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Orbiter discovers evidence of primordial ocean on Mars
Posted: 08 February 2012

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The radar on Europe's Mars Express orbiter detected sediments beneath the red planet's surface strongly indicative of an ocean floor that formed billions of years ago, scientists announced this week.

Artist's concept of the Mars Express orbiter at Mars. The thin booms visible in this image are part of the MARSIS radar instrument. Credit: ESA
The sediments could have been deposited by an ocean 4 billion years ago, when Mars was warmer and supported abundant liquid water, according to researchers.

Another scenario involves a temporary sea that formed when a large comet or asteroid struck Mars, melting subsurface ice and creating outflow channels draining the water into a giant basin.

The material was discovered by the MARSIS radar on Mars Express.

Jeremie Mouginot, a researcher at the Institut de Planetologie et d'Astrophysique de Grenoble in France and the University of California, Irvine, and colleagues analyzed more than two years of data and found that the northern plains of Mars are covered in low-density material.

"We interpret these as sedimentary deposits, maybe ice-rich," Mouginot said. "It is a strong new indication that there was once an ocean here."

Imagery from satellites circling Mars have shown formations resembling ancient shorelines before, but scientists using Mars Express may have found the floor of a primordial ocean.

"Previous Mars Express results about water on Mars came from the study of images and mineralogical data, as well as atmospheric measurments," said Olivier Witasse, ESA's Mars Express project scientist. "Now we have the view from the subsurface radar. This adds new pieces of information to the puzzle, but the question remains: where did all the water go?"

Analysis of radar data from the MARSIS instrument can reveal the density of material up to 200 feet beneath the Martian surface. The material thought to be evidence of an ancient ocean shows low radar reflectivity, and such sediments are usually granular and have a low density, according to the European Space Agency.

"This work provides some of the best evidence yet that there were once large bodies of liquid water on Mars and is further proof of the role of liquid water in the Martian geological history," an ESA statement said.

The Planets
From tiny Mercury to distant Neptune and Pluto, The Planets profiles each of the Solar System's members in depth, featuring the latest imagery from space missions. The tallest mountains, the deepest canyons, the strongest winds, raging atmospheric storms, terrain studded with craters and vast worlds of ice are just some of the sights you'll see on this 100-page tour of the planets.

Hubble Reborn
Hubble Reborn takes the reader on a journey through the Universe with spectacular full-colour pictures of galaxies, nebulae, planets and stars as seen through Hubble's eyes, along the way telling the dramatic story of the space telescope, including interviews with key scientists and astronauts.

3D Universe
Witness the most awesome sights of the Universe as they were meant to be seen in this 100-page extravaganza of planets, galaxies and star-scapes, all in 3D!


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