Space: The final frontier / Διάστημα: Το τελευταίο σύνορο

Posted: 28/05/2011 in World



The most recent spacecraft telemetry was acquired on May 24 from the Deep Space Network tracking complex at Goldstone, California. The Cassini spacecraft is in an excellent state of health and all subsystems are operating normally.


Cassini Nears Four-year Mark

NASA’s Cassini Spacecraft is now reaching the end of its four-year prime mission (on June 30th), and about to enter into its extended mission. What a nice excuse for a retrospective of some of the great images sent back home by Cassini over the past four years.



The Sun is on the opposite side, so all of Saturn is backlit. Courtesy NASA/JPL-Caltech



Swirls in Saturn’s cloud-tops. Courtesy NASA/JPL-Caltech



The surface of Saturn’s moon Dione, up close. Courtesy NASA/JPL-Caltech



Tiny moon Janus, seen before Saturn’s rings, with massive moon Titan beyond. Courtesy NASA/JPL-Caltech



Saturn’s moon Rhea, with Izanagi Crater at center. Courtesy NASA/JPL-Caltech



Saturn’s horizon seen through its thin rings. Courtesy NASA/JPL-Caltech



Small moon Mimas, seen against Saturn’s horizon. Courtesy NASA/JPL-Caltech



A «knot», or small disturbance in one of Saturn’s outer rings. Courtesy NASA/JPL-Caltech



Closeup of small, cratered moon Hyperion. Courtesy NASA/JPL-Caltech



Saturn’s moon Enceladus, seen just in front of Saturn. Courtesy NASA/JPL-Caltech



Saturn’s polar region. Courtesy NASA/JPL-Caltech



Mimas closeup, with rings in background. Courtesy NASA/JPL-Caltech

Cassini’s continued mission



This natural color mosaic was acquired by the Cassini spacecraft as it soared 39 degrees above the unilluminated side of Saturn’s rings. Little light makes its way through the rings to be scattered in Cassini’s direction in this viewing geometry, making the rings appear somewhat dark compared to the reflective surface of Saturn (120,536 km/74,898 mi across). The view combines 45 images taken over the course of about two hours, as Cassini scanned across the entire main ring system. The images in this view were obtained on May 9, 2007 at a distance of approximately 1.1 million kilometers (700,000 miles) from Saturn. (NASA/JPL/SSI)



Pan, a small ring-embedded moon (28 km/17 mi wide) coasts into view from behind Saturn. The view of the rings is distorted near Saturn by the planet’s upper atmosphere. The view was acquired at a distance of approximately 1.8 million km (1.1 million mi) from Pan. Image scale is 11 km (7 mi) per pixel on Pan. (NASA/JPL/SSI) #



Rhea (1,528 km/949 mi wide) drifts in front of Saturn. The view was acquired at a distance of approximately 576,000 km (358,000 mi) from Rhea. Image scale is 3 km (2 mi) per pixel. (NASA/JPL/SSI) #



Cassini peers through Saturn’s delicate, translucent inner C ring to see the diffuse yellow-blue limb of Saturn’s atmosphere. The image was taken on April 25, 2008 at a distance of approximately 1.5 million km (913,000 mi) from Saturn. Image scale is 8 km (5 mi) per pixel. (NASA/JPL/SSI) #



Rhea passes in front of Saturn’s larger, hazy moon Titan (which is lit from behind by the sun) in June of 2006. (NASA/JPL/SSI) #



This mosaic of two Cassini images shows Pan and Prometheus creating features in nearby rings. Pan (28 km/17 mi wide), in the Encke Gap at left, is trailed by a series of edge waves in the outer boundary of the gap. Prometheus (86 km/53 mi wide) just touches the inner edge of Saturn’s F ring at right, and is followed by a series of dark channels in the ring. The view was obtained at a distance of approximately 1.2 million km (746,000 mi) from Pan and Prometheus. Image scale is 7 km (5 mi) per pixel on both moons. (NASA/JPL/SSI) #



This image was taken during Cassini’s close approach to the moon Iapetus in Sept. 2007. The image was taken on Sept. 10, 2007 with the Cassini spacecraft wide-angle camera at a distance of approximately 3,870 km (2,400 mi) from Iapetus. Image scale is 230 meters (755 feet) per pixel. (NASA/JPL/SSI) #



Cassini tracks the shepherd moon Prometheus as it orbits Saturn. Prometheus is just about to pass behind the planet, and a faint streamer of ring material lies below and to the right of Prometheus (86 km/53 mi wide), in the faint, inner strand of the F ring. The view was acquired at a distance of approximately 1.3 million km (804,000 mi) from Prometheus. Image scale is 8 km (5 mi) per pixel. (NASA/JPL/SSI) #



Saturn’s high north is a seething cauldron of activity filled with roiling cloud bands and swirling vortices. A corner of the north polar hexagon is seen at upper left. The image was taken on Aug. 25, 2008 at a distance of approximately 541,000 km (336,000 mi) from Saturn. Image scale is 29 km (18 mi) per pixel. (NASA/JPL/SSI) #



Numerous stars provide a serene background in this view of Enceladus captured by the Cassini spacecraft while the moon was in eclipse, within Saturn’s shadow. The view looks up at Enceladus’ south pole. The image was taken on Oct. 9, 2008 at a distance of approximately 83,000 km (52,000 mi) from Enceladus. Image scale is 5 km (3 mi) per pixel. (NASA/JPL/SSI) #



In this image of the F ring, taken shortly after its ring particles encountered the shepherd moon Prometheus, the disruption to the ring caused by the moon is evident. The bright core of the ring and its neighboring faint strands show kinks where the moon’s gravity has altered the orbits of the ring particles. The image was taken on Oct. 23, 2008 at a distance of approximately 444,000 km (276,000 mi) from Saturn. Image scale is 2 km (1 mile) per pixel. (NASA/JPL/SSI) #



Dark irregular patterns dot the bright outer B ring just left of the large Huygens Gap in the center of this image from Cassini. Cassini scientists speculate that these features are likely the result of transient gravitational clumping. The outer edge of the B ring is anchored and sculpted by a powerful gravitational resonance with the moon, Mimas (396 km/246 mi wide). The mutual gravity between particles may pull them into clumps as they are periodically forced closely together by the action of Mimas. The image was taken on Dec. 8, 2008 at a distance of approximately 710,000 km (441,000 mi) from Saturn. Image scale is 4 km (2 mi) per pixel. (NASA/JPL/SSI) #



The terminator engulfs Penelope (foreground), one of the largest craters on Saturn’s moon, Tethys. The image was taken on Nov. 24, 2008 at a distance of approximately 62,000 km (38,000 mi) from Tethys. Image scale is 366 meters (1,202 feet) per pixel. (NASA/JPL/SSI) #



Against a background of muted atmospheric bands in Saturn’s northern hemisphere, Mimas forges onward in its orbit around the Ringed Planet. Aside from the large crater Herschel, all features on Mimas are named after people and places in Arthurian legend or the legends of the Titans. In fact, the largest crater near the terminator in this view is named Arthur (64 km, 40 mi across). The image was taken on Nov. 26, 2008 at a distance of approximately 915,000 km (569,000 mi) from Mimas. Image scale is 5 km (3 mi) per pixel. (NASA/JPL/SSI) #



Small, battered Epimetheus before Saturn’s A and F rings, and and smog-enshrouded Titan (5,150 km/3,200 mi wide) beyond. The color information in the colorized view is artificial: it is derived from red, green and blue images taken at nearly the same time and phase angle as the clear filter image. This color information was overlaid onto a previously released clear filter view in order to approximate the scene as it might appear to human eyes. The view was acquired on April 28, 2006, at a distance of approximately 667,000 km (415,000 mi) from Epimetheus and 1.8 million km (1.1 million mi) from Titan. The image scale is 4 km (2 mi) per pixel on Epimetheus and 11 km (7 mi) per pixel on Titan. (NASA/JPL/SSI) #



Half an hour after Prometheus tore into Saturn’s F ring, Cassini snapped this image just as the moon was creating a new streamer in the ring. The dark pattern shaped like an upside down check mark in the lower left of the image is Prometheus and its shadow. The potato shaped moon can just be seen coming back out of the ring. The moon’s handiwork also is apparent in two previous streamer-channel formations on the right of the image. The darkest streamer-channel stretching from the top right to the center of the image shows Prometheus’ previous apoapse passage about 15 hours earlier. Prometheus (86 km/53 mi across) dips into the inner edge of the F ring when it reaches apoapse, its farthest point from Saturn. At apoapse, the moon’s gravity pulls out particles of the ring into a streamer. As Prometheus moves back toward periapse – its orbit’s closest point to the planet – the streamer gets longer. Then, as Prometheus moves back toward apoapse, the streamer breaks apart which results in a dark channel. This streamer-channel cycle repeats once every orbit. The image was taken on Jan. 14, 2009 at a distance of approximately 555,000 km (345,000 mi) from Saturn. Image scale is 3 km (2 mi) per pixel. (NASA/JPL/SSI) #



This bizarre scene shows the cloud-streaked limb of Saturn in front of the planet’s B ring. The ring’s image is warped near the limb by the diffuse gas in Saturn’s upper atmosphere. The image was taken on June 24, 2008 using a spectral filter sensitive to wavelengths of infrared light, at a distance of approximately 657,000 km (408,000 mi) from Saturn. Image scale is 4 km (2 mi) per pixel. (NASA/JPL/SSI) #



Cassini looks toward Rhea’s cratered, icy landscape with the dark line of Saturn’s ringplane and the planet’s murky atmosphere as a background. Rhea is Saturn’s second-largest moon, at 1,528 km (949 mi) across. Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were acquired on July 17, 2007 at a distance of approximately 1.2 million km (770,000 mi) from Rhea. Image scale is 7 km (5 mi) per pixel. (NASA/JPL/SSI) #



This image of Saturn’s rings and the shadow of nearby Mimas was taken on April 08, 2009. The rings are now oriented nearly edge-on toward the Sun, and very long moon shadows frequently drape across them. Interesting to note in this image are the various jagged shadows along the outer edge of the B ring. Scientists are closely studying this phenomenon now, and a preliminary hypothesis suggests that the shadows are of clumpy, disturbed ring material, stretching up to 3 km above the ring plane – contrasted with an estimated normal ring thickness of only 10 meters or so. (The ring-shaped mark at right is a camera artifact) (NASA/JPL/SSI) #



Cassini peers through the fine, smoke-sized ice particles of Saturn’s F ring toward the cratered face of Mimas (396 km/246 mi wide). The F ring’s core is dense enough to completely block the light from Mimas. The image was taken on Nov. 18, 2007 at a distance of approximately 772,000 km (480,000 mi) from Mimas. Image scale is 5 km (3 mi) per pixel on the moon. (NASA/JPL/SSI) #



Gray Mimas appears to hover above the colorful rings. The large crater seen on the right side of the moon is named for William Herschel, who discovered Mimas in 1789. Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were acquired on Sept. 9, 2007 at a distance of approximately 3.151 million km (1.958 million mi) from Mimas. Image scale is 19 km (12 mi) per pixel. (NASA/JPL/SSI) #



Saturn is seen through the thick smoggy haze of Titan’s upper atmosphere in this December, 2005 image. The image was taken at a distance of approximately 25,404 kilometers (15,785 mi) from Titan. (NASA/JPL/SSI) #



The shadow of Tethys drifts across the face of Saturn. Nearby, shadows of the planet’s rings form a darkened band above the equator. The image was taken on Oct. 1, 2008 at a distance of approximately 615,000 km (382,000 mi) from Saturn. Image scale is 37 km (23 mi) per pixel. (NASA/JPL/SSI) #



Saturn’s northern hemisphere is seen here against its nested rings. The rings have been brightened relative to the planet to enhance visibility. Images taken using red, green and blue spectral filters were combined to create this natural color view. The images were acquired with the Cassini spacecraft wide-angle camera on Feb. 24, 2009 at a distance of approximately 866,000 km (538,000 mi) from Saturn. Image scale is 38 km (24 mi) per pixel. (NASA/JPL/SSI) #

Martian Skies

announcement by NASA of the discovery of water ice on Mars by its Phoenix Lander probe made big news everywhere. The discovery involved the observation of water ice sublimating into the air – that is, the water went from solid to vapor state without reaching the liquid stage. The Martian atmosphere has perfect conditions for sublimation – extremely thin, dry and cold. How cold? Well, you can check the Live Martian Weather Report, with data from a station on board the Phoenix Lander. Today will see a high temperature of a toasty -26 degrees F.
What more do we know about Mars’ atmosphere? It’s hundreds of times thinner than Earth’s atmosphere and is made of 95% carbon dioxide, 3% nitrogen, 1.6% argon, and contains traces of oxygen, water, and methane. We also know, from observations that it can support dust storms, dust devils, clouds and gusty winds. With an amazing number of six current live probes exploring Mars (two rovers, a lander, and three orbiters), there are many thousands of images available. Only a few, however show atmospheric phenomena. Presented here are some of the best images of Martian atmosphere (and beyond) in action




High, wispy clouds cover a large portion of Mars, seen in this, the first true-colour image of Mars generated with the OSIRIS orange (red), green and blue color filters. The image was acquired by an instrument on the ESA’s Rosetta probe on Feb. 24, 2007 from a distance of about 240,000 km. Image resolution is about 5 km/pixel. (Credits: ESA © 2007 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA)



Mars’ northern orange sky and horizon, seen by NASA’s Phoenix Mars Lander. The lander’s solar panel and Robotic Arm with a sample in the scoop are also visible. The image was taken by the lander’s Surface Stereo Imager looking west during Phoenix’s Sol 16 (June 10, 2008), or the 16th Martian day after landing. The image was taken just before the sample was delivered to the Optical Microscope. (NASA/JPL-Caltech/University of Arizona/Texas A&M University)



The brownish gray sky at sunset as it would be seen by an observer on Mars – true color mosaic taken by Mars Pathfinder on sol 24 (June 22, 1996) The sky near the sun is a pale blue color. (NASA/JPL)



High ice cloud over Mars’ limb. This composite of red and blue Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) images acquired on 6 July 2005 shows an isolated water ice cloud extending more than 30 kilometers (more than 18 miles) above the Martian surface. Clouds such as this are common in late spring over the terrain located southwest of the Arsia Mons volcano. (NASA/JPL/Malin Space Science Systems)



Clouds over crater – the dust storm season in the southern hemisphere of Mars was well underway. This image of an unnamed crater southeast of Hellas Basin shows the encroachment of a storm in the region. Image acquired in 2001 by Mars Odyssey orbiter (17 meter/pixel resolution). (NASA/JPL/ASU)



Dust devil from above. This image taken by the Hi-RISE Camera aboard NASA’s Mars Reconnaissance Orbiter catches a dust devil blowing across the Martian surface. Dust devils generally form in the afternoon because the sunlight needs sufficient time to warm the surface. When this image was taken, the local time was about 3:08 p.m. The bright material is the dust within the vortex, and a dark shadow cast by the dust devil is visible to the left. The diameter of this dust devil is about 200 meters, but at the surface it is probably much smaller. Based on the length of the shadow in this image, the dust devil is on the order of 500 meters tall. (NASA/JPL/University of Arizona)



Several dust devils cross a plain in this animation of a series of images acquired by NASA’s Mars Rover Spirit in May, 2005. (NASA/JPL-Caltech/Cornell/USGS)



A well-defined dust devil crosses in front of the camera in this animation of a series of images acquired by NASA’s Mars Rover Spirit in May, 2005. (NASA/JPL-Caltech/Cornell/USGS)



Martian skies seen above a rolling horizon in this image, part of a larger image called the «McMurdo» panorama, taken in the Martian winter of 2006 by NASA’s Mars Exploration Rover Spirit. The tracks in the soil are from Spirits wheels as it rolled through the area earlier. (NASA/JPL/Cornell)



Clouds above the rim of «Endurance Crater» in this image from NASA’s Mars Exploration Rover Opportunity. These clouds occur in a region of strong vertical shear. The cloud particles (ice in this martian case) fall out, and get dragged along away from the location where they originally condensed, forming characteristic streamers. Opportunity took this picture with its navigation camera during the rover’s 269th martian day (Oct. 26, 2004). (NASA/JPL)



Early Spring Dust Storms at the North Pole of Mars. Early spring typically brings dust storms to northern polar Mars. As the north polar cap begins to thaw, the temperature difference between the cold frost region and recently thawed surface results in swirling winds. The choppy dust clouds of several dust storms are visible in this mosaic of images taken by the Mars Global Surveyor spacecraft in 2002. The white polar cap is frozen carbon dioxide. (NASA/JPL/Malin Space Science Systems)



An exaggerated color image mosaic of images from NASA’s Mars Rover Opportunity. The clouds can be composed of either carbon dioxide ice or water ice, and can move swiftly across the sky. (NASA/JPL/Cornell)



Large dust storms cover much of Mars’ surface in this July, 2001 image, acquired by NASA’s Mars Global Surveyor Mars Orbiter Camera. By early July, the martian atmosphere was so hazy that opportunities for high resolution imaging of the planet were very limited. (NASA/JPL/Malin Space Science Systems)



The air is certainly thick enough to fill a parachute. On May 25th, 2008, the HiRISE camera onboard the Mars Reconnaissance Orbiter acquired this dramatic oblique image of the arrival of its sister probe from NASA, the Phoenix Lander, descending on its parachute. Phoenix and its parachute can be barely seen in the larger image with 10 km wide crater informally called «Heimdall» in the background. Although it appears that Phoenix is descending into the crater, it is actually about 20 kilometers in front of the crater. Given the position and pointing angle of MRO, Phoenix is at about 13 km above the surface, just a few seconds after the parachute opened. (NASA/JPL/University of Arizona)



On May 19th, 2005, NASA’s Mars Exploration Rover Spirit captured this stunning view as the Sun sank below the rim of Gusev crater on Mars. This Panoramic Camera mosaic was taken around 6:07 in the evening of the rover’s 489th martian day, or sol. Spirit was commanded to stay awake briefly after sending that sol’s data to the Mars Odyssey orbiter just before sunset. The image is a false color composite, showing the sky similar to what a human would see, but with the colors slightly exaggerated. (NASA/JPL/Texas A&M/Cornell)



Higher in the Martian skies, we see one of its two moons. The HiRISE camera onboard the Mars Reconnaissance Orbiter acquired this dramatic view of the Martian moon, Phobos, on 23 March 2008, from a distance of 6,800 kilometers. The illuminated part of Phobos is about 21 km across. The most prominent feature is the large impact crater Stickney, in the upper left. With a diameter of 9 km, it is the largest feature on Phobos. (NASA/JPL/University of Arizona)



Even higher in the Martian sky, the Earth and Moon hang in space, as seen from Mars. The HiRISE camera onboard the Mars Reconnaissance Orbiter acquired this image at 5:20 a.m. MST on October 3rd, 2007, at a range of 142 million kilometers, while orbiting Mars.

Martian landscapes



Intersecting swirling trails left by the earlier passage of dust devils across sand dunes, as they lifted lighter reddish-pink dust and exposed the darker material below. Also visible are darker slope streaks along dune edges, formed by a process which is still under investigation. More, or see location on Google Mars. (NASA/JPL/University of Arizona)



An eroded crater in a larger plain with a scalloped appearance near Pavonis Mons. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



Part of the Abalos Undae dune field. The sands appear blueish because of their basaltic composition, while the lighter areas are probably covered in dust. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



A portion of the Martian South Polar Cap, showing stratified layers exposed by a long process of sublimation. More information here. (NASA/JPL/University of Arizona) #



Exposure of Layers and Minerals in Candor Chasma. This image shows a cliff along a light-toned layered deposit in Valles Marineris. Erosion by wind has carved V-shaped patterns along the edges of many of the layers. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



Avalanches on Mars’ North Polar Scarps. Material, likely including fine-grained ice and dust and possibly including large blocks, has detached from a towering cliff and cascaded to the gentler slopes below. The cloud is about 180 meters (590 feet) across and extends about 190 m (625 ft) from the base of the steep cliff. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



Pathfinder spotted on an ancient flood plain of the Ares and Tiu outflow channels. The bright spot visible at lower left is the Mars Pathfinder Lander, its ramps, science deck, and portions of the airbags visible. NASA’s Pathfinder landed on Mars on July 4, 1997 and continued operating until September 27 of that year. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



Victoria Crater at Meridiani Planum. The crater is approximately 800 meters (about half a mile) in diameter. Layered sedimentary rocks are exposed along the inner wall of the crater, and boulders that have fallen from the crater wall are visible on the crater floor. NASA’s Mars rover Opportunity explored this crater and its walls in 2006. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



Close-up of tracks made by NASA’s Mars rover Opportunity in the soil near Victoria Crater. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



Linear dunes in the north polar region of Mars. Polygons formed by networks of cracks cover the substrate between the linear dunes and may indicate that ice-rich permafrost is present or has been present geologically recently in this location. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



Scalloped sand dunes in the southern hemisphere of mars, displaying seasonal frost on the south-facing slopes, which highlights some of the regular patterns, as the frost forms only on parts of the ripples. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



This image shows lineated valley fill and lobate debris aprons in the Deuteronilus Mensae region. Many of the valley floors in this region exhibit complex alignments of small ridges and pits often called «lineated valley fill». The cause of the small-scale texture is not well understood, but may result from patterns in ice-rich soils or ice loss due to sublimation (ice changing into water vapor). More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



A large barchan (crescent-shaped) dune, in a region where some dunes have been observed shrinking over several years. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



The edge of an approximately 6 km diameter crater in the southern hemisphere, laced with gullies leading down to the crater floor. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



Dunes in a crater in Newton Basin that are eroding or covering a more coherent rock structure below. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



The south polar region of Mars is covered every year by a layer of carbon dioxide ice. In a region called the «cryptic terrain,» the ice is translucent and sunlight can penetrate through the ice to warm the surface below. The ice layer sublimates (evaporates) from the bottom. The dark fans of dust seen in this image come from the surface below the layer of ice, carried to the top by gas venting from below. The translucent ice is «visible» by virtue of the effect it has on the tone of the surface below, which would otherwise have the same color and reflectivity as the fans. Bright streaks in this image are fresh frost. More information here. (NASA/JPL/University of Arizona) #



An impact crater on the south polar layered deposits. This is a small, approximately 330 meter (360 yard) diameter impact crater. The polar layered deposits on Mars are believed to be very young because there are no large craters on them and very few small craters. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



Rocky mesas of Nilosyrtis Mensae region. Phyllosilicate (clay) minerals have been detected in this region by imaging spectrometers on the Mars Express and MRO spacecraft, and these minerals are of great interest in the search for evidence of life on ancient Mars. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



Gullies, streaks, ripples and dust devil tracks on Russell Crater Dunes. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



A 4 km diameter feature near the edge of the south polar residual cap. The bright areas in this image are covered by carbon dioxide frost, and the «swiss cheese» terrain typical of the south polar residual cap covers much of the imaged area. The dark walls of the circular depression do not have as much frost on them, and are fractured in a polygonal pattern. Apparently the surface of the walls has been extensively modified by thermal expansion and contraction of water ice. It also appears that the «swiss cheese» terrain of the residual cap has buried the floor of the circular depression, as well as the terrain surrounding the feature, making it difficult to infer the origin of this depression. More information here. (NASA/JPL/University of Arizona) #



HiRISE catches a dust devil blowing across the Martian surface east of the Hellas impact basin and south of Reull Vallis. The diameter of this dust devil is about 200 meters, but at the surface it is probably much smaller. Based on the length of the shadow in this image, the dust devil is on the order of 500 meters tall. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



Erosion of the south polar residual ice cap, with exposed strata in pits surrounded by cracked polygonal features. More information here. (NASA/JPL/University of Arizona) #



Light-toned layered deposits along the floor of Becquerel Crater, an impact crater in Arabia Terra. The deposits consist of stacked, repeating layers which consistently appear to be only a few meters thick. The surface of the deposits also appears to be cracked into blocks a meter or so in length. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



Defrosting dunes in the north. In northern winter a seasonal polar cap composed of carbon dioxide ice (dry ice) forms in the north polar region. This cap covers a vast sea of dunes at high northern latitudes. In the spring the ice sublimates (evaporates directly from ice to gas) and this active process loosens and moves tiny dust particles. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



Dunes line a valley floor in Ladon Valles, an outflow channel forming a segment of a larger system that heads in Argyre basin to the south and eventually links up with the larger Ares Valles outflow channel to the north. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



A small impact crater, surrounded by ejecta, is filled in with rippled sand on the floor of Ritchey Crater. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



Fuzzy-looking landscape near Tharsis Montes. Some parts of this image may appear out-of-focus at first. However, sharper-looking features such as the visible craters show that the fuzzy look is not an artifact of the image, but rather indicative of an extremely smooth surface. That smoothness is due to a thick layer of dust blanketing the landscape. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



A Sample of flows and other landforms in Icaria Planum. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



A sawtooth pattern in carbon dioxide ice in Mars’ south polar region. More information here. (NASA/JPL/University of Arizona) #



A valley in Elysium region volcanic rise. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



A small crater partially buried in wind-blown ejecta from a much larger crater (below, out of frame). More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



A large outcrop of layered rock in Aureum Chaos, an area that has apparently collapsed, leaving a region of irregular knobs and hills. Unlike many of the knobs, the light outcrop shows distinct, nearly horizontal layers. This may indicate that it was deposited after the collapse of the Chaos. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



A gully along the inner wall of Western Hale Crater, shadowed by a raised crater rim. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



Gully-like features in a transition zone between plain and dune field. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #



A small impact crater, pitted knobs, and a criss-cross mesh of dust devil trails across the martian surface. More, or see location on Google Mars. (NASA/JPL/University of Arizona) #

Views of Jupiter

Jupiter is in the news again, this time because its «Baby Red Spot» – a storm less than a year old – appears to have been swallowed up by the massive storm known as the Great Red Spot. This is good occasion to share some of the best photographs of Jupiter and its larger system of rings and moons, as seen by various probes and telescopes over the past 30 years.



Jupiter’s moon Io floats above the cloudtops of Jupiter in this image captured January 1, 2001. The image is deceiving: there are 350,000 kilometers – roughly 2.5 Jupiters – between Io and Jupiter’s clouds. Io is about the size of our own moon (NASA/JPL/University of Arizona)



This image of Jupiter’s moon Europa rising above Jupiter was captured by the New Horizons spacecraft in February just after it passed Jupiter on its way to Pluto and the outer Solar System. (NASA, Johns Hopkins U. APL, SWRI)



The gibbous phase of Jupiter’s moon Europa. The robot spacecraft Galileo captured this image mosaic during its mission orbiting Jupiter from 1995 – 2003. Evidence and images from the Galileo spacecraft, indicated that liquid oceans might exist below the icy surface. (Galileo Project, JPL, NASA; reprocessed by Ted Stryk)



This view of the icy surface of Jupiter’s moon, Europa, is a mosaic of two pictures taken by the Solid State Imaging system on board the Galileo spacecraft during a close flyby of Europa on February 20, 1997. The area shown is about 14 kilometers by 17 kilometers (8.7 miles by 10.6 miles), and has a resolution of 20 meters (22 yards) per pixel. One of the youngest features seen in this area is the double ridge cutting across the picture from the lower left to the upper right. This double ridge is about 2.6 kilometers (1.6 miles) wide and stands some 300 meters (330 yards) high. (NASA/JPL/ASU)



A composite of several images taken in several colors by the New Horizons Multispectral Visual Imaging Camera, or MVIC, illustrating the diversity of structures in Jupiter’s atmosphere, in colors similar to what someone «riding» on New Horizons would see. It was taken near the terminator, the boundary between day and night, and shows relatively small-scale, turbulent, whirlpool-like structures near the south pole of the planet. The dark «holes» in this region are actually places where there is very little cloud cover, so sunlight is not reflected back to the camera. (NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)



This image, acquired during Galileo’s ninth orbit around Jupiter, shows two volcanic plumes on Io. One plume was captured on the bright limb or edge of the moon, erupting over a caldera (volcanic depression) named Pillan Patera. The plume seen by Galileo is 140 kilometers (86 miles) high, and was also detected by the Hubble Space Telescope. The second plume, seen near the terminator, the boundary between day and night, is called Prometheus. The shadow of the airborne plume can be seen extending to the right of the eruption vent. (NASA/JPL/University of Arizona)



A part of the southern hemisphere of Io, seen by the spacecraft Voyager at a range of 74,675 km. In the foreground is gently undulating topography, while in the back-ground are two mountains with their near faces brightly illuminated by the sun. The mountain in the right is approximately 150 km across at its base and its height is probably in excess of 15 km which would make it higher than any mountain on Earth. (NASA/JPL)



This five-frame sequence of New Horizons images captures the giant plume from Io’s Tvashtar volcano. Snapped by the probe’s Long Range Reconnaissance Imager (LORRI) as the spacecraft flew past Jupiter earlier this year, this first-ever «movie» of an Io plume clearly shows motion in the cloud of volcanic debris, which extends 330 kilometers (200 miles) above the moon’s surface. Only the upper part of the plume is visible from this vantage point – the plume’s source is 130 kilometers (80 miles) below the edge of Io’s disk, on the far side of the moon. (NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute)



A volcanic plume rises over 300 kilometers above the horizon of Jupiter’s moon Io in this image from cameras onboard the New Horizons spacecraft. The volcano, Tvashtar, is marked by the bright glow (about 1 o’clock) at the moon’s edge, beyond the terminator or night/day shadow line. The shadow of Io cuts across the plume itself. Also capturing stunning details on the dayside surface, the high resolution image was recorded when the spacecraft was 2.3 million kilometers from Io. Later it was combined with lower resolution color data by astro-imager Sean Walker to produce this sharp portrait of the solar system’s most active moon. (NASA, JHU/APL, SwRI – Additional Processing: Sean Walker)



Jupiter’s moon Io, seen by NASA’s Galileo spacecraft against a backdrop of Jupiter’s cloud tops, which appear blue in this false-color composite. (NASA/JPL/University of Arizona)



A mosaic of Jupiter’s ring system, acquired by NASA’s Galileo spacecraft when the Sun was behind the planet, and the spacecraft was in Jupiter’s shadow peering back toward the Sun. (NASA/JPL/Cornell University)




The first color movie of Jupiter from NASA’s Cassini spacecraft shows what it would look like to peel the entire globe of Jupiter, stretch it out on a wall into the form of a rectangular map, and watch its atmosphere evolve with time. The brief movie clip spans 24 Jupiter rotations between Oct. 31 and Nov. 9, 2000. The darker blips that appear are several moons and their shadows. (NASA/JPL/University of Arizona)



An image of the leading hemisphere of Ganymede seen by NASA’s Galileo spacecraft. Many fragmented regions of dark terrain split by lanes of bright grooved terrain cover the surface. Several bright young craters can be seen, including a linear chain of craters near the center of the image which may have resulted from the impact of a fragmented comet, similar to comet Shoemaker-Levy/9 which hit Jupiter in 1994. (NASA/JPL/Brown University)



The area of Nicholson Regio and Arbela Sulcus illustrates many of the diverse terrain types on Jupiter’s moon Ganymede, as seen in this image taken by NASA’s Galileo spacecraft. The image covers an area approximately 89 by 26 kilometers (55by 16 miles). (NASA/JPL/Brown University)



Jupiter’s Great Red seen by NASA’s Voyager spacecraft. July, 1979 Around the northern boundary a white cloud is seen, which extends to east of the region. The presence of this cloud prevents small cloud vortices from circling the spot in the manner seen in the Voyager 1 encounter. Another white oval cloud (different from the one present in this position three months ago) is seen south of the Great Red Spot. This image was taken on July 6, 1979 from a range of 2,633,003 kilometers. The Red Spot is 20,000 km across. (NASA/JPL)



This true color mosaic of Jupiter was constructed from images taken by the narrow angle camera onboard NASA’s Cassini spacecraft on December 29, 2000, as the spacecraft neared Jupiter during its flyby of the giant planet. It is the most detailed global color portrait of Jupiter ever produced. Although Cassini’s camera can see more colors than humans can, Jupiter here looks the way that the human eye would see it. (NASA/JPL/SSI)

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