NASA's Perseverance rover continues collecting Martian rocks.
The car-sized robot just snagged its fourth Red Planet rock sample, drilling another core from an intriguing stone that it first sampled a little over a week ago.
"A rock so nice, I sampled it twice! Just capped and sealed my fifth sample tube, with another piece from this interesting rock. I'm doubling up on samples at some high-priority targets like this one," Perseverance rover team members wrote Wednesday (Nov. 24) via the mission's official Twitter account, posting two photos of the sampling operation as well.
Perseverance landed in February on the floor of Mars' Jezero Crater, which hosted a big lake and a river delta billions of years ago. The rover is hunting for signs of ancient Mars life and collecting dozens of samples, which a joint NASA-European Space Agency campaign will haul to Earth, perhaps as early as 2031.
Perseverance has sealed five sample tubes to date, as the above tweet notes. But one of those tubes is empty: The first rock the robot tried to sample, back in August, proved to be exceptionally soft, crumbling to bits that didn't make it into the designated titanium tube.
The newly collected sample comes from the same rock that Perseverance drilled on Nov. 15. That stone is rich in the greenish mineral olivine, a magnesium iron silicate that makes up most of Earth's upper mantle.
"There are several ideas among my science team about how it got there. Hypotheses are flying! Science rules," the Perseverance team tweeted on Nov. 16, when it announced the successful collection of sample number three.
Perseverance may be millions of miles from its home planet, but it's not alone. The rover landed with a tiny robotic partner, a 4-pound (1.8 kilograms) helicopter named Ingenuity, which has demonstrated that aerial exploration is possible on Mars.
Ingenuity is now performing scouting work for Perseverance. The little chopper has racked up 16 Red Planet flights to date, the most recent of which took place on Sunday (Nov. 21).
Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or on Facebook.