Mars May Have Supported Life: Martian Underground Could Contain Clues to Life's Origins

Minerals found in the subsurface of Mars, a zone of more than three miles below ground, make for the strongest evidence yet that the red planet may have supported life, according to research "Groundwater activity on Mars and implications for a deep biosphere," published inNature Geoscience on January 20, 2013.
Science Daily, Jan 20, 2013

Joseph R. Michalski, et al.

Wright.Groundwater activity on Mars and implications for a deep biosphere.

Nature Geoscience, 2013; DOI:10.1038/ngeo1706