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Geological map points to ancient seas on Mars
Posted: 9 June 2010

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A geological map, created using data from a plethora of orbiting spacecraft, presents new evidence that lakes persisted early in Mars' history.

The map focuses on Hellas Planitia, an area located in the planet's southern hemisphere that is well known for its giant impact basin – the Hellas basin – which spans over 2,000 kilometres in diameter and plunges to a depth of eight kilometres.

A new geological map of the Hellas Planitia region supports the idea that Mars once hosted large bodies of standing water. Click here for the full map and key. Image: USGS.

Finely layered outcrops of sedimentary deposits seen in the eastern rim of Hellas point to large areas of standing water, such as lakes or seas. Deposits of sedimentary rocks suggest erosion and transport of material from higher to lower ground. Indeed, the highlands surrounding Hellas are well known to have hosted volcanic activity and sedimentary processes over time.

Using data from Viking Orbiter, Mars Odyssey's Thermal Emission Imaging System (THEMIS), Mars Orbiter's narrow-angle camera and the Mars Orbiter Laser Altimeter topographic data, planetary geologists could piece together the geological history of the area.

“This mapping makes geologic interpretations consistent with previous studies, and constrains the timing of these putative lakes to the early-middle Noachian period on Mars, between 4.5 and 3.5 billion years ago,” says Leslie Bleamaster, research scientist at the Planetary Science Institute.

This topographic map of Mars shows the giant Hellas basin (right hand image, lower left) in context of the whole planet. Image: MOLA team, NASA.

Moreover, scrutinizing high-resolution images revealed that the eastern area of Hellas Planitia, where the fine-layered floor deposits were discovered, is unique in nature. It is interpreted as the meeting point of sedimentary sources, and sedimentary sinks – the locations where sediments derived from elsewhere are deposited .

“Our mapping and evaluation of landforms and materials of the Hellas region from the basin rim to floor provides further insight into Martian climate regimes and into the abundance, distribution, and flux of volatiles through history,” says Bleamaster.

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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