The Southwest Research Institute scientists have increased the speed and accuracy of a laboratory-scale instrument for determining the age of planetary specimens onsite. The team is progressively miniaturising the Chemistry, Organics and Dating Experiment (CODEX) instrument to reach a size suitable for spaceflight and lander missions. “In situ ageing is an important scientific goal identified by the National Research Council’s Decadal Survey for Mars and the Moon as well as the Lunar and Mars Exploration Programme Analysis Groups, entities responsible for providing the science input needed to plan and prioritize exploration activities,” said SwRI Staff Scientist Dr F Scott Anderson, who is leading CODEX development.
“Doing this onsite rather than trying to return samples back to Earth for evaluation can resolve major dilemmas in planetary science, offers tremendous cost savings and enhances the opportunities for eventual sample return,” Anderson added. CODEX will be a little larger than a microwave and include seven lasers and a mass spectrometer. In situ measurements will address fundamental questions of solar system history, such as when Mars was potentially habitable. CODEX has a precision of +-20-80 million years, significantly more accurate than dating methods currently in use on Mars, which have a precision of +-350 million years.
“CODEX uses an ablation laser to vaporise a series of tiny bits off of rock samples, such as those on the surface of the Moon or Mars,” said Anderson, who is the lead author of a CODEX paper published in 2020. Anderson further noted, “We recognise some elements directly from that vapour plume, so we know what a rock is made of. Then the other CODEX lasers selectively pick out and quantify the abundance of trace amounts of radioactive rubidium (Rb) and strontium (Sr). An isotope of Rb decays into Sr over known amounts of time, so by measuring both Rb and Sr, we can determine how much time has passed since the rock formed.”