Monday, October 15, 2012

Mars Rover Update

I'm sorry I didn't get a chance to post a blog update yesterday.  I went to the University of Michigan football game on Saturday with my sister, Diana, as well as my college friend, Steve.  It was a very wet and rainy day, but we dressed for it.  I'll post some pictures from Ann Arbor soon.  Then yesterday I spent with family and didn't have time to turn on my computer.  Considering how much time I've spent as of late working on the online rockhounding adventures, it was nice to not touch my computer for a couple of days.

In terms of family, I want to report that I found out I am going to be a grandmother for the first time.  My son and his wife, Jonathan and Jessica, have made the announcement that I've been waiting for!  I see a new museum helper in my future -- in a few years anyway.

For the rest of today's posting, I'll update everyone on the Mars Rover.

This map shows the path on Mars of NASA's Curiosity rover toward Glenelg, an area where three terrains of scientific interest converge. Arrows mark geological features encountered so far that led to the discovery of what appears to be an ancient Martian streambed. The first site, dubbed Goulburn, is an area where the thrusters from the rover's descent stage blasted away a layer of loose material, exposing bedrock underneath. Goulburn gave scientists a hint that water might have transported the pebbly sandstone material making up the outcrop. The second feature, a naturally exposed rock outcrop named Link, stood out to the science team for its embedded, rounded gravel pieces. Such rounded shapes are strong evidence of water transport. The final feature, another naturally exposed rock outcrop named Hottah, offered the most compelling evidence yet of an ancient stream, as it contains abundant rounded pebbles. The grain sizes are also an important part of the evidence for water: the rounded pebbles, which are up to 1.6 inches (4 centimeters) in size, are too large to have been transported by wind.

The white line in the second photo above shows the route traveled by Curiosity so far. The green line shows the planned route in the next few days.

This image shows where NASA's Curiosity rover aimed two different instruments to study a rock known as "Jake Matijevic."

This image was obtained by Curiosity's Mast Camera on Sept. 21, 2012 PDT (Sept. 22 UTC), or sol 46.

This image shows the topography, with shading added, around the area where NASA's Curiosity rover landed on Aug. 5 PDT (Aug. 6 EDT). Higher elevations are colored in red, with cooler colors indicating transitions down slope to lower elevations. The black oval indicates the targeted landing area for the rover known as the "landing ellipse," and the cross shows where the rover actually landed.

An alluvial fan, or fan-shaped deposit where debris spreads out down slope, has been highlighted in lighter colors for better viewing. On Earth, alluvial fans often are formed by water flowing down slope. New observations from Curiosity of rounded pebbles embedded with rocky outcrops provide concrete evidence that water did flow in this region on Mars, creating the alluvial fan. Water carrying the pebbly material is thought to have streamed down slope extending the alluvial fan, at least occasionally, to where the rover now sits studying its ancient history. Elevation data were obtained from stereo processing of images from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter.

This stereo image from the Mast Camera (Mastcam) on NASA's Mars rover Curiosity shows a rock outcrop called "Hottah," cited as evidence for vigorous flow of water in a long-ago Martian stream. The scene covers an area roughly 1 yard or meter across at the near edge.

Curiosity found evidence for an ancient, flowing stream on Mars at a few sites, including this outcrop named after Hottah Lake in Canada. It may look like a broken sidewalk, but this geological feature on Mars is actually exposed bedrock made up of smaller fragments cemented together, or what geologists call a sedimentary conglomerate. Scientists theorize that the bedrock was disrupted in the past, giving it the titled angle, most likely via impacts from meteorites.

The key evidence for the ancient stream comes from the size and rounded shape of the gravel in and around the bedrock. Hottah has pieces of gravel embedded in it, called clasts, up to a couple inches (few centimeters) in size and located within a matrix of sand-sized material. Some of the clasts are round in shape, leading the science team to conclude they were transported by a vigorous flow of water. The grains are too large to have been moved by wind. Erosion of the outcrop results in gravel clasts that protrude from the outcrop and ultimately fall onto the ground, creating the gravel pile at left.

Curiosity's Mastcam acquired component images of this scene on the 39th Martian day, or sol, of the mission (Sept. 14, 2012 PDT/Sept. 15 GMT).

This patch of windblown sand and dust downhill from a cluster of dark rocks is the "Rocknest" site, which has been selected as the likely location for first use of the scoop on the arm of NASA's Mars rover Curiosity. This view is a mosaic of images taken by the telephoto right-eye camera of the Mast Camera (Mastcam) during the 52nd Martian day, or sol, of the mission (Sept. 28, 2012), four sols before the rover arrived at Rocknest. The Rocknest patch is about 8 feet by 16 feet (1.5 meters by 5 meters).

This 360-degree scene shows the surroundings of the location where NASA Mars rover Curiosity arrived on the 59th Martian day, or sol, of the rover's mission on Mars (Oct. 5, 2012). It is a mosaic of images taken by Curiosity's Navigation Camera (Navcam) on sols 59 and 60.

Smooth surfaces of the windblown sand and dust of the "Rocknest" area, in the foreground, are what signaled from a distance that this might be an appropriate place to spend about three weeks collecting and using the mission's first few scoopfuls of soil. The rover scooped up its first sample on Sol 61 (Oct. 7, 2012).

South is at the center of this panorama, north at both ends. Mount Sharp is on the horizon in the southeast. The "Glenelg" area planned as the next destination lies to the east. Tracks that Curiosity's wheels made while driving toward Rocknest recede toward the west. For scale, Curiosity leaves parallel tracks about 9 feet (2.7 meters) apart.

This set of images compares the Link outcrop of rocks on Mars (left) with similar rocks seen on Earth (right). The image of Link, obtained by NASA's Curiosity rover, shows rounded gravel fragments, or clasts, up to a couple inches (few centimeters), within the rock outcrop. Erosion of the outcrop results in gravel clasts that fall onto the ground, creating the gravel pile at left. The outcrop characteristics are consistent with a sedimentary conglomerate, or a rock that was formed by the deposition of water and is composed of many smaller rounded rocks cemented together. A typical Earth example of sedimentary conglomerate formed of gravel fragments in a stream is shown on the right.

An annotated version of the image highlights a piece of gravel that is about 0.4 inches (1 centimeter) across. It was selected as an example of coarse size and rounded shape. Rounded grains (of any size) occur by abrasion in sediment transport, by wind or water, when the grains bounce against each other. Gravel fragments are too large to be transported by wind. At this size, scientists know the rounding occurred in water transport in a stream.

The name Link is derived from a significant rock formation in the Northwest Territories of Canada, where there is also a lake with the same name.

Image Credits: NASA/JPL-Caltech/UofA

1 comment: