NAI Research Archive

Organics Probably Formed Easily in Early Solar System

Still shot from an animation to demonstrate a particle bouncing around different regions of the nebula and seeing different fluxes of photons. Animation credit: Fred Ciesla Complex organic compounds, including many important to life on Earth, were readily produced under conditions that likely prevailed in the primordial solar system. Scott Sandford of NAI's NASA Ames Research Center Team and his colleague Fred Ciesla at the University of Chicago came to this conclusion after linking computer simulations to laboratory experiments. Their study appears in Science Express

Reading the Rocks

David Johnston, Assistant Professor of Earth and Planetary Sciences at Harvard University. For more than a decade, scientists have dismissed claims that examining carbon-rich rocks could yield clues to the atmospheric and oceanic conditions on Earth hundreds of millions of years ago. Now, however, researchers including members of NAI's MIT Team are challenging that belief, and suggesting that data gleaned from the rocks sheds light on how changes in the atmosphere and oceans helped set the stage for the emergence of animal life. In one of the largest studies of its kind, described in the March 14 issue of Nature, a group of researchers led by David Johnston, Assistant Professor of Earth and Planetary Sciences, analyzed hundreds of samples of carbon-rich rock collected from sites in Canada, Mongolia, and Namibia. Their findings show that carbon isotope records from the mid-Neoproterozoic era — between 717 million and 635 million years ago — can be “read” as a faithful snapshot of the surface carbon cycle.

Meteorites Reveal Another Way to Make Life's Components

A meteorite analyzed in the study at its collection site in Antarctica. Credit: Antarctic Search for Meteorites program, Case Western Reserve University Creating some of life’s building blocks in space may be a bit like making a sandwich – you can make them cold or hot. This evidence that there is more than one way to make crucial components of life increases the likelihood that life emerged elsewhere in the Universe, according to the research team led by astrobiologists at NAI’s Goddard Center for Astrobiology. It also gives support to the theory that a “kit” of ready-made parts created in space and delivered to Earth by impacts from meteorites and comets assisted the origin of life. In a recent study published in Meteoritics and Planetary Science, scientists from NAI's Goddard Space Flight Center Team analyzed samples from fourteen carbon-rich meteorites with minerals that indicated they had experienced high temperatures – in some cases, over 2,000 degrees Fahrenheit. They found amino acids, which are the building blocks of proteins, used by life to speed up chemical reactions and build structures like hair, skin, and nails.

Early Earth Air Quality: Code Orange

Titan's hazy atmosphere. Credit: NASA/JPL/Space Science Institute About two and a half billion years ago, Earth might have been confused for Titan. New research suggests that our planet had the same hazy, methane-rich atmosphere as Saturn’s largest moon, Titan. For the first third of the history of life on Earth, the atmosphere was devoid of the oxygen we breathe, supporting a dramatically different chemistry. A new study from a group including memembers of NAI's Virtual Planetary Laboratory Team suggests connections between Earth’s atmosphere and its biosphere that induced an orange, hydrocarbon haze that would have blocked incoming sunlight and cooled the planet. The study, published in Nature Geoscience, provides analyses of 2.5 billion year old rock cores from South Africa that reveal a series of unique chemical signatures of atmospheric change. When these data are plugged into atmospheric models, it is revealed that early Earth oscillated between two atmospheric states: one with a thin, orange haze and the other without any haze. The trigger for these events appears to be atmospheric changes in a potent greenhouse gas, methane. These high concentrations of methane, produced by biological activity, caused the haze and an “anti-greenhouse” effect. This is one of the earliest examples of the tight climatic coupling between Earth and its inhabitants.

New Study Sheds Light on Early Earth's Atmosphere

Geological background of the samples analyzed in this study. Panel A shows the geological map at Marble Bar and the location of the ABDP-1 drill core. Panel B shows the simplified stratigraphic column of the lower part of the Pilbara Supergroup, with ages constrained by zircon U–Pb geochronology. Astrobiologists from NAI’s team at the University of Wisconsin, Madison have recently published a study of drill cores obtained through the NAI-funded Archean Biosphere Drilling Project which sampled the 3.4 billion year old Apex Basalt from the Pilbara Craton in Western Australia. Their innovative approach directly dates oxidation products of the ancient rock, and they show that oxidation occurred in the Phanerozoic during deep weathering. Their results indicate that oxidation of the Apex Basalt did not occur in the Archean, and therefore cannot be used to infer an oxygenated atmosphere at that time. Their paper appears in Earth and Planetary Science Letters.