Grenville Turner
Grenville Turner (born 1 November 1936, in Todmorden) is a research professor at the University of Manchester. He is one of the pioneers of cosmochemistry. Education. In 1962, he was awarded his D.Phil. (Oxford University's equivalent of a PhD) in nuclear physics. Scientific work. Professor Turner has been a leading figure in cosmochemistry since the 1960s. His pioneering work on rare gases in meteorites led him to develop the argon–argon dating technique that demonstrated the great age of meteorites and provided a precise chronology of rocks brought back by the Apollo missions. He was one of  the few UK scientists to be a Principal Investigator of these Apollo samples. His argon-dating technique involved stepped pyrolysis of the rocks to force out the argon, then determining the isotopic ratios in the gas by mass spectrometry. This was later refined by the use of lasers. These techniques have been invaluable to cosmochemists and geochemists, and have been applied (by Turner and others) to determine the geochronology of diamonds and inclusions in them, and the precise ages of mantle and crustal rocks from the Earth. He went on to develop even better techniques, such as iodine-xenon chronology . He used laser resonance ionisation of xenon to measure samples with only a few thousand atoms of xenon; this enabled him to get accurate data from tiny samples, including individual chondrules. He could even trace secondary processes, such as alteration by heat, fluids or shock. Turner set up the first ion microprobe in the United Kingdom intended for use primarily for examining extraterrestrial material. He used it to measure oxygen-isotope variations in the Martian meteorite ALH 84001. His results cast light on the environment in which the carbonate grains and so-called microfossils in that meteorite formed. He was  a founder member, and continues to be a leader, of the UK Cosmochemical Analysis Network, a network of laboratories in research institutions that analyse extraterrestrial material. Despite having formally retired, he continues to be an active researcher. In 2004, he announced a plutonium-xenon technique for dating terrestrial materials.