Amazonian chemical weathering rate derived from stony meteorite finds at Meridiani Planum on Mars

Abstract

Spacecraft exploring Mars such as the Mars Exploration Rovers Spirit and Opportunity, as well as the Mars Science Laboratory or Curiosity rover, have accumulated evidence for wet and habitable conditions on early Mars more than 3 billion years ago. Current conditions, by contrast, are cold, extremely arid and seemingly inhospitable. To evaluate exactly how dry today's environment is, it is important to understand the ongoing current weathering processes. Here we present chemical weathering rates determined for Mars. We use the oxidation of iron in stony meteorites investigated by the Mars Exploration Rover Opportunity at Meridiani Planum. Their maximum exposure age is constrained by the formation of Victoria crater and their minimum age by erosion of the meteorites. The chemical weathering rates thus derived are ∼1 to 4 orders of magnitude slower than that of similar meteorites found in Antarctica where the slowest rates are observed on Earth.

Evaluation of meteorites as habitats for terrestrial microorganisms: Results from the Nullarbor Plain, Australia, a Mars analogue site

“…has been estimated to be on the order of 10 9 years (Bland and Smith, 2000). This is comparable to the slowest estimations for current Amazonian weathering rates of stony meteorites on Mars (Schröder et al, 2016), which also estimates >10 9 year long residencies. Consequently, chondritic meteorites should be plentiful on the surface of Mars, particularly given the absence of a planet wide resurfacing mechanism such as tectonics.…”

“…Rover missions have identified more than 23 iron and/or stony-iron meteorites on the surface of Mars (Ashley et al, 2011b), including some achondrites (Schröder et al, 2016). As of yet there are no confirmed chondritic meteorites that have been found on Mars, although candidates have been proposed, based on weathering profiles .…”

Concerns of Organic Contamination for Sample Return Space Missions

“…The process of the delivery of organic matter originating from meteorite infall is not restricted to the planet Earth. Meteorites have been identified on other celestial bodies, such as (i) Bench Crater (McSween 1976;Zolensky et al 1996) and Hadley Rille (Rubin 1997), which are carbonaceous and enstatite chondrites identified on the Moon, (ii) several iron and stony-iron meteorites (e.g., Meridiani Planum, Lebanon, Littleton) identified on the surface of Mars by Mars Exploration Rovers (MERs) Spirit and Opportunity, and the Curiosity rover of the Mars Science Laboratory (Ashley 2015;Ashley et al 2011;Connolly et al 2006;Schröder et al 2016;Schröder et al 2008), and (iii) the "Black Boulder", which is a possible xenolith originates from a low-albedo body identified on Itokawa (Nagaoka et al 2014). Although the acquisition of exogenous materials is a common process as the target body evolves through time, these 'foreign' materials carry information different from the target body and should be carefully identified to avoid confusing their synthetic histories.…”

Mössbauer Spectroscopy at Gusev Crater and Meridiani Planum

“…The discussion that follows for Gusev Crater is based on publications by Morris et al (2004Morris et al ( , 2006aMorris et al ( , 2010Morris et al ( , 2017, Klingelhöfer et al (2005), Yen et al (2005Yen et al ( , 2008, Clark et al (2007), , and Squyres et al (2008). Relevant publications for Meridiani Planum are Klingelhöfer et al (2004), Morris et al (2006bMorris et al ( , 2017, Clark et al (2005), , Fleischer et al (2010a, 2010b, 2016, and Zipfel et al (2011).…”