As new criteria are required to prioritize the large and growing list of water-rich environments beyond Earth, the ASU Team looks ahead to the next phase of astrobiological exploration. Because all organisms are comprised of a non-random selection of chemical elements, we must learn, in addition to "following the water" and "following the energy," to "follow the elements." The team will focus on two types of elements: bioessential elements such as C, N, S, P and Fe that constitute the raw materials for life as we know it., and short-lived radionuclides such as 26Al and 60Fe, isotopes that may play a key role in determining the water inventories of planets.
The ASU team will conduct three complementary, interdisciplinary research efforts to develop new, more refined criteria to guide the search for life.
The Stoichiometry of Life: Understanding the relationships between the elemental compositions of organisms and their environments, and the ways in which those relationships shape the habitability of planets.
The Habitability of Water-Rich Environments: Understanding the impact of water on the availability of bioessential elements on planets and satellites, using geochemical models of water-rock interactions and geophysical models of the dynamics of mass and heat transfer in icy mantles. Applying these models to determine the chemical composition of Europa's subsurface ocean, ancient aqueous solutions on Mars, oceans on icy satellites, and oceans on waterworlds.
Astrophysical Controls on the Elements of Life: Investigating how astrophysical processes shape the abundances of bioessential elements and radionuclides that affect planetary habitability. Seeking to identify an observable proxy for 26Al that would enable quantitative predictions about whether a given star is more likely to host waterworlds or Earth-like planets.
NASA Astrobiology Institute
January 2009 - January 2014