Mars rover samples what could be one of the oldest rocks on the Martian surface

For the first time in over a year, NASA's Perseverance rover has collected a sample on Mars. On Oct. 24, the rover drilled a new sample called "Singita," which may be roughly as ancient as the oldest rocks preserved on the surface of Earth. 

"It could be among the oldest rocks exposed on the surface of Mars," said Katie Stack Morgan, project scientist for Perseverance, at the American Astronomical Society's Division of Planetary Sciences conference, where the new sample was first announced.

According to Stack Morgan, the rock that Singita was drilled from was likely buried about 1 kilometer (0.6 miles) deep in the Martian crust at one point, but was later thrown to the surface by the impact of an asteroid or comet, or multiple impacts over time. 

Perseverance took the sample in the Lac de Charmes region of Mars, outside the rim of Jezero crater where the rover originally landed five years ago. Since Jezero was originally formed by a giant impact about 3.9 billion years ago (give or take), scientists did not expect to find rocks older than that within the crater. Singita, as the first sample of a crystalline igneous rock that the rover has taken outside the crater, is likely at least as old as Jezero and could be several hundred million years older. The rock Singita is from could also be a fragment of the impact that formed the Isidis Basin, which is one of the largest impact basins on Mars, or it could even predate that basin. However, there's no way to know the rock's exact age without bringing the sample back to Earth.

According to Stack Morgan, after more than a year without collecting a sample, Perseverance actually almost failed to drill Singita. The rock was so hard that the team's first attempt to drill a core failed, and the rover had to switch to a different, less-used drill bit before it succeeded.

Given the potential scientific importance of the sample, Stack Morgan said that Perseverance will stay in this region and attempt to collect two more samples, including one from a different, younger crystalline igneous rock.