R ocks on Mars are more porous and less compacted than scientists expected, according to a study that used datafromNASA’sCuriosity rover. Researchers, including those from Arizona State University (ASU) in the US, measured the density of rock layers in 154- kilometre-wide Gale Crater on Mars. The findings, published in the journal Science, show that the layers are more porous than scientists had suspected. The discovery also givesscientists a novel technique to use in the future as the rover continues its trek across the craterandupMountSharp,afive-kilometre-high mountain at its centre. “What we were able to do is measure the bulk density of the material in Gale Crater,” said Travis Gabriel, a graduate student at ASU. Gabriel worked on computing what the grain density should be for the rocks and ancient lakebed sedimentsthe rover has been driving over.
“Working from the rocks’ mineral abundances as determined by the chemistryandmineralogyinstrument, we estimated a grain density of 2810 kilogrammes per cubic metre,” he said. “However, the bulk density that came out of ourstudy is a lot less -- 1680 kilogrammes per cubic metre,” said Gabriel. The much lower figure shows that the rockshavea reduceddensity, most likely resulting from the rocks being more porous. Thismeanstherockshavebeencompressed less than scientists have thought. The engineering sensors used in the study were accelerometers,muchlikethosefoundineverysmartphone to determine its orientation and motion.