Tuesday, April 22, 2014

Crater Gullies in Tyrrhena Terra Northeast of Briault Crater

Although gullies are most common in the middle latitudes of Mars, they are also found in equatorial regions. This image shows a 3-kilometer-wide impact crater with gullies all along the steep inner slopes.

An enhanced-color cutout better distinguishes the gully deposits from the surrounding boulder fields. These slopes are very steep, so a fluid like water is not required to explain gully formation.

Photo credit: NASA/JPL/University of Arizona

Note: This impact crater is located in Tyrrhena Terra to the northeast of Briault Crater.

Monday, April 21, 2014

Slope Streak in Melas Chasma

HiRISE has been monitoring the recurring slope lineae (RSL) over the mid-latitude and equatorial regions of Mars. One of these sites is a crater on the floor of Melas Chasma; and an animation shows how the RSL follow the sun, changing slope aspect with the seasons.

In one of our most recent images of this site, there was a surprise: a new dark streak just down slope from the RSL. This new streak is about 18 meters wide, whereas most RSL flows (see closer to the crater rim) are less than 5 meters wide. Closer inspection shows that the dark streak corresponds to a topographic slump, similar to several others visible on this slope.

This is one of the largest topographic changes we've seen in equatorial regions of Mars. We are continuing to monitor this location to see if this streak fades in the same manner as RSL, and to understand its relationship, if any, to the RSL activity. If the RSL are due to seeping water, then saturation of a layer downslope could destabilize the slope and lead to such slumps. We continue to be surprised by new discoveries from the Mars Reconnaissance Orbiter after 8 years in orbit.

Photo credit: NASA/JPL/University of Arizona

Sunday, April 20, 2014

Red Bedrock in an Impact Crater Northeast of Hellas Planitia

This image covers a 26-kilometer-wide impact crater northeast of the Hellas impact basin. The crater exposes large blocks of bedrock (called "megabreccia") in both the central uplift and in the walls of the crater.

The enhanced-color subimage from the wall shows a large, approximately 250-meter-wide reddish block, although actually "red" in the infrared-shifted color of HiRISE. These blocks could be ejecta from the ancient Hellas impact or other large impacts from billions of years ago.

Image credit: NASA/JPL/University of Arizona

Saturday, April 19, 2014

Opportunity Self-Portrait, March 2014

This self-portrait of NASA's Mars Exploration Rover Opportunity shows effects of wind events that had cleaned much of the accumulated dust off the rover's solar panels. It combines multiple frames taken by Opportunity's panoramic camera (Pancam) through three different color filters from March 22 to March 24, 2014, the 3,611th through 3,613th Martian days, or sols, of Opportunity's work on Mars.

For a comparison to what the rover looked like before a series of cleaning events in March, see a similar self-portrait taken January 3 through January 6, 2014, at PIA17759.

With the cleaner arrays and lengthening winter days, Opportunity's solar arrays were generating more than 620 watt-hours per day in mid-April 2014, compared to less than 375 watt-hours per day in January 2014.

This image is presented as a vertical projection in approximately true color. The mast on which the Pancam is mounted does not appear in the image, though its shadow does.

Image credit: NASA/JPL-Caltech/Cornell University/Arizona State University

Note: For more information, see PIA18080: Self-Portrait by Freshly Cleaned Opportunity Mars Rover, False Color and NASA Rover Opportunity's Selfie Shows Clean Machine.

Friday, April 18, 2014

Mount Remarkable At The Kimberley

NASA's Curiosity Mars rover used its Navigation Camera (Navcam) to record this scene of a butte called "Mount Remarkable" and surrounding outcrops at a waypoint called "the Kimberley" inside Gale Crater. The butte stands about 16 feet (5 meters) high. Its informal name comes from a mountain and national park in Australia. The rover team plans to drive Curiosity to the flatter outcrop at the base of the Martian Mount Remarkable for a close-up inspection that might include drilling into the rock.

This mosaic view combines multiple images taken during the 597th Martian day, or sol, of Curiosity's work on Mars (April 11, 2014). That same day, the rover had driven 90.2 feet (27.5 meters) and NASA's Mars Reconnaissance Orbiter observed Curiosity at the location from which the rover captured this panorama. The resulting image from the orbiter's High Resolution Imaging Science Experiment (HiRISE) camera is online at PIA18081. A map showing Curiosity's route from the August 2012 landing site to the Kimberley is online at http://mars.jpl.nasa.gov/msl/multimedia/images/?ImageID=6153.

Curiosity's science team chose the Kimberley in 2013 as a waypoint for science investigations along the route to the mission's long-term destinations on the lower slopes of Mount Sharp, in the middle of Gale Crater. This waypoint offers set of outcrops of different types of rock layers exposed close together, so that their relationship to each other can be studied. The team refers to the rock layer surrounding the base of Mount Remarkable as the "middle unit" because it is intermediate in location between rocks that form buttes in the area and lower-lying rocks that show a pattern of striations.

Image credit: NASA/JPL-Caltech

Note: For more information, see PIA18084: Stereo View of 'Mount Remarkable' and Surrounding Outcrops at Mars Rover's Waypoint.

Thursday, April 17, 2014

Labeatis Fossae

This complex graben is part of Labeatis Fossae.

Orbit Number: 54045 Latitude: 30.2428 Longitude: 280.922 Instrument: VIS Captured: 2014-02-18 22:36

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

Curisosity at The Kimberley

NASA's Curiosity Mars rover and tracks from its driving are visible in this view from orbit, acquired on April 11, 2014, by the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter.

The rover is near the largest butte in the lower left quadrant of the image, at about a two o'clock position relative to the butte. It appears bright blue in the exaggerated color of this image.

The multi-layered location filling much of the left half of this image is called "the Kimberley." Curiosity's science team chose it, based on other HiRISE images, as a potential gold mine for the rover mission. Black gold, that is, as organic material that, if found at the Kimberley could be a biomarker (sign of past life) -- the holy grail of Mars exploration.

In December 2013, at the fall meeting of the American Geophysical Union in San Francisco, Curiosity Project Scientist John Grotzinger talked about what the mission had learned that year in a location called "Yellowknife Bay," and why the team was planning to stop Curiosity and drill again at the Kimberley. Mudstones that Curiosity drilled and analyzed at Yellowknife Bay had been exposed at the Martian surface for less than 100 million years, which is relatively recent, geologically speaking. Scientists deduced that this was due to erosion of overlying layers by the wind, and that even younger exposure ages should be possible closer to an eroding scarp. This matters because Mars doesn't have a magnetosphere and thick atmosphere like Earth's, which protect us from energetic particles from space that break down organic material. Thus, rocks that have been near the surface of Mars longer (on geological time scales) are less likely to contain complex organic material. Complex organic material might be the remains of past life, or at least inform us about past habitability. Habitability is the potential to support life, whether or not life ever actually existed there.

By late 2013, Curiosity had left Yellowknife Bay and wasn't going to turn around, but similar scarps lay ahead, on the way to the mission's long-term destinations on lower slopes of Mount Sharp (also known as Aeolis Mons). The team had already chosen Curiosity's next major target: the Kimberley. This location, where Curiosity arrived in early April 2014, has what appear to be geologically young scarps. This HiRISE image shows the rover close to one of the scarps.

Curiosity entered the area included in this image on March 12, along the tracks visible near the upper left corner. The distance between parallel wheel tracks is about 9 feet (2.7 meters). The area included in the image is about 1,200 feet (about 365 meters) wide. This view is an enhanced-color product from HiRISE observation ESP_036128_1755, available at the HiRISE website at http://uahirise.org/releases/msl-kimberley.php. The exaggerated color, to make differences in Mars surface materials more apparent, makes Curiosity appear bluer than the rover really looks. A stereo view combining information from this observation with topography derived from earlier HiRISE observations, for a three-dimensional appearance, is at PIA18082.

A rover's-eye view taken by Curiosity from the location where the rover is seen in this image is online at PIA18083.

Image credit: NASA/JPL-Caltech/University of Arizona

Note: For more information, see NASA Mars Orbiter Spies Rover Near Martian Butte and Curiosity Ready to Drill for Gold at the Kimberley.

Wednesday, April 16, 2014

Streamlined Island in Lobo Vallis

Today's VIS image shows a streamlined island in a broad channel in Chryse Planitia. The channel is part of the outflow region of Lobo Vallis, a northern branch of Kasei Valles.

Orbit Number: 54044 Latitude: 31.689 Longitude: 309.953 Instrument: VIS Captured: 2014-02-18 20:37

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

Tuesday, April 15, 2014

Buvinda Vallis

Today's VIS image shows part of Buvinda Vallis, located just outside the northeastern flank of Hecates Tholus.

Orbit Number: 54037 Latitude: 33.2014 Longitude: 151.998 Instrument: VIS Captured: 2014-02-18 06:47

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

Two-Color Dunes in Meridiani Terra

Why are these dunes different colors? Sand on Mars is typically dark in tone, as it commonly derived from volcanic rocks like lava flows. In HiRISE enhanced color, which operates in long infrared wavelengths (beyond what the human eye can detect), surfaces like these dune crests are dark blue to purple. Sand comes in sizes that are ideal for surface transport by the wind, where sand “hops” along forming bedforms, like these dunes after large amounts of time.

The lighter toned “tan” or “reddish” surfaces are indeed composed of a different material, but not as sand sized particle that makes up the bulk of these dunes. Rather, the light-toned smooth surfaces that dominate the lower, flatter areas of the dunes are a thin coating of global dust. Dust on Mars is composed of a variety of materials, including oxidized iron, like rust.

For a given wind gust, speeds are not constant at different heights. Rather, wind speeds are greater with height above the ground and wind energy drops to nearly zero at the surface. Dust persists on flatter dune areas, because wind energy there has not been sufficient to remove it, whereas “dust free” higher-lying dune crests are subject to more intense winds, which ultimately conspire to make the appearance of two-color dunes.

Photo credit: NASA/JPL/University of Arizona

Monday, April 14, 2014

Terraced Crater Northwest of Alba Mons

This image shows the western rim of a well-preserved 8.5-kilometer (about 5 miles) diameter impact crater.

The wall features a slumped terrace that extends all the way around the crater diameter (the adjacent image show the rest of the terrace). This slumped terrace, a result of the crater formation process, gives the crater a concentric ringed appearance.

Terraces are an expected feature in Martian craters of this size or larger, as the material strength of the surface is overcome by the force of all-of-the-sudden-missing mass. Blocks of rock slump down the steep crater walls and slide inward (by contrast, terraces in smaller craters are often the product of an impact of an object into a surface with layers of differing material strength).

Photo credit: NASA/JPL/University of Arizona

Note: This impact crater is located to the northwest of Alba Mons and its lava flows.

Sunday, April 13, 2014

Butte Remaining at Possible Fissure Vent South of Ascraeus Mons

What is this strange-looking feature? HiRISE scientists first noticed it in images from the Context Camera and acquired this picture to investigate more closely.

The feature indeed does look like a heart. It is located south of Ascraeus Mons, which is a large volcano within the Tharsis volcanic plateau, so it is extremely likely that this feature was formed by a volcanic process. The feature rises above the surrounding terrain and we can see concentric ridges on its top. Perhaps this feature is an ancient vent structure (an opening in the ground from which volcanic lava emerges) that has been more resistant to erosion than the surrounding area, so that it resembles “inverted” terrains.

Topographic inversion or inverted terrain often occurs when low areas of a landscape become filled with lava or sediments that harden into materials which are more resistant to erosion than the materials that surround them. Differential erosion then removes the less resistant surrounding material, leaving behind the younger resistant material which may then appear as a ridge where previously there was a valley, or in our case, a butte, where there was once a pit or depression.

Additional imaging of the feature to create a stereo and a digital terrain model may help in further assessing the structure by making accurate measurement of its height and the steepness of its slopes.

Photo credit: NASA/JPL/University of Arizona