HR: 0800h
AN: P51D-0961 [Abstracts]
TI: Aseptically Sampled Organics in Subsurface Rocks From the Mars Analog Rio Tinto Experiment: An Analog
For The Search for Deep Subsurface Life on Mars.}
AU: * Bonaccorsi, R
EM: bonaccor@units.it
AF: NASA Ames Research Center, MS 245-3, Moffett Field, CA 94035
United States
AU: * Bonaccorsi, R
EM: bonaccor@units.it
AF: Dept. Geological, Environmental, and marine Sciences, Via E. Weiss, 2, Trieste, TS 34127
Italy
AU: Stoker, C R
EM: cstoker@mail.arc.nasa.gov
AF: NASA Ames Research Center, MS 245-3, Moffett Field, CA 94035
United States
AB:
The subsurface is the key environment for searching for life on planets lacking surface life. Subsurface ecosystems are of
great relevance to astrobiology including the search for past/present life on Mars. The surface of Mars has conditions
preventing current life but the subsurface might preserve organics and even host some life [1]. The
Mars-Analog-Rio-Tinto-Experiment (MARTE) is performing a simulation of a Mars drilling experiment. This comprises
conventional and robotic drilling of cores in a volcanically-hosted-massive-pyrite deposit [2] from the Iberian Pyritic Belt
(IBP) and life detection experiments applying anti-contamination protocols (e.g., ATP Luminometry assay). The RT is
considered an important analog of the Sinus Meridiani site on Mars and an ideal model analog for a deep subsurface Martian
environment. Former results from MARTE suggest the existence of a relatively complex subsurface life including aerobic and
anaerobic chemoautotrophs and strict anaerobic methanogens sustained by Fe and S minerals in anoxic conditions. A key
requirement for the analysis of a subsurface sample on Mars is a set of simple tests that can help determine if the sample
contains organic material of biological origin, and its potential for retaining definitive biosignatures. We report here on
the presence of bulk organic matter Corg (0.03-0.05 Wt%), and Ntot (0.01-0.04 Wt%) and amount of measured ATP
(Lightning MVP, Biocontrol) in weathered rocks (tuffs, gossan, pyrite stockwork from Borehole #8; >166m). This provides
key insight on the type of trophic system sustaining the subsurface biosphere (i.e., heterotrophs vs. autotrophs) at RT. ATP
data (Relative-Luminosity-Units, RLU) provide information on possible contamination and distribution of viable biomass with
core depth (BH#8, and BH#7, ~3m). Avg. 153 RLU, i.e., surface vs. center of core, suggest that cleaness/sterility can be
maintained when using a simple sterile protocol under field conditions. Results from this research will support future
drilling mission planned on Mars. [1] Boston, P.J., et al., 1992. Icarus 95,300-308; [2] Leistel et al., 1998.
DE: 0424 Biosignatures and proxies
DE: 1055 Organic and biogenic geochemistry
DE: 5400 PLANETARY SCIENCES: SOLID SURFACE PLANETS
DE: 6207 Comparative planetology
SC: Planetary Sciences [P]
MN: Fall Meeting 2005