Monday, September 1, 2014

Unusual Impact Crater in Promethei Terra


This feature has a strange appearance, as if the crater has feet with toes sticking out of two sides. Let’s try to explain this.

First, there was a highly oblique impact event, with the bolide (or meteorite) striking the ground while flying almost horizontally over the surface. Such oblique impacts tend to send ejecta in two directions to the sides of the bolide trajectory, rather than in all directions around the crater. However, there was ice near the surface, covered and protected by the ejecta, and the unprotected ice sublimated at some later time, so the ejecta now appears especially thick.

Also, there were layers of dust (maybe along with ice) deposited inside the crater. Or maybe something else happened, but likely involving the ice that comes and goes in the middle latitude regions of Mars.

Image credit: NASA/JPL/University of Arizona

Note: This crater is located in Promethei Terra. For more information, see PIA18774: Weird Crater.

Sunday, August 31, 2014

West Rim of Endeavour Crater


NASA's Mars Exploration Rover Opportunity captured this scene looking farther southward just after completing a southward drive, in reverse, during the 3,749th Martian day, or sol, of the rover's work on Mars (August 10, 2014).

The foreground of this view from the rover's mast-mounted navigation camera (Navcam) includes the top of the rover's low-gain antenna, at lower right, and the rear portion of the rover's deck, with the sundial of a camera calibration target. For scale, the largest of the sundial's concentric rings has an outer diameter of 3.15 inches (8 centimeters).

The ground beyond the rover includes some windblown lines of sand. At the horizon is part of the crest line of the west ridge of Endeavour Crater. The Sol 3749 drive covered 338 feet (103 meters) along the outer slope of the crater rim. A map of the area with the Sol 3749 endpoint marked is available online at http://mars.nasa.gov/mer/mission/tm-opportunity/opportunity-sol3751.html.

Image credit: NASA/JPL-Caltech

Note: For more information, see Memory Reformat Planned for Opportunity Mars Rover.

Saturday, August 30, 2014

Slope Streaks in Terra Sabaea


This VIS image shows dark slope streaks in an unnamed crater in Terra Sabaea. These features are believed to be formed by material moving downslope, removing the dust cover and revealing darker material.

Orbit Number: 56045 Latitude: 11.9172 Longitude: 46.5184 Instrument: VIS Captured: 2014-08-02 12:09

Photo credit: NASA/JPL-Caltech/Arizona State University

New Impact Crater in Elysium Planitia


InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) is a NASA Discovery Program mission that will place a single geophysical lander on Mars in September 2016 to study its deep interior.

InSight needs seismic signals, and one sure way to get them is from the impact of bolides onto Mars. InSight can detect large impacts that are far from the lander and smaller impacts that are closer.

This recent HiRISE image, acquired to certify a landing site for the mission, shows a distinctive crater with a very sharp rim and ejecta that is darker and bluer than almost all of this dust-covered region. This must be a very recent impact because there hasn't been sufficient time for atmospheric dust to settle over this spot and re-brighten the surface.

In fact, previous images suggest it formed between 2008 and 2012. This illustrates the type of feature that orbiting cameras will search for during the InSight mission, to attempt to correlate seismic signals to the point of origin.

This is a stereo pair with ESP_037684_1845.

Image credit: NASA/JPL/University of Arizona

Note: For more information, see PIA18776: A New Impact Crater Near NASA's InSight Landing Region.

Friday, August 29, 2014

Ares Vallis


This VIS image shows a portion of Ares Vallis.

Orbit Number: 56035 Latitude: 9.15576 Longitude: 335.227 Instrument: VIS Captured: 2014-08-01 16:23

Photo credit: NASA/JPL-Caltech/Arizona State University

Ice-Rich Mantling Deposits East of Reull Vallis


The mid-latitudes of Mars (approximately 30 to 60 degrees, north and south) are covered in ice-rich mantling deposits in varying states of degradation.

This mantle is thought to be deposited as snow during periods when the angle of the tilt of Mars’ rotational axis—called obliquity—is much higher, which last happened around 10 million years ago.

This HiRISE image shows terrain typical of these mantling deposits in the Southern Hemisphere, east of Reull Vallis. The pitted texture suggests that ice is sublimating out from the deposits as the region is warmed under current lower obliquity conditions.

Image credit: NASA/JPL/University of Arizona

Note: For more information, see PIA18775: Mantled Terrain in the Southern Mid-Latitudes.

Thursday, August 28, 2014

Ravi Vallis


This VIS image shows a portion of Ravi Vallis.

Orbit Number: 56073 Latitude: 0.182473 Longitude: 320.807 Instrument: VIS Captured: 2014-08-04 19:24

Photo credit: NASA/JPL-Caltech/Arizona State University

Wednesday, August 27, 2014

Landslide Deposit Within a Doublet Crater in Tyrrhena Terra


Today's VIS image shows a landslide deposit within a complex crater (note the ejecta to the top and bottom of the image). There is a smaller complex crater on the ejecta to the north of the larger crater. This "doublet" crater with the linear interior rim is formed when two impactors hit the surface simultaneously. The impactors are initially all part of the same meteor. The larger crater may have formed from multiple impactors.

Orbit Number: 56056 Latitude: -19.0844 Longitude: 93.6361 Instrument: VIS Captured: 2014-08-03 09:43

Photo credit: NASA/JPL-Caltech/Arizona State University

Tuesday, August 26, 2014

Dunes in Olympia Undae


The dunes in this VIS image are part of Olympia Undae.

Orbit Number: 55336 Latitude: 79.6049 Longitude: 159.723 Instrument: VIS Captured: 2014-06-05 04:13

Photo credit: NASA/JPL-Caltech/Arizona State University

Saturday, August 23, 2014

Dunes and Gullies in a Vastitas Borealis Crater


This unnamed crater has gullies along the inner rim and dunes on the crater floor.

Orbit Number: 55306 Latitude: 63.6919 Longitude: 292.265 Instrument: VIS Captured: 2014-06-02 17:00

Photo credit: NASA/JPL-Caltech/Arizona State University

Note: This impact crater is located in Vastitas Borealis.

Bonanza King Fails "Start Hole" Test


This image from the front Hazard Avoidance Camera (Hazcam) on NASA's Curiosity Mars rover shows the rover's drill in place during a test of whether the rock beneath it, "Bonanza King," would be an acceptable target for drilling to collect a sample. Subsequent analysis showed that the rock budged during the procedure and did not pass the test.

The image was taken during the 724th Martian day, or sol, of Curiosity's work on Mars (August 19, 2014, PDT). The rover was doing a mini-drill procedure, which is part of evaluating the target in advance of full-depth, sample-collection drilling. One step in the procedure, called "start hole," uses the hammering action of the percussive drill to create a small indentation in the rock. During this part of the test, the rock moved slightly, the rover sensed that instability in the target, and protective software properly halted the procedure. After analysis of the target's instability, the rover team decided on August 21, 2014, to drive Curiosity away from this Bonanza King site and resume the trek toward long-term destinations on the slopes of Mount Sharp and perhaps a shorter-term science destination at an outcrop called "Pahrump Hills."

The site in this southward-looking image is at the northeastern end of sandy-floored "Hidden Valley." The largest of the individual flat rocks in the foreground are a few inches (several centimeters) across. For scale, the rover's left front wheel, visible at left, is 20 inches (0.5 meter) in diameter.

A map showing Hidden Valley is at http://photojournal.jpl.nasa.gov/catalog/PIA18408.

Image credit: NASA/JPL-Caltech

Note: For more information, see Mars Rover Team Chooses Not to Drill 'Bonanza King'.

Friday, August 22, 2014

Galaxias Fossae


The channel-like features at the bottom of this VIS image are part of Galaxias Fossae.

Orbit Number: 55286 Latitude: 38.6943 Longitude: 142.826 Instrument: VIS Captured: 2014-06-01 01:41

Photo credit: NASA/JPL-Caltech/Arizona State University

Impact Craters in Hellas Planitia


Scarring the southern highlands of Mars is one of the Solar System’s largest impact basins: Hellas, with a diameter of 2300 km and a depth of over 7 km.

Hellas is thought to have formed between 3.8 and 4.1 billion years ago, when a large asteroid hit the surface of Mars. Since its formation, Hellas has been subject to modification by the action of wind, ice, water and volcanic activity.

Impact craters have also since pock-marked this vast basin floor, two of which are the focus of this image, taken by the High Resolution Stereo Camera on ESA’s Mars Express on 17 December 2013. The ground resolution is about 15 meters per pixel.

These craters lie in the deepest, western portion of Hellas, and such a clear view is unusual because dust clouds typically obscure the basin floor. Indeed, this region seems to be covered by a thick blanket of dust.

The larger of the two craters is about 25 km across. A flow of material appears to have been transported from the top left of the scene and into the crater. Zooming in to the smooth mound and the area immediately around it reveals interesting textures that likely resulted from this flow.

Flow features are also seen outside of the craters, and in particular, at the center left of the image near the top of the frame. Material also seems to have cascaded from the larger crater’s rim and into a neighboring smaller crater, at the far left of the image.

The morphology of many features in the Hellas Basin and its surroundings strongly suggests the presence of ice and glaciers.

For example, in the foreground and around the crater rim, polygons of patterned ground are visible which indicates the presence of water – this pattern occurs when fine grained and porous wet soil freezes.

Indeed, in the deepest parts of the basin, the atmospheric pressure is about 89% higher than at the surface, which may even offer conditions suitable for water. Radar images from NASA’s Mars Reconnaissance Orbiter suggest that some craters in Hellas might contain water-ice glaciers several hundred meters thick, buried under layers of dust.

See more images from this region at the DLR website and in this previous ESA release.

Image credit: ESA/DLR/FU Berlin

Thursday, August 21, 2014

Marte Vallis


The streamlined islands in this VIS image are part of Marte Vallis.

Orbit Number: 55247 Latitude: 18.925 Longitude: 184.18 Instrument: VIS Captured: 2014-05-28 20:46

Photo credit: NASA/JPL-Caltech/Arizona State University

Brushed-Off Bonanza King


NASA's Curiosity Mars rover used the Dust Removal Tool on its robotic arm to brush aside reddish, more-oxidized dust, revealing a gray patch of less-oxidized rock material at a target called "Bonanza King," visible in this image from the rover's Mast Camera (Mastcam).

The Mastcam's right-eye camera, which has a telephoto lens, took this image on August 17, 2014, during the 722nd Martian day, or sol, of Curiosity's work on Mars. The brushing activity occurred earlier the same sol. The rover team is evaluating Bonanza King as a possible drilling target. The mission has previously drilled into three target rocks to collect sample powder for analysis by the rover's onboard laboratory instruments.

The brushed area is about 2.5 inches (6 centimeters) across. It reveals thin, white, cross-cutting veins. They might be sulfate salts or another type of mineral that precipitated out of solution and filled fractures in the rock. These thin veins might be related to wider light-toned veins and features in the surrounding rock.

To the left of the brushed patch is a row of five smaller and less conspicuous spots where dust has been partially removed. These are at points on Bonanza King that were zapped with the laser of Curiosity's Chemistry and Camera (ChemCam) instrument on Sol 719 (August 14, 2014). Color balancing and contrast adjustment have been used in preparing this image from Mastcam's raw image of this exposure.

Drilling a shallow test hole is the next step in evaluating this location for full-depth drilling to collect a sample. The shallow "mini-drill" test enables assessing whether powder from the drilling tends to clump.

Bonanza King is on a ramp rising from the northeastern end of "Hidden Valley," between Curiosity's August 2012 landing site in Gale Crater and destinations on Mount Sharp within the crater.

Image credit: NASA/JPL-Caltech/MSSS