NASA’s Curiosity rover is providing vital insight about Mars’ past and current environments that will aid plans for future robotic and human missions.
In a little more than a year on the Red Planet, the mobile Mars Science Laboratory has determined the age of a Martian rock, found evidence the planet could have sustained microbial life, taken the first readings of radiation on the surface, and shown how natural erosion could reveal the building blocks of life.
The second rock Curiosity drilled for a sample on Mars, which scientists nicknamed “Cumberland,” is the first ever to be dated from an analysis of its mineral ingredients while it sits on another planet. A report by Kenneth Farley of the California Institute of Technology in Pasadena, and co-authors, estimates the age of Cumberland at 3.86 billion to 4.56 billion years old. This is in the range of earlier estimates for rocks in Gale Crater, where Curiosity is working.
Before they could measure rocks directly on Mars, scientists estimated their ages by counting and comparing the numbers of impact craters on various areas of the planet. The crater densities are correlated with ages based on comparisons with crater densities on the Moon, which were tied to absolute dates after the Apollo lunar missions returned rocks to Earth.
Farley and co-authors also assessed how long Cumberland has been within about an arm’s reach of the Martian surface, where cosmic rays that hit atoms in the rock produce gas buildups that Curiosity can measure. Analyses of three different gases yielded exposure ages in the range of 60 million to 100 million years. This suggests shielding layers above the rock were stripped away relatively recently.