Diamond Light Source – the giant Oxfordshire synchrotron that uses beams of extremely bright light to probe the properties of everything from fossils to jet engines – is being used by a team of international scientists to probe rock samples recovered during the Apollo missions, nearly 50 years ago.
The group, which includes researchers from Tenerife, the US and the UK, is using a new advanced X-ray speckle imaging technique developed at the facility to examine samples from the Apollo 12 and 15 missions.
Dr Matt Pankhurst of Instituto Volcanológico de Canarias and NASA lunar principle investigator explained that the technique is being used to carry out 3D mapping of olivine – a common green mineral found in the Earth’s sub-surface and in these Moon rock samples. These maps will be used to improve understanding of the Moon’s ancient volcanic systems and help to understand active geological processes here on Earth.
Commenting on the technique Dr Hongchang Wang, Senior Optics Scientist, said: “Combined with the recently developed fast fly-scan tomography and novel white beam camera, the X-ray speckle imaging technique has allowed us to swiftly and effectively collect 3D information of olivine inside of the lunar rock in much more detail than ever before.”
The team hopes to recover information such as what the patterns of magma flow within the volcanic system were, what the magma storage duration was like, and potentially even identify eruption triggers. The data will be analysed using advanced diffusion modelling which will establish the history of individual crystals.
In magma, the ratio of iron to magnesium in olivine changes over timeframes ranging from hours to months, and these changes are ‘locked in’ to the mineral as the magma cools. Accurate 3D images of the iron distribution within olivine in the Moon rock samples will ‘unlock’ information about the volcanic processes in which they formed.
Crucially, this new technique does not damage the lunar samples, which are so precious that they are usually kept in a special building at NASA ‘s Johnson Space Center. Whilst scientists wishing to study the rocks require special approval from NASA, the agency’s Apollo sample curator, Ryan Zeigler said that the emergence of non-destructive techniques such as those available at Diamond have made this process easier. “The researchers are now using state-of-the-art diffusion modelling to establish the history of individual crystals of olivine from 3D images,” he said. “These techniques will be applied to the new data gathered during this beam time. The results will add to our understanding of lunar and planetary formation, topics which have been continually debated since the samples were first returned to Earth.”