Thursday, June 12, 2014

Update from Mars

For today's blog posting I decided to check in with the Mars rover.  First I looked at some of the raw images taken from the rover's mastcam.  All the images and information included in this post are from:

Since I took these images from the "raw image" section of the web page, there are no explanations.  The photo below shows scrapes that look similar to glacial scrapes, but of course are not.  Apparently the scrapes were caused by wind erosion.

Let's go for a walk!

Most of the pebbles below look water worn.

This animated blink comparison above shows five versions of observations that NASA's Curiosity rover made about one hour apart while Mercury was passing in front of the sun on June 3, 2014. Two sunspots, each about the diameter of Earth, also appear, moving much less than Mercury during the hour.

This is the first transit of the sun by a planet observed from any planet other than Earth, and also the first imaging of Mercury from Mars. Mercury fills only about one-sixth of one pixel as seen from such great distance, so the darkening does not have a distinct shape, but its position follows Mercury's expected path based on orbital calculations.

In the multimedia section of the webpage I acquired the photo below.

The rock is about 2 feet (about 60 centimeters) across, left-to-right in this image. The informal name for the target comes from Windjana Gorge in Western Australia.

This Martian rock is in a waypoint location called "the Kimberley," where sandstone outcrops with differing resistance to wind erosion result in a stair-step pattern of layers. Windjana is within what the team calls the area's "middle unit," because it is intermediate between rocks that form buttes in the area and lower-lying rocks that show a pattern of striations.

The above map shows the route driven by NASA's Curiosity Mars rover during March and April 2014 in its approach to and arrival at a waypoint called "the Kimberley," which rover team scientists chose in 2013 as the location for the mission's next major investigations.

The numbers along the route designate the sol number of reaching that point. These are the number of Martian days, or sols, since Curiosity's August 2012 landing. The arrival drive, on Sol 589, was on April 2, 2014. The drive entering the area of this map, on Sol 572, was on March 16, 2014.

The Kimberley (formerly called "KMS-9") was selected as a major waypoint for the mission because of the diversity of rock types distinguishable in orbital images, exposed close together at this location in a decipherable geological relationship to each other. The base image for this map is from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter. North is up. The 100-meter scale bar at lower left represents 328 feet.

The photo above shows more of the sedimentary rock.  This mosaic of images from the Mast Camera (Mastcam) instrument on NASA's Curiosity Mars rover shows a series of sedimentary deposits in the Glenelg area of Gale Crater, from a perspective in Yellowknife Bay looking toward west-northwest.

Curiosity's science team has estimated that the "Cumberland" rock that the rover drilled for a sample of the Sheepbed mudstone deposit (at lower left in this scene) has been exposed at the surface for only about 80 million years. The estimate is based on amounts of certain gases that accumulate in a rock when it is close enough to the surface to be bombarded by cosmic rays. An explanation for that unexpectedly young exposure age comes from improved understanding of how the layers are eroding to expose underlying layers. The explanation proposes that the mudstone is being exposed by abrasion by windblown sand. The role for wind is strongly suggested by the undercutting of the Sheepbed layer below the Gillespie Lake sandstone.

The pattern here suggests that the Yellowknife Bay outcrop is being exposed by wind-driven scarp retreat -- the sideways erosion of a vertical face.

Mastcam took the images for this mosaic during the 188th Martian day, or sol, of Curiosity's work on Mars (Feb. 14, 2013). The 100-centimeter scale bars are about 39 inches long. A rock ledge about 8 inches (20 centimeters) high at the bottom of the scene -- where the Gillespie Lake layer meets the Sheepbed layer -- is about 50 feet (about 15 meters) from the rover's location when the images were taken. The midfield escarpment called "Point Lake" is about 118 feet (36 meters) from the rover's location. The outcrop on the near horizon, marked with a white X, is about 43 feet (13 meters) higher in elevation than the Sheepbed-Gillespie contact and at a distance of about 780 feet (240 meters).

The photo above shows rock that contains elongated, light-colored crystals in a darker matrix. Some of the crystals are about 0.4 inch (1 centimeter) in size. This annotated version of the image has a superimposed scale bar of 5 centimeters (about 2 inches).

Based on composition information gathered from an array of ChemCam laser shots on Harrison, the elongated crystals are likely feldspars, and the matrix is pyroxene-dominated. This mineral association is typical of basaltic igneous rocks. The texture provides compelling evidence for igneous rocks at Gale Crater, where Curiosity is on a traverse to reach the lower slopes of Mount Sharp near the center of the crater. 

NASA/JPL-Caltech/Univ. of Arizona

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