I am currently reading my way through a long list of science fiction and fantasy titles. (http://www.npr.org/2011/08/07/138938145/science-fiction-and-fantasy-finalists if you are interested in the list).
In recent years, scientists at the frontiers of biology have hypothesized the existence of life-forms that can only be called “weird”: organisms that live off acid rather than water, microbes that thrive at temperatures and pressure levels so extreme that their cellular structures should break down, perhaps even organisms that reproduce without DNA. The search for these strange life-forms spans the universe, from rock surfaces in the American southwest and hydrothermal vents on the ocean floor to Martian permafrost, the ammonia oceans of Jupiter’s moons, the hydrogen-rich atmospheres of giant planets, the exotic ices on comets, the crusts of neutron stars, and the vast reaches of space itself. David Toomey brings us into the world of the researchers who have devoted their careers to “weird life,” and as they envision and discover ever stranger organisms here on earth, they open up fascinating possibilities for the discovery of life in the rest of the universe.
An interesting little volume, mapping out what to look for with regards to exotic life forms. The search is on, to see if an organism on Earth can be found that doesn't come from the same evolutionary line that has produced all the known plants, animals, fungi, and microbes. There's a strong possibility that in some remote [and awful] part of our Earth, some weird life exists.
Toomey also explores non-Earth locations for weird life, including the rest of our solar system, artificial life, and planets outside our galaxy that include liquids + a source of energy. He really covers all the bases.
There is also some worry that Earth space craft will contaminate other planets with our microbes, something that I just heard a radio interview about last weekend. One scientist is taking a census of the bacteria, fungi, etc. that survive on the objects that we will hurl into space so that we will have some idea of which ones may show up later on Mars, Europa, or wherever. Wouldn't it be dreadful to wipe out the biota of another planet by introducing a pathogenic bacteria?
As far as I could tell, this was a good summary of the available thinking on this field.