Microbial fossil record of rocks from the Ross Desert, Antarctica: implications in the search for past life on Mars

Abstract

: Cryptoendolithic microbial communities living within Antarctic rocks are an example of survival in an extremely cold and dry environment. The extinction of these micro-organisms formerly colonizing sandstone in the Mount Fleming area (Ross Desert), was probably provoked by the hostile environment. This is considered to be a good terrestrial analogue of the first stage of the disappearance of possible life on early Mars. To date, only macroscopically observed indirect biomarkers of the past activity of cryptoendoliths in Antarctic rocks have been described. The present paper confirms, for the first time, the existence of cryptoendolith microbial fossils within these sandstone rocks. The novel in situ application of scanning electron microscopy with backscattered electron imaging and simultaneous use of X-ray energy dispersive spectroscopy allowed the clear detection of microfossils left behind by Antarctic endoliths. Careful interpretation of the morphological features of cells, such as preserved cell walls in algae, fungi and bacteria, cytoplasm elements such as chloroplast membranes in algae and organic matter traces, mineral associations, and the spatial context of these structures all point to their identification as cryptoendolith microfossils. This type of investigation will prompt the development of research strategies aimed at locating and identifying the signs that Martian microbiota, probably only bacteria if they existed, may have been left for us to see.

Desert Potholes: Ephemeral Aquatic Microsystems

“…The search for biosignatures and extraterrestrial life on other planets has relied heavily on understanding potential analogs here on Earth (e.g., Banfield et al, 2001;Wierzchos and Ascaso, 2002). These potholes can serve as a springboard to understanding the relationships, structure, organization, and responses of microbial life in small aquatic systems.…”

Modeling aluminum–silicon chemistries and application to Australian acidic playa lakes as analogues for Mars

“…Alternative mechanisms for acidification include pyrite oxidation (Long et al, 1992a,b;Bishop et al, 2003Bishop et al, , 2004Zolotov and Shock, 2005), ferrolysis (McArthur et al, 1991;Long et al, 1992a,b;Papike et al, 2006), and acidic volatiles emitted by volcanoes (Banin et al, 1997;McCollom and Hynek, 2005). Earth analogues for Meridiani Planum surface geochemistries include: (1) acid mine drainages (AMD) (Fernandez-Remolar et al, 2003Bishop et al, 2004), (2) Antarctic deserts (Wierzchos and Ascaso, 2002;Bishop et al, 2003;Kreslavsky and Head, 2008), and (3) acidic saline lakes (Benison and LaClair, 2003;Benison and Bowen, 2006;Benison et al, 2007;Bowen and Benison, 2008). Potential geochemistries of Meridiani Planum have also been explored using laboratory studies (Banin et al, 1997;Tosca et al, 2004;Golden et al, 2005) and modeling (Schaefer 1990(Schaefer , 1993Morse and Marion, 1999;King et al, 2004;Marion and Kargel, 2008;Marion et al, 2008b).…”

Control of Lunar and Martian Dust—Experimental Insights from Artificial and Natural Cyanobacterial and Algal Crusts in the Desert of Inner Mongolia, China

“…Cyanobacteria are ubiquitous photoautotrophic microorganisms that can survive in various environments: desert mountains, icy regions (including Antarctica), fertile riversides, permafrost, or even heavily polluted regions (Whitton and Potts, 2000;Friedmann and Ocampo-Friedmann, 1995;Cockell et al, 2002;Garcia-Pichel et al, 2001). The structure of terrestrial phototrophic communities has been characterized in the hyper-arid, ultracold Antarctic Dry Valleys, where, with respect to temperature and aridity, the climate is similar to Mars, albeit less extreme (Friedmann, 1980;McKay and Friedmann, 1985;Wierzchos and Ascaso, 2002).…”