Scientists working with the Curiosity Rover used a piece of navigation equipment – an accelerometer like the one in their mobile phone – to make a device important about the mysterious geology of Mars.
Curiosity is currently moving around Mount Sharp, a 5 km high mountain in the center of Gale Crater. However, it is unclear whether the mountain is the result of a once-filled crater and matter loses in erosion or whether the mountain is more like a large dune of deposited material. Curiosity has no scientific instrument to determine the nature of the mountain – but it has a force-sensing navigation equipment. That's how the scientists got creative.
"I realized that you could download an app to your phone, and not with great precision, but you can measure [the force of Earth’s gravity] because your phone has accelerometers," said lead author Kevin Lewis, assistant professor at Johns Hopkins University Gizmodo. He thought he could do the same with Curiosity's accelerometers and do some interesting science.
Gravimetry or the accurate measurement of changes in the local gravitational field is a useful way to understand the subsurface rocks because the force of an object is from an object. Gravity increases with mass. For example, Apollo 17 had a gravimetric experiment to study the moon – but Curiosity does not have a gravimeter. However, it has a navigation system that includes gyroscopes and an accelerometer to measure speed, acceleration and orientation changes.
The navigation system is not quite as sensitive as a gravimeter, but the scientists did. They collected the data on the accelerations experienced by the rover and then adjusted them to take into account the position of Curiosity on Mars and the possible effects of temperature and altitude on the equipment.
Their analysis revealed a surprise: The average density of rocks under Curiosity was lower than expected. This implied that the dirt was much more porous, meaning that it had more holes than the scientists expected. They could further conclude that the sediment would not be very deep, otherwise it would be more compact or filled.
All these points together seem to indicate that the Mount Sharp was not the result. Erosion creates a high peak, which instead has formed by sediment bubbles in the already formed crater, resulting in a huge deposit, as in the article published today in Science
. "My first impression was that it is a skilful trick for the technology. Use on-board instruments that were not designed as scientific instruments to actually do science," said Kirsten Siebach, Marsgeologist and Assistant Professor at Rice University , opposite Gizmodo. She found that the porosity value of the rocks was surprisingly high. She said the work appeared to confirm some earlier observations of the Gale crater, but contradicts others.
"This urges us to better understand how low-porosity rocks behave on Mars," she said.
Measurements such as these have inherent limitations, e.g. For example, introducing potential distortions in trying to figure out which data to use and uncertainties when using an instrument for a task it is not intended to do.
However, this is the science, and the article reveals new information that lets us know what's really going on in the crater and should be considered alongside other experiments, simulations, and data. And there are more experiments to provide evidence: Mars InSight will be able to tell scientists more about the geology of the planet, based on the way heat flows through the planet, while Mars 2020 will have ground radar for underground information Collect At his landing pad, the Jezero Crater.
It's not the first time that scientists have used navigation devices to run science – but this is a particularly ingenious one.
Lewis said, "One of the things I really have. The love of this study is that it's my kind of science to find new ways to use existing data and create a brand new scientific tool. "