Astrobiology is an enormous field with ambitious goals. It seeks to understand the origin and evolution of life on Earth, to determine if life exists elsewhere, and to predict the future of life on our planet and in the rest of the universe. My own work within this field is also cross-disciplinary, and touches upon several elements of this big picture.

In order to understand how life began on Earth I study the origin of the chemical compounds that make up living organisms, and what kind of chemistry and geology are necessary to create an environment capable of supporting life.

My research interests encompass ecology, physiology, biogeochemistry, and geochemistry. Skills and techniques from all these fields help me better understand how an environment will shape, sustain and constrain the origin and evolution of life.

I currently examine four living systems in these studies. I study halophiles, salt-loving microbes in the evaporitic salt crusts that form along marine intertidal zones; microbial mats inhabiting diverse environments (for example, the intertidal area of the Baja coast, the alkaline and acid hot springs of Yellowstone National Park, hypersaline lakes and the perennially ice-covered lakes in the dry valleys of Antarctica; areas where rock (desert) varnish occurs; and the space environment in Earth orbit. I examine the organisms in these unique and challenging environments, study the mechanisms by which they survive and flourish in their current environment, and subject them to further rigors to test the limits of their survival mechanisms.

The results of such experiments allow me to model the interactions of microbes with other microbes, and with their environment, and the role of nitrogen in these living systems. These models help us formulate hypotheses about the evolution of the nitrogen cycle, and the role exogenous sources of fixed nitrogen in the physiology of nitrogen metabolism, biogeochemistry and microbe community structure.

We also use these models to extrapolate from what is known about the environment (geochemistry and climatology) of early Mars in an attempt to determine the potential for life to evolve on that planet. Nitrogen seems a the key element for two reasons: 1) It (fixed-N) is an important limiting nutrient in many terrestrial systems; and 2) It appears that N would have been one of the most important limiting nutrients on Mars as well.

A common thread ties all my research projects together; I am searching for the definitive environmental limits in which life can arise and evolve on planets. Seeking these limits leads my research into examining the potential for life to arise elsewhere in the solar system, for example, Mars. Because Mars shares many common attributes to Earth, (this is particularly true for its early planetary history), it is the only other planet in the solar system that had potential for life to arise. This makes Mars a particularly appropriate test-bed for assessing the probability, and environmental parameters necessary for lifes origin and early evolution.

We know that the essential major and minor biogenic elements exist on Mars, and that its temperatures, pressures and radiation levels would not have precluded the origin and evolution of life. The primary factor in determining if life could have arisen on Mars lies in determining if liquid water existed on its surface for sufficient time. The history of water lies within the mineralogy of the rocks.

My research with Mars soil analogs (using differential thermal analysis coupled with gas chromatography) will allow me to interpret data from the suite of upcoming Mars missions and help answering the question of whether Mars ever possessed sufficient liquid water for life to evolve. This in turn may elucidate and define the limits for the origin and early evolution of life on earth.

To learn more about Dr. Mancinelli and his work please visit http://www.seti.org/about_us/voices/r_mancinelli.html.