Turner was 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 of the UK Cosmochemical Analysis Network, a network of laboratories in research institutions that analyse extraterrestrial material. He continued to be an active researcher during retirement. In 2004, he announced a
plutonium-xenon technique for dating terrestrial materials. == Death ==