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The Spirit Of Soil Science Gets Close Up To The "Serpent"
NASA's Mars Exploration Rover Spirit took this pair of microscopic imager pictures of the drift dubbed "Serpent" on Spirit's 73rd martian day on Mars after successfully digging into the side of the drift. The upper image captures a transition part of the drift where lighter, undisturbed material meets disturbed, darker material. The microscopic view of the undisturbed material reveals sphere-like grains with diameters between one and two millimeters (.04 and .08 inches), which are similar to the grains Spirit observed in other drift areas near Spirit's landing site, Gusev Crater. These larger grains form a single layer or crust on the surface of the drift and are covered in a fine layer of martian dust. The lower image is the first-ever microscopic look inside a drift. It captures only the scuffed interior of the Serpent drift and is dominated by larger pea-shaped particles. These grains are not natural to the inside the drift, but are crust particles that have tumbled into the scuffed area as a result of the digging. These grains lost their dust cover in the process of falling into the scuff, giving scientists clues about the strength - or lack of strength - of the bond between the dust and sand particles. Most interesting to scientists are the fine grains making up the interior of Serpent drift. The grains of sand found within drifts or dunes on Earth are usually about 200 micrometers (.008 inches) in diameter -- much like sand on a beach. On Earth, dunes are formed when sand particles of this size are bounced across a surface by wind and collect together as drifts. Smaller particles, like the ones making up Serpent drift, would not necessarily collect into a dune on Earth, but would more likely be distributed across the surface like dust. The fine grains making up the interior of Serpent drift are no larger than 50 or 60 micrometers (.002 inches) and can be compared to silt on Earth. How did this very fine material managed to accumulate into a drift? Earth-based tests that simulate the wind speed and atmospheric density of Mars have found it difficult to reproduce dunes with grain particles as small as those found in the Serpent drift. However, Earth-based tests cannot duplicate the gravity of Mars, which is one-third that of the gravity on Earth. This environmental factor is a likely contributor to the diminutive material making up Serpent drift. Before capturing of the close-ups began, Spirit acquired miniature thermal emission spectrometer inertia measurements on a disturbed area of soil. It also captured panoramic camera images of the scuffed area, dubbed "Bear Paw," the wheel that did the digging, and a nearby rock target named "White Elephant." The microscopic imager work began at 11:00 am Mars Local Solar Time and was targeted at four points within the scuffed area on Serpent. The targets were given the bear-type names of Polar, Spectacled, Kodiak and Panda. For each target, seven microscopic images were taken to assure proper focus. At the Spectacled and Kodiak targets, a microscopic image with the filter in place was also taken for pseudo-color. Then the Moessbauer was placed on Panda and started an overnight integration. The arm activities were completed by about noon Mars Local Solar time, and were followed by the second thermal inertia measurement on the disturbed soil. The rover took a siesta until 1:00 p.m. Mars Local Solar time, and then woke up for a series of mini thermal emission spectrometer observations on the rocks named "White Elephant," "Fruitcake," and "Dihedral." Then the third and last thermal inertia measurement was taken on the disturbed soil. Spirit took another quick nap in the afternoon, and then completed sky measurements with the mini thermal emission spectrometer and panoramic camera. Sol 74 included a tool change to the alpha particle X-ray spectrometer and the beginning of an integration on the drift target named Panda. Related Links Mars Rovers at JPL Mars Rovers at Cornell SpaceDaily Search SpaceDaily Subscribe To SpaceDaily Express 
Mineral In Mars 'Berries' Adds To Water Story
Pasadena (JPL) Mar 18, 2004A major ingredient in small mineral spheres analyzed by NASA's Mars Exploration Rover Opportunity furthers understanding of past water at Opportunity's landing site and points to a way of determining whether the vast plains surrounding the site also have a wet history.
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