Searching for the Great Oxidation Event in North America: A Reappraisal of the Huronian Supergroup by SIMS Sulfur Four-Isotope Analysis.

Sedimentological observations from the Paleoproterozoic Huronian Supergroup are suggested to mark the rise in atmospheric oxygen at that time, which is commonly known as the Great Oxidation Event (GOE) and typically coupled with a transition from mass-independent fractionation (MIF) to mass-dependent fractionation (MDF) of sulfur isotopes. An early in situ study of S three-isotopes across the Huronian Supergroup by Papineau et al. ( 2007 ) identified a weak MIF-MDF transition.

False Negatives for Remote Life Detection on Ocean-Bearing Planets: Lessons from the Early Earth.

Ocean-atmosphere chemistry on Earth has undergone dramatic evolutionary changes throughout its long history, with potentially significant ramifications for the emergence and long-term stability of atmospheric biosignatures. Though a great deal of work has centered on refining our understanding of false positives for remote life detection, much less attention has been paid to the possibility of false negatives, that is, cryptic biospheres that are widespread and active on a planet's surface but are ultimately undetectable or difficult to detect in the composition of a planet's atmosphere. Here, we summarize recent developments from geochemical proxy records and Earth system models that provide insight into the long-term evolution of the most readily detectable potential biosignature gases on Earth-oxygen (O), ozone (O), and methane (CH).

Data management in astrobiology: challenges and opportunities for an interdisciplinary community.

Data management and sharing are growing concerns for scientists and funding organizations throughout the world. Funding organizations are implementing requirements for data management plans, while scientists are establishing new infrastructures for data sharing. One of the difficulties is sharing data among a diverse set of research disciplines.

The drive to life on wet and icy worlds.

This paper presents a reformulation of the submarine alkaline hydrothermal theory for the emergence of life in response to recent experimental findings. The theory views life, like other self-organizing systems in the Universe, as an inevitable outcome of particular disequilibria. In this case, the disequilibria were two: (1) in redox potential, between hydrogen plus methane with the circuit-completing electron acceptors such as nitrite, nitrate, ferric iron, and carbon dioxide, and (2) in pH gradient between an acidulous external ocean and an alkaline hydrothermal fluid.