Overview of the Microscopic Imager Investigation during Spirit's first 450 sols in Gusev crater

Abstract

[1] The Microscopic Imager (MI) on the Mars Exploration Rover Spirit has returned images of Mars with higher resolution than any previous camera system, allowing detailed petrographic and sedimentological studies of the rocks and soils at the Gusev landing site. Designed to simulate a geologist's hand lens, the MI is mounted on Spirit's instrument arm and can resolve objects 0.1 mm in size or larger. This paper provides an overview of MI operations, data calibration, processing, and analysis of MI data returned during the first 450 sols (Mars days) of the Spirit landed mission. The primary goal of this paper is to facilitate further analyses of MI data by summarizing the methods used to acquire and process the data, the radiometric and geometric accuracy of MI data products, and the availability of archival products. In addition, scientific results of the MI investigation are summarized. MI observations show that poorly sorted soils are common in Gusev crater, although aeolian bedforms have well-sorted coarse sand grains on their surfaces. Abraded surfaces of plains rocks show igneous textures, light-toned veins or fracture-filling minerals, and discrete coatings. The rocks in the Columbia Hills have a wide variety of granular textures, consistent with volcaniclastic or impact origins. Case hardening and submillimeter veins observed in the rocks as well as soil crusts and cemented clods imply episodic subsurface aqueous fluid movement, which has altered multiple geologic units in the Columbia Hills. The MI also monitored Spirit's solar panels and the magnets on the rover's deck.

Aeolian bedforms, yardangs, and indurated surfaces in the Tharsis Montes as seen by the HiRISE Camera: Evidence for dust aggregates

“…In situ observations of martian dust show that dust aggregates are common on the surface. Microscopic Imager data from the MER Spirit rover show dust clumps several hundred microns in diameter (Herkenhoff et al, 2004(Herkenhoff et al, , 2006(Herkenhoff et al, , 2008Sullivan et al, 2008), equivalent to the size proposed here that is needed to participate in saltation. The aggregates are easily crushed (Herkenhoff et al, 2008), indicating a low strength and density.…”

“…The aggregates become suspended again in high wind events, with some broken back down into smaller particles. However, a certain fraction will continue to grow over time, eventually reaching a size, as seen at the MER landing sites (Herkenhoff et al, 2004(Herkenhoff et al, , 2006Sullivan et al, 2008), of a few hundred microns. Subsequent winds above threshold will saltate, rather than suspend, these materials, forming bedforms.…”

Ancient Aqueous Environments at Endeavour Crater, Mars

“…S-7 and S-8). The MI focal sections were used to synthesize a stereo anaglyph using the technique described in (51). The smooth, somewhat pitted nature of the veneer surface is evident standing above the underlying bright layer.…”

Image analysis algorithm for detection and measurement of Martian sand grains

“…Martian images are corrected (Herkenhoff et al 2006;Edgett et al 2012) using additional calibrating images as flat field, dark and bias frames. Such processing improves image quality, however, it does not remove uneven illumination or background noise.…”