Genesis Project
Summary (May 18, 2001): The daily terraforming experiments sponsored by the
Astrobiology Magazine feature a comparative glimpse into what is the science fiction of seeding a planet's biological development.
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The Genesis Project
One of the most hotly contested debates among astrobiologists is the feasibility and wisdom of modifying a planet's evolution, either by seeding weather modifications or by intervening to add life to an otherwise barren world.
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For avid science fiction readers, the prospect of terraforming an entire world is hardly startling. But even for those who witness the scale of global engineering already from El Nino, volcanic dust, and the cratered history of Earth, the genesis of a planet's ecosystem may prove to be relatively frequent spontaneous or
natural occurrences--particularly if meteors, comets and asteroid fragments transport large volumes of dormant life between planets.
The variations in atmospheric cloud cover, ice, glaciers and land-to-ocean borders shown here provide a visual and complex mathematical perspective into how comparative planetary ecosystems might fare if such global engineering ever became realistic. Tune in to this page for a daily glimpse of radical weather swings as continents rise and disappear or violent storms sweep our model planet.
"Current knowledge of Mars suggests that it is possible to transform that planet into one that would be habitable by plants and microorganisms from Earth. This could be done over time-scales of a hundred years or so using technologies that we are already demonstrating, probably to our detriment, on the Earth. Should we do so?" The Environmental Ethics of Bringing Mars to Life, Christopher P. McKay, NASA Ames Research Center
Mars Future?
Based on the world climate models of
McKay, Zubrin,and Fogg, this online planet simulation allows addition of greenhouse gases like water vapor, ammonia, carbon dioxide and perfluorocarbons to Mars. In addition for different amounts of heat retention and reflection, the albedo and insolation can be adjusted. Since Mars has stored greenhouse gases (carbon dioxide) both at the polar caps and in the surface rocks and soil (regolith), those outgassing reservoirs can be freed up with warming and climate forcing.
The calculation is based on a one-dimensional (1D) climate model, and does not account for time-dependent processes. For habitable zones to develop at a particular latitude--either polar or equatorial-- the temperature must rise above water freezing (0 C). The Martian pressures shown currently are about 1% of Earth's atmosphere (~1 bar).
Some intriguing features of this model include:
a dense carbon dioxide layer is not necessary (>1000 millibar). Indeed it is difficult to find a parameter set that can achieve such a thick Martian atmosphere. small additions of perfluorocarbons (>1 microbar CFCs) however can achieve high latitude and polar temperatures above freezing. McKay, et al estimate "the required times scale for [halocarbon] climate and atmosphere modification is on the order of 50 years". positive feedback from outgassing as the planet warms, which frees up more greenhouse gases, can reduce the requirements of terraforming by as much as two orders of magnitude (100x) compared to a planet without a reservoir of trapped gases in the soil and rocks controlling an equilibrium condition is dependent on artificially heating the planet (Tdelta) with some active climate forcing. This is likely a better engineering bet than allowing a runaway greenhouse effect to take hold of a planet's meteorological future. By varying the insolation (S) by 10% (S=1.1), one can show the effects of how orbitting mirror might focus more sunlight onto Mars. <BR
Mars Past
The terraforming simulation also can provide a simple model of the Martian past, when once wet and possibly warm conditions were created by a thicker carbon dioxide atmosphere than today. Many scientists believe that carbonate rocks (regolith) absorbed (or fixed) this atmosphere. Without this blanket of greenhouse gases to trap incoming solar radiation, the planet cooled dramatically, and more carbon dioxide froze at the poles. This primitive Mars can be approximated by adding 300 to 600 millibars of carbon dioxide P CO2 back to the atmosphere.
Melting dry ice from the entire southern polar cap is predicted to give Mars an atmosphere on the order of 50 to 100 millibar (or 5-10 % of the Earth's atmosphere). Once the temperature rises by 4-20 degrees, the trapped soil gases could supplement this atmosphere to around 300 millibars (30 % of the Earth's atmosphere).
Warm, Wet and Wild?
While the atmospheric physics of warming a planet may be simplified, the practical engineering is still daunting. So far, three main proposals have focused on: 1) heating up frozen carbon dioxide with polar mirrors; 2) importing comets and asteroids rich in trapped greenhouse gases like ammonia or methane in orchestrated collisions; 3) perfluorocarbon factories to release perhaps the most powerful greenhouse gas, CFC.
The scale of rocket transport for such large masses however remains a key limit. But the basic Martian ingredients for plant life are available and perhaps self-sustaining once at least tropical latitudes elevate about the water freezing temperature. The three reservoirs of carbon dioxide on Mars - the atmosphere, the dry ice in the polar caps, and gas adsorbed in the soil - provide a positive feedback, since warming will outgas or melt this greenhouse gas, thickening the atmosphere further to trap more sunlight and thus dramatically accelerating Martian habitability.
Pressure units (1 bar ~ 1 atm)
Millibar (mbar) x 100 = Pascals (Pa)
Pascals (Pa) x 0.01 = Millibar (mbar)
Millibar (mbar) x 0.0145 = Pounds-force per square inch (psi; Ibf/in2; Ib/in2)
Pounds-force per square inch (psi; Ibf/in2; Ib/in2) x 68.947 = Millibar (mbar)
Millibar (mbar) x 0.75 = Millimetres of mercury (mmHg)
Millimetres of mercury (mmHg) x 1.333 = Millibar (mbar)
Millibar (mbar) x 0.401 = Inches of water (inH2O)
Inches of water (inH2O) x 2.491 Millibar (mbar)
Note:
Mars Life: [5-23-2001]
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Friday, May 18, 2001
