Curiosity gets a gravimeter--repurposed instruments can now measure rock density
The Curiosity rover landed on Mars without a gravimeter on board. But researchers realized that its accelerometers--normally used to determine the position of the rover--could be repurposed to measure the density of the rock it was passing over. These measurements can help scientists understand how Gale Crater and Mt. Sharp came to be.
Read the paper: http://science.sciencemag.org/content/363/6426/535