Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Calculations favor reducing atmopshere for early Earth

08.09.2005


Was Miller-Urey experiment correct?



Using primitive meteorites called chondrites as their models, earth and planetary scientists at Washington University in St. Louis have performed outgassing calculations and shown that the early Earth’s atmosphere was a reducing one, chock full of methane, ammonia, hydrogen and water vapor.

In making this discovery Bruce Fegley, Ph.D., Washington University professor of earth and planetary sciences in Arts & Sciences, and Laura Schaefer, laboratory assistant, reinvigorate one of the most famous and controversial theories on the origins of life, the 1953 Miller-Urey experiment, which yielded organic compounds necessary to evolve organisms.


Chondrites are relatively unaltered samples of material from the solar nebula, According to Fegley, who heads the University’s Planetary Chemistry Laboratory, scientists have long believed them to be the building blocks of the planets. However, no one has ever determined what kind of atmosphere a primitive chondritic planet would generate.

"We assume that the planets formed out of chondritic material, and we sectioned up the planet into layers, and we used the composition of the mix of meteorites to calculate the gases that would have evolved from each of those layers," said Schaefer. "We found a very reducing atmosphere for most meteorite mixes, so there is a lot of methane and ammonia."

In a reducing atmosphere, hydrogen is present but oxygen is absent. For the Miller-Urey experiment to work, a reducing atmosphere is a must. An oxidizing atmosphere makes producing organic compounds impossible. Yet, a major contingent of geologists believe that a hydrogen-poor, carbon dioxide -rich atmosphere existed because they use modern volcanic gases as models for the early atmosphere. Volcanic gases are rich in water , carbon dioxide, and sulfur dioxide but contain no ammonia or methane.

"Geologists dispute the Miller-Urey scenario, but what they seem to be forgetting is that when you assemble the Earth out of chondrites, you’ve got slightly different gases being evolved from heating up all these materials that have assembled to form the Earth. Our calculations provide a natural explanation for getting this reducing atmosphere," said Fegley.

Schaefer presented the findings at the annual meeting of the Division of Planetary Sciences of the American Astronomical Society, held Sept. 4-9 in Cambridge, England.

Schaefer and Fegley looked at different types of chondrites that earth and planetary scientists believe were instrumental in making the Earth. They used sophisticated computer codes for chemical equilibrium to figure out what happens when the minerals in the meteorites are heated up and react with each other. For example, when calcium carbonate is heated up and decomposed, it forms carbon dioxide gas.

"Different compounds in the chondritic Earth decompose when they’re heated up, and they release gas that formed the earliest Earth atmosphere," Fegley said.

The Miller-Urey experiment featured an apparatus into which was placed a reducing gas atmosphere thought to exist on the early Earth. The mix was heated up and given an electrical charge and simple organic molecules were formed. While the experiment has been debated from the start, no one had done calculations to predict the early Earth atmosphere.

"I think these computations hadn’t been done before because they’re very difficult; we use a special code" said Fegley, whose work with Schaefer on the outgassing of Io, Jupiter’s largest moon and the most volcanic body in the solar system, served as inspiration for the present early Earth atmosphere work.

Tony Fitzpatrick | EurekAlert!
Further information:
http://www.wustl.edu

More articles from Earth Sciences:

nachricht Predicting unpredictability: Information theory offers new way to read ice cores
07.12.2016 | Santa Fe Institute

nachricht Sea ice hit record lows in November
07.12.2016 | University of Colorado at Boulder

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Electron highway inside crystal

Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.

Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...

Im Focus: Significantly more productivity in USP lasers

In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.

Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...

Im Focus: Shape matters when light meets atom

Mapping the interaction of a single atom with a single photon may inform design of quantum devices

Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...

Im Focus: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

Researchers identify potentially druggable mutant p53 proteins that promote cancer growth

09.12.2016 | Life Sciences

Scientists produce a new roadmap for guiding development & conservation in the Amazon

09.12.2016 | Ecology, The Environment and Conservation

Satellites, airport visibility readings shed light on troops' exposure to air pollution

09.12.2016 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>