Ice Layering Near Chasma Australe

Today's VIS image shows the multitude of layers making up the South Polar cap.

Orbit Number: 48506 Latitude: -85.8144 Longitude: 95.4964 Instrument: VIS Captured: 2012-11-20 01:53

Photo credit: NASA/JPL/Arizona State University

Mineral Veins at the Sheepbed Unit

This image of an outcrop at the "Sheepbed" locality, taken by NASA's Curiosity Mars rover with its right Mast Camera (Mastcam), shows well-defined veins filled with whitish minerals, interpreted as calcium sulfate.

These veins form when water circulates through fractures, depositing minerals along the sides of the fracture, to form a vein.These veins are Curiosity's first look at minerals that formed within water that percolated within a subsurface environment. These vein fills are characteristic of the stratigraphically lowest unit in the "Yellowknife Bay" area -- known as the Sheepbed Unit.

Mastcam obtained these images the 126th Martian day, or sol, of Curiosity's mission on Mars (December 13, 2012). The view covers an area about 16 inches (40 centimeters) across.A superimposed scale bar is 8 centimeters (3.15 inch) long.

The image has been white-balanced to show what the rock would look like if it were on Earth.

Photo credit: NASA/JPL-Caltech/MSSS

Note: For more information, see PIA16615: Calcium-Rich Veins in Martian Rocks, PIA16616: Signs of Hydrated Calcium Sulfates in Martian Rocks, and PIA16617: Veins in Rocks on Mars and Earth.

Seasonal Erosion near Chasma Australe

Bright carbon dioxide frost (or, dry ice) highlights this network of channels carved into the surface. The channels are eroded a little bit every spring when the seasonal polar cap, composed of dry ice, sublimates (meaning going directly from a solid to gas) at the ice-surface interface. The erosion occurs under the seasonal ice layer: when trapped pressurized gas finds an escape route it carries along loose surface material. This surface material is blown downwind and deposited in dark fans on top of the seasonal ice layer.

The trapped gas finds the weakest easiest escape route. In this area the gas exploited the existing polygonal structure of the surface below. Polygonal terrain is common at high latitudes, and is caused by the thermal contraction and expansion of water ice frozen in the surface dirt.

Photo credit: NASA/JPL/University of Arizona

Note: This image is located near the western edge of Chasma Australe.

Lava Flows in Daedalia Planum

The lava flows in today's VIS image are located on the northeastern margin of Daedalia Planum. Wind deposits are visible in the lee of the flow fronts.

Orbit Number: 48491 Latitude: -2.75786 Longitude: 223.234 Instrument: VIS Captured: 2012-11-18 19:48

Photo credit: NASA/JPL/Arizona State University

Spherules in Yellowknife Bay

This image from the right Mast Camera (Mastcam) of NASA's Curiosity Mars rover shows roughly spherical features. These are called spherules, and they are common in this stratigraphic unit, the Sheepbed Unit, which defines the lower part of the sequences of strata exposed in "Yellowknife Bay." These features are interpreted as concretions, implying they formed in water that percolated through pores in the sediment. Spherical concretions have previously been discovered in other rocks on Mars.

Mastcam obtained these images on the 139th Martian day, or sol, of Curiosity's surface operations (December 25, 2012). The image has been white-balanced to show what the rock would look like if it were on Earth.

Photo credit: NASA/JPL-Caltech/MSSS

Curiosity's Tracks in Gale Crater

This image was acquired for color coverage of the region that the Curiosity rover may explore, but we acquired some extra RED (monochromatic) coverage of the rover tracks.

This image shows the entire distance traveled from the landing site (dark smudge at left) to its location as of 2 January 2013 (the rover is bright feature at right). The tracks are not seen where the rover has recently driven over the lighter-toned surface, which may be more indurated than the darker soil.

Photo credit: NASA/JPL/University of Arizona

Shaler Outcrop

This image from the Mast Camera (Mastcam) on NASA's Mars rover Curiosity shows inclined layering known as cross-bedding in an outcrop called "Shaler" on a scale of a few tenths of meters, or decimeters (1 decimeter is nearly 4 inches). The superimposed scale bar is 50 centimeters (19.7 inches).

This stratigraphic unit is called the Shaler Unit. Decimeter-scale cross-bedding in the Shaler Unit is indicative of sediment transport in stream flows. Currents mold the sediments into small underwater dunes that migrate downstream. When exposed in cross-section, evidence of this migration is preserved as strata that are steeply inclined relative to the horizontal -- thus the term "cross-bedding." The grain sizes here are coarse enough to exclude wind transport. This cross-bedding occurs stratigraphically above the Gillespie Unit in the "Yellowknife Bay" area of Mars' Gale Crater, and is therefore geologically younger.

Mastcam obtained the image on the 120th Martian day, or sol, of Curiosity's surface operations (December 7, 2012).

The image has been white-balanced to show what the rock would look like if it were on Earth.

Photo credit: NASA/JPL-Caltech/MSSS

Note: For more information, see PIA16700: Wide View of 'Shaler' Outcrop, Sol 120.

Yellowknife Bay Veins and Concretions

The right Mast Camera (Mastcam) of NASA's Curiosity Mars rover provided this view of the lower stratigraphy at "Yellowknife Bay" inside Gale Crater on Mars. The rectangle superimposed on the left image shows the location of the enlarged portion on the right. In the right image, white arrows point to veins (including some under the overhang), and black arrows point to concretions (small spherical concentrations of minerals). Both veins and concretions strongly suggest precipitation of minerals from water.

The scale bar in the left image is 50 centimeters (19.7 inches) long. The scale bar in the right image is 10 centimeters (3.9 inches) long.

Mastcam recorded this view in the morning of the 137th Martian day, or sol, of Curiosity's surface operations (December 24, 2012). The image has been white-balanced to show what the rocks would look like if they were on Earth.

Photo credit: NASA/JPL-Caltech/MSSS

Note: For more information, see PIA16701: View from Inside 'Yellowknife Bay'.

Overflow Channel from Athabasca Vallis

A MOC image over this area showed a channel spilling out of the larger Athabasca Vallis (trending east-west at the north end of this image) and flowing to the south.

The channel splits into multiple branches, creating about ten streamlined mesas. Vague bumps were visible on the channel floor in the MOC image--perhaps large boulders that were deposited by floodwaters?

Our HiRISE image reveals the bumps to be rootless cones that form from lava-water interaction. The entire channel system appears to be coated by lava. There are two leading hypotheses for the origin of these channels: (1) they were carved by water and later coated by lava, or (2) the channels were eroded by the lava itself. If eroded by lava, a source of water was still needed to create the rootless cones, but could have been a much smaller quantity of water than that needed to carve the channels.

(The MOC image can be viewed here, but note that it needs to be flipped left-right to correct the geometry.)

Photo credit: NASA/JPL/University of Arizona

Climbing Dunes in Nereidum Montes

This image shows the southern part of a dune field in Nereidum Montes, which is being monitored for changes in dune and ripple positions.

Many of the dunes in this image are overlying steep slopes. The slopes are dipping to the south, yet the dunes, as evidenced by the north-facing orientation of their steep slip faces, are being blown upslope, to the north. Such "climbing dunes" have been found elsewhere on Mars, such as in Valles Marineris and in this case, indicate relatively strong southerly winds.

A close-up image shows one of these slip faces. In addition, several apparent landslide troughs are present. These are interpreted as sand that has slumped down the slope. Subsequently, the wind has remobilized some of the sand and formed climbing ripples within the troughs. This and other HiRISE images show the dynamic interplay between wind and gravity, two of many processes occurring on Mars today.

(Note: view an unannotated version of the subimage with scale bar.)

Photo credit: NASA/JPL/University of Arizona

Snake River Rock

The sinuous rock feature in the lower center of this mosaic of images recorded by the NASA Mars rover Curiosity is called "Snake River." The images in the mosaic were taken by Curiosity's Navigation Camera during the 133rd Martian day, or sol, of the rover's mission on Mars (December 20, 2012).

On Sol 147 (January 3, 2013), Curiosity drove about 10 feet (3 meters) to get a closer look at Snake River for before proceeding to other nearby rocks.

Photo credit: NASA/JPL-Caltech

On the Edge of Yellowknife Bay

In a shallow depression called "Yellowknife Bay," the NASA Mars rover Curiosity drove to an edge of the feature during the 130th Martian day, or sol, of the mission (December 17, 2012) and used its Navigation Camera to record this view of the ledge at the margin and a view across the "bay."

Photo credit: NASA/JPL-Caltech

Note: For more information, see Curiosity Rover Explores 'Yellowknife Bay'.

Copper Cliff by Opportunity

This 180-degree mosaic of images from the navigation camera on the NASA Mars Exploration Rover Opportunity shows terrain near the rover during the 3,153rd Martian day, or sol, of the rover's work on Mars (December 6, 2012). West is at the center, south at the left edge, north at the right edge.

Opportunity had driven about 7 feet (2.2 meters) westward earlier on Sol 3153 to get close to the outcrop called "Copper Cliff," which is in the center of this scene. The location is on the east-central portion of "Matijevic Hill" on the "Cape York" segment of the western rim of Endeavour Crater.

The view is presented as a cylindrical projection.

Photo credit: NASA/JPL-Caltech

Note: For the anaglyph image, see PIA16561: Opportunity at 'Copper Cliff,' Sol 3153.

Matijevic Hill by Opportunity

This full-circle panorama shows the terrain around the NASA Mars Exploration Rover Opportunity during the 3,105th Martian day, or sol, of the rover's work on Mars (October 18, 2012). It was assembled from images taken by the rover's navigation camera. South is at the center. North is on both ends.

Opportunity had driven about 61 feet (18.5 meters) westward earlier on Sol 3105 to reach this location, which is on the northern portion of "Matijevic Hill" on the "Cape York" segment of the western rim of Endeavour Crater. The wheel tracks created by the drive are visible. For scale, the distance between the two parallel tracks is about 3.3 feet (1 meter).

The basin of Endeavour Crater is in the left half of the image. Opportunity has been working on the western rim of Endeavour since mid-2011.

The panorama is presented as a cylindrical projection.

Photo credit: NASA/JPL-Caltech

Note: For the anaglyph image, see PIA16559: Opportunity's Surroundings on Sol 3105, Stereo View.

Opportunity at Whitewater Lake Outcrop

This full-circle panorama shows the terrain around the NASA Mars Exploration Rover Opportunity during the 3,071st Martian day, or sol, of the rover's work on Mars (September 13, 2012). It was assembled from images taken by the rover's navigation camera. South is at the center. North is on both ends.

Opportunity had driven about 34 feet (10.3 meters) the preceding sol to reach this location, which is on part of a relatively flat, light-toned outcrop called "Whitewater Lake." A darker, adjacent outcrop, called "Kirkwood," lies just east of the rover's location and cuts a band through the middle of this view.

The basin of Endeavour Crater is in the left half of the image. Opportunity has been working on the western rim of Endeavour since mid-2011.

The panorama is presented as a cylindrical projection.

Photo credit: NASA/JPL-Caltech

Note: For the anaglyph image, see PIA16557: Opportunity's Surroundings on Sol 3071, Stereo View.

A Circular Crack in Lucus Planum

This circular crack is very odd-looking. When you zoom in to HiRISE scale, the crack looks a lot like a graben.

Canyonlands, Utah is a great place to see grabens on Earth. Grabens form when solid rock is pulled apart. Two cracks form at distinctive angles, and the material between the cracks collapses downward, forming a straight-walled canyon. Well, they're usually straight-walled, but this one is circular, which is unusual.

The first thing anyone thinks of when they see circular features on Mars is a crater. So one hypothesis about how this formed is that an ancient crater was buried by some material, maybe lava or even multiple layers of wet sediments. Because the center of the crater was deeper, more material settled there, and the high-standing rim was only thinly covered. The mantling material solidified and shrank, creating extensional forces.

The heavy central fill pulled downward, cracking the material at the rim where it was thinnest. That's just one guess, though - what else do you think it could be?

References
Buczkowski, D. L. and M. L. Cooke, 2004. Formation of double-ring circular grabens due to volumetric compaction over buried impact craters: Implications for thickness and nature of cover material in Utopia Planitia, Mars, J. Geophys. Res., 109, E02006, doi:10.1029/2003JE002144.

McGill, G. E., 1986. The giant polygons of Utopia, Northern Martian Plains GeoRL 13, 705-708. DOI:10.1029/GL013i008p00705

This is a stereo pair with ESP_029217_1795.

Photo credit: NASA/JPL/University of Arizona

New Impact Site in Fortuna Fossae

This impact site is located on the floor of a large fracture within Fortuna Fossae. This site formed sometime between September 2005 and May 2008 and consists of five distinct craters each displaying individual dark-toned ejecta patterns.

The resulting craters indicate that the impactor broke up into five parts prior to its collision with the surface. Craters continue to form on Mars today and repeat imaging of these recent impacts--especially in the color portion--provides information about how impact features change with time.

Photo credit: NASA/JPL/University of Arizona

Defrosting Landscape Inside Jeans Crater

This image is from the high latitudes in the Southern hemisphere, about half-way through southern spring.

Just like on the Earth, the frost layer that accumulates over the winter will disappear as summer approaches and Mars heats up. However, most of this frost is not made of water ice and snow -- on Mars, most of the frost/ice is made of carbon dioxide (also known as "dry ice").

This material will not melt, but instead will go directly from solid into vapor (a process called sublimation) as it heats up (above approximately 147 K, which is -195 F, or -126 C). In doing so, it'll create all sorts of interesting landforms.

In this image, we can see sublimation spots (small spots where the frost/ice has sublimated away, exposing the darker ground). We also see small fans, which form when jets of gaseous carbon dioxide erupt through a weak spot in the surface ice, ejecting dark surface material that then gets smeared across the surface by the wind (so the different directions of the fans show us how the wind varies across this landscape).

Large darker "flows" are also visible; these are avalanches of material that extend downslope (and scientists are still debating if flows are dry or wet features). In the next few weeks, more of these features will appear and grow, until Mars heats up enough for all of the frost and ice (and sublimation features) to disappear.

References:
Gardin, E., et al. (2010). Defrosting, dark flow features, and dune activity on Mars: Example in Russell crater. J. Geophys. Res. 115, E06016.

Hansen, C.J., et al. (2010). HiRISE observations of gas sublimation-driven activity in Mars' southern polar regions: I. Erosion of the surface. Icarus 205, 283-295.

Kereszturi, A., et al. (2009). Recent rheologic processes on dark polar dunes of Mars: Driven by interfacial water? Icarus 201, 492-503.

Photo credit: NASA/JPL/University of Arizona

Note: This image is located inside Jeans Crater, which itself is located in Terra Cimmeria.

Layers, Dunes and Cliffs in Hydrae Chasma

Hydrae Chasma is a deep, circular depression approximately 50 kilometers across, situated between Juventae Chasma to the north and the large canyon system Valles Marineris to the south. The Chasma has steep walls flanked by numerous landslides and a massive scarp along its southern boundary where the surface has collapsed into this depression.

This closeup is of an isolated flat-topped mountain (known as a mesa) rising out of a sea of dunes located in the center of Hydrae Chasma. Darker-toned dunes, likely composed of basaltic sands, form an apron along the base of the mesa's northern margin. The western side of the mesa is gently sloping and is composed of a highly fractured light-toned rubbly base. It is overlaid by alternating light and dark layered cliff-forming units and is covered by a sediment cap containing still more dunes.

The layered sequences are present only in the interior deposits and not in the walls of the Chasma. Similar deposits are located on the floors of Valles Marineris and other chasmata and may be the sediment remnants of ancient lakes formed within these canyon systems.

Photo credit: NASA/JPL/University of Arizona

Charitum Montes Topographical Map

This color-coded overhead view is based on an ESA Mars Express HRSC digital terrain model of the region, from which the topography of the landscape can be derived. The color coding shows the very edge of the Charitum Montes mountain region at the top of the image, with the highest elevation, while the subtle pedestal craters that dot the image almost fade away with just a small amount of relief difference between the elevated ejecta and the surrounding area. Centered at around 53°S and 334°E, the image has a ground resolution of about 20 m per pixel. The image was taken during revolution 10778 on 18 June 2012.

Image credit: ESA/DLR/FU Berlin (G. Neukum)