1 October 2012

The Mars rover Curiosity finds an old riverbed on Mars

The rover Curiosity, which landed on Mars on the 6th of August, has found deposits formed in the Martian past by a fast moving stream of water with a depth between ankle and hip height.

Pebbles in the sandstones on mars

A large quantity of rounded pebbles in the sandstone deposits at
the bottom of the Gale Crater that shows that there was a fast
moving stream of water in the Martian past.

The proof that water once flowed swiftly at the rover’s landing site is a large amount of large, rounded stones in sandstone deposits on the bottom of the Gale Crater. The round and smooth shape of the stones show that they have been transported over significant distances and, since they are much too large to be moved by the wind, the transportation must have happed in a stream of water.

Images taken by probes in orbit around Mars show a river valley that cuts through the crater rim and ends in a fan-shaped deposit on the crater floor. The Curiosity rover has landed right on top of this fan-shaped deposit.

Researchers from the Niels Bohr Institute are participating in the project, both from the institute in Denmark and from the mission control centre at NASA’s Jet Propulsion Laboratory in California.

Carefully selected landing site

“Gale Crater was carefully selected as a landing site because we expected to find traces of a period in Mars’ distant past, when there was water on the planet in liquid form such as streams, rivers and lakes. This discovery spectacularly confirms that Mars was once wetter and warmer than the dry and cold desert planet we see today,” says researcher Kjartan Kinch.

Rover on Mars

The new results are based on images from the rover’s came-
ras. The researchers are looking forward to the rover’s other
instruments becoming operational and revealing the mineral
composition of the sandstone deposits.

Mars researchers have long studied images taken by probes in orbit around Mars for traces of past liquid water. Geological formations, such as river beds that are hundreds of kilometres long delta deposits, where the rivers flowed into the meteor craters, eroded mountains with river valleys and fan-shaped deposits like the one Curiosity studies, have long indicated that Mars went through a period in its early history when the planet was warmer, the atmosphere was thicker and the planet maintained a water cycle, similar to the Earth’s. However, there have been sceptical voices and alternative explanations for the observed geological formations.

“Curiosity’s new discoveries provide very, very solid support for the leading theory that river beds, delta sediments and the other traces that we see in many places on the surface of Mars really originate from liquid water at a time when Martian climate was very different from today,” says Kjartan Kinch.

The new results are based solely on images from the rover’s cameras. The researchers are looking forward to seeing what is revealed when the rover’s other instruments become operational and reveal the mineral composition of the distinctive sandstone deposits.

NASA’s Jet Propulsion Laboratory >>