* Astronomy

Blobrana · L

RE: Mars - more water

Blobrana · L

River deltas hint at ancient Martian ocean

Similar heights of channel mouths suggest they fed into one body of water.

Planetary geologists in the United States have analysed data that suggest Mars was once home to a huge ocean of water, covering nearly one-third of its surface. Their evidence, a ring of dry river deltas and valleys all at a similar elevation, adds weight to the idea that the red planet once supported an Earth-like water cycle.
Hints that an ocean once occupied the northern lowlands of ancient Mars first arose in the late 1980s. Scientists examining pictures of the surface claimed to recognize extensive shorelines and vast networks of river valleys and outflow channels feeding in the same direction. Other researchers used thermal physics to imply that such networks could only have been carved by a complete water cycle, fuelled by one or more huge bodies of water.
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Mars rover finds conditions 'more conducive to life'

More than four years after they were gathered, hard-to-interpret data from the Mars rover Spirit have finally been cracked. They reveal carbonate minerals to be a major component of a rock formation known as Comanche in the Columbia Hills region of the Gusev Crater.

"The discovery is significant, because of the intimate connection between the formation of carbonates and persistent liquid water" - Oded Aharonson, a planetary scientist at the California Institute of Technology in Pasadena.

That connection helps to solidify the view that Mars was once warm, wet and perhaps capable of supporting life.

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Blobrana · L

Mars minerals point to warmer and wetter past

The Red Planet harbours rocks rich in carbonate minerals, suggesting there was more water there in the past than previously thought, say scientists.
Nasa's Mars Exploration Rover Spirit detected the carbonate-rich rocks in the Columbia Hills of Gusev Crater.
This was in 2005, but Martian dust had partially blinded one of the rover's instruments, clouding the data.
The team described in Science journal how they calibrated the instrument to "remove the effects of the dust".
Nasa scientist Richard Morris, from the Johnson Space Centre in Houston, led the research. He said that the rocks, which are about 25% carbonate by weight, contain about 10 times more carbonate than had previously been detected in the planet's rocks.
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Blobrana · L

Martian water most likely flowed as slurries of mud rather than trickling streams, according to a recent NASA report.
The report, which compared signs of recent water activity in gullies on Mars with similar deposits on Earth, has implications for searching for evidence of water on the red planet. It could also indicate whether Mars has had liquid water within the last decade.
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A series of meteor strikes on Mars have uncovered pure water ice - and maybe liquid water - in the red planet's relatively balmy mid-latitudes.
Sharp-eyed spacecraft discovered the ice when several meteors slammed into Mars's surface and created five craters some 0.5 to 2.5 metres deep and 8 metres in diameter.
A single meteor shower created the craters, which revealed bright blue ice that vaporised in about 200 days.

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Blobrana · L

Patterns in Mars crater floors give picture of drying lakes
Networks of giant polygonal troughs etched across crater basins on Mars have been identified as desiccation cracks caused by evaporating lakes, providing further evidence of a warmer, wetter martian past. The findings were presented today at the European Planetary Science Congress by PhD student Mr M Ramy El Maarry of the Max Planck Institute for Solar System Research.
The polygons are formed when long cracks in the surface of the martian soil intersect. El Marry investigated networks of cracks inside 266 impact basins across the surface of Mars and observed polygons reaching up to 250 metres in diameter. Polygonal troughs have been imaged by several recent missions but, until now, they have been attributed to thermal contractions in the martian permafrost. El Maarry created an analytical model to determine the depth and spacing of cracks caused by stresses building up through cooling in the martian soil. He found that polygons caused by thermal contraction could have a maximum diameter of only about 65 metres, much smaller than the troughs he was seeing in the craters.

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Blobrana · L

A new hypothesis has suggested that Mars may have a water table hidden underground, despite satellite data suggesting otherwise.
Today the small amount of water detected on the planet is locked in the polar ice caps, but recently discovered geological features suggest liquid water once flowed on its surface.
This could now be hiding beneath the rocky crust.

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New instrument has potential to detect water deep underground on Mars
With the whoosh of compressed gas and the whir of unspooling wire, a team of Boulder scientists and engineers tested a new instrument prototype that might be used to detect groundwater deep inside Mars.
The Mars Time Domain Electromagnetic Sounder (MTDEM) uses induction to generate electrical currents in the ground, whose secondary magnetic fields are in turn detected at the planetary surface. In this way, the electrical conductivity of the subsurface can be reconstructed.

"Groundwater that has been out of atmospheric circulation for eons will be very salty. It is a near-ideal exploration target for inductive systems" - Dr. Robert Grimm, the project's principal investigator, a director in the Space Science and Engineering Division at Southwest Research Institute.

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Mars Orbiter finds 50km canyon and evidence of ancient lake
The discovery of a deep canyon and beaches on Mars could be the best evidence to date of an ancient lake that existed after the planet had already supposedly dried up.
Images from the High Resolution Imaging Science Experiment (HiRISE) riding aboard NASA's Mars Reconnaissance Orbiter indicate water carved a 50km-long canyon that would have covered 200 sq km and been up to 450m deep, a team at the University of Colorado at Boulder reported in the journal Geophysical Research Letters.

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