Search results for "mars"
showing 10 items of 384 documents
Search for magnetic minerals in Martian rocks: Overview of the Rock Abrasion Tool (RAT) magnet investigation on Spirit and Opportunity
2008
[1] The Rock Abrasion Tool (RAT) on board the Mars Exploration Rovers (MER) is a grinding tool designed to remove dust coatings and/or weathering rinds from rocks and expose fresh rock material. Four magnets of different strengths that are built into the structure of the RAT have been attracting substantial amounts of magnetic material during RAT activities from rocks throughout both rover missions. The RAT magnet experiment as performed on Spirit demonstrates the presence of a strongly ferrimagnetic phase in Gusev crater rocks, which based on Mossbauer and visible/near-infrared reflectance spectra is interpreted as magnetite. The amount of abraded rock material adhering to the magnets vari…
Field reconnaissance geologic mapping of the Columbia Hills, Mars, based on Mars Exploration Rover Spirit and MRO HiRISE observations
2011
Chemical, mineralogic, and lithologic ground truth was acquired for the first time on Mars in terrain units mapped using orbital Mars Reconnaissance Orbiter's High Resolution Imaging Science Experiment (MRO HiRISE) image data. Examination of several dozen outcrops shows that Mars is geologically complex at meter length scales, the record of its geologic history is well exposed, stratigraphic units may be identified and correlated across significant areas on the ground, and outcrops and geologic relationships between materials may be analyzed with techniques commonly employed in terrestrial field geology. Despite their burial during the course of Martian geologic time by widespread epiclasti…
The new Athena alpha particle X-ray spectrometer for the Mars Exploration Rovers
2003
[1] The new alpha particle X-ray spectrometer (APXS) is part of the Athena payload of the two Mars Exploration Rovers (MER). The APXS sensor head is attached to the turret of the instrument deployment device (IDD) of the rover. The APXS is a very light-weight instrument for determining the major and minor elemental composition of Martian soils, rocks, and other geological materials at the MER landing sites. The sensor head has simply to be docked by the IDD on the surface of the selected sample. X-ray radiation, excited by alpha particles and X rays of the radioactive sources, is recorded by a high-resolution X-ray detector. The X-ray spectra show elements starting from sodium up to yttrium…
Weathering of Fe-bearing minerals under Martian conditions, investigated by Mössbauer spectroscopy
2004
Abstract The surface of Mars is covered by weathered material. Mars' rusty red colour in particular is commonly ascribed to ferric iron-bearing minerals. The planet's surface is generally iron rich. Mossbauer spectroscopy is a powerful tool for quantitative mineralogical analysis of Fe-bearing minerals. Consequently, the miniaturized Mossbauer spectrometer MIMOS II is part of the payload of NASA's twin Mars Exploration Rovers “Spirit” and “Opportunity”, and ESA's ill-fated Mars Express lander “Beagle 2”. Both Mars Exploration Rovers are currently conducting successful surface operations on Mars. In this paper, we give a brief insight into mission operations with respect to the reconstructio…
Identification of carbonate-rich outcrops on Mars by the Spirit rover.
2010
Ancient Carbonate Minerals on Mars The historical presence of liquid water on Mars together with a CO 2 -rich atmosphere should have resulted in the accumulation of large deposits of carbonate minerals. Yet, evidence for the presence of carbonates on the surface of Mars has been scarce. Using data collected by the Mars Exploration Rover, Spirit, Morris et al. (p. 421 , published online 3 June; see the Perspective by Harvey ) now present evidence for carbonate-rich outcrops in the Comanche outcrops within the Gusev crater. The carbonate is a major outcrop component and may have formed in the Noachian era (∼4 billion years ago) by precipitation from hydrothermal solutions that passed through …
Athena Mars rover science investigation
2003
[1] Each Mars Exploration Rover carries an integrated suite of scientific instruments and tools called the Athena science payload. The primary objective of the Athena science investigation is to explore two sites on the Martian surface where water may once have been present, and to assess past environmental conditions at those sites and their suitability for life. The remote sensing portion of the payload uses a mast called the Pancam Mast Assembly (PMA) that provides pointing for two instruments: the Panoramic Camera (Pancam), and the Miniature Thermal Emission Spectrometer (Mini-TES). Pancam provides high-resolution, color, stereo imaging, while Mini-TES provides spectral cubes at mid-inf…
Zvaigžņotā Debess: 2010, Rudens (209)
2010
Contents: G.Carevsky, I.Daube. Comet Bennett ; E.Fogels. Srinivasa Ramanujan ; M.Krastiņš. Smallest Planet of the Solar System: a Riddle of Centuries (1st part) ; A.Alksnis, Z.Alksne. Hot Jupiters and Their Retrograde Motion ; V.Karitāns. James Webb Space Telescope. What will it Be? ; K.Salmiņš. GFZ CHAMP Laser Tracking Award to SLR Station Riga ; J.Jansons. Vladimir Afanasjev, Officer of the Baikonur Cosmodrom in the 1970s (concluded) ; J.Limansky. International Year of Astronomy 2009 in Philately. Series EUROPA (2nd sequel) ; J.Dambītis. Centenary of Prominent Latvian Mathematician Ernests Fogels (1910-1985) ; J.Klētnieks. Sketches of History of Astronomy (concluded) ; M.Gills. Public Sun…
Stiffness design of laminates using the polar method
2001
This paper is devoted to the analysis of elastic properties of anisotropic laminas using the so-called polar representation method: this is an effective mathematical tool to analyse two-dimensional elastic problems. By this method, the authors have been able to find a particular class of solutions to some special inverse problems concerning laminates made by anisotropic layers. The properties of these solutions are described and discussed, along with some general results.
Influence of orientation errors on quasi-homogeneity of composite laminates
2003
This paper presents a study on the effects of layer orientation defects on the property of quasi-homogeneity for composite laminates: a measure of the deviation from quasi-homogeneity, introducing the concept of degree of quasi-homogeneity, is proposed. Complete theoretical developments which lead to exact formulae in the case of a single orientation error on a layer of the laminate are showed and the results of a wide numerical analysis in the case of orientation errors randomly distributed on the stacking sequence are also presented. All the theoretical and numerical calculations are developed thanks to the polar method of representation of fourth order tensors introduced by Verchery.
Anisotropy and symmetry for elastic properties of laminates reinforced by balanced fabrics
2001
In this article, we present a theoretical study on elastic properties of laminates composed by balanced fabric layers. Using the polar representation method for plane elastic tensors, we first describe some properties of symmetry of a general laminate composed by balanced fabrics and we write the formulas expressing positions of its axes of symmetry. Then, limiting our study to laminates composed of identical plies, we solve two problems of symmetry of the laminate elastic tensors: uncoupling and quasi-homogeneity. We found all the solutions of the uncoupling problem for the case of 3-, 4- and 5-ply laminate and all those of the quasi-homogeneity problem for the case of 4-, 5- and 6-ply lam…