Rhea – Crater Upon Crater

Close-up image of Rhea showing numerous craters.

Craters imprinted upon other craters record the long history of impacts endured by Saturn’s moon Rhea. This view looks toward the mid-southern latitudes of the Saturn-facing side of Rhea (1.528 kilometers across). The image was taken by Cassini’s narrow-angle camera on October 13, 2009, from a distance of approximately 45.000 kilometers. Image scale is 262 meters per pixel.

Image Credit: NASA/JPL/Space Science Institute/astroarts.org

Fog in Valles Marineris

Dense, low lying fog in Valles Marineris.

Image of the western part of Valles Marineris, taken by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express spacecraft on May 25, 2004, showing dense ground fog.
This image has not yet been officially released by ESA.

Image Credit: ESA/DLR/FU Berlin (G. Neukum)/astroarts.org

References:
A. Inada et al.:
Wavelength Dependency and Angular Effects of Reflectance of Fog in Valles Marineris (PDF; 1.7 MB)

A. Inada et al.: Dust Haze in Valles Marineris observed by HRSC and OMEGA onboard Mars Express (PDF; 1.9 MB)

D. Möhlmann: Adsorption water driven processes on Mars (PDF; 1.7 MB)

Chaitén Volcano

Eruption of Chile's Chaitén volcano,
generating a spectacular lightning storm.

Lightning bolts appear above and around the Chaitén volcano in southern Chile as seen from Chana, some 30 kilometers north of the volcano. The mingling of lightning and ash is a so called dirty thunderstorm. These storms may be sparked when rock fragments, ash, and ice particles in the plume collide to produce static charges, just as ice particles collide to create charge in regular thunderstorms.

Image Credit: Carlos Gutierrez/UPI/astroarts.org

Tethys – Battered and Grooved

Saturn's Moon Tethys from Cassini.

A mosaic of four images of Tethys (1.071 kilometers across) taken on October 14, 2009, with Cassini’s narrow angle camera. The view is towards the Saturn-facing hemisphere.
Near center lies the large crater Penelope, overprinted by many smaller, younger impact sites.
Three smaller impact features of roughly similar size make a line to the right of Penelope. Those craters are (from top) Ajax, Polyphemus and Phemius.

Image Credit: NASA/JPL/Space Science Institute/Mosaic by astroarts.org

Thaumasia Region

The geology of the Thaumasia region on Mars includes a wide array of rock materials, depositional and erosional landforms, and tectonic structures. The region is dominated by the Thaumasia plateau, which is about 2.900 km across and rises over 4 km above the surrounding terrain. The plateau includes central high lava plains ringed by highly deformed highlands; it may comprise the ancestral center of Tharsis tectonism. The extensive structural deformation of the region, which is without parallel on Mars in both complexity and diversity, occurred largely throughout the Noachian and Hesperian periods (about 4 billion years ago). The deformation produced small and large extensional and contractional structures that resulted from stresses related to the formation of Tharsis, from magmatic-driven uplifts, such as at Syria Planum and central Valles Marineris, and from the Argyre impact. In addition, volcanic, eolian, and fluvial processes have highly modified the older surfaces in this region.

Fractured terrain
of the Thaumasia region.

An escarpment in the center of this picture is at the south extension of the end of Claritas Fossae. The fractures are roughly radial to the Tharsis bulge and cut mostly old cratered terrain. Crater counts indicate that most of the fractures are older than the corresponding fractures north of the Tharsis bulge.

Mosaic of the Viking 1 Orbiter images f057a04 to f057a13, taken on August 17, 1976.
North is at approximately the eleven o’clock position.

Image Credit: NASA/JPL/Arizona State University/Mosaic by astroarts.org

Dust storm over the Thaumasia region on Mars.

This Viking 2 Orbiter image (f176b02), taken on February 17, 1977, shows a large dust storm over the Thaumasia region on Mars. This large disturbance soon grew into the first global dust storm observed by the Viking Orbiters.
The image covers a region of nearly 1.400 km. North is at approximately the one o’clock position.

Image Credit: NASA/JPL/Arizona State University/astroarts.org

See also:
ESA – Mars Express – Solis Planum, Thaumasia region

ESA – Mars Express – The grabens of Claritas Fossae

LROC Image Of The Apollo 14 Landing Site #1

LROC NAC image
of the Apollo 14 landing site
and nearby Cone crater.

This picture is a slightly enhanced crop from the original LROC NAC image of the Fra Mauro highlands and shows the Apollo 14 landing site and nearby Cone crater. The faint trails left by the astronauts’ footprints can be clearly seen.

Image Credit: NASA/GSFC/Arizona State University/astroarts.org

Panorama of Saddle Rock

This panorama, stitched from the Hasselblad photographs AS14-68-9449/50/51 taken by Apollo 14 astronaut Edgar D. Mitchell, shows Saddle Rock, the largest boulder seen during the second extravehicular activity (EVA) of the Apollo 14 mission. Named for its shape, Saddle Rock is 4,5 meters across.

Image Credit: NASA/Panorama by astroarts.org

Identifying Saddle Rock in the LROC NAC image
of the Apollo 14 landing site.

This picture combines a crop (scaled by a factor of 233 %) from the LROC NAC image of the Apollo 14 landing site with the panorama of Saddle Rock shown above. The arrow points to the location of Saddle Rock at the Apollo 14 geology station C1 near the rim of Cone crater.

Image Credit: NASA/GSFC/Arizona State University/astroarts.org

First close-up image of the Galilean moon Europa

This black and white image of Europa,
the smallest of Jupiter's four Galilean satellites,
was acquired by Voyager 2 on July 9, 1979.

On July 9, 2009, was the thirtieth anniversary of the flyby of the Voyager 2 probe past Jupiter.
The picture shown here, taken by Voyager 2 from a distance of 246.000 kilometers, was the first close look ever obtained of Jupiter’s satellite, Europa.
The linear crack-like features had been seen from a much greater distance by Voyager 1, but this image provides a resolution of about four kilometers. The complicated linear features appear even more like cracks or huge fractures in this image. Also seen are somewhat darker mottled regions which appear to have a slightly pitted appearance, due to small scale craters.
No large craters (more than five kilometers in diameter) are easily identifiable in the Europa photographs to date, suggesting that this satellite has a young surface.
Various models for Europa’s structure were tested during analysis of this image, including the possibility that the surface is a thin ice crust overlying water or softer ice and that the fracture systems seen are breaks in that crust. Resurfacing mechanisms such as production of fresh ice or snow along the cracks and cold glacier-like flows were considered as possibilities for removing evidence of impact events.

Photo-ID: JPL P-21758; Raw Image Name: A79-7087; Date: July 9, 1979.
The image here is a scan from a print of the original data, so some image quality is lost.
Image Credit: NASA Ames Research Center/astroarts.org

Landslides in Ganges Chasma

Lobes from several enormous landslides are visible along the floor of Ganges Chasma.

This image shows a portion of Ganges Chasma, a several kilometers-deep side canyon at the east end of the Valles Marineris canyon system.
Ganges Chasma slices through almost 5 kilometers of the martian crust and reveals ancient rocks and layers in the walls of the canyons that would otherwise be unseen. Lobes from several enormous landslides are visible along the floor of the canyon. Material in a landslide off the north wall of the canyon flowed more than 17 kilometers across the canyon floor, eventually coming to rest atop an older landslide from the south wall, that had travelled nearly as far.
Landslides have very characteristic morphologies on Earth, which they also display on Mars. These morphologies include a distinctive escarpment at the uppermost part of the land slide, called a head scarp, a down-dropped block of material below that escarpment that dropped almost vertically, and a deposit of debris that moved away from the escarpment at high speed.
The image was taken by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express spacecraft and has not yet been officially released by ESA.

Further reading:
Landslide Features and Their Relative Ages

Image Credit: ESA/DLR/FU Berlin (G. Neukum)/astroarts.org

Perspective view of landslide features in Ganges Chasma.

Perspective view of Ganges Chasma – looking east.
The vertical exaggeration is 2.

Image Credit: ESA/DLR/FU Berlin (G. Neukum)/astroarts.org

Arsia Mons

Collapse features on the southern flank of
the giant shield volcano Arsia Mons.

This colour composite from infrared, green and blue channel images shows a zone of collapse features on the southern flank of the giant shield volcano Arsia Mons. The total height difference in the land surfaces in this scene is about 7 kilometres, and some individual collapse pits have a depth of more than 2 kilometres. The pits probably formed when lava erupted from the side of Arsia Mons. When lava, or molten rock, finds its way to the surface, it produces several veins and chambers. These slowly empty as the lava erupts and runs down the volcano flanks. Some of the lava reaching the surface cools down and becomes solid, often building a roof over the emptied chamber. The resulting voids collapse due to the weight of the overlying material. At several places, the walls of the pits have been modified by later landslides. The overall trend of the collapse zone runs from the south-west to the north-east, following exactly a giant zone of crustal weakness in the Tharsis region, along which the three large Tharsis volcanoes are aligned. Arsia Mons is the southernmost of these volcanoes. It is 435 kilometres in diameter, almost 20 kilometres high, and the summit caldera is 116 kilometres wide.

The images that were used to create this colour composite were taken on April 2, 2004, by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express spacecraft. The images were taken from an altitude of 400 kilometres and cover an area of about 80 by 105 kilometres.
The colour composite has not yet been officially released by ESA.

Image Credit: ESA/DLR/FU Berlin (G. Neukum)/astroarts.org

Tyrrhena Patera

The flanks of this ancient, southern hemisphere volcano have been strongly modified and embayed. At the summit is an irregular depression that is continuous with a valley, extending down the outer flanks. Concentric graben surround the summit. The volcano is so degraded that there are no well-defined primary volcanic depositional features to provide clues regarding the nature of the erupted materials. However, the low profile of the volcano, and the way in which outliers of the volcano form mesa-like bodies, suggest ash flow deposits rather than lavas.

The summit region of Tyrrhena Patera.

This mosaic of nine Viking 1 Orbiter images (f445a48 to f445a56) of the summit region of Tyrrhena Patera, taken on September 5, 1977, shows late stage caldera filling material, ring fractures, and volcano-tectonic channels. Small mare ridges are observed within the caldera-filling material. Erosional scarps and remnant mesas are evident at the margin of the basal shield unit to the northwest of Tyrrhena Patera.
The image covers a length of approximately 250 kilometers.

Image Credit: NASA/JPL/Arizona State University/Mosaic by astroarts.org

The margin of the summit shield unit.

This high-resolution Viking 1 Orbiter image (f794a01) of the margin of the summit shield unit to the northwest of Tyrrhena Patera, taken on August 20, 1978, shows erosional scarps bounding the edge of a large volcano-tectonic channel. The morphology of the channel floor is apparently the result of mass wasting. Different levels of erosion of the summit shield suggest layering in the deposits, and faint lineations may be indicative of a drainage pattern.
The image covers a length of approximately 15 kilometers.

Image Credit: NASA/JPL/Arizona State University/astroarts.org

The north and northwestern sections of
Tyrrhena Patera.

Viking 1 Orbiter image (f480a48) of the north and northwestern sections of Tyrrhena Patera, taken on October 10, 1977. Erosional scarps and mesas are evident at the margins of the basal and summit shield units. Multiple layering is observed in the deposits, with many layers apparent to the north along the path of the northeastern volcano-tectonic channel and segments of the outer ring fracture set.
The image covers a length of approximately 200 kilometers.

Image Credit: NASA/JPL/Arizona State University/astroarts.org

The smooth plains to the west of
Tyrrhena Patera.

This Viking 1 Orbiter image (f087a12), taken on September 16, 1976, shows the surface of the smooth plains to the west of Tyrrhena Patera containing erosional scarps and mare-type ridges.
The image covers a length of approximately 140 kilometers.

Image Credit: NASA/JPL/Arizona State University/astroarts.org