Solar System Origin & Evolution at Imperial

How did dust and gas produce a planet capable of supporting life? This is one of the most fundamental of questions, and engages everyone from school children to scientists. Our planet formed 4.5 billion years ago along with the Sun and the other planets and minor bodies in our Solar System, and it is the only habitable world yet discovered on which life evolved. By understanding the details of how our Solar System formed we can hope to find an answer. We now know much about how stars and their accompanying planetary systems form in general. We know that stars form by the collapse of interstellar clouds of dust and gas. Planets are constructed in disks known as planetary nebula formed by the rotation of the collapsing gas cloud. It was in the solar nebula, surrounding the young Sun, that all the objects in our Solar System were created through a process called accretion. There is, however, a long list of details we don't know about how our Solar System formed. Why, for example, are all the planets so different? Why is Venus an inferno with a thick carbon dioxide atmosphere, Mars a frozen rock with a thin atmosphere, and Earth a haven for life? The answer lies in events that predated the assembly of these planets, it lies in the early history of the nebula and the events that occurred as fine-dust stuck together to form larger objects known as planetesimals, and as those planetesimals changed through collisions, heating and the effects of water to become the building blocks of planets. Our research intends to follow the evolution of planetary materials from the sources of dust prior to solar system formation, through the assembly of precursor objects within the solar nebula to the alteration of these objects as they became planets. The source of presolar dust provides a context to our solar system. From what types of star was dust derived and how did dust from these different sources mix and change in the solar nebula? These questions can be answered by analysis of isotopes of high temperature, refractory elements, within meteorites - rocks from asteroids that preserve a history of the early solar system. Meteorites, together with cosmic dust particles, also retain the fine-dust particles from the solar nebula. These dust grains are smaller than a millionth of a metre but modern microanalysis can expose their minerals and compositions. We will study the fine-grained components of meteorites and cosmic dust to investigate how fine-dust began accumulating in the solar nebula, how heating by an early hot nebula and repeated short heating events affected aggregates of dust grains, and whether magnetic fields helped control the distribution of dust in the solar nebula. In addition to the rocky and metallic materials that make up the planets, our research will examine the fate of organic materials that were crucial to the origins of life. Through newly developed methods we can trace this history of organic matter in meteorites from their formation in interstellar space, through the solar nebula and into planetesimals. This research will examine the effect of events also recorded in rocky and metallic fine-dust on the organic components of the early planetary materials from which the first living things on Earth were constructed. Once the planets finally formed, their materials continued to change. Our research focuses on the planet Mars, which provides a second example of a planetary body on which life could have appeared. We will trace the evolution of water and organics from planetary formation to the present day. Research on landforms on Mars will examine a crucial period in the planet's history, when global climate change transformed the planet into an arid wasteland, to evaluate the opportunity for organisms to adapt and survive. Research on the survival or organic compounds in martian soil will test whether the signature of life can still be detected on the planet.