NAI Alumni Seminar Series Clues to Atmospheric Evolution in Earth's Earliest Sediments

Status Report From: NASA Astrobiology Institute
Posted: Friday, April 11, 2014


Presenter: Mark Claire (University of St. Andrews)

When: April 14th, 11AM PDT

Understanding how the Earth system has evolved through time is a grand challenge for astrobiologists. In particular, study of atmospheric oxygen concentrations through time has led us to the realization that the early Earth was truly an alien planet. Anomalies in the minor isotopes of sulfur indicate the complete absence of O2 from Earth's atmosphere prior to 2.4 billion years ago.

The goal of this NPP project was to identify additional constraints on the early atmosphere beyond the absence of O2. We enhanced a 1-D photochemical model to include 3 isotopes of sulfur and used it to make quantitative predictions that can be compared to sediments in the rock record. We test hypothesis for how sulfur MIF forms in the atmosphere and show that multiple atmospheric compositions including O2, CH4, CO2, total sulfur, and organic haze are capable of altering the 32/33/34 S isotopes signatures. We will discuss how ongoing laboratory measurements and experiments should allow for quantitative constraints on the early atmosphere in the near future.

How to Participate in this Virtual Seminar

To join using a web browser:

The slides and audio/video for this meeting will be presented using Adobe Connect. To join the meeting, connect to:

If you are having problems connecting, you can try joining, rebooting your computer, or try joining from another network.

To join using a videoconferencing system:

Please RSVP to Mike Toillion ( ONLY if you will be joining by videoconference.

To view the slides, connect to


// end //

More status reports and news releases or top stories.

Please follow SpaceRef on Twitter and Like us on Facebook.