Key research themes are:
The nature of specific asteroid families
Models of the orbital evolution of dust to Earth indicate that the majority of asteroidal dust particles are derived from the Koronis, Themis and Veritas asteroid familes. These families formed during catastrophic disruption of larger parent asteroids and are associated with bands of dust, generated by collisions between family members, that extend through the solar system to the Earth. Micrometeorites, therefore, unlike the majority of meteorites, provide samples of known primitive asteroids for detailed characterisation in the laboratory. Dust particles derived from the Koronis asteroid have recently been discovered by Genge (1) and indicate that the Koronis asteroids, including 243 Ida, consist of ordinary chondrite-like materials and have experienced thermal metamorphism. Carbonaceous chondrite-like dust is expected to be derived from the Themis and Veritas asteroids. This research theme aims to identify the key characteristics of the materials of these asteroid familes, such as their chondrule to matrix ratios, the abundance of refractory inclusions, and the presence of presolar grains, and to establish the degree and style of aqueous, thermal and shock metamorphism through characterisation of the mineralogy, texture and composition of micrometeorites and meteorites. The image opposite shows Koronis asteroid 243 Ida (NASA).
The nature of comets
Comets are highly enigmatic icy objects accreted in the outer solar nebula. Telescopic and spacecraft observations of comets can provide only limited information on the formation and evolution of these objects. Anhydrous interplanetary dust particles, collected in the Earth's atmosphere by NASA, are thought to be derived from comets. The recent return of the NASA STARDUST mission also provides particles from a known study, comet Wild-2, for direct study in the laboratory by modern microanalysis tools. This research theme aims to evaluate the mineral grain assemblages within comets, their structure and microstructure and their degree of reprocessing. The theme currently represents a contribution to the NASA STARDUST preliminary examination team.
Chondrules are mm-sized igneous objects found within the chondritic (primitive) meteorites. The prevailing current model for the formation of chondrules is by gas-drag heating in shockwaves in the solar nebula. Chondrules, however, exhibit significant differences in size-distribution, texture, mineralogy and composition between chondrite groups that have yet to be satisfactorily explained by any formation model. This research theme aims to provide base line quantitative data on chondrule populations by which physical and chemical models for their diveristy can be determined. The image opposite shows chondrules within an ordinary chondrite.
Microbial habitats on Mars
The existence of water on Mars, both on and below its surface, over a large proportion of its history, raises the possibility that living organisms may have been present, and are perhaps still extant, on the planet. This research theme investigates the potential habitats available to micro-organisms on Mars and examines the necessary adaptive strategies that such communities would require to survive the changes in environmental conditions that Mars has experienced over the last 3.5 Ga. Key projects in this theme involve study of terestrial analogs of two very different microbial strategies: cryptoendolithic organisms and microbes within hydrothermal systems. A particular emphasis in these projects is identifying mineralogical and textural biomarkers that could be used by planetary space missions to identify the existance of life on Mars.
Meteorite and Micrometeorite Collection
The discovery of meteorites and new sources of micrometeorites are an important means of increasing the inventory of extraterrestrial samples available for analysis within the laboratory. This programme involves evaluating the potential of new collection areas and techniques. The programme has involved examination of aeolian dust in Antarctica on the 2006/7 US Antarctic Programme ANSMET expedition with Ralph Harvey (Case Western Uni. USA), reconnaisance meteorite searching in Egypt and Morocco, and evaluation of ancient micrometeorite deposits in evaporites (with Dr Monica Grady, Open Uni).
Earth science projects include:
- The nature of natrocarbonatite eruptions at Oldoinyo Lengai, northern Tanzania
- The petrology of native iron-bearing basalts from Disko Island, western Greenland
- Unusual magmatic textures within lamprophyres from northwest Scotland.
Dr Ralph Harvey, Case Western University, Ohio, USA, Micrometeorites
Prof. Monica Grady, PSSSRI, Open University, UK, Micrometeorites
Dr Mike Zolensky, Johnson Space Center, NASA, Team leader, Min and Pet Team, NASA STARDUST
Dr Susan Taylor, US Army Cold Regions Research Centre, Micrometeorites
Dr Donald Brownlee, University of Washington, PI NASA Stardust Mission
Dr Cecile Engrand, University of Paris, Micrometeorites
Research Student Supervision
Blackhurst,MR, The History of Water on Mars
Preston,ML, Microbial habitats in geothermal systems: biomarkers for Mars.