In colonial times, hard apple cider was put into big barrels and in the winter the liquid would partly freeze. “You’d crystallize out ice and you’d make more and more and more concentrated apple-flavored liquor,” Stolper said.

Magma inside a planet can undergo a similar process.

“You melt the interior and it comes to the surface and, just like the applejack, when you cool it, it crystallizes,” Stolper said, adding that it takes very particular conditions on Earth to produce this type of magma.

The rover meanwhile has moved on to testing and cleaning of its soil scoop. Eventually, scientists want to funnel soil samples to Curiosity’s onboard laboratory for more extensive chemical analysis.

The rover is part way to its first science target, an area known as Glenelg, which has three different types of rock intersecting.

The car-sized Curiosity rover landed inside a giant impact basin called Gale Crater, located near the Martian equator, for a two-year, $2.5 billion astrobiology mission, NASA’s first since the 1970s-era Viking probes.