Reconstructing thermal and fluid alteration histories of planetary materials

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In this consortium scientists from three UK institutions have come together to explore the development of rocky bodies within our solar system, and particularly in relation to the presence and properties of the key ingredients for life, namely water and carbon-rich molecules.One focus of our work will be on asteroids, samples of which have come to Earth as meteorites. These objects formed very early in the history of the solar system and evolved quickly, probably driven by internal heat from the decay of radioactive chemical elements. We want to know where in the solar system some of these asteroids formed, how long it took them to grow and how quickly they cooled down. We would also like to understand how heating and cooling affected water and carbon-rich molecules that became incorporated into the asteroids as they grew. These questions will be answered by using isotope analysis to determining the ages of different types of minerals, and by studying changes to the structure of carbon-rich compounds with laser beam techniques. Results from this work will provide new understandings of the evolution of asteroids that can be used to help interpret samples of them that will soon be returned to Earth by robotic missions.We will also study meteorites from Mars. This planet is an intermediate stage in evolution between the asteroids, which 'died' as they lost their heat and liquid water thousands of millions of years ago, and the Earth that remains an active planet with internal heat, liquid water and complex carbon-rich molecules including life. The Martian meteorites that we will analyse formed about 1300 million years ago when the planet was still hot enough that parts of its outer surface could melt, and they preserve traces of liquid water that flowed through the rocks. By studying the minerals in these rocks and the chemical elements from which they are made, we will explore how crystals grew as the molten rock cooled, and will also determine when the water was present. Today the surface of Mars is very hostile to life, with extremes of temperature, little or no liquid water and intense irradiation by ultraviolet light. However, brief occurrences of water on the surface of Mars today, and past hot-spring sinter deposits, may contain evidence of life, yet their propensity to do so is poorly understood. As sending robotic geologists to Mars is very costly, we will discover whether these environments can harbor molecular signs of life by studying martian analogue sites in the mountains of Chile. Soils in these areas are very dry, their temperatures fluctuate over a wide range and they are bathed in ultraviolet light. We will try to find traces of past life in these soils, and we will explore molecular preservation further by simulating martian conditions in the laboratory. This new information will tell us where on Mars we should focus the search for traces of life during future robotic and manned missions.The results of this research will be made freely available to other scientists worldwide so that improved models of planetary evolution can be developed. These new data and models will then help to guide the future exploration of asteroids and Mars, including the exciting missions in the next few tens of years that will return samples to Earth. Our research will also be of interest to scientists who study the history of the Earth, its climate and its life, and to industry through the new analytical procedures and technologies that we will develop. As our work will explore new and exciting science topics, it will be of great interest to the public and will be communicated via science festivals, newspapers and social media.