Geosciences attempts to understand how planets form and ultimately become habitable for life. What factors make a planet suitable for life? Are plate tectonics necessary? How early does liquid water become available for life? Are the subsurface water bodies or oceans of icy moons habitable environments? To understand the history of life on Earth, when it came into existence and whether other planets in our Universe are habitable requires that we know about the past geological history of the Earth.
Early history of the Solar System. The search for habitable environments in our Solar System and in extrasolar systems. Deep subsurface environments as locations for life. Search for habitable conditions on Mars.
Want to learn more?
Mars Curiosity rover web site: http://www.jpl.nasa.gov/msl/
The exoplanets encylopedia: http://exoplanet.eu/
A good general web site for geology information: http://geology.com/
The geological society web site: http://www.geolsoc.org.uk/