Astrobiology is the study of life, or the possibility of life, on other planets by scientists at universities or organizations such as NASA. Astrobiology is a growing discipline, especially with the recent discovery of hundreds of exoplanets orbiting distant stars and recent finds of water ice on Mars and some of the solar system's moons.
Habitable Zones Might Support Life
Astrobiologists recognize that certain conditions must be met for life to develop. In the study of other star systems, scientists recognize an area around each star that they call the habitable zone. This zone has carbon dioxide, water vapour and nitrogen, all the necessary ingredients for life as we know it.
Carbon is an important chemical for life because of its ability to bond to many different types of molecules and form different structures to support a living cell. Many scientists also view water as a major requirement because it stays liquid over a large temperature range and can act as a solvent for the development of life. This is why scientists get so excited when they find water in places like Mars or on the moon.
Extremophiles as Examples of Life at Extremes
Astrobiologists like to focus on Earth life that lives at extreme conditions, often called extremophiles. Scientists think these types of organisms could serve as examples of what might be found on other planets.
Thermophiles are heat-loving bacteria that live in environments with extremely hot temperatures, such as volcanic vents. Some of these thermophiles have been found to be able to survive as dormant spores in extremely cold conditions, such as in the Arctic ice, waiting to be revived when temperatures rise again. Many thermophiles don't use oxygen, instead relying on other compounds to provide them with energy.
Astrobiology and Exotic Compounds
Extremophiles like those found on Earth aren't the only possibility for extraterrestrial life, according to some scientists. Austrian scientists from the University of Vienna are looking at how life might evolve using exotic ingredients instead of the carbon.
Ammonia is a popular example, since it can form many different associations with other chemicals, as carbon can. Looking for compounds such as these could also extend out the potential habitable zone around other stars, since ammonia oceans can exist in conditions where water oceans cannot. This also leads astrobiologists to search for signs of life in places like the methane oceans on the surface of Saturn's moon Titan.
No matter how exotic the life form, any discovery of life on other planets or moons would be a major event for astrobiologists. For that would mean truly moving the study of astrobiology onto other worlds.
Resources:
Europlanet Media Centre (2009, September 21). Exotic Life Beyond Life? Looking For Life As We Don't Know It. ScienceDaily.
Casey Hubert; et al. A Constant Flux of Diverse Thermophilic Bacteria into the Cold Arctic Seabed. Science, September 18, 2009
 |
 |
 |
 |
 |
