On Mars right now, the Curiosity rover is sifting and testing grains of sand to learn their mineral and chemical composition at a place called "Rock Nest" in the Gale Crater.

For the testing, Curiosity is using a shoe-box sized device called a CheMin, a chemistry and mineralogy instrument designed by David Blake, a geologist and exobiologist working at at NASA's Ames Research Center in Mountain View.

KQED's Cy Musiker spoke with Blake about what the rover is finding now and what it will be looking for.