For the past two years, the seemingly unstoppable Mars rover, Opportunity, has traversed the Victoria crater on Mars, picking up clues about the Red Planet's wet and windy past. Now researchers - including two scientists from Washington University - have published a report on their findings, which bolster our knowledge about how water shaped Mars. The research was published last week in the journal Science. Steven Squyres, the principal investigator for NASA's Mars Rover mission, and his colleagues report that the pattern of sedimentary rocks inside the crater is similar to those within the Endurance crater. Opportunity explored that crater in 2004.
Mars may have had a wet, life-friendly past without ever getting warmer than the freezing point of water. So concludes a new study that investigates what would happen to various mineral solutions on Mars. Researchers found that solutions containing certain combinations of sulphur, silicon and other ions stay liquid even down to -28 °C - a much more plausible temperature for early Mars than one above 0 °C.
Using two cameras on the Mars Reconnaissance Orbiter (MRO) spacecraft, scientists based at the University of Arizona scoured Mars' surface for fresh meteorite craters. These natural excavations, tens of meters deep and as little as a month old, have revealed something bright and white that looks suspiciously like clean ice. At one crater, astronomers were even able to watch as the freshly exposed ice evaporated away over the course of a few months. The purity of the ice was the biggest surprise. Some believe it could be a relic of an ancient Martian ice age. Read more
Planetary geologists at Brown University, US, have found a gully fan system on Mars that formed about 1.25 million years ago, which shows tantalising signs of recent water activity on the Red Planet. The fan offers compelling evidence that it was formed by melt water that originated in nearby snow and ice deposits and may stand as the most recent period when water flowed on the planet.
Scientists at the Tucson-based Planetary Science Institute (PSI) have found further evidence for the large role that water has likely played in shaping the Martian landscape. Their results, which will be published in "Icarus" (search doi:10.1016/j.icarus.2008.10.026), provide strong evidence that multiple wet and/or icy climate cycles have shaped the topography of the planet's large craters. "Icarus" is the journal of the American Astronomical Society's Division of Planetary Sciences.
"Studying crater degradation in potentially ice-rich environments is vital to understanding the geology of craters and their surroundings, as well as for determining whether the ice comes from the atmosphere or from below the ground" - Daniel Berman, a PSI associate research scientist and lead author of the paper.
High in the sky above Mars, it is snowing right now. Very gently snowing. The snow does not settle on the rubble-strewn land below - not these days, anyway - but instead vaporises into the thin atmosphere long before it reaches the ground. The first flakes of snow, on a planet that until fairly recently was believed to be waterless, were spotted just a few months ago. A Nasa lander near the planet's north pole was scanning the sky with a laser when it noticed the telltale signs of snowfall. The probe, called Phoenix, announced the news in a radio signal that was picked up by an overhead orbiter and beamed back to Earth. Nothing like it had ever been seen before.
Stone circles on Mars are prompting a rethink about the planet's ancient climate. Using cameras on NASA's Mars Reconnaissance Orbiter, Matt Balme of the Open University in Milton Keynes, UK, and his colleagues mapped the Elysium Planitia, a region near the equator. They saw rings up to 23 metres across made up of stones sorted by size into concentric bands. On Earth, similar structures form via repeated freezing and thawing of ice, but with the stones sorted into layers. Water in soil under stones freezes faster than in surrounding soil, and the expanding ice pushes the stones upwards. Larger stones rise faster, and so layers sorted by size form.
Ice glaciers hundreds of metres deep are lurking just underneath the Martian surface around the planet's mid-latitudes, new radar measurements suggest. The discovery represents the largest cache of ice yet found beyond Mars's polar regions and bolsters the case that the planet's tilt changes periodically. The ice could also be an ideal place to study the ancient Martian climate and look for evidence of life. The glaciers, found at latitudes between 30 and 60° in both the northern and southern hemispheres, sit underneath fields of rocky debris. The appearance of the landscape suggests the debris flowed from hills lying up to 20 kilometres away.
Gamma-Ray Evidence Suggests Ancient Mars Had Oceans An international team of scientists who analysed data from the Gamma Ray Spectrometer onboard NASA's Mars Odyssey reports new evidence for the controversial idea that oceans once covered about a third of ancient Mars. Mars Odyssey's GRS, or Gamma Ray Spectrometer, led by William Boynton of UA's Lunar and Planetary Laboratory, has the unique ability to detect elements buried as much as 1/3 meter, or 13 inches, below the surface by the gamma rays they emit. That capability led to GRS' dramatic 2002 discovery of water-ice near the surface throughout much of high-latitude Mars.
NASA finds evidence of a wetter Mars The U.S. space agency says its Mars Reconnaissance Orbiter has found evidence that liquid water remained on Mars far longer than previously theorised. The National Aeronautics and Space Administration spacecraft has observed hydrated silica, or opal, spread across large regions of Mars. That, scientists said, suggests liquid water was on the planet's surface as recently as 2 billion years ago.