Word Encounters: Terraforming and Ecopoiesis
Can we terraform Mars, as illustrated in this image, or other planets, to make them habitable for human life?
We share interesting science words and ideas in our regular “Word Encounters" series. Here, Staff Writer Stewart Mittnacht explores whether new habitats for humans may be a real possibility or still the stuff of science fiction.
Terraforming
The word terraforming first appeared in Jack Williamson’s short story “Collision Orbit,” one of the gems produced by Astounding Science Fiction during the Golden Age of Science Fiction (1938 to 1946). Though terraforming is often used as a synonym for planetary engineering, the two terms are not actually interchangeable, as terraforming is a very specific, as yet unrealized, branch of planetary engineering. In general, planetary engineering refers to any megaproject or human activity that leads to the alteration of a global habitat. In some sense, humanity has been engaged in planetary engineering here on Earth since the Paleolithic era—the over-hunting and eventual extinction of Earth’s megafauna is attributed to the decline of the steppes ecosystem that once dominated northern Siberia and its replacement with tundra.
Terraforming, though, is a horse of a different color, as it involves the intentional alteration of a planet to improve its habitability for Earth-based life. Since the 1960s, NASA has commissioned several think tanks to come up with potential terraforming strategies. One such strategy proposes altering the albedo [the reflection of light or radiation] of the surface of Mars by coating its North Pole with a lichen or a cyanobacteria that has been genetically modified to produce black pigments, which would better absorb heat than white snow and gradually warm the surface temperature to the melting point of water. By doing so, more advanced plants could be introduced to begin the process of oxygenating the Martian atmosphere.
Such a strategy would be relatively inexpensive and could use current levels of technology. Recent tests have demonstrated that certain arctic lichens and hardy cyanobacteria are actually capable of growth and reproduction in a simulated Martian environment (the German team responsible for these experiments affectionately named their apparatus the “Martian hell-jar”). The ethics of such an experiment are questionable, however, until we have firmly established whether or not Mars supports native microbial life, as terraforming could threaten this potential microbial ecosystem or even drive it to extinction.
Ecopoiesis
Ecopoiesis is a term coined by Robert Haynes to describe the origins of an ecosystem on a planet. Though Haynes meant the term to refer to the initial introduction of life to a planet during the process of terraforming, the term is now applied in a broader context to the idea of creating a new form of ecosystem that is pre-adapted for an alien world. In terraforming, a planet is altered to be more habitable for Earth-based life, but in ecopoiesis, life is altered or synthetically created to be able to survive in that planet’s current surface conditions.
In the future it may be possible to adapt primitive methods of anaerobic respiration to service higher life forms, either as an alternative to aerobic respiration or a supplementary system for supporting higher forms of life in oxygen-poor environments. Methanogenesis is one such form of respiration, in which carbon dioxide gas acts as the final receptor for the generation of ATP—your body’s energy supply— rather than oxygen. Instead of needing oxygen in the atmosphere to breathe, an organism capable of methanogenesis could breathe carbon dioxide gas—the main component of the Martian atmosphere.
Such a creature could potentially survive on Mars’ surface today, without the need to heavily change or modify the planet’s existing environment. Whole ecosystems of such organisms might be created and introduced to Mars, generating an entirely novel and new form of ecosystem and extending the definition of “life as we know it.”