One idea suggests that the crater was once completely filled with sediment, and many millions of years of wind erosion eventually excavated all but the mountain at the center of the crater. Scientists still aren't sure how the mountain grew inside of Gale Crater. There are many mountains nestled inside craters and canyons on Mars, but few approach the scale of Mount Sharp. That data helped to determine the porosity of the rocks. The team also compared their results with mineral density estimates from Curiosity's chemistry and mineralogy instrument, which characterizes the crystalline minerals in rock samples using an X-ray beam. The team then compared its calculations to models of Mars' gravity fields to check their accuracy. These data were calibrated to filter out noise, such as the effects of temperature and the tilt of the rover during its climb. The researchers used more than 700 measurements from Curiosity's accelerometers, taken between October 2012 and June 2017. But this finding suggests they weren't buried by as much material as we thought." "We know the bottom layers of the mountain were buried over time. "The lower levels of Mount Sharp are surprisingly porous," said the study's lead author Kevin Lewis of Johns Hopkins University. As Curiosity ascends Mount Sharp, which it has been doing since 2014, the mountain tugs on the rover's sensors-but not as much as scientists expected. Using engineering data from the first five years of the Curiosity mission, the researchers measured the gravitational tug of Mars. Knowing the rover's orientation also allows engineers to point its instruments and multidirectional, high-gain antenna.īy happy coincidence, the rover's accelerometers can be used just like Apollo 17's gravimeter, because the accelerometers detect Mars' gravity whenever the rover stands still. Curiosity's sensors do the exact same thing but with far more precision, enabling the rover to navigate the Martian surface. Moving a smartphone allows these sensors to determine the phone's location and orientation. Either way, it seems that Mars has had the capability to lay down significant amounts of low-density sedimentary rocks that record a complex environmental history."Ĭuriosity carries accelerometers and gyroscopes just like a smartphone. "This could mean that Mount Sharp was not excavated by erosion, but rather was constructed by wind deposition and other processes. The low density of rocks in Gale Crater suggests that they did not undergo deep burial," Schmerr said. "This study represents the first gravity traverse and measurement of rock density on Mars. The findings call into question a competing theory that Gale Crater was once completely filled with sediment then later excavated by erosion, leaving only Mount Sharp behind. The results suggest that these rock layers are much less dense than scientists had predicted. This enabled the research team-which includes University of Maryland Geology Assistant Professor Nicholas Schmerr-to measure the subtle tug from rock layers on the lower slopes of Mount Sharp, a peak that rises more than 3 miles from the center of Gale Crater. In a research paper published Januin the journal Science, the researchers detail how they repurposed data from navigational sensors aboard NASA's Curiosity rover, essentially turning the sensors into gravimeters. Although there are no astronauts on Mars yet, a group of clever researchers here on Earth realized there is a buggy there-and it has just the right tools for similar experiments. view moreĪpollo 17 astronauts drove a moon buggy across the lunar surface in 1972, measuring subtle changes in gravitational pull with an instrument called a gravimeter. Researchers have used data from Curiosity’s navigational sensors to suggest a new explanation for the formation of Gale Crater and Mount Sharp. The rim of Gale Crater can be seen in the distance, on the left horizon in the image. Image: In this photo, NASA’s Curiosity rover pauses for a “selfie” on Vera Rubin Ridge, on the lower slopes of Mount Sharp-the peak of which can be seen directly behind Curiosity’s mast.
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