Ecopoeisis

Humanity is on the verge of having the capability of
constructively directing environmental changes on a planetary
scale. Within the foreseeable future, we will have the
technology to modify Mars' environment, and make it a
habitable planet. However, we do not have enough information
to determine the course of such an event. To our knowledge, no
known terrestrial organism has the capability of living on Mars'
surface under present conditions. However, with some
modification, Mars' environment could be brought into the
survival and growth range of currently known microorganisms.
Using the SHOT Ecopoesis Testbed, we performed
survival/growth experiments to determine the suitability of
potential pioneering life forms for Mars. Included among the
potential pioneers were five genera of cyanobacteria (Anabaena,
Chroococcidiopsis, Plectonema, Synechococcus and
Synechocystis), three partially-characterized Atacama Desert
heterotrophic eubacterial strains, and several desert varnish
isolates. Microorganisms were exposed to a present-day mix of
martian atmospheric gases, but at a pressure of 100 mbar (10
times Mars' current atmospheric pressure). Cultures were
inoculated into samples of JSC Mars-1 soil stimulant and
exposed to full-spectrum simulated martian sunlight. Day/night
temperature cycled from 26°C to -80°C and back. Preliminary
results indicate that both autotrophic and heterotrophic bacteria
can survive in the simulated engineered martian environment.

The notion of ecologically terraforming another planet (aka ecopoiesis) has been discussed by a number of scholars.
Some theoretical treatments of various aspects of ecopoiesis have appeared in the literature. However, experimental
terraforming studies have been rare to non-existent. This is not surprising because of the planetary scale and long durations
typically discussed. We describe a concept to perform basic ecopoietic experiments in a test facility constructed on the lunar
surface. Such a facility can provide long-term observation of organisms and their ecological, physiological, and evolutionary
interactions in a low gravity environment. Salient features of other extraterrestrial environments (e.g. the 0.38g Mars gravity)
can be simulated more easily in the lunar milieu than on Earth while providing much greater access for experimenters than
ecopoiesis experiments on Mars itself. Besides application of these proposed studies to possible future terraforming efforts,
basic evolutionary and ecological processes could be studied under extreme selection pressures including fractional gravity,
high radiation, and with a variety of atmospheres, soils, and other parameters. Novel, genetically engineered and selectively
bred organisms could be tested in such a facility without concern for accidental release into Earth’s environment.

The growth of Pseudomonas aeruginosa in denitrifying medium was observed for 14 days in the presence of a
martian soil analog (JSC Mars-1) and elevated CO2 levels. A four-way test was conducted comparing growth of
experimental samples to growth in the presence of inert silica (“Earth soil”) and normal terrestrial atmosphere.
The combination of 50 mL of fluorescence-denitrification medium and 10 grams of soil additive simulated an
aquatic environment, which was contained in sealed culture bottles. Nitrite assays of the media (to test for
consumption during denitrification), gas sampling from the bottles to observe nitrogen production, and colony
counts to quantify growth rate were all performed at 0, 7 and 14 days after inoculation. Supplemental tests
performed included nitrate assays (to confirm the occurrence of denitrification) and culture fluorescence (as a
non-invasive growth test). Growth and denitrification took place under all conditions, and no significant differences
were observed between samples. These data indicate that the presence of simulated martian regolith and
elevated CO2 have little or no effect on the growth of or denitrification by P. aeruginosa at the concentrations
used.

Three cyanobacteria (Anabaena sp., Plectonema boryanum and Chroococcidiopsis CCMEE171) and an alga (Chlorella llipsoidea) were grown under simulated martian ecopoesis conditions. A xenon arc lamp with a solar filter provided simulated martian sunlight, and temperature cycled diurnally from x80 xC to 26 xC. A Mars-like atmosphere of 100% CO2 was provided at 50, 100,
300, 500 and 1000 mbar. The cyanobacteria and alga were inoculated into JSC Mars-1 soil simulant and exposed to each atmospheric pressure for five weeks. Survival and growth were determined via extractable chlorophyll a and total esterase (fluorescein diacetate hydrolysis) activity. Maximum survival occurred at 100 and 300 mbar. At 50, 500 and 1000 mbar, esterase activity was near zero, and extractable chlorophyll a was less than 10% of control samples. Overall, the cyanobacteria survived better than the alga. Low survival at 50 mbar was probably due to desiccation. Low survival at 500 and 1000 mbar may have been due to CO2 toxicity.