Planetary scientists from Brown University have developed a new remote-sensing technique to study a mineral called olivine on the moon. Researchers say that olivine could help them understand the early evolution of the moon and other planetary bodies. The mineral is important because it’s understood to be a significant component of the interiors of rocky planets.
Christopher Kremer, lead author of the new paper describing the work, says olivine is a primary constituent of the Earth’s mantle and has been detected on the surface of the moon and Mars. Olivine has been detected in volcanic deposits or in impact craters that bring material up from the subsurface. Currently, remote sensing techniques are good enough to spot olivine from orbit, but the scientists want to do more than spot the mineral.
Researchers want to be able to learn more about the chemical makeup of olivine. They note that all olivines have silicon and oxygen, but some are rich in iron, while others are rich in magnesium. The composition of the olivine sheds light on the environment where they formed, in particular the temperature. Higher temperatures during formation lead to more magnesium, while lower temperatures lead to more iron.
By learning the composition of olivine on the moon, Mars, and other planetary bodies, scientists could learn more about how the planetary bodies evolved since the formation. One method used to study rocks on other planets is spectroscopy. Different elements or compounds absorbed or reflected different wavelengths of light to various degrees. By looking at the light spectra, rocks reflect, scientists can learn about their composition.
Kremer looked at a small range of wavelengths of light between infrared spectroscopy and middle infrared spectroscopy. He found a band between four and eight microns in those wavelengths that could predict the amount of magnesium or iron in an olivine sample to within 10 percent of the actual content. Instruments available now could say there was “a little bit of this or little bit of that,” but the new process allows researchers to put a number on content marking a significant step forward.