The Potential for Extraterrestrial Life
Michael Russo
Professor Nieter
Science Inquiry: Geoscience Introduction Astrobiology is the area of study dealing with alien life, the likelihood of finding it, where it might be found, how it evolved, its morphology, its culture, etc. It's a huge field that overlaps all the sciences but especially the geosciences, evolutionary biology, chemistry and bio-chemistry and astronomy. In the following report I focus on astrobiology as it applies to geology, or what kinds of planets, stars and solar systems are the most likely to play host to life in some form or another.
Basic Assumptions Earth is the only planet in the universe we know supports life and the life indigenous to Earth is the only life we know of in the universe. Although it is possible, and in fact likely when considering the size of the universe, that life exists in forms that we can not at this point conceive of, we are limited in this field by what we know for certain, and that is that all life we've studied is carbon based, evolved in an environment rich in oxygen, nitrogen hydrogen and carbon, and uses water as a solvent to facilitate biochemical reactions. Although alternative biochemistries are entirely possible, and life that is not biochemical but rather electrical or mineral may also be possible, if we open the door to these possibilities this report might never end. For the sake of brevity the information I present here will be based on the assumption that life that life is organic, carbon based, is dependent on some sort of energy source, either tidal, geothermal or solar and requires some sort of solvent, either water, liquid ammonia or liquid hydrocarbons.
Division
Issues of habitability, that is, "the measure of an astronomical body's potential for developing and sustaining life" (http://en.wikipedia.org/wiki/Planetary_habitability), can be placed into three groups, planetary, solar and galactic (or other). Planetary