SPIRIT AT CUSEV CRATER RESEARCH ARTICLE The Spirit Rover's Athena Science Investigation at Gusev Crater, Mars S. W. Squyres,^* R. E. Arvidson,^ J. F. Bell III/ J. Bruckner,' N. A. Cabrol,'* W. Calvîn,= M. H. Carr,® P. R. Christensen/ B. C. Clark,® L Crumpler,® D. J. Des Marais,^" C. d'Uston,''^ T. Economou,^^ J. Farmer,^ W. Farrand," W. Folkner,^^ M. Colombek,^'* S. Corevan," J. A. Crant,^^ R. Creeley,'^ J. Crotzinger,^'^ L Haskin,^ K. E. Herkenhoff,^® S. Hvîid," J. Johnson,^® C. Klîngelhofer,^" A. Knoll,^^ C. Landis,^^ M. Lemmon,^' R. Li,^* M. B. Madsen,2= M. C. Malin,^^ s. M. McLennan,^^ H. Y. McSween,^« D. W. Ming,^^ J. Moersch,^« R. V. Morris,^^ T. Parker,^'* J. W. Rice Jr.,' L Richter,'" R. Rieder,' M. Sims,^° M. Smitli,'^ P. Smith,'^ L A. Soderblom,^® R. Sullivan,^ H. Wanke,' T. Wdowiak," M. Wolff,'^ A. Yen^'* The Mars Exploration Rover Spirit and its Atliena science payload liave been used to sediment carried by the water that cut investigate a landing site in Gusev crater. Gusev is hypothesized to be the site of a Ma'adim before it overflowed and exited former lake, but no clear evidence for lacustrine sedimentation has been found to through a gap in the northern rim of the date. Instead, the dominant lithology is basalt, and the dominant geologic processes are impact events and eolian transport. I^jany rocks exhibit coatings and other characteristics that may be evidence for minor aqueous alteration. Any lacustrine ^Department of Astronomy, Cornell University, Ithaca, NY 14853, USA. ^Department of Earth and sediments that may exist at this location within Gusev apparently have been buried Planetary Sciences, Washington University, St. Louis, by lavas that have undergone subsequent impact disruption. |v|0 63130, USA. ^Abteilung Kosmochemie, l^lax- Plancl<-lnstitut für Chemie, Postfach 3060, D-S5128 Spirit landed in Gusev crater on 4 January es and two detection modes (alpha and x-ray) l^lainz, Germany. ''NASA Ames/SETI Institute, Moffett Field, CA 94035, USA. ^Department of Geological 2004 UTC. It was followed 21 days later by in the APXS reveal elemental abundances of Sciences, University of Nevada, Reno, NV 89557, Opportunity, which landed on Meridiani Plan- rocks and soils (8). The Mössbauer Spec- USA. «U.S. Geological Survey, Menlo Park, CA 94025, urn. Both vehicles landed using a variant of trometer measures the resonant absorption of USA. 'Department of Geological Sciences, Arizona the airbag landing system that was developed gamma rays produced by a ^^Co source to State University, Tempe, AZ 85287, USA. "Lockheed for the Mars Pathfinder mission, deploying determine splitting of nuclear energy levels in Martin Corporation, Littleton, CO 80127, USA. ^New Mexico Museum of Natural History and Science, Al- the rovers after the landers had come to rest ^^Fe atoms, revealing the mineralogy and buquerque, NM 87104, USA. '"NASA Ames Research on the surface (1). The primary scientific oxidation state of Fe-bearing phases. The in- Center, Moffett Field, CA 94035, USA. "Centre objective of their mission is to explore two strument arm also carries a Microscopic Imager d'Etude Spatiale des Rayonnements, 31028 Toulouse sites on the martian surface where water may [MI (P)] that has been used to obtain high- Cedex 4, France. '^Enrico Fermi Institute, University of Chicago, Chicago, IL 60637, USA. '^Space Science once have been present, and to assess past resolution (30 jjim/pixel) images of rock and Institute, Boulder, CO 80301, USA. '''Jet Propulsion environmental conditions at those sites and soil surfaces and a Rock Abrasion Tool [RAT Laboratory, California Institute of Technology, Pasa- their suitability for life. Here we provide an (10)] that can remove up to ~5 mm of material dena, CA 91109, USA. '^Honeybee Robotics, New overview of the results from the 90-sol (2) over a circular area 45 mm in diameter. Finally, York, NY 10012, USA. '«Center for Earth and Plane- tary Studies, Smithsonian Institution, Washington, DC nominal mission of Spirit. the payload includes the Magnetic Properties 20560, USA. "Department of Earth, Atmospheric and Like Opportunity, Spirit carries a copy of Experiment consisting of seven magnets that Planetary Sciences, Massachusetts Institute of Tech- the Athena science payload (3) (Fig. 1). The have attracted fine-grained magnetic materials nology, Cambridge, MA 02139, USA. '"U.S. Geological topography, morphology, and mineralogy of for viewing by payload instruments (11). Survey, Flagstaff, AZ 86001, USA. '^Max-Planck-lnsti- the scene around the rover have been re- The rover itself uses a six-wheel rocker- tut für Aeronomie, D-37191 Katlenburg-Lindau, Ger- many. ^"Johannes Gutenberg-Universität, Staudinger vealed by two remote sensing instruments: a bogie suspension system and onboard auton- Weg 9, D-55099 Mainz, Germany. ^'Botanical Muse- panoramic camera (Pancam) and a miniature omous navigation and hazard avoidance ca- um, Harvard University, Cambridge, MA 02138, USA. thermal emission spectrometer (Mini-TES). pability, allowing traverse distances of tens ^^NASA Glenn Research Center, Cleveland, OH Pancam (4) is a stereo camera whose filters of meters per sol (1). Navigation and hazard 44135, USA. "Department of Atmospheric Sciences, Texas A&M University, College Station, TX 77843, provide 11 unique color spectral bandpasses avoidance are aided by two monochromatic USA. ^"Department of Civil and Environmental Engi- over the spectral region from 0.4 to 1.1 mm, navigation cameras (Navcams) mounted on neering and Geodetic Science, Ohio State University, as well as two other filters for direct imaging the mast, and by four hazard avoidance cam- Columbus, OH 43210, USA. ^=Niels Bohr Institute, of the Sun. Mini-TES (5) produces high spec- eras (Hazcams) mounted in fore- and aft- 0rsted Laboratory, DK-2100 Copenhagen 0, Den- mark. ^«Malin Space Science Systems, San Diego, CA tral resolution (10 cm^') infrared image facing stereo pairs on the rover body (12). 92191, USA. ^'Department of Geosciences, State Uni- cubes with a wavelength range of 5 to 29 jjim. Prelanding mission success criteria dictated versity of New York, Stony Brook, NY 11794, USA. The Pancam cameras and the Mini-TES scan- that at least one of the rovers should travel a ^"Department of Earth and Planetary Sciences, Uni- ning mirrors are mounted atop a mast (3) at a minimum of 600 m over its lifetime, with a versity of Tennessee, Knoxville, TN 37996, USA. "NASA Johnson Space Center, Houston, TX 77058, height of ~ 1.5 m above the ground. goal of 1 km. The design surface lifetime for USA. ^"Institut für Raumsimulation, Deutschen Zen- Once potential science targets have been both vehicles was 90 sols. trum für Luft- und Raumfahrt (DLR), Dj-51170 Köln, identified using Pancam and Mini-TES, they The landing site chosen for Spirit lies Germany. ^'NASA Goddard Space Flight Center, have been studied in more detail with the use within Gusev crater, a fiat-floored crater that Greenbelt, MD 20771, USA. ^^Lunar and Planetary of two in situ compositional sensors mounted is 160 km in diameter and of Noachian age. Laboratory, University of Arizona, Tucson, AZ 85721, USA. ^^Department of Physics, University of Alabama, on a 5-degree-of-freedom robotic arm (3). The southern rim of Gusev is breached by Birmingham, AL 35294, USA. "Space Science Insti- These are an Alpha Particle-X-Ray Spec- Ma'adim Vallis, one of the largest branching tute, Martinez, GA 30907, USA. trometer [APXS (6)] and a Mössbauer Spec- valley networks on the planet. Gusev is ex- *To whom correspondence should be addressed. E- trometer (7). Radioactive ^^^Cm alpha sourc- pected to have acted as a settling pool for mail: [email protected] 794 6 AUGUST 2004 VOL 305 SCIENCE www.sciencemag.org SPIRIT AT CUSEV CRATER crater. Exploration of the floor of Gusev did not command Spirit to drive away from Spirit drove away from Adirondack on sol therefore was anticipated to offer opportuni- Adirondack until sol 36. 36, arriving at a low circular depression ties to study sediments that were derived The traverse path of Spirit from Columbia (probably a small impact crater) named La- from the southern highlands of Mars and Memorial Station through the end of the guna Hollow on sol 45. During sols 46 to 49 deposited in a lacustrine environment (13). nominal mission on sol 91 (Plate 14) consist- we used the rover's wheels to excavate a Given the great length and depth of ed of a drive toward the northeast to the rim trench in the soil of Laguna Hollow (Plate 7). Ma'adim Vallis and the shallow depth and flat of Bonneville crater, in situ investigation of We resumed the drive toward Bonneville on floor of Gusev crater, the quantity of lacustrine the Bonneville rim region and remote sensing sol 50, stopping on sol 54 at a large boulder sediments flUing the crater is likely to be sub- of the crater floor, and then a turn toward the named Humphrey (Plate lOA). Sols 55 to 60 stantial (14-16). The aqueous sedimentation southeast and the beginning of the long drive were spent investigating Humphrey in detail, events at Gusev probably occurred more than 3 toward the Columbia Hills. The traverse to including brushing (Plate lOB) and grinding billion years ago, however, and we recognized and then away from Bonneville yielded the (Plate IOC) with the RAT, acquisition of com- before landing that any water-lain deposits flrst transect through the éjecta deposits of an positional data at several steps in the process, could have been buried by more recent volcanic impact crater on another planet. Along the and acquisition of a mosaic of MI images and/or eolian materials (13). Small impact cra- way we made several extended stops during (Plate 12). We resumed the drive toward the ters are common across the floor of Gusev, and which we investigated high-priority science rim of Bonneville on sol 61, and arrived there the interiors and éjecta of such craters may targets with the full Athena payload.