It is widely considered that the earliest living organisms arose from simple prebiotic organic compounds by a process of chemical evolution. The Earth-based record of pre-biotic chemical evolution has been obliterated by geological processing. However, remains of the materials that were involved in the construction of the Earth are preserved in ancient asteroids, fragments of which are naturally-delivered to the Earth as meteorites. Carbonaceous chondrites are a particularly primitive class of meteorite that contain many of the compound classes utilised by life. Chondritic organic matter represents pre-life organic chemistry that has been frozen in time. By fully understanding the reactions that led to its origin we can extrapolate forward and appreciate how life itself began. Our meteorite work takes place within the Impacts and Astromaterials Research Centre.
Habitable planets are characterised by atmospheres that maintain surface clement conditions, allowing the maintenance of the liquid water essential to life. The climates of Earth and Mars at the time of the origin of life on Earth were strongly influenced by nature of their atmospheres, particularly the abundances of greenhouse gases such as water vapour, methane and carbon dioxide. Significant proportions of planetary atmospheres may be supplied by a late stage accretion of volatile-rich extraterrestrial objects. Understanding the production and delivery of the gaseous envelopes that shroud habitable planets is an important step in establishing how life arises and persists. Moreover the presence of certain gases in planetary atmospheres can reflect the activity of life. Recognising the origin of potential atmospheric biosignatures is essential to both the search for life in our solar system and in newly discovered planets orbiting other stars.
Life Detection on Space Missions
The quest to determine whether life existed, or still exists, on Mars is underway with a number of missions planned in the next few decades. In the summer of 2018, ExoMars, the first flagship mission of the European Space Agency’s Aurora programme, will be launched towards the Red Planet. Its stated aim is "to further characterise the biological environment on Mars in preparation for robotic missions and then human exploration". Detection of organic matter on Mars is unlikely to be straightforward. The National Aeronautics and Space Administration Viking I and II missions in 1976 detected no organic compounds above a threshold of a few parts per billion. ExoMars will use a rover fitted with a drill to obtain subsurface samples. New instrument packages will then search for trace levels of specific organic molecules. Imperial is part of the effort to develop instruments and techniques for ExoMars. The challenge of designing activities and producing equipment to a firm deadline inspires scientific endeavour. Preparing for ExoMars is expected to be a scientifically fruitful adventure. Advances made during the lead up to space missions have numerous terrestrial applications.
Layers of rocks contain a chemical testimony of environmental change through time. These changes are most dramatic during events known as mass extinctions where substantial percentages of species disappear. The big five mass extinctions are the end Ordovician, Late Devonian, end Permian, end Triassic, and end Cretaceous. At times of mass extinctions rock chemistries tellingly display distinct perturbations. Specifically, the organic remains of the organisms that lived and died during the events are entombed in rocks and can be extracted and analysed using organic geochemical methods. Interpreting these molecular fossils allows us to reconstruct the environments in which these organisms prevailed and thereby understand the causes and consequences of the extinction events. The biggest of the mass extinctions occurred at the end of the Permian. Understanding the end Permian catastrophe helps us to put the current human disturbance of our environment in geological context.
Utilizable energy resources are essential to the global economy. Conventional crude oil is a staple energy resource and accounts for over 35% of the world’s energy consumption. Recently the demand for oil is focusing scientific attention on unconventional hydrocarbon deposits. Imperial College Organic Geochemistry activities involve research into both conventional and unconventional petroleum deposits. Unique approaches are provided by endeavours associated with space missions. Elegant solutions are effectively transferred between scientific fields and can help to meet society’s demand for energy.
Organisms are biochemically adapted to their environment. By examining the nature of organic matter through time a record of changing environments can be constructed. For instance plant spores contain pigments that protect their genetic cargo from mutation by UV light. By tracking the pigment contents of spores collected over hundre ds of years trends in the amount of UV penetrating to the Earth’s surface can be established. Other environmental records are contained in rock matrices deposited in layers at regular intervals. Examining these layers and studying the diagnostic molecules present allows the generation of data that can reflect changing environmental conditions.
The type of carbon in the body’s molecules is present as two stable isotopes (carbon-13 and carbon-12). The ratio of these stable isotopes reflects the carbon ingested as part of any diet. Drugs manufactured in the lab contain very different ratios, allowing the two sources of molecules to be distinguished by scientific instruments. For drug cheats in athletics, you are what you eat plus a little bit of what you might inject. Conventional techniques, however, struggle to analyse molecules such as steroids in their natural form. We develop new approaches that delicately strip molecules of their analytically troublesome parts preparing them for carbon isotope analysis. Producing easy-to-handle molecules without destroying their carbon source signal opens up the whole of the body’s molecules to intense scientific scrutiny.