Astrochemistry: July 2010

A NASA Astrobiology Institute-funded study led by Chris Dupont of the J. Craig Venter Institute indicates that environmental availability of trace elements over Earth's history influenced the selection of elements used by life as biological evolution progressed. Their results show that environmental concentrations of trace metals influenced which types of metal-binding proteins evolved, and the relative timing of their evolution.

The study implies that the geochemistry of the Archean ocean (>2.5 billion years ago) influenced both the evolution of metal-binding protein architectures and the selection of elements by the ancestors of modern Archaea and Bacteria (simple single cell organisms). Specifically, low Zn, Mo, and Cu concentrations in the Archean ocean likely prevented the widespread emergence and diversification of Eukaryotic life (including plants, animals, and fungi) until the oceans became oxic, relatively late in Earth's history. The study also revealed that although modern Archaea and Bacteria still predominantly use ancient metal-binding protein structures, most Eukaryotes use both early- and late- evolving structures. The paper appears in the May 24 Early Edition of PNAS.

Source: NAI Newsletter

Many of the most well known comets, including Halley, Hale-Bopp and, most recently, McNaught, may have been born in orbit around other stars, according to a new theory by an international team of astronomers led by Harold F. Levison, co-investigator on NAI's NASA Goddard Space Flight Center Team.

The team used computer simulations to show that the Sun may have captured small icy bodies from its sibling stars while it was in its birth star cluster, thereby creating a reservoir for observed comets. Their paper appears in the June 10, 2010 issue of Science Express.

Source: NAI Newsletter