NASA Rover results include first age-measurement on Mars, and helps human exploration

January 13th, 2014, Published in Articles: EngineerIT

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 age of “Cumberland”

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 is on another planet. A report by Kenneth Farley of the California Institute of Technology (Caltech) 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.

The age is not surprising, but what is surprising is that this method worked using measurements performed on Mars. “When you’re confirming a new methodology, you don’t want the first result to be something unexpected. Our understanding of the antiquity of the Martian surface seems to be right.”

The analysis of Cumberland from a sample drilled by Curiosity was a fundamental and unprecedented measurement considered unlikely when the rover landed in 2012. Farley and his co-authors adapted a 60-year-old radiometric method for dating Earth rocks that measures the decay of an isotope of potassium as it slowly changes into argon, an inert gas. Argon escapes when a rock is melted. This dating method measures the amount of argon that accumulates when the rock hardens again.

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. Combined with clues of wind erosion, Curiosity observed, the exposure-age discovery points to a pattern of windblown sand chewing away at relatively thick layers of rock. The eroding layer forms a retreating vertical face, or scarp.

“The exposure rate is surprisingly fast,” Farley said. “The place where you’ll find the rocks with youngest exposure age will be right next to the downwind scarps.”

Related Articles

  • Charging electric cars is not without its challenges
  • Half-brick 150 W DC-DC converters
  • Engineer@Leisure – Steaming into history
  • Quality inspection for food and beverage packaging
  • Telecoms developments in Africa – February 2019