Researchers have, for the first time, successfully determined the age of a Martian rock - with experiments being performed on the Red Planet.
The work, led by geochemist Ken Farley of the California Institute of Technology (Caltech), would not only help in understanding the geologic history of Mars but also aid in the search for evidence of ancient life on the planet. Many of the experiments carried out by the Mars Science Laboratory (MSL) mission’s Curiosity rover were painstakingly planned by NASA scientists more than a decade ago.
In March, Curiosity drilled holes into the mudstone and collected powdered rock samples from two locations about three meters apart. Once the rock samples were drilled, Curiosity’s robotic arm delivered the rock powder to the Sample Analysis on Mars (SAM) instrument, where it was used for a variety of chemical analyses, including the geochronology—or rock dating—techniques.
One technique, potassium-argon dating, determines the age of a rock sample by measuring how much argon gas it contains. Over time, atoms of the radioactive form of potassium—an isotope called potassium-40—will decay within a rock to spontaneously form stable atoms of argon-40. This decay occurs at a known rate, so by determining the amount of argon-40 in a sample, researchers can calculate the sample’s age.
Farley and his colleagues determined the age of the mudstone to be about 3.86 to 4.56 billion years old. The study has been published in the journal Science Express.