Cette galrie comprend des photos provenant des observations réalisées par le télescope spatial Hubble, de la mission MSG Mars Global Surveyor, quelques photos de Mariner, de Mars Express et des phtos diverses.

Galerie de photos de la planète Mars

<h1>PIA00935: MGS Approach Image - 37.2° W longitude</h1><div class="PIA00935" lang="en" style="width:512px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This image of Mars shows an area centered near the Pathfinder landing site. The dark area north of the center of the image along the sunrise terminator is Acidalia Planitia--the Pathfinder landing site is about a third of the way down from this dark area across the light Chryse plains. The bright area near the edge of the planet is Arabia. The lower 40% of the image contains the Xanthe, Margaritifer, and Meridiani highlands, heavily-cratered, ancient areas of the most intense erosion seen on Mars. These will be among the more important targets of the MOC when it begins detailed studies in March 1998.<p>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 operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00935" onclick="window.open(this.href); return false;" title="Voir l'image PIA00935: MGS Approach Image - 37.2° W longitude sur le site de la NASA">Voir l'image PIA00935: MGS Approach Image - 37.2° W longitude sur le site de la NASA.</a></div>
PIA00935: MGS Approach Image - 37.2° W longitude
<h1>PIA00936: MGS Approach Image - 127.2° W longitude</h1><div class="PIA00936" lang="en" style="width:512px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This image, the last in sequence of 8 taken by the Mars Global Surveyor (MGS) spacecraft prior to its arrival at Mars on September 11, 1997, shows a spectacular view of the large volcano, Olympus Mons, very close to the morning sunrise line (called the terminator). Taken early in the morning of August 21, the view clearly shows the summit crater (the caldera) and the 3,000 m (9,800 feet) high escarpment that surrounds the base of the 25,000 meter (82,000 feet) high, 550 km (340 mile) wide volcano. To the right of Olympus Mons are three other large volcanoes (Ascraeus Mons, top; Pavonis Mons, middle; Arsia Mons, bottom). The image is centered near 23.6° N, 127.2° W, and was acquired when MGS was 5.38 million kilometers (3.34 million miles) from Mars. At this distance, the MOC's resolution is about 20 km per picture element, and the 6800 km (4200 mile) diameter planet is about 340 pixels across. In the 46 hours between the first and last images in the sequence, the diameter of Mars in the pictures grew by almost 10%.<p>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 operates the Mars Global Surveyor spacecraft with its industrial partner, Lockheed Martin Astronautics, from facilities in Pasadena, CA and Denver, CO.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00936" onclick="window.open(this.href); return false;" title="Voir l'image PIA00936: MGS Approach Image - 127.2° W longitude sur le site de la NASA">Voir l'image PIA00936: MGS Approach Image - 127.2° W longitude sur le site de la NASA.</a></div>
PIA00936: MGS Approach Image - 127.2° W longitude
<h1>PIA00991: Valles Marineris</h1><div class="PIA00991" lang="en" style="width:717px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MOC images P013_01 and P013_02 were acquired with the low resolution red and blue wide angle cameras at 2:14 PM PDT on October 3, 1997, about 11 minutes after Mars Global Surveyor passed close to the planet for the thirteenth time. To make a color image, a third component (green) was synthesized from the red and blue images. During the imaging period, the spacecraft was canted towards the sun-lit hemisphere by 25°, and the MOC was obliquely viewing features from about 600 to 1000 km (360 to 600 miles) away. The resolution at those distances was between 350 and 600 meters (0.25 to 0.37 miles) per picture element. The image covers an area from 73° to 86° W longitude and 5° N to 10° S).<p>In the image above, north is to the top. The camera is viewing towards the west. The image is the composite of MOC frames P013_01 and P013_02. Because the MOC acquires its images one line at a time, the cant angle towards the sun-lit portion of the planet, the spacecraft orbital velocity, and the spacecraft rotational velocity combine to distort the image slightly. However, the wide angle cameras provide a fairly realistic portrayal of what one would see looking out across Mars from the Orbiter. Notable in this image are the late afternoon clouds and hazes that are concentrated within the Valles Marineris canyon system.<p>Launched on November 7, 1996, Mars Global Surveyor entered Mars orbit on Thursday, September 11, 1997. From the planned 400 km (248 mi) orbit altitude, MOC wide angle images will be 2-4 times higher resolution than these pictures.<p>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.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00991" onclick="window.open(this.href); return false;" title="Voir l'image PIA00991: Valles Marineris sur le site de la NASA">Voir l'image PIA00991: Valles Marineris sur le site de la NASA.</a></div>
PIA00991: Valles Marineris
<h1>PIA00992: Valles Marineris</h1><div class="PIA00992" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">MOC images P013_01 and P013_02 were acquired with the low resolution red and blue wide angle cameras at 2:14 PM PDT on October 3, 1997, about 11 minutes after Mars Global Surveyor passed close to the planet for the thirteenth time. To make a color image, a third component (green) was synthesized from the red and blue images. During the imaging period, the spacecraft was canted towards the sun-lit hemisphere by 25°, and the MOC was obliquely viewing features from about 600 to 1000 km (360 to 600 miles) away. The resolution at those distances was between 350 and 600 meters (0.25 to 0.37 miles) per picture element. The image covers an area from 73° to 86° W longitude and 5° N to 10° S).<p>In both of the two images shown above, north is to the top. In the MOC image, the camera was viewing towards the west.<p>The left image is excepted from a U.S. Geological Survey shaded relief map, showing the footprint of the MOC wide angle color image. The large canyon system (Valles Marineris) spans this view; chaotic terrain is seen at the far right and the eastern-most of the four large Tharsis volcanoes (Ascraeus Mons) is shown in upper left.<p>The right image is the composite of MOC frames P013_01 and P013_02. Because the MOC acquires its images one line at a time, the cant angle towards the sun-lit portion of the planet, the spacecraft orbital velocity, and the spacecraft rotational velocity combine to distort the image slightly. However, the wide angle cameras provide a fairly realistic portrayal of what one would see looking out across Mars from the Orbiter. Notable in this image are the late afternoon clouds and hazes that are concentrated within the canyon system. This image is available at higher resolution as PIA00991.<p>Launched on November 7, 1996, Mars Global Surveyor entered Mars orbit on Thursday, September 11, 1997. From the planned 400 km (248 mi) orbit altitude, MOC wide angle images will be 2-4 times higher resolution than these pictures.<p>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.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00992" onclick="window.open(this.href); return false;" title="Voir l'image PIA00992: Valles Marineris sur le site de la NASA">Voir l'image PIA00992: Valles Marineris sur le site de la NASA.</a></div>
PIA00992: Valles Marineris
<h1>PIA00993: Olympus Mons in Color</h1><div class="PIA00993" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Sections of MOC images P024_01 and P024_02, shown here in color composite form, were acquired with the low resolution red and blue wide angle cameras over a 5 minute period starting when Mars Global Surveyor was at its closest point to the planet at the beginning of its 24th orbit (around 4:00 AM PDT on October 20, 1997). To make this image, a third component (green) was synthesized from the red and blue images. During the imaging period, the camera was pointed straight down towards the martian surface, 176 km (109 miles) below the spacecraft. During the time it took to acquire the image, the spacecraft rose to an altitude of 310 km (193 miles). Owing to data camera scanning rate and data volume constraints, the image was acquired at a resolution of roughly 1 km (0.609 mile) per pixel. The image shown here covers an area from 12° to 26° N latitude and 126° N to 138° W longitude. The image is oriented with north to the top.<p>As has been noted in other MOC releases, Olympus Mons is the largest of the major Tharsis volcanoes, rising 25 km (15.5 miles) and stretching over nearly 550 km (340 miles) east-west. The summit caldera, a composite of as many as seven roughly circular collapse depressions, is 66 by 83 km (41 by 52 miles) across. Also seen in this image are water-ice clouds that accumulate around and above the volcano during the late afternoon (at the time the image was acquired, the summit was at 5:30 PM local solar time). To understand the value of orbital observations, compare this image with the two taken during approach (PIA00929 and PIA00936), that are representative of the best resolution from Earth.<p>Through Monday, October 28, the MOC had acquired a total of 132 images, most of which were at low sun elevation angles. Of these images, 74 were taken with the high resolution narrow angle camera and 58 with the low resolution wide angle cameras. Twenty-eight narrow angle and 24 wide angle images were taken after the suspension of aerobraking. These images, including the one shown above, are among the best returned so far.<p>Launched on November 7, 1996, Mars Global Surveyor entered Mars orbit on Thursday, September 11, 1997. The original mission plan called for using friction with the planet's atmosphere to reduce the orbital energy, leading to a two-year mapping mission from close, circular orbit (beginning in March 1998). Owing to difficulties with one of the two solar panels, aerobraking was suspended in mid-October and is scheduled to resume in mid-November. Many of the original objectives of the mission, and in particular those of the camera, are likely to be accomplished as the mission progresses.<p>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.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA00993" onclick="window.open(this.href); return false;" title="Voir l'image PIA00993: Olympus Mons in Color sur le site de la NASA">Voir l'image PIA00993: Olympus Mons in Color sur le site de la NASA.</a></div>
PIA00993: Olympus Mons in Color
<h1>PIA01031: Evidence for Recent Liquid Water on Mars: Basic Features of Martian Gullies</h1><div class="PIA01031" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Water is the chief agent of weathering and erosion on Earth. Mars is a much drier, colder planet on which liquid water cannot exist very long at the surface because it will immediately begin to boil, evaporate, and freeze--all at the same time. However, new pictures from the Mars Orbiter Camera (MOC) onboard the Mars Global Surveyor (MGS) have provided an astonishing observation which suggests that liquid water may have played a role in shaping some recent gully-like features found on the slopes of various craters, troughs, and other depressions on the red planet.<p>These pictures introduce the basic features of a martian gully. The figure on the left is an example from Mars, the figure on the right is a gully on Earth. In the Earth picture, rain water flowing under and seeping along the base of a recently-deposited volcanic ash layer has created the gully. For Mars, water is not actually seen but is inferred from the landforms and their similarity to examples on Earth.<p>The landforms both on Earth and Mars are divided into three parts: the alcove, the channel, and the apron. Water seeps from between layers of rock on the wall of a cliff, crater, or other type of depression. The alcove forms above the site of seepage as water comes out of the ground and undermines the material from which it is seeping. The erosion of material at the site of seepage causes rock and debris on the slope above this area to collapse and slide downhill, creating the alcove.<p>The channel forms from water and debris running down the slope from the seepage area. The point where the top of the channel meets the bottom of the alcove is, in many cases, the site where seepage is occurring. Channels are probably flushed-clean of debris from time to time by large flash floods of water released from behind an ice barrier that might form at the site of seepage during more quiescent times.<p>The aprons are the down-slope deposits of ice and debris that were moved down the slope and through the channel. Whether any water--likely in the form of ice--persists in these deposits is unknown. The fact that the aprons do not go very far out onto the floors of craters and troughs (e.g., the foreground of the figure on the left) indicates that there is a limit as to how much water actually makes it to the bottom of the slope in liquid form. Most of the water by the time it reaches the bottom of the slope has probably either evaporated or frozen.<p>The MOC image on the left was acquired July 3, 1999, and is located on the south-facing wall of an impact crater near 54.8°S, 342.5°W. The MOC image is illuminated from the upper left; north is toward the upper right. The MOC image covers an area 1.3 km (0.8 mi) wide by 2 km (1.2 mi) long. The pictures from the flank of the Mount St. Helens volcano in Washington (right; large image and inset) were taken by MGSMOC Principal Investigator, Michael C. Malin, in the 1980s after the eruptions of May 1980. They are illuminated from the left; note footprints on left side of the picture for scale, also note the colored bar, which is 30 cm (11.8 in) long.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01031" onclick="window.open(this.href); return false;" title="Voir l'image PIA01031: Evidence for Recent Liquid Water on Mars: Basic Features of Martian Gullies sur le site de la NASA">Voir l'image PIA01031: Evidence for Recent Liquid Water on Mars: Basic Features of Martian Gullies sur le site de la NASA.</a></div>
PIA01031: Evidence for Recent Liquid Water on Mars: Basic Features of Martian Gullies
<h1>PIA01033: Evidence for Recent Liquid Water on Mars: Gullies in Gorgonum Chaos</h1><div class="PIA01033" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><br><a href="/figures/moc2_236b.jpg">Full Resolution Color View</a>.<br><a href="/figures/moc2_236bbw.gif">Full Resolution Grayscale View</a>.<br><b>Warning!</b>These images are very large. These are too long for some web browsers <br>(in these cases, you must save the link to your desktop and view with other software)<br><a href="/figures/moc2_236c.jpg">Larger View</a><br><br><br><p>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.<p>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.<br><br><p><b>NOTE</b>: A Full Resolution Grayscale view of the release image can be found <a href="/figures/moc2_236bw.gif">here</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01033" onclick="window.open(this.href); return false;" title="Voir l'image PIA01033: Evidence for Recent Liquid Water on Mars: Gullies in Gorgonum Chaos sur le site de la NASA">Voir l'image PIA01033: Evidence for Recent Liquid Water on Mars: Gullies in Gorgonum Chaos sur le site de la NASA.</a></div>
PIA01033: Evidence for Recent Liquid Water on Mars: Gullies in Gorgonum Chaos
<h1>PIA01035: Evidence for Recent Liquid Water on Mars: Gullies in Crater Wall, Noachis Terra</h1><div class="PIA01035" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><a href="/figures/moc2_238b.jpg"></a><br><br><p>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.<p>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 54.8°S, 342.5°W. 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.<p><b>A brief description of how the color was generated:</b>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 pallette 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 only a crude approximation of martian color and should only be considered representative of Mars. It is likely Mars would not look like this to a human observer at Mars.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01035" onclick="window.open(this.href); return false;" title="Voir l'image PIA01035: Evidence for Recent Liquid Water on Mars: Gullies in Crater Wall, Noachis Terra sur le site de la NASA">Voir l'image PIA01035: Evidence for Recent Liquid Water on Mars: Gullies in Crater Wall, Noachis Terra sur le site de la NASA.</a></div>
PIA01035: Evidence for Recent Liquid Water on Mars: Gullies in Crater Wall, Noachis Terra
<h1>PIA01040: Evidence for Recent Liquid Water on Mars: Gullies in Sirenum Fossae Trough</h1><div class="PIA01040" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This mosaic of two Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images shows about 20 different gullies coming down the south-facing wall of a trough in the Sirenum Fossae/Gorgonum Chaos region of the martian southern hemisphere. Each channel and its associated fan--or apron--of debris appears to have started just below the same hard, resistant layer of bedrock located approximately 100 meters (about 325 feet) below the top of the trough wall. The layer beneath this hard, resistant bedrock is interpreted to be permeable, which allows ground water to percolate through it and--at the location of this trough--seep out onto the martian surface. The channels and aprons only occur on the south-facing slope of this valley created by faults on each side of the trough. The depression is approximately 1.4 km (0.9 mi) across.<p>The mosaic was constructed from two pictures taken on September 16, 1999, and May 1, 2000. The black line is a gap between the two images that was not covered by MOC. The scene covers an area approximately 5.5 kilometers (3.4 miles) wide by 4.9 km (3.0 mi) high. Sunlight illuminates the area from the upper left. The image is located near 38.5°S, 171.3°W. 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.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01040" onclick="window.open(this.href); return false;" title="Voir l'image PIA01040: Evidence for Recent Liquid Water on Mars: Gullies in Sirenum Fossae Trough sur le site de la NASA">Voir l'image PIA01040: Evidence for Recent Liquid Water on Mars: Gullies in Sirenum Fossae Trough sur le site de la NASA.</a></div>
PIA01040: Evidence for Recent Liquid Water on Mars: Gullies in Sirenum Fossae Trough
<h1>PIA01239: Coprates Catena</h1><div class="PIA01239" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This picture of Coprates Catena (14.7°S, 55.8°W) was obtained in the early evening of January 1, 1998 by the Mars Orbiter Camera (MOC), shortly after the Mars Global Surveyor spacecraft began its 80th orbit. The image covers a tiny fraction of the Valles Marineris canyons (that stretch over 4000 km, or 2500 miles, east-west) at very high resolution: it extends only 10 km by 12 km (6 mi by 7.5 mi) and captures features as small as 6 m (20 ft) across. Slopes descend to the north and south (upper and lower part of image, respectively) in broad, debris-filled gullies with intervening rocky spurs. Multiple rock layers, varying from a few to a few tens of meters thick, are visible in the steep slopes on the spurs and gullies. Layered rocks on Earth form from sedimentary processes (such as those that formed the layered rocks now seen in Arizona's Grand Canyon) and volcanic processes (such as layering seen in the Waimea Canyon on the island of Kauai). Both origins are possible for the Martian layered rocks seen in this image. In either case, the total thickness of the layered rocks seen in this image implies a complex and extremely active early history for geologic processes on Mars.<p>Low-resolution Viking color images were used to "colorize" this frame. The process takes the red, green, and blue (RGB) low-resolution images and transforms them to hue (color), saturation (whether the colors are bold or pastel), and intensity (the brightness of the scene), or HSI. The high resolution grayscale image is then used to replace the low-resolution intensity image, and the images are transformed back to RGB. The colors were additionally modified to appear less saturated and more "Earth-like."<p><b> This image does not represent the "true" color of Mars</b><br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01239" onclick="window.open(this.href); return false;" title="Voir l'image PIA01239: Coprates Catena sur le site de la NASA">Voir l'image PIA01239: Coprates Catena sur le site de la NASA.</a></div>
PIA01239: Coprates Catena
<h1>PIA01243: Hubble Watches the Red Planet as Mars Global Surveyor Begins Aerobraking</h1><div class="PIA01243" lang="en" style="width:400px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>[RIGHT] This NASA Hubble Space Telescope picture of Mars was taken on Sept. 12, one day after the arrival of the Mars Global Surveyor (MGS) spacecraft and only five hours before the beginning of autumn in the Martian northern hemisphere. (Mars is tilted on its axis like Earth, so it has similar seasonal changes, including an autumnal equinox when the Sun crosses Mars' equator from the northern to the southern hemisphere).<p>This Hubble picture was taken in support of the MGS mission. Hubble is monitoring the Martian weather conditions during the early phases of MGS aerobraking; in particular, the detection of large dust storms are important inputs into the atmospheric models used by the MGS mission to plan aerobraking operations.<p>Though a dusty haze fills the giant Hellas impact basin south of the dark fin-shaped feature Syrtis Major, the dust appears to be localized within Hellas. Unless the region covered expands significantly, the dust will not be of concern for MGS aerobraking.<p>Other early signs of seasonal transitions on Mars are apparent in the Hubble picture. The northern polar ice cap is blanketed under a polar hood of clouds that typically start forming in late northern summer. As fall progresses, sunlight will dwindle in the north polar region and the seasonal polar cap of frozen carbon dioxide will start condensing onto the surface under these clouds.<p>Hubble observations will continue until October 13, as MGS carefully uses the drag of the Martian atmosphere to circularize its orbit about the Red Planet. After mid-October, Mars will be too close to the Sun, in angular separation, for Hubble to safely view.<p>The image is a composite of three separately filtered colored images taken with the Wide Field Planetary Camera 2 (WFPC2). Resolution is 35 miles (57 kilometers) per pixel (picture element). The Pathfinder landing site near Ares Valles is about 2200 miles (3600 kilometers) west of the center of this image, so was not visible during this observation. Mars was 158 million miles (255 million kilometers) from Earth at the time.<p>[LEFT]<p>An image of this region of Mars, taken in June 1997, is shown for comparison. The Hellas basin is filled with bright clouds and/or surface frost. More water ice clouds are visible across the planet than in the Sept. image, reflecting the effects of the changing season. Mars appears larger because it was 44 million miles (77 million kilometers) closer to Earth than in the September image.<p>This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL <a href="http://oposite.stsci.edu/" class="external free" target="wpext">http://oposite.stsci.edu/</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01243" onclick="window.open(this.href); return false;" title="Voir l'image PIA01243: Hubble Watches the Red Planet as Mars Global Surveyor Begins Aerobraking sur le site de la NASA">Voir l'image PIA01243: Hubble Watches the Red Planet as Mars Global Surveyor Begins Aerobraking sur le site de la NASA.</a></div>
PIA01243: Hubble Watches the Red Planet as Mars Global Surveyor Begins Aerobraking
<h1>PIA01244: Decay of a Martian Dust Storm</h1><div class="PIA01244" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>NASA Hubble Space Telescope images of Mars, taken on June 27, 1997 (left) and July 9, 1997 (right), document the dissipation of a large dust storm during the 12 days separating the two observations.<p>The images were taken to monitor the weather conditions near Ares Vallis, the site where NASA's Pathfinder spacecraft landed on July 4. Maps of the equatorial region were constructed from the images and are shown at the bottom of the figure; a green cross marks the Pathfinder landing site. (All images are oriented with North to the top).<p>These two sets of observations show a number of dramatic changes in the planet's atmosphere. At about the 7 o'clock position on the June 27 image, the eastern end of the Valles Marineris canyon system is just coming into daylight and can be seen to be filled with yellowish dust. The dust appears to be confined to the canyons, which can be as much as 8 km deep and hundreds of km wide. Estimates of the quantity of dust involved in this storm indicate that 96% of the incoming sunlight is being blocked from reaching the surface by the dust clouds. Note that on the July 9 image, the dust storm appears to be subsiding; it is estimated that the dust quantity in most of the visible canyon system has dropped to only 10% to 20% of that seen on June 27.<p>However, on July 9 a streamer of dust is visible in the North polar region, extending about 1200 km southward from the dark sand dunes surrounding the polar ice cap; diffuse dust is visible over much of Acidalia, the dark region to the north of the Pathfinder landing site. The extent of clouds visible across the planet has also changed considerably between the two dates. Just to the west (left) of the July 9 dust streamer, a very bright area of water-ice clouds is seen; this area was considerably cloudier on June 27.<p>These images dramatically show that atmospheric conditions can change rapidly on Mars. Observations such as these will continue to be made over the next several months, allowing the detailed surface observations made by Pathfinder to be placed into the broader context of the global images available from HST.<p>This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL <a href="http://oposite.stsci.edu/" class="external free" target="wpext">http://oposite.stsci.edu/</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01244" onclick="window.open(this.href); return false;" title="Voir l'image PIA01244: Decay of a Martian Dust Storm sur le site de la NASA">Voir l'image PIA01244: Decay of a Martian Dust Storm sur le site de la NASA.</a></div>
PIA01244: Decay of a Martian Dust Storm
<h1>PIA01245: Hubble's Look at Mars Shows Canyon Dust Storm, Cloudy Conditions for Pathfinder Landing</h1><div class="PIA01245" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Hubble Space Telescope images of Mars, taken on June 27, 1997, reveal a significant dust storm which fills much of the Valles Marineris canyon system and extends into Xanthe Terra, about 600 miles (1000 kilometers) south of the landing site.<p>It is difficult to predict the evolution of this storm and whether it will affect the Pathfinder observations.<p>The pictures were taken in order to monitor the site in Ares Vallis where the Pathfinder spacecraft will land on July 4.<p>The two images of Mars at the top of the figure are Hubble observations from June 27 (right) and May 17 (left). Visual comparison of these two images clearly shows the dust storm between 5 and 7 o'clock and about 2/3 of the way from the center of the planet's disk to the southern edge of the June image.<p>The digital data were projected to form the map of the equatorial portion of the planet which is shown in the bottom portion of the figure. The green cross marks the location of the Pathfinder landing site, and the yellowish ribbon of dust which runs horizontally across the bottom of the map traces the location of Valles Marineris, a system of canyons which would stretch from Los Angeles to New York if placed on Earth.<p>Most of the dust is confined within the canyons, which are up to 5-8 kilometers deep. The thickness of the dust cloud near the eastern end of the storm is similar to that observed by Viking lander 1 during the first of the two 1977 global dust storms which it studied.<p>Other interesting features appear in this image. The northwestern portions of the planet are enveloped in unusually thick water ice clouds, similar to cirrus clouds on Earth; some clouds extend as far as Lunae Planum, the slightly darker region about halfway from the center to the left side of the map. The dark spot near the terminator (boundary between day and night) at about 9:00 in the June 27 planet image is Ascraeus Mons, a 27 kilometer high volcano, protruding through the clouds.<p>The remnant north polar cap, composed of water ice, is at the top of the May and June images, and a bluish south polar hood, composed of water ice clouds, is seen along the southern edge. Because the planet's axis is tipped towards us during this season, we cannot see the south polar cap, which is in winter darkness.<p>This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL <a href="http://oposite.stsci.edu/" class="external free" target="wpext">http://oposite.stsci.edu/</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01245" onclick="window.open(this.href); return false;" title="Voir l'image PIA01245: Hubble's Look at Mars Shows Canyon Dust Storm, Cloudy Conditions for Pathfinder Landing sur le site de la NASA">Voir l'image PIA01245: Hubble's Look at Mars Shows Canyon Dust Storm, Cloudy Conditions for Pathfinder Landing sur le site de la NASA.</a></div>
PIA01245: Hubble's Look at Mars Shows Canyon Dust Storm, Cloudy Conditions for Pathfinder Landing
<h1>PIA01247: Seasonal Changes in Mars' North Polar Ice Cap</h1><div class="PIA01247" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>These images, which seem to have been taken while NASA's Hubble Space Telescope (HST) was looking directly down on the Martian North Pole, were actually created by assembling mosaics of three sets of images taken by HST in October, 1996 and in January and March, 1997 and projecting them to appear as they would if seen from above the pole. This first mosaic is a view which could not actually be seen in nature because at this season a portion of the pole would have actually been in shadow; the last view, taken near the summer solstice, would correspond to the Midnight Sun on Earth with the pole fully illuminated all day. The resulting polar maps begin at 50 degrees N latitude and are oriented with 0 degrees longitude at the 12 o'clock position. This series of pictures captures the seasonal retreat of Mars' north polar cap.<p>October 1996 (early spring in the Northern hemisphere): In this map, assembled from images obtained between Oct. 8 and 15, the cap extends down to 60 degrees N latitude, nearly it's maximum winter extent. (The notches are areas where Hubble data were not available). A thin, comma-shaped cloud of dust can be seen as a salmon-colored crescent at the 7 o'clock position. The cap is actually fairly circular about the geographic pole at this season; the bluish "knobs" where the cap seems to extend further are actually clouds that occurred near the edges of the three separate sets of images used to make the mosaic.<p>January 1997 (mid-spring): Increased warming as spring progresses in the northern hemisphere has sublimated the carbon dioxide ice and frost below 70 degrees north latitude. The faint darker circle inside the cap boundary marks the location of circumpolar sand dunes (see March '97 map); these dark dunes are warmed more by solar heating than are the brighter surroundings, so the surface frost sublimates from the dunes earlier than from the neighboring areas. Particularly evident is the marked hexagonal shape of the polar cap at this season, noted previously by HST in 1995 and Mariner 9 in 1972; this may be due to topography, which isn't well known, or to wave structure in the circulation. This map was assembled from WFPC2 images obtained between Dec. 30, 1996 and Jan. 4, 1997.<p>March 30, 1997 (early summer): The cap has fully retreated to its remnant core of water-ice. This residual cap is actually almost cut into two by a large, horn-shaped canyon called Chasma Borealis which is cut deeply into the polar terrain. The HST images also reveal a curious layered terrain which is evidence of past climatic changes on Mars. The sublimation of all of the carbon dioxide has exposed the ring of dark sand dunes which encircle the North Polar Cap. Outliers of ice persist south of the polar sand sea (between the 3 o'clock and 9 o'clock positions). The bright circular features at 3, 6, and 9 o'clock are ice-filled craters.<p>All images were taken with the Wide Field and Planetary Camera 2. The color is constructed from images taken in red (673 nm) , blue (410 nm) and green (502 nm) light. The resolution at the North Pole ranges from about 115 km/pixel in October '96 to about 45 km/pixel in March '97.<p>This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL <a href="http://oposite.stsci.edu/" class="external free" target="wpext">http://oposite.stsci.edu/</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01247" onclick="window.open(this.href); return false;" title="Voir l'image PIA01247: Seasonal Changes in Mars' North Polar Ice Cap sur le site de la NASA">Voir l'image PIA01247: Seasonal Changes in Mars' North Polar Ice Cap sur le site de la NASA.</a></div>
PIA01247: Seasonal Changes in Mars' North Polar Ice Cap
<h1>PIA01248: Four Views of Mars in Northern Summer</h1><div class="PIA01248" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Four faces of Mars as seen on March 30, 1997 are presented in this montage of NASA Hubble Space Telescope images. Proceeding in the order upper-left, upper-right, lower-left, lower-right, Mars has rotated about ninety degrees between each successive time step. For example the Tharsis volcanoes, which are seen (between 7:30 and 9 o'clock positions) in mid-morning in the UPPER-RIGHT view, are seen near the late afternoon edge of the planet (about 3 o'clock position) in the lower-left image. All of these color images are composed of individual red (673 nanometers), green (502 nm), and blue (410 nm) Planetary Camera exposures.<p>Upper left: This view is centered on Ares Valles, where Pathfinder will land on July 4, 1997; the Valles Marineris canyon system stretches to the west across the lower left portion of the planet, while the bright, orangish desert of Arabia Planitia is to the east. The bright polar water-ice cap, surrounded by a dark ring of sand dunes, is obvious in the north; since it is northern summer and the pole is tilted toward us, the residual north polar cap is seen in its entirety in all four images. Acidalia Planitia, the prominent dark area fanning southward from the polar region, is thought to have a surface covered with dark sand. Numerous "dark wind streaks" are visible to the south of Acidalia, resulting from wind-blown sand streaming out of the interiors of craters.<p>Upper right: The Tharsis volcanos and associated clouds are prominent in the western half of this view. Olympus Mons, spanning 340 miles (550 km) across its base and reaching an elevation of 16 miles (25 km), extends through the cloud deck near the western limb, while (from the south) Arsia Mons, Pavonis Mons, and Ascraeus Mons are to the west of center. Valles Marineris stretches to the east, and the Pathfinder landing site is shrouded in clouds near the afternoon limb.<p>Lower left: This relatively featureless sector of Mars stretches from the Elysium volcanic region in the west to the Tharsis volcanoes (shrouded by the bright clouds near the afternoon limb) in the east. The group of three dark specks just left of center are all that remain of Cerberus, a very prominent dark region during the Viking and Mariner 9 missions. This is an example of the remarkable large scale changes which can occur on Mars due to windblown dust: the former dark area has now been covered by a layer of bright dust, masking the underlying material.<p>Lower right: The dark Syrtis Major region dominates this image. Syrtis Major is one of the most prominent dark features on Mars, and has been visible since ground-based observers first peered at Mars through telescopes. The bright cloud at 3 o'clock is associated with Elysium Mons. The bright bluish-white feature near the southern limb of the planet is Hellas, a 1,200 mile (2,000 km) diameter impact basin formed by the collision of a large body with Mars long ago. Hellas is covered with dry ice frost and clouds during this season (winter in the south).<p>This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL <a href="http://oposite.stsci.edu/" class="external free" target="wpext">http://oposite.stsci.edu/</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01248" onclick="window.open(this.href); return false;" title="Voir l'image PIA01248: Four Views of Mars in Northern Summer sur le site de la NASA">Voir l'image PIA01248: Four Views of Mars in Northern Summer sur le site de la NASA.</a></div>
PIA01248: Four Views of Mars in Northern Summer
<h1>PIA01249: Hubble's Sharpest View Of Mars</h1><div class="PIA01249" lang="en" style="width:335px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>The sharpest view of Mars ever taken from Earth was obtained by the recently refurbished NASA Hubble Space Telescope (HST). This stunning portrait was taken with the HST Wide Field Planetary Camera-2 (WFPC2) on March 10, 1997, just before Mars opposition, when the red planet made one of its closest passes to the Earth (about 60 million miles or 100 million km).<p>At this distance, a single picture element (pixel) in WFPC2's Planetary Camera spans 13 miles (22 km) on the Martian surface.<p>The Martian north pole is at the top (near the center of the bright polar cap) and East is to the right. The center of the disk is at about 23 degrees north latitude, and the central longitude is near 305 degrees.<p>This view of Mars was taken on the last day of Martian spring in the northern hemisphere (just before summer solstice). It clearly shows familiar bright and dark markings known to astronomers for more than a century. The annual north polar carbon dioxide frost (dry ice) cap is rapidly sublimating (evaporating from solid to gas), revealing the much smaller permanent water ice cap, along with a few nearby detached regions of surface frost. The receding polar cap also reveals the dark, circular sea of sand dunes that surrounds the north pole (Olympia Planitia).<p>Other prominent features in this hemisphere include Syrtis Major Planitia, the large dark feature seen just below the center of the disk. The giant impact basin Hellas (near the bottom of the disk) is shrouded in bright water ice clouds. Water ice clouds also cover several great volcanos in the Elysium region near the eastern edge of the planet (right). A diffuse water ice haze covers much of the Martian equatorial region as well.<p>The WFPC2 was used to monitor dust storm activity to support the Mars Pathfinder and Mars Global Surveyor Orbiter Missions, which are currently en route to Mars. Airborne dust is most easily seen in WFPC2's red and near-infrared images. Hubble's "weather report" from these images in invaluable for Mars Pathfinder, which is scheduled for a July 4 landing. Fortunately, these images show no evidence for large-scale dust storm activity, which plagued a previous Mars mission in the early 1970s.<p>The WFPC2 was used to observe Mars in nine different colors spanning the ultraviolet to the near infrared. The specific colors were chosen to clearly discriminate between airborne dust, ice clouds, and prominent Martian surface features. This picture was created by combining images taken in blue (433 nm), green (554 nm), and red (763 nm) colored filters.<p>This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL <a href="http://oposite.stsci.edu/" class="external free" target="wpext">http://oposite.stsci.edu/</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01249" onclick="window.open(this.href); return false;" title="Voir l'image PIA01249: Hubble's Sharpest View Of Mars sur le site de la NASA">Voir l'image PIA01249: Hubble's Sharpest View Of Mars sur le site de la NASA.</a></div>
PIA01249: Hubble's Sharpest View Of Mars
<h1>PIA01250: Hubble Captures A Full Rotation Of Mars</h1><div class="PIA01250" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Pictures of the planet Mars taken with the recently refurbished NASA Hubble Space Telescope (HST) will provide the most detailed global view of the red planet ever obtained from Earth.<p>The images were taken by HST's Wide Field Planetary Camera-2 on March 10, 1997, just before Mars opposition, when the red planet made one of its closest to the Earth (about 60 million miles or 100 million km).<p>These pictures were taken during three HST orbits that were separated by about six hours. This timing was chosen so that Mars, with its 24-hour 39- minute day, would rotate about 90 degrees between orbits. This imaging sequence therefore covers most of the Martian surface. These observations will be combined with others planned for March 30 to provide complete coverage.<p>During each orbit, Mars was observed in nine different colors spanning the ultraviolet to the near infrared. The specific colors were chosen to clearly discriminate between airborne dust, ice clouds, and prominent Martian surface features. The color picture shown here was created by combining images taken in blue (433 nm), green (554 nm), and red (763 nm) colored filters. The Martian north pole is at the top (near the center of the bright polar cap) and East is to the right. The center of the disk is at about 23 degrees north latitude, and the central longitudes are near 160, 210, and 305 degrees.<p>These images show the planet on the last day of Martian spring in the northern hemisphere (just before summer solstice). The annual north polar carbon dioxide frost (dry ice) cap is rapidly sublimating, revealing the much smaller permanent water ice cap. This polar cap remnant, along with a few nearby detached regions of surface frost are most obvious in pictures taken through ultraviolet, blue, and green filters. These filters also show numerous bright water ice clouds. The brightest clouds are in the vicinity of the giant volcanos on the Tharsis Plateau (to right of center on left image), and in the giant impact basin, Hellas (near bottom of right-hand image), but a diffuse haze covers much of the Martian tropics as well.<p>The familiar bright and dark markings on the Martian surface are most obvious in images taken through red and near-infrared filters. These images clearly reveal the large, dark, circular "sea" of sand dunes (Olympia Planitia) that surrounds the north pole, as well a number of other familiar features, including the giant Tharsis volcanos. The 16-mile (27 km) high Olympus Mons is near the center of the left-hand image, with Arsia, Povonis, and Ascraeus Mons forming a south-west to north-east line just to its right. The volcano, Elysium Mons is near the center of the middle image. The prominent dark feature just below the center on the disk on the rightmost image is Syrtis Major Planitia.<p>Hubble is being used to monitor dust storm activity to support the Mars Pathfinder and Mars Global Surveyor Orbiter Missions, which are currently en route to Mars. Airborne dust is most easily seen in WFPC2's red and near-infrared images. Weather reports derived from these observations are particularly valuable for Mars Pathfinder, which is scheduled for a July 4, 1997 landing on the red planet. A preliminary analysis of these HST data reveals enhanced dust activity over the dark Vastitas Borealis region in the northern hemisphere, and over the Noachis Terra and Terra Tyrrhena regions just south of the Martian equator. There is also evidence for airborne dust and ice clouds in the Hellas basin. However, these images show no evidence for large-scale dust storm activity.<p>This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL <a href="http://oposite.stsci.edu/" class="external free" target="wpext">http://oposite.stsci.edu/</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01250" onclick="window.open(this.href); return false;" title="Voir l'image PIA01250: Hubble Captures A Full Rotation Of Mars sur le site de la NASA">Voir l'image PIA01250: Hubble Captures A Full Rotation Of Mars sur le site de la NASA.</a></div>
PIA01250: Hubble Captures A Full Rotation Of Mars
<h1>PIA01251: Springtime Dust Storm Swirls at Martian North Pole</h1><div class="PIA01251" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Two Hubble Space Telescope images of Mars, taken about a month apart on September 18 and October 15, 1996, reveal a state-sized dust storm churning near the edge of the Martian north polar cap. The polar storm is probably a consequence of large temperature differences between the polar ice and the dark regions to the south, which are heated by the springtime sun. The increased sunlight also causes the dry ice in the polar cap to sublime and shrink.<p>Mars is famous for large, planet-wide dust storms. Smaller storms resembling the one seen here were observed in other regions by Viking orbiters in the late 1970s. However, this is the first time that such an event has been caught near the receding north polar cap. The Hubble images provide valuable new insights into the behavior of localized dust storms on Mars, which are typically below the resolution of ground-based telescopes. This kind of advanced planetary "weather report" will be invaluable for aiding preparation for the landing of NASA's Pathfinder spacecraft in July 1997 and the arrival of Mars Global Surveyor orbiter in September 1997.<p>Top (September 18, 1996) - The salmon colored notch in the white north polar cap is a 600-mile (1,000 kilometer) long storm -- nearly the width of Texas. The bright dust can also be seen over the dark surface surrounding the cap, where it is caught up in the Martian jet stream and blown easterly. The white clouds at lower latitudes are mostly associated with major Martian volcanos such as Olympus Mons. This image was taken when Mars was more than 186 million miles (300 million kilometers) from Earth, and the planet was smaller in angular size than Jupiter's Great Red Spot!<p>Bottom (October 15, 1996) - Though the storm has dissipated by October, a distinctive dust-colored comma-shaped feature can be seen curving across the ice cap. The shape is similar to cold fronts on Earth, which are associated with low pressure systems. Nothing quite like this feature has been seen previously either in ground-based or spacecraft observation. The snow line marking the edge of the cap receded northward by approximately 120 miles (200 kilometers), while the distance to the Red Planet narrowed to 170 million miles (275 million kilometers).<p>Technical notes: To help compare locations and sizes of features, map projections (right of each disk) are centered on the geographic north pole. Maps are oriented with 0 degrees longitude at the top and show meridians every 45 degrees of longitude (longitude increases clockwise); latitude circles are also shown for 40, 60, and 80 degrees north latitude. The color images were assembled from separate exposures taken with the Wide Field Planetary Camera 2.<p>This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL <a href="http://oposite.stsci.edu/" class="external free" target="wpext">http://oposite.stsci.edu/</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01251" onclick="window.open(this.href); return false;" title="Voir l'image PIA01251: Springtime Dust Storm Swirls at Martian North Pole sur le site de la NASA">Voir l'image PIA01251: Springtime Dust Storm Swirls at Martian North Pole sur le site de la NASA.</a></div>
PIA01251: Springtime Dust Storm Swirls at Martian North Pole
<h1>PIA01252: Mars At Opposition</h1><div class="PIA01252" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>These NASA Hubble Space Telescope views provide the most detailed complete global coverage of the red planet Mars ever seen from Earth. The pictures were taken on February 25, 1995, when Mars was at a distance of 65 million miles (103 million km).<p>To the surprise of researchers, Mars is cloudier than seen in previous years. This means the planet is cooler and drier, because water vapor in the atmosphere freezes out to form ice-crystal clouds. Hubble resolves Martian surface features with a level of detail only exceeded by planetary probes, such as impact craters and other features as small as 30 miles (50 kilometers) across.<p>[Tharsis region] - A crescent-shaped cloud just right of center identifies the immense shield volcano Olympus Mons, which is 340 miles (550 km) across at its base. Warm afternoon air pushed up over the summit forms ice-crystal clouds downwind from the volcano. Farther to the east (right) a line of clouds forms over a row of three extinct volcanoes which are from north to south: Ascraeus Mons, Pavonis Mons, Arsia Mons. It's part of an unusual, recurring "W"-shaped cloud formation that once mystified earlier ground-based observers.<p>[Valles Marineris region] - The 16 mile-high volcano Ascraeus Mons pokes through the cloud deck along the western (left) limb of the planet. Other interesting geologic features include (lower left) Valles Marineris, an immense rift valley the length of the continental United States. Near the image center lies the Chryse basin made up of cratered and chaotic terrain. The oval-looking Argyre impact basin (bottom) appears white due to clouds or frost.<p>[Syrtis Major region] - The dark "shark fin" feature left of center is Syrtis Major. Below it the giant impact basin Hellas. Clouds cover several great volcanos in the Elysium region near the eastern (right) limb. As clearly seen in the Hubble images, past dust storms in Mars' southern hemisphere have scoured the plains of fine light dust and transported the dust northward. This leaves behind a relatively coarser, and less reflective sand in, predominantly, the southern hemisphere.<p>The pictures were taken with Hubble's Wide Field Planetary Camera 2.<p>This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL <a href="http://oposite.stsci.edu/" class="external free" target="wpext">http://oposite.stsci.edu/</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01252" onclick="window.open(this.href); return false;" title="Voir l'image PIA01252: Mars At Opposition sur le site de la NASA">Voir l'image PIA01252: Mars At Opposition sur le site de la NASA.</a></div>
PIA01252: Mars At Opposition
<h1>PIA01253: Springtime on Mars: Hubble's Best View of the Red Planet</h1><div class="PIA01253" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>This NASA Hubble Space Telescope view of the planet Mars was, at the time it was taken, the clearest picture ever taken from Earth, surpassed only by close-up shots sent back by visiting space probes. The picture was taken on February 25, 1995, when Mars was at a distance of approximately 65 million miles (103 million km) from Earth.<p>Because it is spring in Mars' northern hemisphere, much of the carbon dioxide frost around the permanent water-ice cap has sublimated, and the cap has receded to a core of solid water-ice several hundred miles across.<p>Towering 16 miles (25 km) above the surrounding plains, volcano Ascraeus Mons pokes above the cloud deck near the western or limb. This extinct volcano, measuring 250 miles (402 km) across, was discovered in the early 1970s by Mariner 9 spacecraft. Other key geologic features include (lower left) the Valles Marineris, an immense rift valley the length of the continental United States. Near the center of the disk lies the Chryse basin made up of cratered and chaotic terrain. The oval-looking Argyre impact basin (bottom), appears white due to clouds or frost.<p>Seasonal winds carry dust to form striking linear features reminiscent of the legendary martian "canals." Many of these "wind streaks" emanate from the bowl of these craters where dark coarse sand is swept out by winds. Hubble resolves several dozen impact craters down to 30-mile diameter. The dark areas, once misinterpreted as regions of vegetation by several early Mars watchers, are really areas of coarse sand that is less reflective than the finer, lighter dust. Seasonal changes in the surface appearance occur as winds move the dust and sand around.<p>This picture was taken with Hubble's Wide Field Planetary Camera 2 in PC mode. The pictures were map-projected onto a sphere for accurate registration and perspective.<p>This image and other images and data received from the Hubble Space Telescope are posted on the World Wide Web on the Space Telescope Science Institute home page at URL <a href="http://oposite.stsci.edu/" class="external free" target="wpext">http://oposite.stsci.edu/</a>.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01253" onclick="window.open(this.href); return false;" title="Voir l'image PIA01253: Springtime on Mars: Hubble's Best View of the Red Planet sur le site de la NASA">Voir l'image PIA01253: Springtime on Mars: Hubble's Best View of the Red Planet sur le site de la NASA.</a></div>
PIA01253: Springtime on Mars: Hubble's Best View of the Red Planet
<h1>PIA01337: Laser Provides First 3-D View of Mars' North Pole</h1><div class="PIA01337" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">This first three-dimensional picture of Mars' north pole enables scientists to estimate the volume of its water ice cap with unprecedented precision, and to study its surface variations and the heights of clouds in the region for the first time.<p>Approximately 2.6 million of these laser pulse measurements were assembled into a topographic grid of the north pole with a spatial resolution of 0.6 miles (one kilometer) and a vertical accuracy of 15-90 feet (5-30 meters).<p>The principal investigator for MOLA is Dr. David E. Smith of Goddard. The MOLA instrument was designed and built by the Laser Remote Sensing Branch of Laboratory for Terrestrial Physics at Goddard. The Mars Global Surveyor Mission is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for the NASA Office of Space Science.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01337" onclick="window.open(this.href); return false;" title="Voir l'image PIA01337: Laser Provides First 3-D View of Mars' North Pole sur le site de la NASA">Voir l'image PIA01337: Laser Provides First 3-D View of Mars' North Pole sur le site de la NASA.</a></div>
PIA01337: Laser Provides First 3-D View of Mars' North Pole
<h1>PIA01432: Opposition Surge: Sunlight Glinting off Mars</h1><div class="PIA01432" lang="en" style="width:624px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Mars Global Surveyor was presented with a unique opportunity February 13-18, 1998, to image sunlight glinting off of the surface and atmospheric haze of Mars. Orbits 130-137 were devoted to obtaining MOC images of this effect, also known as opposition surge. During each orbit in mid-February, the Mars Global Surveyor spacecraft passed close to and through the line between the Sun and the center of Mars. In other words, the phase angle (angle between the Sun's incident light and the direction from the surface to the spacecraft) was near zero degrees. The sunlight reflecting from Mars near the zero phase angle produces the rare sun-glint phenomenon. The size and brightness of the glint depends on the physical properties of the surface (dust, sand, and rock distribution) and the atmosphere (haze/suspended dust). Studies of these images are expected to yield important information that can be compared with thermal emission observations.<p>The picture is a color composite of MOC images 13601 (red wide angle) and 13602 (blue wide angle). The green-color band is synthesized from the red and blue using a relationship well-understood from Viking images of the late 1970s. The large, dark region near the top-center of the picture is Sinus Meridiani. The circular feature at the upper right is the impact basin, Schiaparelli. The opposition surge feature --the sun glint-- is centered around 21.0°S latitude, 4.1°W longitude.<p>The two images were taken on Mars Global Surveyor's 136th orbit on February 18, 1998. Orbit 136 was the second-to-last orbit on which MOC obtained images of Mars during the first aerobraking phase (AB-1) of the mission. MOC was off between the end of AB-1 on February 19, 1998, until the start of Science Phasing Orbit-1 phase (SPO-1), which began March 28 and ended April 28, 1998.<p>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.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01432" onclick="window.open(this.href); return false;" title="Voir l'image PIA01432: Opposition Surge: Sunlight Glinting off Mars sur le site de la NASA">Voir l'image PIA01432: Opposition Surge: Sunlight Glinting off Mars sur le site de la NASA.</a></div>
PIA01432: Opposition Surge: Sunlight Glinting off Mars
<h1>PIA01435: Winter Morning in Northern Tharsis</h1><div class="PIA01435" lang="en" style="width:689px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Mars Global Surveyor's camera, MOC, provided this hemispheric view of the northern Tharsis region on June 1, 1998. This picture shows the giant volcano, Olympus Mons, and one of the Tharsis Montes volcanoes, Ascraeus Mons. Another volcano, Alba Patera, is lurking under the haze and clouds at the top of the image. Olympus Mons is about 550 kilometers (340 miles) wide.<p>MGS is now in a "morning" orbit (when it arrived at Mars in September 1997, it was inserted into a "late afternoon" orbit). The orbit will continue to change, about one hour a month, until aerobraking into a circular orbit is complete about seven months from now. When this picture was taken, the local time on the ground beneath the spacecraft was about 9:30 a.m. The terminator-- the line that divides night and day-- was located west of Olympus Mons (left part of the image). It is winter in the northern hemisphere of Mars, and the high latitudes (i.e., north of Olympus Mons in this picture) exhibit clouds and haze. These clouds most likely contain water ice.<p>MOC images 33901 (the red wide angle image) and 33902 (the blue wide angle image) were obtained on Mars Global Surveyor's 339th orbit about the planet. The pictures were taken around 7:37 p.m. PDT on June 1, 1998.<p><p>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.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01435" onclick="window.open(this.href); return false;" title="Voir l'image PIA01435: Winter Morning in Northern Tharsis sur le site de la NASA">Voir l'image PIA01435: Winter Morning in Northern Tharsis sur le site de la NASA.</a></div>
PIA01435: Winter Morning in Northern Tharsis
<h1>PIA01436: Detailed Cloud Patterns in Martian Northern Hemisphere</h1><div class="PIA01436" lang="en" style="width:434px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Cold and cloudy mornings; cool, hazy afternoons. High winds aloft and weather fronts moving slowly to the east. It is winter in the Martian northern hemisphere. One of the many reasons to study Mars is that, at times, its weather is very "Earth-like." At this time of the Martian year, clouds are abundant, especially in the morning and especially in the high northern latitudes. Clouds and fogs are also observed in low-lying areas farther to the south, in some lowlands they are as far south as the equator.<p>The above color composite images, obtained by Mars Global Surveyor's camera on June 4, 1998, illustrate this Martian "weather report." Most of the thick, white clouds seen here occur north of latitude 35°N (roughly equivalent to Albuquerque NM, Memphis TN, and Charlotte, NC). Fog (seen as bright orange because it is lighter than the ground but some of the ground is still visible) occupies the lowest portions of the Kasei Valles outflow channel around 30°N and at 25°N.<p>Several different types of cloud features are seen. The repetitious, wash-board pattern of parallel lines are "gravity wave clouds". These commonly form, in the lee--downwind side-- of topographic features such as mountain ranges (on Earth) or crater rims (on Mars), under very specific atmospheric conditions (low temperatures, high humidity, and high wind speeds). In this area, the wave clouds are lower in the atmosphere than some of the other clouds. These other clouds show attributes reflecting more the regional weather pattern, occasionally showing the characteristic "slash" shape (southwest to northeast) of a weather front. These clouds probably contain mostly crystals of water ice but, depending on the temperature at high altitude (and more likely closer to the pole), some could also contain frozen carbon dioxide ("dry ice").<p>MOC images 34501 (the red wide angle image) and 34502 (the blue wide angle image) were obtained on Mars Global Surveyor's 345th orbit about the planet. The pictures were taken around 5: 34 p.m. PDT on June 4, 1998. Winter in the northern hemisphere began in mid-February, 1998, and continues to mid-July, 1998.<p><p>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.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01436" onclick="window.open(this.href); return false;" title="Voir l'image PIA01436: Detailed Cloud Patterns in Martian Northern Hemisphere sur le site de la NASA">Voir l'image PIA01436: Detailed Cloud Patterns in Martian Northern Hemisphere sur le site de la NASA.</a></div>
PIA01436: Detailed Cloud Patterns in Martian Northern Hemisphere
<h1>PIA01457: Elysium Mons Volcanic Region</h1><div class="PIA01457" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">On July 4, 1998--the first anniversary of the Mars Pathfinder landing--Mars Global Surveyor's latest images were radioed to Earth with little fanfare. The images received on July 4, 1998, however, were very exciting because they included a rare crossing of the summit caldera of a major martian volcano. Elysium Mons is located at 25°N, 213°W, in the martian eastern hemisphere. Elysium Mons is one of three large volcanoes that occur on the Elysium Rise-- the others are Hecates Tholus (northeast of Elysium Mons) and Albor Tholus (southeast of Elysium Mons). The volcano rises about 12.5 kilometers (7.8 miles) above the surrounding plain, or about 16 kilometers (9.9 miles) above the martian datum-- the "zero" elevation defined by average martian atmospheric pressure and the planet's radius.<p>Elysium Mons was discovered by Mariner 9 in 1972. It differs in a number of ways from the familiar Olympus Mons and other large volcanoes in the Tharsis region. In particular, there are no obvious lava flows visible on the volcano's flanks. The lack of lava flows was apparent from the Mariner 9 images, but the new MOC high resolution image--obtained at 5.24 meters (17.2 feet) per pixel--illustrates that this is true even when viewed at higher spatial resolution.<p>Elysium Mons has many craters on its surface. Some of these probably formed by meteor impact, but many show no ejecta pattern characteristic of meteor impact. Some of the craters are aligned in linear patterns that are radial to the summit caldera--these most likely formed by collapse as lava was withdrawn from beneath the surface, rather than by meteor impact. Other craters may have formed by explosive volcanism. Evidence for explosive volcanism on Mars has been very difficult to identify from previous Mars spacecraft images. This and other MOC data are being examined closely to better understand the nature and origin of volcanic features on Mars.<p>The three MOC images, 40301 (red wide angle), 40302 (blue wide angle), and 40303 (high resolution, narrow angle) were obtained on Mars Global Surveyor's 403rd orbit around the planet around 9:58 - 10:05 p.m. PDT on July 2, 1998. The images were received and processed at Malin Space Science Systems (MSSS) around 4:00 p.m. PDT on July 4, 1998.<p>This image: Elysium Volcanic Region as seen by MOC on July 2, 1998. Volcano near top center is Hecates Tholus--note bright clouds off its northeast flank. Volcano near center is Elysium Mons; volcano toward lower right is Albor Tholus. Red channel is MOC red wide angle image 40301, the blue channel is MOC blue wide angle image 40302, and the green channel is synthesized by averaging the red and blue bands. Image is an orthographic projection centered at 24.85°N, 213.25°W. The scale at the center of the projection is 4.65 kilometers (2.9 miles) per pixel. North is up, illumination is from the lower right.<p>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.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01457" onclick="window.open(this.href); return false;" title="Voir l'image PIA01457: Elysium Mons Volcanic Region sur le site de la NASA">Voir l'image PIA01457: Elysium Mons Volcanic Region sur le site de la NASA.</a></div>
PIA01457: Elysium Mons Volcanic Region
<h1>PIA01471: Martian North Polar Cap on September 12, 1998 (color)</h1><div class="PIA01471" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;"><p>Mars Global Surveyor's Mars Orbiter Camera obtained its last SPO-2 images of Mars on September 12, 1998. SPO-2, or "Science Phasing Orbit-2," took place between early June and mid-September 1998. Shown above are MOC wide angle (red and blue band) images of the martian north polar region obtained around 3:15 a.m. PDT on September 12, 1998. This color composite was made using red and blue wide angle MOC images 55001 and 55002--these were the last pictures taken of the planet until the camera resumes its work in late-March 1999.<p>The north polar layered deposits, a terrain believed composed of ice and dust deposited over millions of years, dominates this view. The swirled pattern in the images above are channels eroded into this deposit. The pattern is accentuated by the illumination and seasonal frost differences that arise on sun-facing slopes during the summer. The permanent portion of the north polar cap covers most of the region with a layer of ice of unknown thickness.<p>At the time this picture was obtained, the martian northern hemisphere was in the midst of the early Spring season. The margin of the seasonal carbon dioxide frost cap was at about 67° N, so the ground throughout this image is covered by frost. The frost appears pink rather than white; this may result from textural changes in the frost as it sublimes or because the frost is contaminated by a small amount of reddish martian dust. Please note that these pictures have not been "calibrated" and so the colors are not necessarily accurately portrayed.<p>In addition to the north polar cap, the pictures also show some clouds (bluish-white wisps). Some of the clouds on the right side of the images are long, linear features that cast similar long, dark shadows on the ground beneath them.<p>When the MOC resumes imaging of Mars in March 1999, summer will have arrived in the north polar regions and the area surrounding the permanent polar cap will appear much darker than it does here. The dark features surrounding the cap are sand dunes, and these are expected to darken over the next several months as seasonal ice sublimes and is removed from the surface.<p><p>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.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01471" onclick="window.open(this.href); return false;" title="Voir l'image PIA01471: Martian North Polar Cap on September 12, 1998 (color) sur le site de la NASA">Voir l'image PIA01471: Martian North Polar Cap on September 12, 1998 (color) sur le site de la NASA.</a></div>
PIA01471: Martian North Polar Cap on September 12, 1998 (color)
<h1>PIA01476: Olympus Mons, 1998 (color)</h1><div class="PIA01476" lang="en" style="width:573px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">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 2° to 5°.<p>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.<p>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.<p>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.<p><p>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.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01476" onclick="window.open(this.href); return false;" title="Voir l'image PIA01476: Olympus Mons, 1998 (color) sur le site de la NASA">Voir l'image PIA01476: Olympus Mons, 1998 (color) sur le site de la NASA.</a></div>
PIA01476: Olympus Mons, 1998 (color)
<h1>PIA01543: Martian Colors Provide Clues About Martian Water</h1><div class="PIA01543" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">NASA Hubble Space Telescope images of Mars taken in visible and infrared light detail a rich geologic history and provide further evidence for water-bearing minerals on the planet's surface.<p>LEFT<p>This "true-color" image of Mars shows the planet as it would look to human eyes. It is clearly more Earth-toned than usually depicted in other astronomical images, including earlier Hubble pictures. The slightly bluer shade along the edges of the disk is due to atmospheric hazes and wispy water ice clouds (like cirrus clouds) in the early morning and late evening Martian sky. The yellowish-pink color of the northern polar cap indicates the presence of small iron-bearing dust particles. These particles are covering or are suspended in the air above the blue-white water ice and carbon dioxide ice, which make up the polar cap.<p>Accurate colors are needed to determine the composition and mineralogy of Mars. This can tell how water has influenced the formation of rocks and minerals found on Mars today, as well as the distribution and abundance of ice and subsurface liquid water. Confirmation of the presence of certain oxidized (rusted) minerals (processed by heat or water action) would imply the possibility of different, perhaps much more Earth-like, past Martian climate periods. Because the smallest features visible in this image are only about 14 miles (22 km) across, Hubble can track small-scale variations in the distribution of minerals that do not follow global trends. The image was generated from three separate Wide Field and Planetary Camera 2 images acquired at wavelengths of 410, 502, and 673 nanometers, in March 1997.<p>RIGHT<p>A false-color picture taken in infrared light reveals features that cannot be seen in visible light. Hubble's unique infrared view pinpoints variations in the abundance and distribution of unknown water-bearing minerals on the planet. While it has been known for decades that small amounts of water-bearing minerals exist on the planet's surface, the reddish regions in this image indicate areas of enhanced concentrations of these as-yet-unidentified deposits. They are perhaps related to the water-rich history of this part of Mars. In particular, the large reddish region known as Mare Acidalium was the site of massive flooding early in Martian history. (NASA's Pathfinder spacecraft landed at the southern edge of this region in 1997.) This composite image was taken in July 1997 with Hubble's Near Infrared Camera and Multi-Object Spectrometer. Red corresponds to the strength of an absorption band detected near 1450 nanometers; green to the brightness of the surface in the near-infrared; and blue to topographic elevation, determined from Viking Orbiter data.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01543" onclick="window.open(this.href); return false;" title="Voir l'image PIA01543: Martian Colors Provide Clues About Martian Water sur le site de la NASA">Voir l'image PIA01543: Martian Colors Provide Clues About Martian Water sur le site de la NASA.</a></div>
PIA01543: Martian Colors Provide Clues About Martian Water
<h1>PIA01545: Hubble Views Colossal Polar Cyclone on Mars</h1><div class="PIA01545" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">[left]: Here is the discovery image of the Martian polar storm as seen in blue light (410 nm). The storm is located near 65 deg. N latitude and 85 deg. W longitude, and is more than 1000 miles (1600 km) across. The residual north polar water ice cap is at the top of the image. A belt of clouds like that seen in previous telescopic observations during this Martian season can also be seen in the planet's equatorial regions and northern mid-latitudes, as well as in the southern polar regions. The volcano Ascraeus Mons can be seen as a dark spot poking above the cloud deck near the western (morning) limb. This extinct volcano towers nearly 16 miles (25 km) above the surrounding plains and is about 250 miles (400 km) across.<p>[upper right]: This is a color polar view of the north polar region, showing the location of the storm relative to the classical bright and dark features in this area. The color composite data (410, 502, and 673 nm) indicate that the storm is fairly dust-free and therefore likely composed mostly of water ice clouds. The bright surface region beneath the eye of the storm can be seen clearly. This map covers the region north of 45 degrees latitude and is oriented with 0 degrees longitude at the bottom.<p>[lower right]: This is an enhanced orthographic view of the storm centered on 65 deg. N latitude, 85 deg. W longitude. The image has been processed to bring out additional detail in the storm's spiral cloud structures.<p>The pictures were taken on April 27, 1999 with the NASA Hubble Space Telescope's Wide Field and Planetary Camera 2<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01545" onclick="window.open(this.href); return false;" title="Voir l'image PIA01545: Hubble Views Colossal Polar Cyclone on Mars sur le site de la NASA">Voir l'image PIA01545: Hubble Views Colossal Polar Cyclone on Mars sur le site de la NASA.</a></div>
PIA01545: Hubble Views Colossal Polar Cyclone on Mars
<h1>PIA01587: A Closer Hubble Encounter With Mars - 4 Views</h1><div class="PIA01587" lang="en" style="width:800px;text-align:left;margin:auto;background-color:#000;padding:10px;max-height:150px;overflow:auto;">Taking advantage of Mars's closest approach to Earth in eight years, astronomers using NASA's Hubble Space Telescope have taken the space-based observatory's sharpest views yet of the Red Planet. NASA is releasing these images to commemorate the second anniversary of the Mars Pathfinder landing. The lander and its rover, Sojourner, touched down on the Red Planet's rolling hills on July 4, 1997, embarking on an historic three-month mission to gather information on the planet's atmosphere, climate, and geology.<p>The telescope's Wide Field and Planetary Camera 2 snapped these images between April 27 and May 6, when Mars was 54 million miles (87 million kilometers) from Earth. From this distance the telescope could see Martian features as small as 12 miles (19 kilometers) wide.<p>The telescope obtained four images, which, together, show the entire planet. Each view depicts the planet as it completes one quarter of its daily rotation. In these views the north polar cap is tilted toward the Earth and is visible prominently at the top of each picture. The images were taken in the middle of the Martian northern summer, when the polar cap had shrunk to its smallest size. During this season the Sun shines continuously on the polar cap. Previous telescopic and spacecraft observations have shown that this summertime "residual" polar cap is composed of water ice, just like Earth's polar caps.<p>These Hubble telescope snapshots reveal that substantial changes in the bright and dark markings on Mars have occurred in the 20 years since the NASA Viking spacecraft missions first mapped the planet. The Martian surface is dynamic and ever changing. Some regions that were dark 20years ago are now bright red; some areas that were bright red are now dark. Winds move sand and dust from region to region, often in spectacular dust storms. Over long time scales many of the larger bright and dark markings remain stable, but smaller details come and go as they are covered and then uncovered by sand and dust.<p>The upper-left image is centered near the location of the Pathfinder landing site. Dark sand dunes that surround the polar cap merge into a large, dark region called Acidalia. This area, as shown by images from the Hubble telescope and other spacecraft, is composed of dark, sand-sized grains of pulverized volcanic rock. Below and to the left of Acidalia are the massive Martian canyon systems of Valles Marineris, some of which form long linear markings that were once thought by some to be canals. Early morning clouds can be seen along the left limb of the planet, and a large cyclonic storm composed of water ice is churning near the polar cap. See also <a href="/catalog/PIA01589">PIA01589</a>.<p>The upper-right image is centered on the region of the planet known as Tharsis, home of the largest volcanoes in the solar system. The bright, ring-like feature just to the left of center is the volcano Olympus Mons, which is more than 340 miles (550 kilometers) across and 17 miles(27 kilometers) high. Thick deposits of fine-grained, windblown dust cover most of this hemisphere. The colors indicate that the dust is heavily oxidized ("rusted"), and millions (or perhaps billions) of years of dust storms have homogenized its composition. Prominent late afternoon clouds along the right limb of the planet can be seen. See also <a href="/catalog/PIA01590">PIA01590</a>.<p>The lower-left image is centered near another volcanic region known as Elysium. This area shows many small, dark markings that have been observed by the Hubble telescope and other spacecraft to change as a result of the movement of sand and dust across the Martian surface. In the upper left of this image, at high northern latitudes, a large chevron-shaped area of water ice clouds mark a storm front. Along the right limb, a large cloud system has formed around the Olympus Mons volcano. See also <a href="/catalog/PIA01591">PIA01591</a>.<p>The lower-right image is centered on the dark feature known as Syrtis Major, first seen telescopically by the astronomer Christian Huygens in the 17th century. Many small, dark, circular impact craters can be seen in this region, attesting to the Hubble telescope's ability to reveal fine detail on the planet's surface. To the south of Syrtis a large circular feature called Hellas. Viking and more recently Mars Global Surveyor have revealed that Hellas is a large and deep impact crater. These Hubble telescope pictures show it to be filled with surface frost and water ice clouds. Along the right limb, late afternoon clouds have formed around the volcano Elysium. See also <a href="/catalog/PIA01592">PIA01592</a>.<p>Shown here are color composites generated from data using three filters: blue (410 nanometers), green (502 nanometers), and red (673 nanometers). A total of 12 color filters, spanning ultraviolet to near-infrared wavelengths, were used in the observation.<br /><br /><a href="http://photojournal.jpl.nasa.gov/catalog/PIA01587" onclick="window.open(this.href); return false;" title="Voir l'image PIA01587: A Closer Hubble Encounter With Mars - 4 Views sur le site de la NASA">Voir l'image PIA01587: A Closer Hubble Encounter With Mars - 4 Views sur le site de la NASA.</a></div>
PIA01587: A Closer Hubble Encounter With Mars - 4 Views