Open AccessSearch for magnetic minerals in Martian rocks: Overview of the Rock Abrasion Tool (RAT) magnet investigation on Spirit and Opportunity
Author(s) -
Goetz Walter,
Leer Kristoffer,
Gunnlaugsson Haraldur P.,
Bartlett Paul,
Basso Brandon,
Bell Jim,
Bertelsen Preben,
Binau Charlotte S.,
Chu Phillip C.,
Gorevan S.,
Hansen Mikkel F.,
Hviid Stubbe F.,
Kinch Kjartan M.,
Klingelhöfer Göstar,
Kusack Alastair,
Madsen Morten B.,
Ming Douglas W.,
Morris Richard V.,
Mumm Erik,
Myrick Tom,
Olsen Malte,
Squyres Steven W.,
Wilson Jack,
Yen Albert
Publication year - 2008
Publication title -
journal of geophysical research: planets
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2006je002819
Subject(s) - magnetite , ferrimagnetism , geology , maghemite , magnet , outcrop , weathering , mineralogy , abrasion (mechanical) , astrobiology , mars exploration program , magnetization , materials science , geochemistry , composite material , physics , magnetic field , paleontology , quantum mechanics
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 Mössbauer and visible/near‐infrared reflectance spectra is interpreted as magnetite. The amount of abraded rock material adhering to the magnets varied strongly during the mission and is correlated in a consistent way to the amount of magnetite inferred from Mössbauer spectra for the corresponding rock. The RAT magnet experiment as performed on Opportunity also indicates the presence of a strongly ferrimagnetic phase in outcrops, such as magnetite or an altered version of magnetite. However, the evidence is weaker than in the case of Spirit. According to data from the α particle X‐ray spectrometer (APXS) and the Mössbauer spectrometer (MB), the Eagle crater outcrops should not contain magnetite and their magnetization should not exceed 0.03 A m 2 kg −1 . However, this assertion seems to be in contradiction with the results of the RAT magnet experiment. The evidence for a strongly ferrimagnetic phase at low abundance in the Meridiani outcrops is discussed.