Spirit Mars Rover Mission to the Columbia Hills, Gusev Crater: Mission overview and selected results from the Cumberland Ridge to Home Plate

Abstract

[1] This paper summarizes the Spirit rover operations in the Columbia Hills of Gusev Crater from sols 513 to 1476 and provides an overview of selected findings that focus on synergistic use of the Athena Payload and comparisons to orbital data. Results include discovery of outcrops (Voltaire) on Husband Hill that are interpreted to be altered impact melt deposits that incorporated local materials during emplacement. Evidence for extensive volcanic activity and aqueous alteration in the Inner Basin is also detailed, including discovery and characterization of accretionary lapilli and formation of sulfate, silica, and hematite-rich deposits. Use of Spirit's data to understand the range of spectral signatures observed over the Columbia Hills by the Mars Reconnaissance Orbiter's Compact Reconnaissance Imaging Spectrometer (CRISM) hyperspectral imager (0.4-4 mm) is summarized. We show that CRISM spectra are controlled by the proportion of ferric-rich dust to ferrous-bearing igneous minerals exposed in ripples and other windblown deposits. The evidence for aqueous alteration derived from Spirit's data is associated with outcrops that are too small to be detected from orbital observations or with materials exposed from the shallow subsurface during rover activities. Although orbital observations show many other locations on Mars with evidence for minerals formed or altered in an aqueous environment, Spirit's data imply that the older crust of Mars has been altered even more extensively than evident from orbital data. This result greatly increases the potential that the surface or shallow subsurface was once a habitable regime.

Microbialites at Gusev Crater, Mars.

“…From the landing site to "Pot of Gold" site (on sol 200 about), extensive/destroyed volcanic outcroppings, often covered by weathering coatings and/or floating on eolic sands, as crater ejecta were found. The Rover then reached the inner basin of Columbia Hills, the images showed here layered sequences, containing sulfate and other soluble elements, due to ancient large process of aqueous alteration [1][2][3]. At Home Plate, where are the most evident geologic feature investigated in the Inner Basin, these layered sequences appeared formed by erosion of basaltic rocks and pyroclastic rocks, deposited as alluvial fans and/or as eolian sand sheets [4][5][6][7].…”

Spectral, mineralogical, and geochemical variations across Home Plate, Gusev Crater, Mars indicate high and low temperature alteration

“…2B) scarps, several targets were selected along 1-2 m stratigraphic sections. Elsewhere, Spirit examined the upper surface of Home Plate (Texas Chili, Pecan Pie, and Chanute; Arvidson et al, 2008).…”

“…But over the last three of its five years on Mars, Spirit has completed a circumnavigation of Home Plate ( Fig. 1; Arvidson et al, 2008), an~80 m-diameter platform of basaltic pyroclastic layered deposits that were variably reworked by eolian processes ( Fig. 2; Squyres et al, 2007).…”

Lassen Volcanic Fumaroles and Hot Springs: Analog for Mars

“…Ruff et al (2011) argue that Gusev silica is not consistent with acid-sulfate fumarole leaching but rather with precipitation of a Si-rich sinter from near-neutral fluids. The extent of the Gusev alteration products is unknown since most soils were trenched from the sub-surface by Spirit's wheel and have not been detected remotely; hydrothermal deposits may thus be more widespread than orbital data would indicate (Arvidson et al, 2008). The interpretation of these deposits depends on our ability to distinguish between the products of low and high-T alteration under varied aqueous and fumarolic conditions, which can be addressed in part by studying analog environments on Earth.…”