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NASA Mars Orbiters See Clues To Possible Water Flows
Image credit: NASA/JPL-Caltech/UA/JHU-APL
NASA spacecraft orbiting Mars have returned clues for understanding seasonal features that are the strongest indication of possible liquid water that may exist today on the Red Planet.
The features are dark, finger-like markings that advance down some Martian slopes when temperatures rise. The new clues include corresponding seasonal changes in iron minerals on the same slopes and a survey of ground temperatures and other traits at active sites. These support a suggestion that brines with an iron-mineral antifreeze, such as ferric sulfate, may flow seasonally, though there are still other possible explanations.
Researchers call these dark flows “recurring slope lineae.” As a result, RSL has become one of the hottest acronyms at meetings of Mars scientists.
“We still don’t have a smoking gun for existence of water in RSL, although we’re not sure how this process would take place without water,” said Lujendra Ojha, a graduate student at the Georgia Institute of Technology, Atlanta,
NASA Mars Spacecraft Reveals A More Dynamic Red Planet
NASA’s Mars Reconnaissance Orbiter has revealed to scientists slender dark markings — possibly due to salty water – that advance seasonally down slopes surprisingly close to the Martian equator.
“The equatorial surface region of Mars has been regarded as dry, free of liquid or frozen water, but we may need to rethink that,” said Alfred McEwen of the University of Arizona in Tucson, principal investigator for the Mars Reconnaissance Orbiter (MRO) High Resolution Imaging Science Experiment (HiRISE) camera.
Tracking how these features recur each year is one example of how the longevity of NASA orbiters observing Mars is providing insight about changes on many time scales. Researchers at the American Geophysical Union meeting Tuesday in San Francisco discussed a range of current Martian activity, from fresh craters offering glimpses of subsurface ice to multi-year patterns in the occurrence of large, regional dust storms.
Mars Crater May Actually Be Ancient Supervolcano
Credit: NASA/JPL/GSFC
A research project led by Joseph R. Michalski, Senior Scientist at the Planetary Science Institute, has identified what could be a supervolcano on Mars – the first discovery of its kind. In a paper published Oct. 3 in the journal Nature, Michalski and co-author Jacob E. Bleacher of NASA Goddard Space Flight Center describe a new type of volcanic construction on Mars that until now has gone unrecognized.
The volcano in question, a vast circular basin on the face of the Red Planet, previously had been classified as an impact crater. Researchers now suggest the basin is actually the remains of an ancient supervolcano eruption. Their assessment is based on images and topographic data from NASA’s Mars Odyssey, Mars Global Surveyor and Mars Reconnaissance Orbiter spacecraft, as well as the European Space Agency’s Mars Express orbiter.
“On Mars, young volcanoes have a very distinctive appearance that allows us to identify them,” Michalski said. “The long-standing question has been what ancient volcanoes on Mars look like. Perhaps they look like this one.”
NASA Helps See Buried Mars Flood Channels In 3-D
NASA’s Mars Reconnaissance Orbiter has provided images allowing scientists for the first time to create a 3-D reconstruction of ancient water channels below the Martian surface.
The spacecraft took numerous images during the past few years that showed channels attributed to catastrophic flooding in the last 500 million years. During this period, Mars had been otherwise considered cold and dry. These channels are essential to understanding the extent to which recent hydrologic activity prevailed during such arid conditions. They also help scientists determine whether the floods could have induced episodes of climate change.
“Our findings show the scale of erosion that created the channels previously was underestimated and the channel depth was at least twice that of previous approximations,” said Gareth Morgan, a geologist at the National Air and Space Museum’s Center for Earth and Planetary Studies in Washington and lead author on the paper. “This work demonstrates the importance of orbital sounding radar in understanding how water has shaped the surface of Mars.”
Full Story: http://www.jpl.nasa.gov/news/news.php?release=2013-087
Ridges On Mars Suggest Ancient Flowing Water
Credit: NASA Mars Reconnaissance Orbiter
Networks of narrow ridges found in impact craters on Mars appear to be the fossilized remnants of underground cracks through which water once flowed, according to a new analysis by researchers from Brown University.
The study, in press in the journal Geophysical Research Letters, bolsters the idea that the subsurface environment on Mars once had an active hydrology and could be a good place to search for evidence of past life. The research was conducted by Lee Saper, a recent Brown graduate, with Jack Mustard, professor of geological sciences.
The ridges, many of them hundreds of meters in length and a few meters wide, had been noted in previous research, but how they had formed was not known. Saper and Mustard thought they might once have been faults and fractures that formed underground when impact events rattled the planet’s crust. Water, if present in the subsurface, would have circulated through the cracks, slowly filling them in with mineral deposits, which would have been harder than the surrounding rocks. As those surrounding rocks eroded away over millions of years, the seams of mineral-hardened material would remain in place, forming the ridges seen today.
Full Story: http://news.brown.edu/pressreleases/2013/01/marswater
Thawing ‘Dry Ice’ Drives Groovy Action On Mars
Image Credit: NASA/JPL-Caltech/Univ. of Arizona
Researchers using NASA’s Mars Reconnaissance Orbiter see seasonal changes on far-northern Martian sand dunes caused by warming of a winter blanket of frozen carbon dioxide.
Earth has no naturally frozen carbon dioxide, though pieces of manufactured carbon-dioxide ice, called “dry ice,” sublime directly from solid to gas on Earth, just as the vast blankets of dry ice do on Mars. A driving factor in the springtime changes where seasonal coverings of dry ice form on Mars is that thawing occurs at the underside of the ice sheet, where it is in contact with dark ground being warmed by early-spring sunshine through translucent ice. The trapped gas builds up pressure and breaks out in various ways.
Transient grooves form on dunes when gas trapped under the ice blanket finds an escape point and whooshes out, carrying out sand with it. The expelled sand forms dark fans or streaks on top of the ice layer at first, but this evidence disappears with the seasonal ice, and summer winds erase most of the grooves in the dunes before the next winter. The grooves are smaller features than the gullies that earlier research linked to carbon-dioxide sublimation on steeper dune slopes.
Full Story: http://www.jpl.nasa.gov/news/news.php?release=2013-034
Also: http://www.psi.edu/news/press-releases#marscotwo
Groundwater-Fed Martian Lake Could Contain Clues To A Subsurface Biosphere
Image Credit: NASA/JPL-Caltech/Univ. of Arizona
The subsurface environment on Mars may hold clues to the origin of life, scientists argue in a recently published research article led by Planetary Science Institute’s Joseph Michalski. A large fraction of the life on Earth may exist as microbes deep underground on our home planet. The same could have been true in the past on Mars.
“Recent results produced by several authors using data from the Compact Reconnaissance Imaging Spectrometer for Mars instrument aboard NASA’s Mars Reconnaissance Orbiter have shown that the subsurface of Mars was widely altered by subsurface water” Michalski said. “Here, we argue that all of the ingredients for life existed in the subsurface, and it may have been the most habitable part of Mars.”
Full Story: http://www.psi.edu/news/press-releases#michalskilake
Also: http://www.jpl.nasa.gov/news/news.php?release=2013-028
Images: http://www.psi.edu/news/press-releases/michalski_012013
NASA Observations Point To ‘Dry Ice’ Snowfall On Mars
NASA’s Mars Reconnaissance Orbiter data have given scientists the clearest evidence yet of carbon-dioxide snowfalls on Mars. This reveals the only known example of carbon-dioxide snow falling anywhere in our solar system.
Frozen carbon dioxide, better known as “dry ice,” requires temperatures of about minus 193 degrees Fahrenheit (minus 125 Celsius), which is much colder than needed for freezing water. Carbon-dioxide snow reminds scientists that although some parts of Mars may look quite Earth-like, the Red Planet is very different. The report is being published in the Journal of Geophysical Research.
“These are the first definitive detections of carbon-dioxide snow clouds,” said the report’s lead author, Paul Hayne of NASA’s Jet Propulsion Laboratory in Pasadena, Calif. “We firmly establish the clouds are composed of carbon dioxide — flakes of Martian air — and they are thick enough to result in snowfall accumulation at the surface.”
Full Story: http://www.jpl.nasa.gov/news/news.php?release=2012-286
Mars’s Dramatic Climate Variations Are driven By The Sun
Image Credit: NASA/JPL/UA
The ice caps on Mars’s poles are kilometres thick and composed of ice and dust. There are layers in the ice caps, which can be seen in cliffs and valley slopes and we have known about these layers for decades, since the first satellite images came back from Mars. The layers are believed to reflect past climate on Mars, in the same way that the Earth’s climate history can be read by analysing ice cores from the ice caps on Greenland and Antarctica.
Solar insolation on Mars has varied dramatically over time, mainly due to large variations in the tilt of Mars’s rotational axis (obliquity) and this led to dramatic climate variations on Mars. For years people have tried to link the solar insolation and layer formation by looking for signs of periodic sequences in the visible layers, which can be seen in the upper 500 meters. Periodic signals might be traceable back to known variations in the solar insolation on Mars, but so far it has been unclear whether one could find a correlation between variations in insolation and the layers.
“Here we have gone in a completely different direction. We have developed a model for how the layers are built up based on fundamental physical processes and it demonstrates a correlation between ice and dust accumulation and solar insolation, explains Christine Hvidberg, a researcher in ice physics at the Centre for Ice and Climate at the Niels Bohr Institute at the University of Copenhagen.
Full Story: http://www.nbi.ku.dk/english/news/news12/marss-dramatic-climate-variations-are-driven-by-the-sun/
Exhumed Rocks Reveal Mars Water Ran Deep
By studying rocks blasted out of impact craters, ESA’s Mars Express has found evidence that underground water persisted at depth for prolonged periods during the first billion years of the Red Planet’s existence.
Impact craters are natural windows into the history of planetary surfaces – the deeper the crater, the further back in time you can probe.
In addition, rocks blasted out during the impact offer a chance to study material that once lay hidden beneath the surface.
Full Story: http://www.esa.int/export/esaSC/SEMKT91VW3H_index_0.html
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