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Andrew C. Schuerger, Ph.D. Dept. of Plant Pathology, University of Florida

The Harsh Mars Surface Environment may Mitigate Against the Forward Contamination of Mars During Robotic and Human Missions. Andrew C. Schuerger, Ph.D. Dept. of Plant Pathology, University of Florida Space Life Sciences Lab, Kennedy Space Center, FL.

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Andrew C. Schuerger, Ph.D. Dept. of Plant Pathology, University of Florida

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  1. The Harsh Mars Surface Environment may Mitigate Against the Forward Contamination of Mars During Robotic and Human Missions Andrew C. Schuerger, Ph.D. Dept. of Plant Pathology, University of Florida Space Life Sciences Lab, Kennedy Space Center, FL

  2. Adapted from Applebaum and Flood (1990), Buhler and Calle (2003), Cockell and Andrady (1999), Horneck et al. (2001,2003), Kuhn and Atreya (1979), Owen (1992), and Schuerger et al. (2003, 2004).

  3. Microbial Bioload at Launch is Finite: Limited Species Diversity and Biomass. Spore-formers ≈ 10% total biomass (range: 1-34%; Dillon et al., 1973). Culturable species are typically human-associated, airborne, and soil borne microbes. Non-culturable species are present but poorly defined at the moment. Average bioload launched: 3.0 x 105 spore-formers; + ≈1 decade higher non- spore forming species; +≈2 decades higher non-culturable species.

  4. Effects of Vacuum on Survival of Endospores of Bacillus subtilis. Spirit at Gusev Crater

  5. Mars Electrostatic Chamber (MEC), KSC. Schuerger et al., 2003, Icarus 165:253-276. Mars Simulation Chamber (MSC), KSC.

  6. Effects of UV dosage on the Survival of Bacillus subtilis HA101 under Mars-Normal UV and Earth-Normal Environmental Conditions. Rapid inactivation kinetics under equatorial Mars UV simulations. Schuerger, Newcombe, Venkateswaran 2005, Icarus, submitted.

  7. Survival of Bacteria on Sun-Exposed Spacecraft Surfaces. Spirit Lander Lander Pad 3; Viking 1

  8. Growth of Seven Bacillus spp. under Martian Conditions. • Pressure: down to 15 mb • Temp: 30, 20, 15, 10, & 5 C • Gases: CO2 vs ppO2/ppN2 • Pressure: down to 0.1 mb • Temp: -100 to +200 C (programmable) • Gases: CO2; O2/N2; Mars mix (top 5 gases) • UV-VIS-NIR: equatorial to polar fluence rates • Dust loading from tau 0.1 to 3.5

  9. Effects of Temperature on Growth of Vegetative Cells 7 Bacillus spp. 48 hrs at 1013 mb O2/N2 atmosphere CO2 atmosphere Rating scale: 4 = large robust colonies > 5 mm in diameter; 3 = colonies 2-4 mm in diameter; 2 = colonies ≈ 1 mm in diameter; 1 = colonies ≈ 0.5 mm in diameter; 0.50 = colonies < 0.5 mm in diameter; 0.1 = smallest visually discernable growth; 0 = no growth ;0 = no growth (n = 5).

  10. Effects of Pressure on Vegetative Cells of 7 Bacillus spp. 48 hrs at 30 C O2/N2 atmosphere CO2 atmosphere Rating scale: 4 = large robust colonies > 5 mm in diameter; 3 = colonies 2-4 mm in diameter; 2 = colonies ≈ 1 mm in diameter; 1 = colonies ≈ 0.5 mm in diameter; 0.50 = colonies < 0.5 mm in diameter; 0.1 = smallest visually discernable growth; 0 = no growth ;0 = no growth (n = 5).

  11. Effects of Pressure on Germination and Growth of Endospores 7 Bacillus spp. 48 hrs at 30 C O2/N2 atmosphere CO2 atmosphere Rating scale: 4 = large robust colonies > 5 mm in diameter; 3 = colonies 2-4 mm in diameter; 2 = colonies ≈ 1 mm in diameter; 1 = colonies ≈ 0.5 mm in diameter; 0.50 = colonies < 0.5 mm in diameter; 0.1 = smallest visually discernable growth; 0 = no growth ;0 = no growth (n = 3).

  12. Effects of Pressure on Growth of 6 Non-Spore Forming Species. 48 hrs at 30 C O2/N2 atmosphere CO2 atmosphere Rating scale: 4 = large robust colonies > 5 mm in diameter; 3 = colonies 2-4 mm in diameter; 2 = colonies ≈ 1 mm in diameter; 1 = colonies ≈ 0.5 mm in diameter; 0.50 = colonies < 0.5 mm in diameter; 0.1 = smallest visually discernable growth; 0 = no growth ;0 = no growth (n = 3).

  13. Mars Base-1: 2030+ Courtesy of Carter Emmart.

  14. Conclusions • Spacecraft are assembled under strict conditions which constrain bioloads at launch to low numbers of species and low total biomass. • During cruise phase to Mars, spore-forming species are reduced about 1 order of magnitude; non-spore formers likely 2-3 orders of magnitude. • Once on Mars, UV irradiation rapidly reduces bioloads on sun-exposed surfaces by up to 6 orders of magnitude within a few tens of minutes to a few hours. • And for those lucky microbes to survive on UV shielded surfaces, the synergistic effects of low pressure, low temperature, and CO2 atmospheres (+ other biocidal factors) create significant hurdles over which common spacecraft contaminants must cope with for continued survival and growth on Mars.

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