Terraforming
Planetary Engineering
Terraforming or “Planetary Ecosynthesis” is the process of changing a planet’s atmosphere to resemble that of the Earth’s, with the goal of sustaining terrestrial life. It is predicted that establishment of life will be similar to Earth’s history, starting with basic unicellular microorganisms. The most pheasible pioneer to begin life on a new planet would be some kind of photosynthetic microbe. (Graham)
The strategy of using photosynthesis to engineer a habitable planet for humans through photosynthesis would not be unlike the Great Ogygenation Event that took place on Earth 2.4 billion years ago, some time after cyanobacteria first evolved (2.7-2.8 billion years ago.) This pivotal event paved the way for evolution of multi-cellular organisms and later, human beings.(Farquar)
The topic has sprung much speculation as well as the ethical debates surrounding the idea.
Candidates for Terraformation
Mars: the winner
Mars is the preferred planet of interest for terraforming because it's history of once being a water planet, and the fact that it still retains much of its CO2, nitrogen, and H2O. (Graham) Currently Mars is very cold and it's atmosphere is relatively thin and mostly consists of CO2 (95.3%) with very little O2 and N2. Mars only recieves 43% of the light Earth gets from the Sun, yet it is still sufficient enough for photosynthesis.. (Thomas)
Proposed Terraformation of Mars would require:
- Warming the planet substantially
- Increase atmospheric pressure while adding O2
- Melt water (which Mars has frozen in Ice caps)
(Birch)
Venus
Venus has been proposed but it’s problems far surpass Mars in that it has a very thick atmosphere, little water, and it’s temperatures are much warmer than Earth. (Sagan 1961) Venus also has clouds made of searing sulfuric acid, and one Venus day is equivalent to 127 Earth days. (Birch)
Proposed Terraformation of Venus would require:
- Cooling the planet substantially
- Removing CO2 and other poisonous gases from the atmosphere while replacing it with O2
- Reduce day length to 24 hours
- Provide water
(Birch)
Biological interaction
The interaction of pioneering microbial species within an alien atmosphere will hopefully pave the way for future organisms such as plants and eventually humans to be able to colonize that planet.
The primary function of photosynthetic pioneers would be to take CO2 out of the atmosphere while adding O2 to the atmosphere.
One negetive effect of terraformation that has been proposed is the effect planetary changes will have on life already exsisting on Mars, though there's been proof of life in the past, no current life as we know it lives there.
Niche: A New World
To lay the foundation for microbial terraforming, the agreed plan for Mars begins with:
- the release of man-made greenhouse gases into the atmosphere, heating the planet substantially,
- Initial warming will then cause CO2 evaporation from the planet’s own glaciers and soil, producing further warming
- Melting glaciers will produce hydrologic cycles and evaporated H2O into the air, creating a denser atmosphere. This suggests a global temperature of at least 0 degrees Celsius.
- Water will be stable on the surface and temperatures will be more moderate, but the atmosphere will be mostly CO2 and have little O2. So long as UV radiation remains high, microorganisms will be confined to living in or under rocks. (Martyn Fogg 1995)
- Must be photoautotrophs
- Must be anaerobic and respire without O2
- Osmotic tolerance
- Resistance to UV radiation
- Cold tolerance
- Tolerance for Nutrient limitations
- Tolerance to limited water
- Resistance to oxides
- Adaptation to lowered intracellular pH due to CO2 in atmosphere
- Can form Endospores
UV radiation screens have been proposed for microbial access to surfaces. (Graham)
Microbial populations set to colonize Mars can expect extreme cold temperatures, high radiation, little to no moisture, and limited nutrients.(Graham)
Microbial processes
Mars has no tectonic activity so no biogeochemical cycling occurs there. It's thought that biological and photochemical processes can run the cycles on Mars.
Carbon cycling
Photosynthetic microorganisms removie CO2 from the atmosphere by photosynthesis:
6CO2 + 12H2O + Light -> C6H12O6 + 6O2+ 6H2O
Eventually heterotrophic microbes will release CO2 back into the atmosphere through respiration:
C6H12O6 + 6O2 --> 6CO2 + 6H2O + energy
Certain Microrganisms such as Matteia have been proposed to release CO2 from carbonate rock to complete the cycle in the early stages of colonization, just until enough enough carbohydrate is available to support heterotrophs.
Oxygen
Cyanobacteria and algae will be used to increase O2 through photosynthesis
6CO2 + 12H2O + Light -> C6H12O6 + 6O2+ 6H2O
Nitrogen cycling
Besides CO2 and O2, a buffer gas is needed to support human life, and nitrogen is necessary for photosynthesis at the start of terraformation.
Currently there is not enough N2 in Mars' atmosphere for nitrogen fixation and therefore, denitrifican is necessary as long as the regolith contains nitrate as is proposed
Denitrification:
NO3− → NO2− → NO + N2O → N2 (g)
Cyanobacteria can reduce N2 to ammonia:
N2 + 8 H+ + 8 e− → 2 NH3 + H2
Sulfur cycling
Most microbes utilize oxidized sulfur for protein synthesis.
Phosphorous cycling
Phosphates are insoluble minerals that are highly conserved in stable environments but through time losses can be a possible issue for terraformation. This may be the case with other non-volatile, minerals such as iron, manganese, and magnesium. (Thomas)
Key Microorganisms
Microorganisms are the best option for colonization of a new planet because of their wide range of physiologic and metabolic funtions and are capable of horizontal gene transfer. Two strategies have been proposed for choosing the best pioneers. One can either choose a generalist extremophile on Earth that inhabits environments similar to the new planet, or genetically modifying a new species with all the best traits required for the job. (Creating a Genetically Engineered Mars Organism "GEMO") (Hiscox)
Proposed Photoautotrophs
Cyanidium caldarium
A unicellular red algae found in diverse extreme environments such as bogs, wet acidic soils, and hot streams. It has been found to survive with little to no oxygen. (Sechbach et al.)
Cryptoendolith Lichens
Literally "hiding in rocks" An extremophile found in porous rock in Antarctica where temperatures are normally -89.2°C to -93.4°C. There has been no rain or snowfall in the Antarctic Desert for over 100 years.[3]
Chroococcidiopsis
The primitive characteristics of the cyanobacterium Chroococcidiopsis suggest that it represents a very ancient type of this group. Its morphology is simple but shows a wide range of variability, and it resembles certain Proterozoic microfossils. Chroococcidiopsis is probably the nost desiccation-resistant cyanobacterium, the sole photosynthetic organism in extreme arid habitats. It is also present in a wide range of other extreme environnents, from Antarctic rocks to thermal springs and hypersaline habitats, but it is unable to compete with more specialized organisms.
Proposed Denitrifers
Matteia
Matteia sp., a cyanobacterium found on desert rocks, has been proposed to dissolve carbonate rocks both for release of CO2 and in hopes of creating a Martian carbon cycle. (Friedmann)
Psuedomonads and Alcaligenes
Psuedomonads and Alcaligenes could be appropriate denitrifiers once enough oxygen and carbonate are present to sustain them. (Thomas)
Proposed GEMOs
Bacillus Polymyxa
A Facultative anaerobe that can form endospores, can fix nitrogen aerobically and anaerobically, and has tolerance to heavy metals. A good start for an eventual GEMO. (Hiscox)
Current Research
Enter summaries of recent research here--at least three required
References
[1]Birch, P. “Terraforming Mars Quickly” Journal of the British Interplanetary Society. 1992. Volume 45. p. 331-340
[2]Birch, P. “Terraforming Venus Quickly” Journal of the British Interplanetary Society. 1991. Volume 44. p. 157-167
[3]Blackhurst, R., Verchovsky, A., Jarvis, K., Grady, M.M. “Cryptoendolith communities in Antarctic Dry Valley Region Sanstones: Potential Analogues of Martian Life-Forms”
Lunar and Planetary Science. 2003. Volume 34.
[4]Farquhar, J., Bao, H., Thiemens, M. Atmospheric Influence of Earth’s Earliest Sulfur Cycle” Science. 2000. Volume 289. P. 756-758 [5]Fogg, M. J., "Terraforming" Society of Automotive Engineers. 1995. Warrendale, PA
[6]Friedmann, EI., Hua, M., Ocampo-Friedmann, R. “Terraforming Mars: dissolution of carbonate rocks by cyanobacteria” Journal of Interplanetary Society. 1993. Volume 46. P. 291-292 [7]Friedmann, EI., Ocampo-Friedmann, R. "A Primitive Cyanobacterium as Pioneer Microorganism for Terraforming Mars" Adv. Space Res. 1994. Volume 15, No. 3. p. 243-246
[8]Graham, J., Graham L. "Chapter 18: Terraforming Mars" 1989.
[9]Hiscox, J., Thomas, D. “Genetic Modification and Selection of Microorganisms for Growth on Mars” Journal of the British Interplanetary Society. 1995 Volume 48. P. 419-426. [10]Thomas, D. “Biological Aspects of the Ecopoeisis and Terraformation of Mars: Current Perspectives and Research” Journal of the British Interplanetary Society. 1995. Volume 48. P. 415-418
[11]Seckbach, J., Baker, F.A., Shugarman, P.M. "Algae Thrive in Pure CO2" Nature. 1977. Volume 227. p. 774-775
Edited by Samantha Chavez, a student of Angela Kent at the University of Illinois at Urbana-Champaign.
