|
|
Uranius Tholus
| title |
Uranius Tholus |
| description |
This Viking orbiter image shows Uranius Tholus, one of the smaller volcanos in the Tharsis region of Mars. It is only 60 kilometers across and 3 kilometers higher than the surrounding plains. In comparison with Olympus Mons, the greater number of impact craters near Uranius Tholus implies that it is substantially older than Olympus Mons. One such crater in the top center of the image has been flooded by lava from the surrounding plains. Because this crater must have formed after the volcano but before the plains, the plains must be younger than the volcano. (This is an example of using superposition relationships to determine the relative age of a series of features by determining which features lie on top of other features.) This area is believed to be more than 3 billion years old. This image was taken by NASA's Viking 1 orbiter in 1977. *Image Credit*: NASA |
|
Ancient Martian Highlands
| title |
Ancient Martian Highlands |
| description |
The meteorite ALH 84001, where possible traces of martian life have been found, is one of the oldest rocks ever studied The meteorite probably came from one of the oldest regions on Mars. These ancient parts of Mars, most of its southern hemisphere, are covered with asteroid impact craters, like this area in the bright region of Noachis. This part of Mars is as cratered as the Moon's highlands and is about the same age, more than 4 billion years old. The biggest crater here is Proctor, named for a nineteenth-century British astronomer. The dark splotches inside Proctor and many other craters are fields of sand dunes. In high-resolution images, these linear dunes look like waves on the ocean, but they actually show how dry and desolate Mars is now. This image was taken by the Viking 1 orbiter in 1977. *Image Credit*: NASA, Lunar and Planetary Institute |
|
Ulysses Patera
| title |
Ulysses Patera |
| description |
This feature is an example of a class of volcanos that are considerably smaller than either the broad shield volcanos or Alba Patera. The summit consists of a single, very circular caldera with a smooth floor that predates the ejecta from two large impact craters. The lower flanks of the volcano, including portions of the impact craters, have been buried by the material that makes up the surrounding plains. This superpositional relationship indicates that the plains were emplaced subsequent to both the volcano and large impact craters on the volcano. The plains are probably made up of lava supplied from the Tharsis Montes that flowed down the sides of the broad uplift associated with the Tharsis shields. Both the plains and the volcano are cut by a graben (a paired set of linear faults), indicating tectonic activity subsequent to the emplacement of the plains. This image was taken by NASA's Viking 2 orbiter in 1977. *Image Credit*: NASA |
|
Martian Landslide
| title |
Martian Landslide |
| description |
Although Valles Marineris originated as a tectonic structure, it has been modified by other processes. This image shows a close-up view of a landslide on the south wall of Valles Marineris. This landslide partially removed the rim of the crater that is on the plateau adjacent to Valles Marineris. Note the texture of the landslide deposit where it flowed across the floor of Valles Marineris. Several distinct layers can be seen in the walls of the trough. These layers may be regions of distinct chemical composition or mechanical properties in the martian crust. This image is 60 kilometers across. This image was taken by the Viking 1 orbiter in 1977. *Image Credit*: NASA |
|
Gaspra, Deimos and Phobos
| title |
Gaspra, Deimos and Phobos |
| description |
This montage shows asteroid 951 Gaspra (top) compared with Deimos (lower left) and Phobos (lower right), the moons of Mars. The three bodies are shown at the same scale and nearly the same lighting conditions. Gaspra is about 17 kilometers (10 miles) long. All three bodies have irregular shapes due to past catastrophic conditions. However, their surfaces appear remarkably different, possibly because of differences in composition but most likely because of very different impact histories. The Phobos and Deimos images were obtained by the Viking Orbiter spacecraft in 1977, the Gaspra image is the best of a series obtained by the Galileo spacecraft on October 29, 1991. *Image Credit*: NASA, Jet Propulsion Laboratory |
|
Rampart Crater
| title |
Rampart Crater |
| description |
The ejecta deposits around Mars' impact crater Yuty (18 kilometers in diameter) consist of many overlapping lobes. Craters with this type of ejecta deposit are known as rampart craters. This type of ejecta morphology is characteristic of many craters at equatorial and midlatitudes on Mars, but is unlike that seen around small craters on the Moon. This style of ejecta deposit is believed to form when an impacting object rapidly melts ice in the subsurface. The presence of liquid water in the ejected material allows it to flow along the surface, giving the ejecta blanket its characteristic, fluidized appearance. This image was taken in 1977 by the Viking 1 orbiter. *Image Credit*: NASA |
|
Dr. James C. Fletcher
| Title |
Dr. James C. Fletcher |
| Full Description |
Dr. James C. Fletcher served as NASA Administrator from April 27, 1971, to May 1, 1977, and from May 12, 1986, to April 8, 1989. During his first administration at NASA, Dr. Fletcher was responsible for beginning the Shuttle effort, as well as the Viking program that sent landers to Mars. He oversaw the Skylab missions and Viking probes and approved the Voyager space probe, the Hubble Space Telescope and the Apollo-Soyuz Test Project. During his second tenure, he presided over the effort to recover from the Challenger accident. Dr. Fletcher died in December 1991 of lung cancer. |
| Date |
UNKNOWN |
| NASA Center |
Headquarters |
|
Evidence for Recent Liquid W
…
| Title |
Evidence for Recent Liquid Water on Mars |
| Full Description |
This image, acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) in May 2000 shows numerous examples of martian gullies that all start--or head--in a specific layer roughly a hundred meters beneath the surface of Mars. These features are located on the south-facing wall of a trough in the Gorgonum Chaos region, an area found to have many examples of gullies proposed to have formed by seepage and runoff of liquid water in recent martian times. The layer from which the gullies emanate has recessed backward to form an overhang beneath a harder layer of rock. The larger gullies have formed an alcove--an area above the overhang from which debris has collapsed to leave a dark-toned scar. Below the layer of seepage is found a dark, narrow channel that runs down the slope to an apron of debris. The small, bright, parallel features at the base of the cliff at the center-right of the picture is a series of large windblown ripples. Although the dark tone of the alcoves and channels in this image is not likely to be the result of wet ground (the contrast in this image has been enhanced), it does suggest that water has seeped out of the ground and moved down the slope quite recently. Sharp contrasts between dark and light areas are hard to maintain on Mars for very long periods of time because dust tends to coat surfaces and reduce brightness differences. To keep dust from settling on a surface, it has to have undergone some process of erosion (wind, landslides, water runoff) relatively recently. There is no way to know how recent this activity was, but educated guesses center between a few to tens of years, and it is entirely possible that the area shown in this image has water seeping out of the ground today. Centered near 37.9S, 170.2W, sunlight illuminates the MOC image from the upper left, north is toward the upper right. The context view above is from the Viking 1 orbiter and was acquired in 1977. The Viking picture is illuminated from the upper right, north is up. The small white box in the context frame shows the location of the high resolution MOC view. |
| Date |
06/22/2000 |
| NASA Center |
Jet Propulsion Laboratory |
|
AC77-1157
Artwork: JPL Viking Spacecra
…
10/4/77
| Description |
Artwork: JPL Viking Spacecraft to explore planet Mars |
| Date |
10/4/77 |
|
Explanation: Hurtling throug
…
| Title |
Explanation: Hurtling through space a mere 3,000 miles above the Martian surface [ http://antwrp.gsfc.nasa.gov/apod/ap960720.html ], the diminutive moon Phobos [ http://antwrp.gsfc.nasa.gov/apod/ap951002.html ] (below and left of center) was imaged against the backdrop of a large shield volcano [ http://antwrp.gsfc.nasa.gov/apod/ap950719.html ] by the Viking 2 Orbiter [ http://nssdc.gsfc.nasa.gov/planetary/viking.html ] in 1977. This dramatic picture [ http://nssdc.gsfc.nasa.gov/imgcat/html/object_page/vo2_304b88.html ] looks down from the Orbiter's viewpoint about 8,000 miles above the volcano, Ascraeus Mons. Phobos itself is 5,000 miles below the Orbiter. North is toward the top with the Sun illuminating the scene from the South (black dots are reference marks). For scale, Ascraeus Mons is about 200 miles across at its base while asteroid sized [ http://hurlbut.jhuapl.edu:80/NEAR/Education/intro/minorobjects.html ] Phobos is about 15 miles in diameter. In this spectacular moon-planet [ http://antwrp.gsfc.nasa.gov/apod/ap961007.html ] image, volcanic calderas [ http://bang.lanl.gov/solarsys/marsvolc.htm ] (craters) are visible at the summit of Ascraeus Mons -- while impact craters on the sunlit side of Phobos [ http://seds.lpl.arizona.edu/nineplanets/nineplanets/phobos.html ]' surface can also be seen! |
|
Phobos Over Mars
| Title |
Phobos Over Mars |
| Explanation |
Hurtling through space a mere 3,000 miles above the Martian surface [ http://nssdc.gsfc.nasa.gov/planetary/ mars_panoramas.html ], the diminutive moon Phobos [ http://antwrp.gsfc.nasa.gov/apod/ap980914.html ] (below and left of center) was imaged against the backdrop of a large shield volcano [ http://antwrp.gsfc.nasa.gov/apod/ap981019.html ] by the Viking 2 Orbiter [ http://nssdc.gsfc.nasa.gov/database/ MasterCatalog?sc=1975-083A ] in 1977. This dramatic picture [ http://nssdc.gsfc.nasa.gov/imgcat/html/object_page/ vo2_304b88.html ] looks down from the Orbiter's viewpoint about 8,000 miles above the volcano, Ascraeus Mons. Phobos itself is 5,000 miles below the Orbiter. North is toward the top with the Sun illuminating the scene from the South (black dots are reference marks). For scale, Ascraeus Mons is about 200 miles across at its base while asteroid sized [ http://stardate.org/resources/ssguide/asteroids.html ] Phobos is about 15 miles in diameter. In this spectacular moon-planet [ http://antwrp.gsfc.nasa.gov/apod/ap990311.html ] image, volcanic calderas (craters) are visible at the [ http://volcano.und.nodak.edu/vwdocs/planet_volcano/mars/ Overview.html ] summit of Ascraeus Mons -- while impact craters on the sunlit side of Phobos [ http://seds.lpl.arizona.edu/nineplanets/nineplanets/ phobos.html ]' surface can also be seen! |
|
18 Miles From Deimos
| Title |
18 Miles From Deimos |
| Explanation |
Diminutive Deimos [ http://seds.lpl.arizona.edu/nineplanets/nineplanets/ datamax.html#smallest ] is the smallest of the two tiny Moons of Mars. [ http://www.literature.org/Works/Edgar-Rice-Burroughs/ chessmen/prelude.html ] Potato-shaped and barely 6 miles wide this asteroid-like body [ http://antwrp.gsfc.nasa.gov/apod/ap951003.html ] was visited by the Viking 2 orbiter in 1977. This image was made [ http://nssdc.gsfc.nasa.gov/imgcat/html/object_page/vo2_423b63.html ] when the spacecraft approached to within 18 miles of Deimos' surface. One of the most detailed pictures of a celestial body ever taken [ http://nssdc.gsfc.nasa.gov/imgcat/ ] by an orbiting spacecraft, the field of view is less than a square mile and features just under 10 feet across are visible. Craters and large chunks of rock are seen scattered on the surface while some of the craters appear to be covered by a layer of powdery soil or "regolith" [ http://antwrp.gsfc.nasa.gov/apod/ap980327.html ]. |
|
Phobos Over Mars
| Title |
Phobos Over Mars |
| Explanation |
Hurtling through space a mere 3,000 miles above the Martian surface [ http://nssdc.gsfc.nasa.gov/planetary/mars_panoramas.html ], the diminutive moon Phobos [ http://antwrp.gsfc.nasa.gov/apod/ap980914.html ] (below and left of center) was imaged against the backdrop of a large shield volcano [ http://antwrp.gsfc.nasa.gov/apod/ap981019.html ] by the Viking 2 Orbiter [ http://nssdc.gsfc.nasa.gov/cgi-bin/database/www-nmc?75-083A ] in 1977. This dramatic picture [ http://nssdc.gsfc.nasa.gov/imgcat/html/object_page/vo2_304b88.html ] looks down from the Orbiter's viewpoint about 8,000 miles above the volcano, Ascraeus Mons. Phobos itself is 5,000 miles below the Orbiter. North is toward the top with the Sun illuminating the scene from the South (black dots are reference marks). For scale, Ascraeus Mons is about 200 miles across at its base while asteroid sized [ http://stardate.utexas.edu/resources/ssguide/asteroids.html ] Phobos is about 15 miles in diameter. In this spectacular moon-planet [ http://antwrp.gsfc.nasa.gov/apod/ap990311.html ] image, volcanic calderas (craters) are visible at the [ http://volcano.und.nodak.edu/vwdocs/planet_volcano/mars/Overview.html ] summit of Ascraeus Mons -- while impact craters on the sunlit side of Phobos [ http://seds.lpl.arizona.edu/nineplanets/nineplanets/phobos.html ]' surface can also be seen! |
|
Martian Moon Phobos
| Title |
Martian Moon Phobos |
| Description |
Caption: "Close up of the Martian Moon Phobos taken by Viking Orbiter 1 on February 20, 1977. Viking Orbiter 1 took this close-up photo of the Martian satellite phobos from a range of 120 kilometers at 5:15 p.m. (PST) February 20, 1977. That is the closest range at which any spacecraft has photographed the tiny satellite. At that range, Phobos is too large to be captured in a single frame. This picture covers an area 3 by 3.5 kilometers across. However, the high relative speed of Orbiter 1 and Phobos caused some image smear so that the smallest surface feature identifiable is between 10 and 15 meters (32 and 49 feet) across. Special processing in JPL's Image Processing Lab should improve resolution. The picture shows a region in the northern hemisphere of Phobos that has striations and is heavily cratered. The striations, which appear to be grooves rather than crater chains, are about 100 to 200 meters wide and tens of kilometers long. Craters range in size from 10 meters to 1.2 kilometers in diameter. The surface of Phobos appears similar to the highland regions of the Moon which also was heavily cratered and ancient terrain. The dark region above the limb of Phobos is an artifact of processing and does not indicate an atmosphere. |
| Date |
02.20.1977 |
|
Newton Crater
| title |
Newton Crater |
| 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 MOC high resolution view is located near 41.1°S, 159.8°W 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. The context picture was acquired in 1977 by the Viking 1 orbiter and is illuminated from the upper right. Photo Credit: NASA/JPL/Malin Space Science Systems |
|
South Polar Residual Ice Cap
PIA00301
Sol (our sun)
Visual Imaging Subsystem - C
…
| Title |
South Polar Residual Ice Cap |
| Original Caption Released with Image |
This mosaic is composed of 18 Viking Orbiter images (6 each in red, green, and violet filters), acquired on September 28, 1977, during revolution 407 of Viking Orbiter 2. The south pole is located just off the lower left edge of the polar cap, and the 0 degree longitude meridian extends toward the top of the mosaic. The large crater near the right edge (named "South") is about 100 km in diameter. These images were acquired during southern summer on Mars (Ls = 341 degrees), the sub-solar declination was 8 degrees S., and the south polar cap was nearing its final stage of retreat just prior to vernal equinox. The south residual cap is approximately 400 km across, and the exposed surface is thought to consist dominantly of carbon-dioxide frost. This is in contrast to the water-ice surface of the north polar residual cap. It is likely that water ice is present in layers that underlie the south polar cap and that comprise the surrounding layered terrains. Near the top of this image, irregular pits with sharp-rimmed cliffs appear "etched", presumably by wind. A series of rugged mountains (extending toward the upper right corner of the image) are of unknown origin. |
|
Gaspra, Deimos, and Phobos C
…
PIA00078
Sol (our sun)
Solid-State Imaging
| Title |
Gaspra, Deimos, and Phobos Comparison |
| Original Caption Released with Image |
This montage shows asteroid 951 Gaspra (top) compared with Deimos (lower left) and Phobos (lower right), the moons of Mars. The three bodies are shown at the same scale and nearly the same lighting conditions. Gaspra is about 17 kilometers (10 miles) long. All three bodies have irregular shapes, due to past catastrophic conditions. However their surfaces appear remarkably different, possibly because of differences in composition but most likely because of very different impact histories. The Phobos and Deimos images were obtained by the Viking Orbiter spacecraft in 1977, the Gaspra image is the best of a series obtained by the Galileo spacecraft on October 29, 1991. Galileo is scheduled to add the detailed view of another asteroid when it flies by Ida in August 1993. The Galileo project, whose primary mission is the exploration of the Jupiter system in 1995-97, is managed for NASA's Office of Space Science and Applications by the Jet Propulsion Laboratory. |
|
Surface Changes in Chryse Pl
…
PIA00532
Sol (our sun)
Camera 1
| Title |
Surface Changes in Chryse Planitia |
| Original Caption Released with Image |
At the conclusion of the Viking Continuation Mission (May to November, 1978), all four cameras on the Viking Landers - two on each spacecraft - continued to function normally. During the two and one-half years since the landers touched down on Mars, images totaled 2,255 for Viking Lander 1 and 2,016 for Viking Lander 2. The surface around the landers was completely photographed by the end of 1976, subsequent images acquired during 1977-1978 have concentrated on searching for changes in the scene - changes which can be used to infer both the types of erosive processes which modify the landscape around the landers and the rates at which these processes may occur. The major surface changes have included the water-ice snow seen by Lander 2 during the winter at Utopia Planitia, and a thin dust layer deposited at both sites during the dust storms of 1977. The most recently identified change occurred at Chryse Planitia between VL-1 sols 767 (Sept. 16, 1978) and 771 (Sept. 20, 1978) as seen in the lower photo. Picture at top, selected to show similar lighting conditions, was taken during sol 25 (August 15, 1976). The change (A) appears as a small circle-like formation on the side of a drift in the lee, or downwind, side of Whale Rock. This is believed to have been a small-scale landslide of an unstable dust layer which had accumulated behind the rock. Interpretation of this feature would be difficult without an earlier change (B) near Big Joe, a slump which occurred between sols 74 and 183. The new slump is approximately 25- 35 meters from the lander, and just under a meter across. The slumping probably was initiated by the daily heating and cooling of the surface by solar radiation. More importantly, it is now believed that, based on the repeated occurrence of such slumping features, a dust layer which overlies the surface may in fact be redistributed fairly regularly during periods of high wind activity. There are no obvious indications of fossil slump features, therefore similar features must be destroyed on a regular basis. After the end of February, when Viking operations essentially terminate, Lander 1 will continue preselected observations over a period of possibly up to 10 years, following the instructions stored in its computer memory. Earth commands will be required only to initiate data transmission to Earth. During this time, it is now anticipated that one of the yearly planetwide global dust storms may reach an intensity necessary to shift the dust cover around the lander significantly. |
|
Evidence for Recent Liquid W
…
PIA02824
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Channeled Aprons in a Small Crater within Newton Crater |
| Original Caption Released with Image |
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 upon 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 MOC high resolution view is located near 41.1°S, 159.8°W 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. The context picture was acquired in 1977 by the Viking 1 orbiter and is illuminated from the upper right. Note: This is an updated color version of PIA01039 [ http://photojournal.jpl.nasa.gov/catalog/PIA01039 ]. |
|
Evidence for Recent Liquid W
…
PIA02824
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Channeled Aprons in a Small Crater within Newton Crater |
| Original Caption Released with Image |
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 upon 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 MOC high resolution view is located near 41.1°S, 159.8°W 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. The context picture was acquired in 1977 by the Viking 1 orbiter and is illuminated from the upper right. Note: This is an updated color version of PIA01039 [ http://photojournal.jpl.nasa.gov/catalog/PIA01039 ]. |
|
Evidence for Recent Liquid W
…
PIA02824
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Channeled Aprons in a Small Crater within Newton Crater |
| Original Caption Released with Image |
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 upon 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 MOC high resolution view is located near 41.1°S, 159.8°W 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. The context picture was acquired in 1977 by the Viking 1 orbiter and is illuminated from the upper right. Note: This is an updated color version of PIA01039 [ http://photojournal.jpl.nasa.gov/catalog/PIA01039 ]. |
|
Boulder 'Big Joe' And Surfac
…
PIA00397
Sol (our sun)
Camera 1
| Title |
Boulder 'Big Joe' And Surface Changes On Mars |
| Original Caption Released with Image |
This pair of pictures from Viking Lander 1 at Mars' Chryse Planitia shows the only unequivocal change in the Martian surface seen by either lander. Both images show the one-meter (3-foot) high boulder nicknamed 'Big Joe.' Just to the lower right of the rock (right photo) is a small-scale slump feature. The picture at left shows a smooth, dust-covered slope, in the picture at right the top surface layer can be seen to have slipped downslope. The event occurred sometime between Oct. 4, 1976, and Jan 24, 1977. (Pictures taken before Oct. 4 do not show the slump, the first picture in which it appears was taken Jan. 24.) The surface layer, between one-half and one centimeter (one-fifth to one-third inch) thick, is apparently less cohesive than the underlying material. The layer that slipped formed a 30-centimeter-long (11.8-inch) 'tongue' of soil and a patch of exposed underlying material. The triggering mechanism for the event is unknown, but could have been temperature variations, wind gusts, a seismic event, or perhaps the lander's touchdown on July 20, 1976. |
|
Evidence for Recent Liquid W
…
PIA01033
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Gullies in Gorgonum Chaos |
| Original Caption Released with Image |
The first two pictures (top and above left) are from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) and show a series of troughs and layered mesas in the Gorgonum Chaos region of the martian southern hemisphere. The picture at the top of the page is a portion of the picture on the left above. The Viking view (above right) shows the location of the MOC image in the chaotic terrain. Gullies proposed to have been formed by seeping groundwater emanate from a specific layer near the tops of trough walls, particularly on south-facing slopes (south is toward the bottom of each picture). The presence of so many gullies associated with the same layer in each mesa suggests that this layer is particularly effective in storing and conducting water. Such a layer is called an aquifer, and this one appears to be present less than a few hundred meters (few hundred yards) beneath the surface in this region. The MOC pictures were taken on January 22, 2000. The sample at the top of the page is an area 3 kilometers (1.9 miles) wide by 2.6 km (1.6 mi) high. The long view (above left) covers an area 3 kilometers (1.9 miles) wide by 22.6 km (14 mi) long. Sunlight illuminates each scene from the upper left. The images are located near 37.5°S, 170.5°W. The context image (above right) was acquired by the Viking 1 orbiter in 1977 and is illuminated from the upper right, north is up. MOC 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. NOTE: A Full Resolution Grayscale view of the release image can be found here. |
|
Evidence for Recent Liquid W
…
PIA01033
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Gullies in Gorgonum Chaos |
| Original Caption Released with Image |
The first two pictures (top and above left) are from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) and show a series of troughs and layered mesas in the Gorgonum Chaos region of the martian southern hemisphere. The picture at the top of the page is a portion of the picture on the left above. The Viking view (above right) shows the location of the MOC image in the chaotic terrain. Gullies proposed to have been formed by seeping groundwater emanate from a specific layer near the tops of trough walls, particularly on south-facing slopes (south is toward the bottom of each picture). The presence of so many gullies associated with the same layer in each mesa suggests that this layer is particularly effective in storing and conducting water. Such a layer is called an aquifer, and this one appears to be present less than a few hundred meters (few hundred yards) beneath the surface in this region. The MOC pictures were taken on January 22, 2000. The sample at the top of the page is an area 3 kilometers (1.9 miles) wide by 2.6 km (1.6 mi) high. The long view (above left) covers an area 3 kilometers (1.9 miles) wide by 22.6 km (14 mi) long. Sunlight illuminates each scene from the upper left. The images are located near 37.5°S, 170.5°W. The context image (above right) was acquired by the Viking 1 orbiter in 1977 and is illuminated from the upper right, north is up. MOC 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. NOTE: A Full Resolution Grayscale view of the release image can be found here. |
|
Evidence for Recent Liquid W
…
PIA01033
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Gullies in Gorgonum Chaos |
| Original Caption Released with Image |
The first two pictures (top and above left) are from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) and show a series of troughs and layered mesas in the Gorgonum Chaos region of the martian southern hemisphere. The picture at the top of the page is a portion of the picture on the left above. The Viking view (above right) shows the location of the MOC image in the chaotic terrain. Gullies proposed to have been formed by seeping groundwater emanate from a specific layer near the tops of trough walls, particularly on south-facing slopes (south is toward the bottom of each picture). The presence of so many gullies associated with the same layer in each mesa suggests that this layer is particularly effective in storing and conducting water. Such a layer is called an aquifer, and this one appears to be present less than a few hundred meters (few hundred yards) beneath the surface in this region. The MOC pictures were taken on January 22, 2000. The sample at the top of the page is an area 3 kilometers (1.9 miles) wide by 2.6 km (1.6 mi) high. The long view (above left) covers an area 3 kilometers (1.9 miles) wide by 22.6 km (14 mi) long. Sunlight illuminates each scene from the upper left. The images are located near 37.5°S, 170.5°W. The context image (above right) was acquired by the Viking 1 orbiter in 1977 and is illuminated from the upper right, north is up. MOC 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. NOTE: A Full Resolution Grayscale view of the release image can be found here. |
|
Evidence for Recent Liquid W
…
PIA01033
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Gullies in Gorgonum Chaos |
| Original Caption Released with Image |
The first two pictures (top and above left) are from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) and show a series of troughs and layered mesas in the Gorgonum Chaos region of the martian southern hemisphere. The picture at the top of the page is a portion of the picture on the left above. The Viking view (above right) shows the location of the MOC image in the chaotic terrain. Gullies proposed to have been formed by seeping groundwater emanate from a specific layer near the tops of trough walls, particularly on south-facing slopes (south is toward the bottom of each picture). The presence of so many gullies associated with the same layer in each mesa suggests that this layer is particularly effective in storing and conducting water. Such a layer is called an aquifer, and this one appears to be present less than a few hundred meters (few hundred yards) beneath the surface in this region. The MOC pictures were taken on January 22, 2000. The sample at the top of the page is an area 3 kilometers (1.9 miles) wide by 2.6 km (1.6 mi) high. The long view (above left) covers an area 3 kilometers (1.9 miles) wide by 22.6 km (14 mi) long. Sunlight illuminates each scene from the upper left. The images are located near 37.5°S, 170.5°W. The context image (above right) was acquired by the Viking 1 orbiter in 1977 and is illuminated from the upper right, north is up. MOC 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. NOTE: A Full Resolution Grayscale view of the release image can be found here. |
|
Evidence for Recent Liquid W
…
PIA01033
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Gullies in Gorgonum Chaos |
| Original Caption Released with Image |
The first two pictures (top and above left) are from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) and show a series of troughs and layered mesas in the Gorgonum Chaos region of the martian southern hemisphere. The picture at the top of the page is a portion of the picture on the left above. The Viking view (above right) shows the location of the MOC image in the chaotic terrain. Gullies proposed to have been formed by seeping groundwater emanate from a specific layer near the tops of trough walls, particularly on south-facing slopes (south is toward the bottom of each picture). The presence of so many gullies associated with the same layer in each mesa suggests that this layer is particularly effective in storing and conducting water. Such a layer is called an aquifer, and this one appears to be present less than a few hundred meters (few hundred yards) beneath the surface in this region. The MOC pictures were taken on January 22, 2000. The sample at the top of the page is an area 3 kilometers (1.9 miles) wide by 2.6 km (1.6 mi) high. The long view (above left) covers an area 3 kilometers (1.9 miles) wide by 22.6 km (14 mi) long. Sunlight illuminates each scene from the upper left. The images are located near 37.5°S, 170.5°W. The context image (above right) was acquired by the Viking 1 orbiter in 1977 and is illuminated from the upper right, north is up. MOC 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. NOTE: A Full Resolution Grayscale view of the release image can be found here. |
|
Evidence for Recent Liquid W
…
PIA01033
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Gullies in Gorgonum Chaos |
| Original Caption Released with Image |
The first two pictures (top and above left) are from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) and show a series of troughs and layered mesas in the Gorgonum Chaos region of the martian southern hemisphere. The picture at the top of the page is a portion of the picture on the left above. The Viking view (above right) shows the location of the MOC image in the chaotic terrain. Gullies proposed to have been formed by seeping groundwater emanate from a specific layer near the tops of trough walls, particularly on south-facing slopes (south is toward the bottom of each picture). The presence of so many gullies associated with the same layer in each mesa suggests that this layer is particularly effective in storing and conducting water. Such a layer is called an aquifer, and this one appears to be present less than a few hundred meters (few hundred yards) beneath the surface in this region. The MOC pictures were taken on January 22, 2000. The sample at the top of the page is an area 3 kilometers (1.9 miles) wide by 2.6 km (1.6 mi) high. The long view (above left) covers an area 3 kilometers (1.9 miles) wide by 22.6 km (14 mi) long. Sunlight illuminates each scene from the upper left. The images are located near 37.5°S, 170.5°W. The context image (above right) was acquired by the Viking 1 orbiter in 1977 and is illuminated from the upper right, north is up. MOC 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. NOTE: A Full Resolution Grayscale view of the release image can be found here. |
|
Evidence for Recent Liquid W
…
PIA01033
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Gullies in Gorgonum Chaos |
| Original Caption Released with Image |
The first two pictures (top and above left) are from the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) and show a series of troughs and layered mesas in the Gorgonum Chaos region of the martian southern hemisphere. The picture at the top of the page is a portion of the picture on the left above. The Viking view (above right) shows the location of the MOC image in the chaotic terrain. Gullies proposed to have been formed by seeping groundwater emanate from a specific layer near the tops of trough walls, particularly on south-facing slopes (south is toward the bottom of each picture). The presence of so many gullies associated with the same layer in each mesa suggests that this layer is particularly effective in storing and conducting water. Such a layer is called an aquifer, and this one appears to be present less than a few hundred meters (few hundred yards) beneath the surface in this region. The MOC pictures were taken on January 22, 2000. The sample at the top of the page is an area 3 kilometers (1.9 miles) wide by 2.6 km (1.6 mi) high. The long view (above left) covers an area 3 kilometers (1.9 miles) wide by 22.6 km (14 mi) long. Sunlight illuminates each scene from the upper left. The images are located near 37.5°S, 170.5°W. The context image (above right) was acquired by the Viking 1 orbiter in 1977 and is illuminated from the upper right, north is up. MOC 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. NOTE: A Full Resolution Grayscale view of the release image can be found here. |
|
Evidence for Recent Liquid W
…
PIA01034
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Gullies at 70°S in Polar Pit Walls |
| Original Caption Released with Image |
Gully landforms proposed to have been caused by geologically-recent seepage and runoff of liquid water on Mars are found in the most unlikely places. They typically occur in areas that are quite cold--well below freezing--all year round. Like the old adage about moss on trees, nearly all of them form on slopes that face away from sunlight. Most of the gullies occur at latitudes between 30° and 70°. The highest latitude at which martian gullies have been found is around 70°-75°S on the walls of pits developed in the south polar pitted plains. If you were at this same latitude on Earth, you would be in Antarctica. This region spends much of the winter--which lasts approximately 6 months on Mars--in darkness and at temperatures cold enough to freeze carbon dioxide (around -130°C or -200°F). Nevertheless, gullies with very sharp, deep, v-shaped channels are seen on the pit walls (above, left). Based upon the locations of the tops of the channels on the slope shown here, the inferred site of liquid seepage is located at a layer in the pit wall about 1/3 of the way down from the top of the MOC image. The channels start wide and taper downslope. The area above the channels is layered and has been eroded by mass movement--dry avalanching of debris--to form a pattern of chutes and ridges on the upper slope of the pit wall. The top layer appears to have many boulders in it (each about the size of a small house), these boulders are left behind on the upper slopes of the pit wall as debris is removed. Centered near 70.7°S, 355.7°W, the MOC image was acquired July 14, 1999, and covers an area approximately 2.8 km (1.7 mi) wide by 2.1 km(1.3 mi) high. Sunlight illuminates the MOC image from the upper left and north is toward the upper left. The context view (right) is from the Viking 2 orbiter and was acquired in 1977. The Viking picture is illuminated from the top/upper left, north is toward the upper right. The small white box in the context frame (upper right corner) shows the location of the high resolution MOC view. |
|
Evidence for Recent Liquid W
…
PIA01034
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Gullies at 70°S in Polar Pit Walls |
| Original Caption Released with Image |
Gully landforms proposed to have been caused by geologically-recent seepage and runoff of liquid water on Mars are found in the most unlikely places. They typically occur in areas that are quite cold--well below freezing--all year round. Like the old adage about moss on trees, nearly all of them form on slopes that face away from sunlight. Most of the gullies occur at latitudes between 30° and 70°. The highest latitude at which martian gullies have been found is around 70°-75°S on the walls of pits developed in the south polar pitted plains. If you were at this same latitude on Earth, you would be in Antarctica. This region spends much of the winter--which lasts approximately 6 months on Mars--in darkness and at temperatures cold enough to freeze carbon dioxide (around -130°C or -200°F). Nevertheless, gullies with very sharp, deep, v-shaped channels are seen on the pit walls (above, left). Based upon the locations of the tops of the channels on the slope shown here, the inferred site of liquid seepage is located at a layer in the pit wall about 1/3 of the way down from the top of the MOC image. The channels start wide and taper downslope. The area above the channels is layered and has been eroded by mass movement--dry avalanching of debris--to form a pattern of chutes and ridges on the upper slope of the pit wall. The top layer appears to have many boulders in it (each about the size of a small house), these boulders are left behind on the upper slopes of the pit wall as debris is removed. Centered near 70.7°S, 355.7°W, the MOC image was acquired July 14, 1999, and covers an area approximately 2.8 km (1.7 mi) wide by 2.1 km(1.3 mi) high. Sunlight illuminates the MOC image from the upper left and north is toward the upper left. The context view (right) is from the Viking 2 orbiter and was acquired in 1977. The Viking picture is illuminated from the top/upper left, north is toward the upper right. The small white box in the context frame (upper right corner) shows the location of the high resolution MOC view. |
|
Evidence for Recent Liquid W
…
PIA01034
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Gullies at 70°S in Polar Pit Walls |
| Original Caption Released with Image |
Gully landforms proposed to have been caused by geologically-recent seepage and runoff of liquid water on Mars are found in the most unlikely places. They typically occur in areas that are quite cold--well below freezing--all year round. Like the old adage about moss on trees, nearly all of them form on slopes that face away from sunlight. Most of the gullies occur at latitudes between 30° and 70°. The highest latitude at which martian gullies have been found is around 70°-75°S on the walls of pits developed in the south polar pitted plains. If you were at this same latitude on Earth, you would be in Antarctica. This region spends much of the winter--which lasts approximately 6 months on Mars--in darkness and at temperatures cold enough to freeze carbon dioxide (around -130°C or -200°F). Nevertheless, gullies with very sharp, deep, v-shaped channels are seen on the pit walls (above, left). Based upon the locations of the tops of the channels on the slope shown here, the inferred site of liquid seepage is located at a layer in the pit wall about 1/3 of the way down from the top of the MOC image. The channels start wide and taper downslope. The area above the channels is layered and has been eroded by mass movement--dry avalanching of debris--to form a pattern of chutes and ridges on the upper slope of the pit wall. The top layer appears to have many boulders in it (each about the size of a small house), these boulders are left behind on the upper slopes of the pit wall as debris is removed. Centered near 70.7°S, 355.7°W, the MOC image was acquired July 14, 1999, and covers an area approximately 2.8 km (1.7 mi) wide by 2.1 km(1.3 mi) high. Sunlight illuminates the MOC image from the upper left and north is toward the upper left. The context view (right) is from the Viking 2 orbiter and was acquired in 1977. The Viking picture is illuminated from the top/upper left, north is toward the upper right. The small white box in the context frame (upper right corner) shows the location of the high resolution MOC view. |
|
Evidence for Recent Liquid W
…
PIA01036
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Seepage Sites in "Aerobraking Crater" Revisited |
| Original Caption Released with Image |
The first clue that there might be places on Mars where liquid groundwater seeps out onto the surface came from a picture taken by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) during the pre-mapping Orbit Insertion Phase of the mission. The picture, shown in (A)above, was taken at the end of December 1997 while the spacecraft was still in the midst of aerobraking maneuvers to put it into the circular orbit needed for the Mapping Phase of the project. The Aerobraking 1 image, AB1-07707, showed dark, v-shaped scars on the western wall of a 50 kilometer-(31 mile)-diameter impact crater in southern Noachis Terra at 65°S, 15°W (see B, above, for context). The v-shaped features taper downslope to form narrow, somewhat curved channels. The relationship seen here was interpreted by MOC scientists to be similar to seepage landforms on Earth that form where springs emerge on a slope and water runs downhill. Once MGS achieved its Mapping Orbit in March 1999, the MOC was in a better position to take pictures of 10 times higher resolution than the Aerobraking AB1-07707 image. The opportunity to take a new picture of the proposed "seepage" sites on the wall of the crater in southern Noachis finally arose in January 2000. The result is MOC image M11-00530, shown above in (top) and (C). This new close-up shows that the darkly-shaped scars host many small channels of only a few meters (yards) across. These small channels run downslope and coalesce at the apex (or point) of each "v". Amid the small channels are many large boulders, some of them the size of houses, that have eroded out of the crater wall. A 3-D view created using the AB1 and M11 images is shown in (D). The stereo picture (red-blue "3D" glasses required) emphasizes the presence of small channels and valleys, and shows that these valleys start almost at the very top of the v-shaped dark areas. The context picture in (B) is a mosaic of Viking 2 orbiter images 497B47 and 497B48 acquired December 28, 1977. The Aerobraking MGS MOC image, AB1-07707, is shown overlain on the Viking context image, it was taken 20 years later on December 29, 1997. The smaller white box in the context picture shows the location of MOC Mapping Phase image M11-00530, roughly 2 years later on January 4, 2000. North is "up" in pictures (A) and (B), and to the lower right in (top), (C), and (D). Sunlight illuminates (A) from the upper left, (B) from the upper right, and (top) and (C) from the upper right. The top image in (top) is the aerobraking image, AB1-07707, with a white box indicating the location of the lower image, M11-00530, and the stereo pair in (D). The white box on the left in (C) shows the location of the close-up on the right in (C). |
|
Evidence for Recent Liquid W
…
PIA01036
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Seepage Sites in "Aerobraking Crater" Revisited |
| Original Caption Released with Image |
The first clue that there might be places on Mars where liquid groundwater seeps out onto the surface came from a picture taken by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) during the pre-mapping Orbit Insertion Phase of the mission. The picture, shown in (A)above, was taken at the end of December 1997 while the spacecraft was still in the midst of aerobraking maneuvers to put it into the circular orbit needed for the Mapping Phase of the project. The Aerobraking 1 image, AB1-07707, showed dark, v-shaped scars on the western wall of a 50 kilometer-(31 mile)-diameter impact crater in southern Noachis Terra at 65°S, 15°W (see B, above, for context). The v-shaped features taper downslope to form narrow, somewhat curved channels. The relationship seen here was interpreted by MOC scientists to be similar to seepage landforms on Earth that form where springs emerge on a slope and water runs downhill. Once MGS achieved its Mapping Orbit in March 1999, the MOC was in a better position to take pictures of 10 times higher resolution than the Aerobraking AB1-07707 image. The opportunity to take a new picture of the proposed "seepage" sites on the wall of the crater in southern Noachis finally arose in January 2000. The result is MOC image M11-00530, shown above in (top) and (C). This new close-up shows that the darkly-shaped scars host many small channels of only a few meters (yards) across. These small channels run downslope and coalesce at the apex (or point) of each "v". Amid the small channels are many large boulders, some of them the size of houses, that have eroded out of the crater wall. A 3-D view created using the AB1 and M11 images is shown in (D). The stereo picture (red-blue "3D" glasses required) emphasizes the presence of small channels and valleys, and shows that these valleys start almost at the very top of the v-shaped dark areas. The context picture in (B) is a mosaic of Viking 2 orbiter images 497B47 and 497B48 acquired December 28, 1977. The Aerobraking MGS MOC image, AB1-07707, is shown overlain on the Viking context image, it was taken 20 years later on December 29, 1997. The smaller white box in the context picture shows the location of MOC Mapping Phase image M11-00530, roughly 2 years later on January 4, 2000. North is "up" in pictures (A) and (B), and to the lower right in (top), (C), and (D). Sunlight illuminates (A) from the upper left, (B) from the upper right, and (top) and (C) from the upper right. The top image in (top) is the aerobraking image, AB1-07707, with a white box indicating the location of the lower image, M11-00530, and the stereo pair in (D). The white box on the left in (C) shows the location of the close-up on the right in (C). |
|
Evidence for Recent Liquid W
…
PIA01036
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Seepage Sites in "Aerobraking Crater" Revisited |
| Original Caption Released with Image |
The first clue that there might be places on Mars where liquid groundwater seeps out onto the surface came from a picture taken by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) during the pre-mapping Orbit Insertion Phase of the mission. The picture, shown in (A)above, was taken at the end of December 1997 while the spacecraft was still in the midst of aerobraking maneuvers to put it into the circular orbit needed for the Mapping Phase of the project. The Aerobraking 1 image, AB1-07707, showed dark, v-shaped scars on the western wall of a 50 kilometer-(31 mile)-diameter impact crater in southern Noachis Terra at 65°S, 15°W (see B, above, for context). The v-shaped features taper downslope to form narrow, somewhat curved channels. The relationship seen here was interpreted by MOC scientists to be similar to seepage landforms on Earth that form where springs emerge on a slope and water runs downhill. Once MGS achieved its Mapping Orbit in March 1999, the MOC was in a better position to take pictures of 10 times higher resolution than the Aerobraking AB1-07707 image. The opportunity to take a new picture of the proposed "seepage" sites on the wall of the crater in southern Noachis finally arose in January 2000. The result is MOC image M11-00530, shown above in (top) and (C). This new close-up shows that the darkly-shaped scars host many small channels of only a few meters (yards) across. These small channels run downslope and coalesce at the apex (or point) of each "v". Amid the small channels are many large boulders, some of them the size of houses, that have eroded out of the crater wall. A 3-D view created using the AB1 and M11 images is shown in (D). The stereo picture (red-blue "3D" glasses required) emphasizes the presence of small channels and valleys, and shows that these valleys start almost at the very top of the v-shaped dark areas. The context picture in (B) is a mosaic of Viking 2 orbiter images 497B47 and 497B48 acquired December 28, 1977. The Aerobraking MGS MOC image, AB1-07707, is shown overlain on the Viking context image, it was taken 20 years later on December 29, 1997. The smaller white box in the context picture shows the location of MOC Mapping Phase image M11-00530, roughly 2 years later on January 4, 2000. North is "up" in pictures (A) and (B), and to the lower right in (top), (C), and (D). Sunlight illuminates (A) from the upper left, (B) from the upper right, and (top) and (C) from the upper right. The top image in (top) is the aerobraking image, AB1-07707, with a white box indicating the location of the lower image, M11-00530, and the stereo pair in (D). The white box on the left in (C) shows the location of the close-up on the right in (C). |
|
Evidence for Recent Liquid W
…
PIA01036
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Seepage Sites in "Aerobraking Crater" Revisited |
| Original Caption Released with Image |
The first clue that there might be places on Mars where liquid groundwater seeps out onto the surface came from a picture taken by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) during the pre-mapping Orbit Insertion Phase of the mission. The picture, shown in (A)above, was taken at the end of December 1997 while the spacecraft was still in the midst of aerobraking maneuvers to put it into the circular orbit needed for the Mapping Phase of the project. The Aerobraking 1 image, AB1-07707, showed dark, v-shaped scars on the western wall of a 50 kilometer-(31 mile)-diameter impact crater in southern Noachis Terra at 65°S, 15°W (see B, above, for context). The v-shaped features taper downslope to form narrow, somewhat curved channels. The relationship seen here was interpreted by MOC scientists to be similar to seepage landforms on Earth that form where springs emerge on a slope and water runs downhill. Once MGS achieved its Mapping Orbit in March 1999, the MOC was in a better position to take pictures of 10 times higher resolution than the Aerobraking AB1-07707 image. The opportunity to take a new picture of the proposed "seepage" sites on the wall of the crater in southern Noachis finally arose in January 2000. The result is MOC image M11-00530, shown above in (top) and (C). This new close-up shows that the darkly-shaped scars host many small channels of only a few meters (yards) across. These small channels run downslope and coalesce at the apex (or point) of each "v". Amid the small channels are many large boulders, some of them the size of houses, that have eroded out of the crater wall. A 3-D view created using the AB1 and M11 images is shown in (D). The stereo picture (red-blue "3D" glasses required) emphasizes the presence of small channels and valleys, and shows that these valleys start almost at the very top of the v-shaped dark areas. The context picture in (B) is a mosaic of Viking 2 orbiter images 497B47 and 497B48 acquired December 28, 1977. The Aerobraking MGS MOC image, AB1-07707, is shown overlain on the Viking context image, it was taken 20 years later on December 29, 1997. The smaller white box in the context picture shows the location of MOC Mapping Phase image M11-00530, roughly 2 years later on January 4, 2000. North is "up" in pictures (A) and (B), and to the lower right in (top), (C), and (D). Sunlight illuminates (A) from the upper left, (B) from the upper right, and (top) and (C) from the upper right. The top image in (top) is the aerobraking image, AB1-07707, with a white box indicating the location of the lower image, M11-00530, and the stereo pair in (D). The white box on the left in (C) shows the location of the close-up on the right in (C). |
|
Evidence for Recent Liquid W
…
PIA01036
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Seepage Sites in "Aerobraking Crater" Revisited |
| Original Caption Released with Image |
The first clue that there might be places on Mars where liquid groundwater seeps out onto the surface came from a picture taken by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) during the pre-mapping Orbit Insertion Phase of the mission. The picture, shown in (A)above, was taken at the end of December 1997 while the spacecraft was still in the midst of aerobraking maneuvers to put it into the circular orbit needed for the Mapping Phase of the project. The Aerobraking 1 image, AB1-07707, showed dark, v-shaped scars on the western wall of a 50 kilometer-(31 mile)-diameter impact crater in southern Noachis Terra at 65°S, 15°W (see B, above, for context). The v-shaped features taper downslope to form narrow, somewhat curved channels. The relationship seen here was interpreted by MOC scientists to be similar to seepage landforms on Earth that form where springs emerge on a slope and water runs downhill. Once MGS achieved its Mapping Orbit in March 1999, the MOC was in a better position to take pictures of 10 times higher resolution than the Aerobraking AB1-07707 image. The opportunity to take a new picture of the proposed "seepage" sites on the wall of the crater in southern Noachis finally arose in January 2000. The result is MOC image M11-00530, shown above in (top) and (C). This new close-up shows that the darkly-shaped scars host many small channels of only a few meters (yards) across. These small channels run downslope and coalesce at the apex (or point) of each "v". Amid the small channels are many large boulders, some of them the size of houses, that have eroded out of the crater wall. A 3-D view created using the AB1 and M11 images is shown in (D). The stereo picture (red-blue "3D" glasses required) emphasizes the presence of small channels and valleys, and shows that these valleys start almost at the very top of the v-shaped dark areas. The context picture in (B) is a mosaic of Viking 2 orbiter images 497B47 and 497B48 acquired December 28, 1977. The Aerobraking MGS MOC image, AB1-07707, is shown overlain on the Viking context image, it was taken 20 years later on December 29, 1997. The smaller white box in the context picture shows the location of MOC Mapping Phase image M11-00530, roughly 2 years later on January 4, 2000. North is "up" in pictures (A) and (B), and to the lower right in (top), (C), and (D). Sunlight illuminates (A) from the upper left, (B) from the upper right, and (top) and (C) from the upper right. The top image in (top) is the aerobraking image, AB1-07707, with a white box indicating the location of the lower image, M11-00530, and the stereo pair in (D). The white box on the left in (C) shows the location of the close-up on the right in (C). |
|
Evidence for Recent Liquid W
…
PIA01036
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Seepage Sites in "Aerobraking Crater" Revisited |
| Original Caption Released with Image |
The first clue that there might be places on Mars where liquid groundwater seeps out onto the surface came from a picture taken by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) during the pre-mapping Orbit Insertion Phase of the mission. The picture, shown in (A)above, was taken at the end of December 1997 while the spacecraft was still in the midst of aerobraking maneuvers to put it into the circular orbit needed for the Mapping Phase of the project. The Aerobraking 1 image, AB1-07707, showed dark, v-shaped scars on the western wall of a 50 kilometer-(31 mile)-diameter impact crater in southern Noachis Terra at 65°S, 15°W (see B, above, for context). The v-shaped features taper downslope to form narrow, somewhat curved channels. The relationship seen here was interpreted by MOC scientists to be similar to seepage landforms on Earth that form where springs emerge on a slope and water runs downhill. Once MGS achieved its Mapping Orbit in March 1999, the MOC was in a better position to take pictures of 10 times higher resolution than the Aerobraking AB1-07707 image. The opportunity to take a new picture of the proposed "seepage" sites on the wall of the crater in southern Noachis finally arose in January 2000. The result is MOC image M11-00530, shown above in (top) and (C). This new close-up shows that the darkly-shaped scars host many small channels of only a few meters (yards) across. These small channels run downslope and coalesce at the apex (or point) of each "v". Amid the small channels are many large boulders, some of them the size of houses, that have eroded out of the crater wall. A 3-D view created using the AB1 and M11 images is shown in (D). The stereo picture (red-blue "3D" glasses required) emphasizes the presence of small channels and valleys, and shows that these valleys start almost at the very top of the v-shaped dark areas. The context picture in (B) is a mosaic of Viking 2 orbiter images 497B47 and 497B48 acquired December 28, 1977. The Aerobraking MGS MOC image, AB1-07707, is shown overlain on the Viking context image, it was taken 20 years later on December 29, 1997. The smaller white box in the context picture shows the location of MOC Mapping Phase image M11-00530, roughly 2 years later on January 4, 2000. North is "up" in pictures (A) and (B), and to the lower right in (top), (C), and (D). Sunlight illuminates (A) from the upper left, (B) from the upper right, and (top) and (C) from the upper right. The top image in (top) is the aerobraking image, AB1-07707, with a white box indicating the location of the lower image, M11-00530, and the stereo pair in (D). The white box on the left in (C) shows the location of the close-up on the right in (C). |
|
Evidence for Recent Liquid W
…
PIA01036
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Seepage Sites in "Aerobraking Crater" Revisited |
| Original Caption Released with Image |
The first clue that there might be places on Mars where liquid groundwater seeps out onto the surface came from a picture taken by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) during the pre-mapping Orbit Insertion Phase of the mission. The picture, shown in (A)above, was taken at the end of December 1997 while the spacecraft was still in the midst of aerobraking maneuvers to put it into the circular orbit needed for the Mapping Phase of the project. The Aerobraking 1 image, AB1-07707, showed dark, v-shaped scars on the western wall of a 50 kilometer-(31 mile)-diameter impact crater in southern Noachis Terra at 65°S, 15°W (see B, above, for context). The v-shaped features taper downslope to form narrow, somewhat curved channels. The relationship seen here was interpreted by MOC scientists to be similar to seepage landforms on Earth that form where springs emerge on a slope and water runs downhill. Once MGS achieved its Mapping Orbit in March 1999, the MOC was in a better position to take pictures of 10 times higher resolution than the Aerobraking AB1-07707 image. The opportunity to take a new picture of the proposed "seepage" sites on the wall of the crater in southern Noachis finally arose in January 2000. The result is MOC image M11-00530, shown above in (top) and (C). This new close-up shows that the darkly-shaped scars host many small channels of only a few meters (yards) across. These small channels run downslope and coalesce at the apex (or point) of each "v". Amid the small channels are many large boulders, some of them the size of houses, that have eroded out of the crater wall. A 3-D view created using the AB1 and M11 images is shown in (D). The stereo picture (red-blue "3D" glasses required) emphasizes the presence of small channels and valleys, and shows that these valleys start almost at the very top of the v-shaped dark areas. The context picture in (B) is a mosaic of Viking 2 orbiter images 497B47 and 497B48 acquired December 28, 1977. The Aerobraking MGS MOC image, AB1-07707, is shown overlain on the Viking context image, it was taken 20 years later on December 29, 1997. The smaller white box in the context picture shows the location of MOC Mapping Phase image M11-00530, roughly 2 years later on January 4, 2000. North is "up" in pictures (A) and (B), and to the lower right in (top), (C), and (D). Sunlight illuminates (A) from the upper left, (B) from the upper right, and (top) and (C) from the upper right. The top image in (top) is the aerobraking image, AB1-07707, with a white box indicating the location of the lower image, M11-00530, and the stereo pair in (D). The white box on the left in (C) shows the location of the close-up on the right in (C). |
|
Evidence for Recent Liquid W
…
PIA01036
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Seepage Sites in "Aerobraking Crater" Revisited |
| Original Caption Released with Image |
The first clue that there might be places on Mars where liquid groundwater seeps out onto the surface came from a picture taken by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) during the pre-mapping Orbit Insertion Phase of the mission. The picture, shown in (A)above, was taken at the end of December 1997 while the spacecraft was still in the midst of aerobraking maneuvers to put it into the circular orbit needed for the Mapping Phase of the project. The Aerobraking 1 image, AB1-07707, showed dark, v-shaped scars on the western wall of a 50 kilometer-(31 mile)-diameter impact crater in southern Noachis Terra at 65°S, 15°W (see B, above, for context). The v-shaped features taper downslope to form narrow, somewhat curved channels. The relationship seen here was interpreted by MOC scientists to be similar to seepage landforms on Earth that form where springs emerge on a slope and water runs downhill. Once MGS achieved its Mapping Orbit in March 1999, the MOC was in a better position to take pictures of 10 times higher resolution than the Aerobraking AB1-07707 image. The opportunity to take a new picture of the proposed "seepage" sites on the wall of the crater in southern Noachis finally arose in January 2000. The result is MOC image M11-00530, shown above in (top) and (C). This new close-up shows that the darkly-shaped scars host many small channels of only a few meters (yards) across. These small channels run downslope and coalesce at the apex (or point) of each "v". Amid the small channels are many large boulders, some of them the size of houses, that have eroded out of the crater wall. A 3-D view created using the AB1 and M11 images is shown in (D). The stereo picture (red-blue "3D" glasses required) emphasizes the presence of small channels and valleys, and shows that these valleys start almost at the very top of the v-shaped dark areas. The context picture in (B) is a mosaic of Viking 2 orbiter images 497B47 and 497B48 acquired December 28, 1977. The Aerobraking MGS MOC image, AB1-07707, is shown overlain on the Viking context image, it was taken 20 years later on December 29, 1997. The smaller white box in the context picture shows the location of MOC Mapping Phase image M11-00530, roughly 2 years later on January 4, 2000. North is "up" in pictures (A) and (B), and to the lower right in (top), (C), and (D). Sunlight illuminates (A) from the upper left, (B) from the upper right, and (top) and (C) from the upper right. The top image in (top) is the aerobraking image, AB1-07707, with a white box indicating the location of the lower image, M11-00530, and the stereo pair in (D). The white box on the left in (C) shows the location of the close-up on the right in (C). |
|
Evidence for Recent Liquid W
…
PIA01039
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars: Channeled Aprons in a Small Crater within Newton Crater |
| Original Caption Released with Image |
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 upon 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 MOC high resolution view is located near 41.1°S, 159.8°W 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. The context picture was acquired in 1977 by the Viking 1 orbiter and is illuminated from the upper right. |
|
Evidence for Recent Liquid W
…
PIA01032
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars:"Weeping" Layer in Gorgonum Chaos |
| Original Caption Released with Image |
This image, acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) in May 2000 shows numerous examples of martian gullies that all start--or head--in a specific layer roughly a hundred meters beneath the surface of Mars. These features are located on the south-facing wall of a trough in the Gorgonum Chaos region, an area found to have many examples of gullies proposed to have formed by seepage and runoff of liquid water in recent martian times. The layer from which the gullies emanate has recessed backward to form an overhang beneath a harder layer of rock. The larger gullies have formed an alcove--an area above the overhang from which debris has collapsed to leave a dark-toned scar. Below the layer of seepage is found a dark, narrow channel that runs down the slope to an apron of debris. The small, bright, parallel features at the base of the cliff at the center-right of the picture is a series of large windblown ripples. Although the dark tone of the alcoves and channels in this image is not likely to be the result of wet ground (the contrast in this image has been enhanced), it does suggest that water has seeped out of the ground and moved down the slope quite recently. Sharp contrasts between dark and light areas are hard to maintain on Mars for very long periods of time because dust tends to coat surfaces and reduce brightness differences. To keep dust from settling on a surface, it has to have undergone some process of erosion (wind, landslides, water runoff) relatively recently. There is no way to know how recent this activity was, but educated guesses center between a few to tens of years, and it is entirely possible that the area shown in this image has water seeping out of the ground today. Centered near 37.9°S, 170.2°W, sunlight illuminates the MOC image from the upper left, north is toward the upper right. The context view above is from the Viking 1 orbiter and was acquired in 1977. The Viking picture is illuminated from the upper right, north is up. The small white box in the context frame shows the location of the high resolution MOC view. |
|
Evidence for Recent Liquid W
…
PIA01032
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars:"Weeping" Layer in Gorgonum Chaos |
| Original Caption Released with Image |
This image, acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) in May 2000 shows numerous examples of martian gullies that all start--or head--in a specific layer roughly a hundred meters beneath the surface of Mars. These features are located on the south-facing wall of a trough in the Gorgonum Chaos region, an area found to have many examples of gullies proposed to have formed by seepage and runoff of liquid water in recent martian times. The layer from which the gullies emanate has recessed backward to form an overhang beneath a harder layer of rock. The larger gullies have formed an alcove--an area above the overhang from which debris has collapsed to leave a dark-toned scar. Below the layer of seepage is found a dark, narrow channel that runs down the slope to an apron of debris. The small, bright, parallel features at the base of the cliff at the center-right of the picture is a series of large windblown ripples. Although the dark tone of the alcoves and channels in this image is not likely to be the result of wet ground (the contrast in this image has been enhanced), it does suggest that water has seeped out of the ground and moved down the slope quite recently. Sharp contrasts between dark and light areas are hard to maintain on Mars for very long periods of time because dust tends to coat surfaces and reduce brightness differences. To keep dust from settling on a surface, it has to have undergone some process of erosion (wind, landslides, water runoff) relatively recently. There is no way to know how recent this activity was, but educated guesses center between a few to tens of years, and it is entirely possible that the area shown in this image has water seeping out of the ground today. Centered near 37.9°S, 170.2°W, sunlight illuminates the MOC image from the upper left, north is toward the upper right. The context view above is from the Viking 1 orbiter and was acquired in 1977. The Viking picture is illuminated from the upper right, north is up. The small white box in the context frame shows the location of the high resolution MOC view. |
|
Evidence for Recent Liquid W
…
PIA01032
Sol (our sun)
Mars Orbiter Camera
| Title |
Evidence for Recent Liquid Water on Mars:"Weeping" Layer in Gorgonum Chaos |
| Original Caption Released with Image |
This image, acquired by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) in May 2000 shows numerous examples of martian gullies that all start--or head--in a specific layer roughly a hundred meters beneath the surface of Mars. These features are located on the south-facing wall of a trough in the Gorgonum Chaos region, an area found to have many examples of gullies proposed to have formed by seepage and runoff of liquid water in recent martian times. The layer from which the gullies emanate has recessed backward to form an overhang beneath a harder layer of rock. The larger gullies have formed an alcove--an area above the overhang from which debris has collapsed to leave a dark-toned scar. Below the layer of seepage is found a dark, narrow channel that runs down the slope to an apron of debris. The small, bright, parallel features at the base of the cliff at the center-right of the picture is a series of large windblown ripples. Although the dark tone of the alcoves and channels in this image is not likely to be the result of wet ground (the contrast in this image has been enhanced), it does suggest that water has seeped out of the ground and moved down the slope quite recently. Sharp contrasts between dark and light areas are hard to maintain on Mars for very long periods of time because dust tends to coat surfaces and reduce brightness differences. To keep dust from settling on a surface, it has to have undergone some process of erosion (wind, landslides, water runoff) relatively recently. There is no way to know how recent this activity was, but educated guesses center between a few to tens of years, and it is entirely possible that the area shown in this image has water seeping out of the ground today. Centered near 37.9°S, 170.2°W, sunlight illuminates the MOC image from the upper left, north is toward the upper right. The context view above is from the Viking 1 orbiter and was acquired in 1977. The Viking picture is illuminated from the upper right, north is up. The small white box in the context frame shows the location of the high resolution MOC view. |
|
| General Description |
Exploration Imagery |
|
|
![Explanation: Hurtling through space a mere 3,000 miles above the Martian surface [ http://antwrp.gsfc.nasa.gov/apod/ap960720.html ], the diminutive moon Phobos [ http://antwrp.gsfc.nasa.gov/apod/ap951002.html ] (below and left of center) was imaged against the backdrop of a large shield volcano [ http://antwrp.gsfc.nasa.gov/apod/ap950719.html ] by the Viking 2 Orbiter [ http://nssdc.gsfc.nasa.gov/planetary/viking.html ] in 1977. This dramatic picture [ http://nssdc.gsfc.nasa.gov/imgcat/html/object_page/vo2_304b88.html ] looks down from the Orbiter's viewpoint about 8,000 miles above the volcano, Ascraeus Mons. Phobos itself is 5,000 miles below the Orbiter. North is toward the top with the Sun illuminating the scene from the South (black dots are reference marks). For scale, Ascraeus Mons is about 200 miles across at its base while asteroid sized [ http://hurlbut.jhuapl.edu:80/NEAR/Education/intro/minorobjects.html ] Phobos is about 15 miles in diameter. In this spectacular moon-planet [ http://antwrp.gsfc.nasa.gov/apod/ap961007.html ] image, volcanic calderas [ http://bang.lanl.gov/solarsys/marsvolc.htm ] (craters) are visible at the summit of Ascraeus Mons -- while impact craters on the sunlit side of Phobos [ http://seds.lpl.arizona.edu/nineplanets/nineplanets/phobos.html ]' surface can also be seen!](http://mm04.nasaimages.org/MediaManager/srvr?mediafile=/Size1/NVA2-4-NA/8086/phobosmars_viking2_big.jpg&userid=1&username=admin&resolution=1&servertype=JVA&cid=4&iid=NVA2&vcid=NA&usergroup=NASA_Astronomy_Picture_of_the_Day_Collecti-4-Admin&profileid=16)
