Servicio de Información Comunitario sobre Investigación y Desarrollo - CORDIS

Final Activity Report Summary - ESPS (Earth System and Planetary Studies)

In this project, research was conducted in the following two areas:
1. the co-evolution of life and the composition of the atmosphere over Earth's geologic history;
2. studies on the surface and climate of planet Mars.

These research topics were part of 'astrobiology', a new branch of science concerned with the origin and evolution of life on Earth and the possible variety of life beyond Earth. Both research areas were consistent with the joint European Community and European Space Agency (ESA) policy on space, as well as with the European Union objective to promote research in new and emerging interdisciplinary areas. A further goal of the project was to develop a rigorous training programme.

In the first research area, the main result was a detailed theory explaining how levels of oxygen increased in Earth's very ancient atmosphere. Ample evidence showed that over 2.4 billion years ago the Earth's atmosphere contained hardly any oxygen molecules. While some very simple microbes existed under such conditions, more complex life could not do so.

Oxygen in the atmosphere is a product of photosynthesis. Nevertheless, microbes capable of photosynthesis existed on Earth half a billion years or more before atmospheric oxygen accumulated. This has always been a major puzzle. However, it could be explained in case reactions with gases coming out of the Earth's crust initially soaked up oxygen as fast as photosynthesis churned oxygen out. If the supply of oxygen devouring gases, such as hydrogen, petered out about 2.4 billion years ago, oxygen levels would rise. In this project, a computer model was developed to keep track of oxygen comings and goings as well as of the solid Earth evolution. The project produced the first ever self-consistent quantitative model for the early history of atmospheric oxygen.

Another aspect of the research was to demonstrate how an anomalous distribution of atoms of sulphur of different mass, i.e. isotopes, in ancient minerals was caused by chemical reactions in the atmosphere involving abundant levels of methane. There has previously been no method to indicate abundant methane levels in the ancient atmosphere. Furthermore, an additional piece of research addressed the biological role of oxygen. It showed why significant oxygen in the air and oceans was essential for the evolution of multicellular life by considering the energy advantage of oxygen-based respiration for growth.

In the second research area, large deposits of salts on Mars were analysed with spacecraft images, topographic data and spectral data. The results allowed for two alternative hypotheses. One possibility was that large bodies of salty water evaporated to leave salts behind. The possibility that there once were large seas or lakes on Mars was important for the question of whether Mars was once habitable, since large bodies of liquid water on Earth always contain life. The other hypothesis on how the salts formed was that sulphur-rich volcanic gases on Mars turned into particles in the atmosphere and settled on the ground, slowly building up salt deposits.

The large deposits of salts in some areas of Mars have blueberry-sized spheres of iron oxides embedded within them. Research in this project showed that the iron oxide spherules would have formed relatively quickly in geological terms, in less than 2 000 years, and that the iron in the spherules was probably supplied from the surrounding salts' leaching out, explaining why the salts and spheres occur together.

For the training component of this project, two new undergraduate courses were developed, namely geobiology and global environmental change. The geobiology course examined the inter-relationships between life and geochemistry. The global environmental change course covered biodiversity, ozone depletion and global warming. A research seminar series in geobiology was also organised. The audience included university staff and students and, sometimes, members of the public. In addition, the chair gave at least one public lecture each year.

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United Kingdom
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