Surveyor for NASA's Science Mission Directorate, Washington. Credit: NASA/JPL/MSSS |
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Scarp at Head of Chasma Bore
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| title |
Scarp at Head of Chasma Boreale |
| Description |
This view shows sharp detail of a scarp at the head of Chasma Boreale, a large trough cut by erosion into the martian north polar cap and the layered material beneath the ice cap. The picture is a mosaic of two images acquired in January 2005 by the Mars Orbiter Camera on NASA's Mars Global Surveyor, using a resolution-enhancing technique called "compensated pitch and roll targeted observation." The camera team considers this the best pair of images yet acquired using that technique. During each northern summer on Mars, there occurs a narrow window in time of two to three months when conditions are ideal to image the north polar cap at high resolution. Throughout this period, the atmosphere is generally clear over the cap, and the seasonal carbon-dioxide frost from the previous winter and spring has sublimed away, permitting a good view of the surface geology. The two images in this mosaic were acquired during this brief period during the most recent northern summer. Within a few weeks of when these images were acquired, dust storm activity picked up in the north polar region, making the atmosphere too dusty to obtain any more detailed views until late 2006. Chasma Boreale is cut into the layered material that lies beneath the water ice of the north polar cap. For decades, these layered materials were assumed to consist of a mixture of ice and dust. Mars Orbiter Camera images obtained in 1999 and 2001 began to show that some of the layers are a source for windblown sand. The science objective for the two images shown in this mosaic was to look for boulders in the debris shed from the steep slopes cut into the north polar layers by Chasma Boreale. Finding boulders would imply that the layers that are the most resistant to erosion in the polar region are as competent as solid rock, perhaps giving a new insight into the nature of the polar layered materials. The pictured site is near 84.8 degrees north latitude, 356.4 degrees west longitude. Examination of the high-resolution mosaic shows that there are indeed some large boulders that have eroded out of the layered materials and rolled down the slopes. It is possible, therefore, that the north polar layers are not simply a mixture of ice, dust, and sand. Some layers may actually be rock, cemented by minerals rather than by ice. Alternatively, if the materials are cemented by ice, then a future high-resolution view might show that the boulders have become smaller over time. In addition to the observation of boulders eroding out of the polar layered materials, the mosaic also helps confirm that dark sand is eroding out of the polar layered materials, and that there are three different groups of layers under the polar ice. The upper unit is light-toned, finely layered, and more resistant to erosion (more competent, less easily destroyed by erosion) than the middle unit, which is rich in dark sand but also has several shelf-forming layers in it. Finally, below the dark, sandy layer is a third unit, that is light-toned and has a different appearance relative to the other two units. Some of its layers have surfaces that have been broken by shallow fractures into polygonal and linear forms, also implying that they are hard, resistant rock. The level of detail seen in the mosaic was made possible by the development of a resolution-enhancing technique for using the Mars Orbiter Camera. During 2003 and 2004, the Mars Orbiter Camera operations team at Malin Space Science Systems, San Diego, Calif., worked closely with the Mars Global Surveyor operations teams at the Jet Propulsion Laboratory, Pasadena, Calif., and Lockheed Martin Space Systems, Denver, Colo., to develop a new technique in which the spacecraft does a maneuver that permits the camera to acquire images at a higher spatial resolution than normal. Usually, Mars Orbiter Camera images have a resolution of about 1.5 meters (5 feet) per pixel, and the camera can be commanded to acquire lower resolution data when desired. To obtain a higher resolution, the whole spacecraft must be pitched at such a rate that the camera over-samples its view of the martian surface in the down-track direction. Called compensated pitch and roll targeted observation, or cPROTO, this technique allows Mars Orbiter Camera to obtain images that have a resolution of about 50 centimeters (20 inches) per pixel in the down-track direction, and 150 centimeters (5 feet) per pixel in the cross-track dimension. The Mars Orbiter Camera was built and is operated by Malin Space Science Systems, San Diego, Calif. Mars Global Surveyor left Earth on Nov. 7, 1996, and began orbiting Mars on Sept. 12, 1997. JPL, a division of the California Institute of Technology, Pasadena, manages Mars Global Surveyor for NASA's Science Mission Directorate, Washington Credit: NASA/JPL/MSSS |
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Eberswalde Delta in High Res
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| title |
Eberswalde Delta in High Resolution |
| Description |
Scientifically, perhaps the most important result from use of the Mars Orbiter Camera on NASA's Mars Global Surveyor during that spacecraft's extended mission has been the discovery and documentation of a fossil delta. The feature is located in a crater northeast of Holden Crater, near 24.0 degrees south latitude, 33.7 degrees west longitude. Since the announcement of the discovery of the delta in November 2003, the International Astronomical Union has provided a provisional name (pending final approval) for the crater in which the landforms occur. The crater has been named Eberswalde, for a town in Germany. This image offers a higher-resolution view of a portion of the fossil delta than any seen earlier. North is up. At the bottom of the frame, the image includes the north end of a looping, inverted, meandering channel. The image covers an area of about 3 by 3 kilometers (1.9 x 1.9 miles). It was produced using a technique called "compensated pitch and roll targeted observation," in which the rotation rate of the spacecraft is adjusted to match the ground speed under the camera. At full resolution, this map-projected image is at 50 centimeters (20 inches) per pixel. Additional images from Mars Orbiter Camera provide some context and show a nearby portion of the fossil delta's inverted channels at a spatial scale of 1.5 meters (about 5 feet) per pixel. The relative positions of these three images are indicated in a mosaic image of the entire delta, for which the unmarked version was released in November 2003. The first Mars Orbiter Camera narrow angle images of some of the landforms in the delta were acquired in 2000, during the Mars Global Surveyor primary mission, but those pictures did not show very well the unambiguous inverted channel forms. Not until the second Earth year of the orbiter's extended mission were the deltaic features recognized in Mars Orbiter Camera images obtained in March and June of 2002. Following the initial observations in 2002, the Mars Orbiter Camera team began a systematic effort to map the entire Eberswalde Crater delta. Most of this imaging required slewing the whole spacecraft in a technique called "roll only targeted observation" so that it pointed the camera toward the feature. In this way, the camera team was able to build up a mosaic of the delta much more quickly than would have been the case if the team had simply relied upon chance crossing of the delta by the orbiter's usual ground track. This technique was not employed during Mars Global Surveyor's primary mission, except in the search for Mars Polar Lander, but became a routine part of the tool kit during the extended mission. Even with the "roll only targeted observation" technique, it took more than one Earth year to build up a complete mosaic of images of the delta. In the meantime, the first data showing the deltaic landforms were archived and released to the public and scientific community, long before the Mars Orbiter Camera team's, analysis and mosaic were complete. Some scientists began independent analyses of the landform at that time. The initial analysis and announcement of the feature was finally published in November 2003. The Eberswalde delta provides the first clear, "smoking gun" evidence that some valleys on Mars experienced persistent flow of a liquid with the physical properties of water over an extended period of time, as do rivers on Earth. In addition, because the delta today is lithified -- that is, hardened to form rock -- it provided the first unambiguous evidence that some martian sedimentary rocks were deposited in a liquid (presumably, water) environment. The presence of meandering channels, a cut-off meander, and crisscrossing channels at different elevations (one above the other), provided the clear geologic evidence for these interpretations. After the sediments were deposited to form the delta, the material was further buried by other materials -- probably sediments -- that are no longer present. The entire package of buried material became cemented and hardened to form rock. Later, erosive processes such as wind stripped away the overlying rock, re-exposing the delta. Now preserved essentially as a fossil, the former floors of channels in the delta became inverted, to form ridges, by erosion. Channels can be inverted by erosion on both Earth and Mars. Usually this happens when the channel floor, or the material filling the channel, is harder to erode than the surrounding material into which the channel was cut. In some cases, the channels on Earth and Mars have been filled by lava to make them more resistant to erosion. In the case of Eberswalde, there are no lava flows, instead, the channel floors may have been rendered resistant to erosion either by being better-cemented than the surrounding material, or composed of coarser-grained sediment (such as sand and gravel as opposed to silt), or both. The Mars Orbiter Camera was built and is operated by Malin Space Science Systems, San Diego, Calif. Mars Global Surveyor left Earth on Nov. 7, 1996, and began orbiting Mars on Sept. 12, 1997. JPL, a division of the California Institute of Technology, Pasadena, manages Mars Global Surveyor for NASA's Science Mission Directorate, Washington. Credit: NASA/JPL/MSSS |
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Recently-Formed Impact Crate
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Recently-Formed Impact Crater |
| Description |
Scientists using the Mars Orbiter Camera on NASA's Mars Global Surveyor spacecraft have discovered a crater that appears to have formed on Mars in the past 20 or so Earth years, and have used it and several other similar craters to estimate the present cratering rate on Mars. One of the basic tenets of planetary geology is that impact craters have accumulated on planetary surfaces at roughly a constant rate since the early history of the solar system. This appears to have been the case for small craters on the surface of the Moon, as shown by measurements of the length of time that lunar rocks created by small impacts have been exposed to cosmic rays, as determined by laboratory measurements of samples returned to Earth by the Apollo astronauts. This principle should permit the number of craters found on a planetary surface to be used to determine the age of that surface, if the rate at which new craters form is known. Scientists have previously estimated the cratering rate of Mars by scaling the lunar cratering rate based on the proximity of Mars to the asteroid belt, and by performing calculations based on orbital mechanics. Another way to establish the cratering rate of Mars would be to use long-term observations, say, from orbiting spacecraft, to actually locate new craters. The new crater is located on the southern rim of the summit crater, or caldera, of the intermediate-sized martian volcano, Ulysses Patera. The site was imaged by the Viking 2 orbiter in 1976 (left, an enlarged portion of the image) and in narrow-angle views by the Mars Orbiter Camera in 1999 (center) and 2005 (right). The new crater, about 25 meters (82 feet) across, is marked by a distinct dark, rayed pattern of ejected material, or ejecta, which is seen to have faded somewhat between 1999 and 2005. Ulysses Patera, a volcanic shield about 100 kilometers (62 miles) in diameter volcanic shield, located near 2.5 degrees north latitude, 121.3 degrees west longitude, is one of the Tharsis volcanoes and is partly buried by younger lava flows. The summit caldera is about 55 kilometers (34 miles) in diameter. The amount that the crater's rays faded between 1999 and 2005 can be used to help estimate how many years ago the crater formed. The actual contrast between the ejecta and the undisturbed volcano summit materials is actually much less than it appears to be in these processed images, and the amount of fading is also much less. Images of disturbed surfaces from various parts of Mars, such as dust devil tracks, dark slope streaks and rover tracks, indicate that disturbed surfaces on Mars are dark and that they lighten with time. Using these other examples to estimate how dark the ejecta from the Ulysses crater was originally, and how much it has faded in six years, suggests the crater formed in the early to mid 1980s. The rate at which dark surfaces lighten on Mars is not uniform over the whole planet, but scientists using the Mars Orbiter Camera have found a number, of other craters with dark ejecta that have faded during the Mars Global Surveyor mission. The scientists estimate that these craters probably formed within the past 100 years. Although the sample is very small (the Mars Orbiter Camera narrow angle camera has imaged barely 4 percent of Mars), it appears that the recent cratering rate for craters on Mars 25 to 100 meters (82 to 328 feet) in diameter is about 0.000000003 to 0.000000006 craters per square kilometer (0.39 square mile) per Earth year, which is about five times lower than previous estimates. The site of the new crater is shown in wider context in a comparison of the 1976 Viking image with wide-angle views taken by the Mars Orbiter Camera in 1999 and 2005 (insert MOC2-1214b), and in even wider context in a regional mosaic of Viking images (insert MOC2-1214c). The Mars Orbiter Camera was built and is operated by Malin Space Science Systems, San Diego, Calif. Mars Global Surveyor left Earth on Nov. 7, 1996, and began orbiting Mars on Sept. 12, 1997. JPL, a division of the California Institute of Technology, Pasadena, manages Mars Global Surveyor for NASA's Science Mission Directorate, Washington. Credit: NASA/JPL/MSSS/USGS |
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