Icarus 197 (2008) 470–479 Contents lists available at ScienceDirect Icarus www.elsevier.com/locate/icarus Mojave Mars simulant—Characterization of a new geologic Mars analog Gregory H. Peters a , William Abbey b , Gregory H. Bearman a , Gregory S. Mungas a , J. Anthony Smith a , Robert C. Anderson b , Susanne Douglas b , Luther W. Beegle b,∗ a In Situ Instrument Systems Section, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099, USA b Planetary Science Section, Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099, USA article info abstract Article history: Received 4 March 2007 Revised 1 May 2008 Available online 27 May 2008 Keywords: Mars, surface Geological processes Experimental techniques Regoliths We have identified and characterized a basaltic Mars simulant that is available as whole rocks, sand and dust. The source rock for the simulant is a basalt mined from the Tertiary Tropico Group in the western Mojave Desert. The Mojave Mars Simulant (MMS) was chosen for its inert hygroscopic characteristics, its availability in a variety of forms, and its physical and chemical characteristics. The MMS dust and MMS sand are produced by mechanically crushing basaltic boulders. This is a process that more closely resembles the weathering/comminution processes on Mars where impact events and aerodynamic interactions provide comminution in the (relative) absence of water and organics. MMS is among the suite of test rocks and soils that was used in the development of the 2007/8 Phoenix Scout and is being used in the 2009 Mars Science Laboratory (MSL) missions. The MMS development team is using the simulant for research that centers on sampling tool interactions in icy soils. Herein we describe the physical properties and chemical composition of this new Mars simulant.  2008 Elsevier Inc. All rights reserved. 1. Introduction In order to better design and test the next generation of Mars missions, a regolith simulant that adequately represents the vari- ous dust, soil and rock properties that exist on the martian surface is required. As one recent MEPAG (Mars Exploration Program Anal- ysis Group) report specifically states, an important strategy for re- ducing the risks related to the effects of granular materials on both engineering and biological systems on Mars is to establish one or more martian dust/regolith simulants, then make them available in bulk quantities for the development and testing of sample acqui- sition/processing hardware, as well as scientific instruments, here on Earth (Beaty et al., 2005). The Mars simulant currently in common use is JSC Mars-1 (Allen et al., 1998). JSC Mars-1 is a glassy, meteorically altered vol- canic ash from Pu’u Nene, a late Pleistocene cinder cone located on the flanks of Mauna Kea, Hawaii (Allen et al., 1998). This material is basaltic in nature and has long been recognized as a good spec- tral analog for the bright regions on Mars (Evans and Adams, 1979; Singer, 1982; Morris et al., 1993). In 1997, researchers from the Johnson Space Center excavated a 40–60 cm thick zone of this unconsolidated material and then dried and sieved it to separate out the <1 mm size fraction. This size fraction has been made available to researchers for the past decade as JSC Mars-1 and has * Corresponding author. Fax: +1 818 393 4445. E-mail address: luther.beegle@jpl.nasa.gov (L.W. Beegle). seen widespread use throughout the scientific community (exam- ples include Lepper and McKeever, 2000; Carpenter et al., 2003; Ormond and Kral, 2006). When JSC-Mars-1 was developed, the knowledge of the physi- cal characteristics of the martian surface was limited primarily to orbital/remote observations and those made by the Viking landers. At both Viking landing sites (VL-1 and VL-2), the regolith was clas- sified as a fine-grained, cohesionless to rocky soil that contained small duricrust clods and possible rock fragments (Banin et al., 1992). Over the past decade three additional landing sites have been examined demonstrating a range of martian surface charac- teristics. At the Mars Pathfinder site, regolith can best be described as a combination of thin drifts of bright red, fine-grained material, soil-like deposits and rocks (Moore et al., 1999). In contrast, the Mars Exploration Rover (MER) Spirit found that the floor of Gusev Crater is dominated by basaltic sand grains and lithic fragments that have been disrupted by impact events and modified by eolian processes (Greeley et al., 2004; Herkenhoff et al., 2004a; Squyres et al., 2004a). At the same time MER Opportunity discovered that sur- face material throughout Meridiani Planum is dominated by sand- sized basaltic grains (<125 μm), sulfate-rich outcrop debris, and hematite-rich spherules and fragments (Herkenhoff et al., 2004b; Soderblom et al., 2004; Squyres et al., 2004b). All of these locations also contain variable amounts of fine-grained atmospheric dust. For other regions, where landed missions have yet to investigate, including ones where recent observations indicate the presence of sulfate and phyllosilicate minerals, there is likely a good deal of re- golith and dust mixing from impacts and planet-wide dust storms 0019-1035/$ – see front matter  2008 Elsevier Inc. All rights reserved. doi:10.1016/j.icarus.2008.05.004