jeudi 16 mars 2017

MRO: A Closer Look at Holden Crater & Bedrock Outcrops in Kaiser Crater












NASA - Mars Reconnaissance Orbiter (MRO) logo.

March 15, 2017

A Closer Look at Holden Crater


Holden Crater in southern Margaritifer Terra displays a series of finely layered deposits on its floor (white and light purple in an enhanced color image). The layered deposits are especially well exposed in the southwestern section of the crater where erosion by water flowing through a breach in the crater rim created spectacular outcrops.

In this location, the deposits appear beneath a cap of alluvial fan materials (tan to brown in this image). Within the deposits, individual layers are nearly flat-lying and can be traced for hundreds of meters to kilometers. Information from the CRISM instrument on the Mars Reconnaissance Orbiter suggests that at least some of these beds contain clays.

By contrast, the beds in the overlying alluvial fan are less continuous and dip in varying directions, showing less evidence for clays. Collectively, the characteristics of the finely bedded deposits suggest they may have been deposited into a lake on the crater floor, perhaps fed by runoff related to formation of the overlying fans.

The map is projected here at a scale of 25 centimeters (9.8 inches) per pixel. [The original image scale is 25.9 centimeters (10.2 inches) per pixel (with 1 x 1 binning); objects on the order of 78 centimeters (30.7 inches) across are resolved.] North is up.

Bedrock Outcrops in Kaiser Crater


This enhanced-color image shows a patch of well-exposed bedrock on the floor of Kaiser Crater.

The wind has stripped off the overlying soil, and created grooves and scallops in the bedrock. The narrow linear ridges are fractures that have been indurated, probably by precipitation of cementing minerals from groundwater flow. The rippled dark blue patches consist of sand.

The map is projected here at a scale of 25 centimeters (9.8 inches) per pixel. [The original image scale is 25.3 centimeters (9.9 inches) per pixel (with 1 x 1 binning); objects on the order of 76 centimeters (29.9 inches) across are resolved.] North is up.

This is a stereo pair with http://www.uahirise.org/ESP_012516_1330

Mars Reconnaissance Orbiter (MRO)

The University of Arizona, Tucson, operates HiRISE, which was built by Ball Aerospace & Technologies Corp., Boulder, Colo. NASA's Jet Propulsion Laboratory, a division of Caltech in Pasadena, California, manages the Mars Reconnaissance Orbiter Project for NASA's Science Mission Directorate, Washington.

Mars Reconnaissance Orbiter (MRO): http://www.nasa.gov/mission_pages/MRO/main/index.html

Images, Text, Credits: NASA/Tony Greicius/JPL-Caltech/Univ. of Arizona.

Greetings, Orbiter.ch

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