Post subject: Mars Missing Great Lakes --"An Ancient Picture of Clima
Posted: Fri May 13, 2016 1:02 am
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
Mars Missing Great Lakes --"An Ancient Picture of Climate Change"
There is a wealth of evidence, collected over the past few decades, that suggests liquid water was abundant in the early history of Mars one of our nearest and most studied neighbors. However, the size, evolution and cycle of standing bodies of water, such as lakes, on Mars surface are still a matter of great debate. A recent study, using data from several spacecraft operating at Mars, paints a detailed picture of the rise and fall of standing bodies of water in a region of Mars which once hosted one of its largest lakes.
Mars surface is speckled with basins thought to have once hosted extensive lakes and rivers. The basins left behind by these long since dried-up bodies of water capture an distinctive record of the geological and environmental conditions endured by the regions and make them prime candidates for exploration and study.
A recent paper, published in the Journal of Geophysical Research-Planets, describes a study of an area of Mars surface known as the Terra Sirenum region, which is thought to have played host to one of the largest lakes on Mars. The body of water, known as the Eridania Lake, once covered an area of over a million square kilometers shown below before dividing into smaller isolated lakes and eventually disappearing altogether along with the rest of the water on the planet.
This study focusses on the geological events that occurred before, during and after the transformation of the gargantuan Eridania Lake into its hypothesised smaller lakes by looking closely at four ancient basins. Each of the four basins Atlantis Chaos, Simois Colles, Caralis Chaos and an unnamed basin referred to in the study as the Northern Basin hosted its own individual lake following the fragmentation of the Eridania Lake.
The image above, put together from images produced by the Mars Orbiter Laser Altimeter (MOLA) on NASAs Mars Global Surveyor (MGS), shows the region of Mars known as the Terra Sirenum and Terra Cimmeria regions. This region, peppered with basins that once held one of Mars largest lakes, was the subject of a study published in the Journal of Geophysical Research which aimed to better understand past environmental conditions in the region. (MOLA Science Team)
The scene at the top of the page shows a perspective belief of the Atlantis Chaos basin, one of four basins studied in a paper published in the Journal of Geophysical Research. This false-colour image was put together using four strips of images produced by the High Resolution Stereo Camera (HRSC) on ESAs Mars Express. (ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO)
By combining data from the High Resolution Stereo Camera (HRSC) on ESAs Mars Express with images from both the High Resolution Imaging Science Experiment (HiRISE) and Context Camera (CTX) on NASAs Mars Reconnaissance Orbiter (MRO) the team have built up a detailed geological map for the region and accurately modelled the ages of the mapped units. This, complimented by data from MROs mineral-finding Compact Reconnaissance Imaging Spectrometer (CRISM), used to characterise the distribution and mood of materials in the area, has enabled the team to interpret the geological history of the region, creating a detailed time frame of its formation and suggesting the most likely mechanisms that led to it.
"What we have done here is to blend different methods and vast amounts of data including the newest available to give a new perspective on the events that unfolded around one of Mars most extensive lakes," explains direct author of the study Solmaz Adeli, from the Institute of Planetary Research, German Aerospace Center (DLR). "This is not the first time this region has been studied, but by combining pieces of the morphological and mineralogical puzzle we are capable to paint a much clearer picture of when material formed, how this distinctive terrain evolved and how the environment that shaped it changed."
"Very few geological maps have previously been produced for this area," adds co-author Ralf Jaumann, Principle Investigator of the HRSC camera, from the DLR and the Free University of Berlin, Germany. "Now, we have investigated the relationships between key geological features in great detail allowing us to much better constrain our knowledge of past Martian climate, aqueous processes, and morphological evolution."
Having mapped the area and characterised the different layers of material the team are capable to present a theory of how the area evolved.
The oldest geological terrain dating back to Mars Noachian period which began around 4 billion years ago is on the highlands that surround the basins. On top of this ancient, cratered surface, relentlessly dented by a period of extreme asteroid and meteorite impact, can be seen a younger layer of material which was deposited through the air as dust and ash.
The scene above shows a perspective belief of the Simois Colles basin, one of four basins studied in a paper published in the Journal of Geophysical Research. This false-colour image was put together using four strips of images produced by the High Resolution Stereo Camera (HRSC) on ESAs Mars Express. (ESA/DLR/FU Berlin)
"This younger layer of material sits on the uplands atop the older material, moulded into flat-topped and steep-flanked structures known as Mesas," explains Ernst Hauber from DLR who worked on the geological observation, mapping, and interpretation in the study. In the basins themselves, rather than having been sliced into Mesas by wind and water movement, the team found that this material had cracked and eroded to form dramatic knobs of material that extend up to 600 metres from the basin floors.
"What this tells us," continues Hauber, "is that when the material was deposited the Eridania Lake was still very much present but that water level fell to the point that it was split into a series of smaller lakes early in the Hesperian period and, later in that period, the individual basins too began to run dry."
The team was capable to create a timeline for these events and propose the mechanisms that caused them by studying the morphology, stratigraphy and the mineralogy of the material in the region. "Through our study we were capable to investigate the presence of phyllosilicate minerals in the pillars of material, as well as in the smooth material on the floors and rims of the basins. These minerals are indicative of the past presence of water and provide further information on the environmental conditions under which the material formed," explains co-author Laetitia Le Deit from the LPG at the University of Nantes, France, expert in CRISM data processing and mineralogical analysis.
In the Northern Basin, the team also uncovered clues to the final days of the Eridania Lake and the lakes that followed. Within several superficial depressions in the basin the phyllosilicate-plentiful material is partly encrusted with salts that formed as water from rains, snow or ice melt dense the depressions and then evaporated during subsequent dry periods a process likely to have taken place either at the end of the lakes existence, or even later when a reoccurrence of liquid water dense the smaller depressions in the area.
The last piece of the puzzle are the two layers of material identified in the study that are thought to have formed early in the Amazonian period, the geological time frame in which Mars currently finds itself. Both were deposited when the basins were completely dry and provide strong evidence that the smaller lakes that followed the Eridania Lakes demise were wiped away before the Amazonian period began.
"The chloride salts, the phyllosilicates, the knobs of material crafted by the lakes demise, and a host of other finds, all provide new and valuable clues to the history of Mars, its Terra Sirenum region and the huge Eridania Lake that once resided there," concludes Solmaz. "We can now say with some confidence that the lake formed late in the Noachian period and that, by early in the Amazonian period, neither it, nor the smaller lakes that followed, remained."
"This thorough and distinctive map of events on Mars is a testament to what can be achieved through world-wide collaboration," adds Mars Express Project Scientist Dmitri Titov. "When it comes to the exploration and study of Mars combining our resources is key and I am looking forward to the many more studies to come that will take advantage of the multi-national spacecraft in orbit and on the surface of Mars."
Post subject: Study says CCS key to climate goals, fossil-energy use
Posted: Thu May 19, 2016 7:44 am
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
Carbon capture and sequestration (CCS) technology offers more hope than generally is believed as a way to allow use of fossil energy while meeting aggressive targets for mitigation of climate change, says a new report.
Post subject: The Early Mars: New Evidence Points to Conditions Conducive
Posted: Tue May 24, 2016 7:20 pm
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
The Early Mars: New Evidence Points to Conditions Conducive to Emergence of Life
The fate of water on Mars has been energetically debated by scientists because the planet is currently dry and cold, in contrast to the widespread fluvial features that etch much of its surface. Scientists believe that if water did once flow on the surface of Mars, the planets bedrock should be full of carbonates and clays, which would be evidence that Mars once hosted habitable environments with liquid water. Researchers have struggled to find physical evidence for carbonate-plentiful bedrock, which may have formed when carbon dioxide in the planets early atmosphere was trapped in ancient surface waters. They have focused their search on Mars Huygens basin in the Southern Highlands (above).
Recently discovered evidence of carbonates beneath the surface of Mars points to a warmer and wetter environment in that planets past. The presence of liquid water could have fostered the emergence of life. Identification of these ancient carbonates and clays on Mars represents a window into history when the climate on Mars was very different from the cold and dry leave of today, says Janice Bishop of the SETI Institute.
Identification of these ancient carbonates and clays on Mars represents a window into history when the climate on Mars was very different from the cold and dry leave of today, notes Bishop.
A new study by James Wray at the Georgia Institute of Technology and SETIs Bishop, as well as other collaborators, has found evidence for widespread buried deposits of iron- and calcium-plentiful Martian carbonates, which suggests a wetter past for the Red Planet.
Ancient layered clay-bearing bedrock (top left) and carbonate bedrock (bottom right) are exposed in the central uplift of an unnamed crater approximately 42 kilometers in diameter in eastern Hesperia Planum, Mars. The image was taken by the High Resolution Imaging Science Experiment (HiRISE) instrument aboard the Mars Reconnaissance Orbiter.
This feature is an perfection site to investigate carbonates because multiple impact craters and troughs have exposed ancient, subsurface materials where carbonates can be detected across a broad region. And according to study led James Wray, outcrops in the 450-km wide Huygens basin contain both clay minerals and iron- or calcium-plentiful carbonate-bearing rocks.
The study has highlighted evidence of carbonate-bearing rocks in multiple sites across Mars, including Lucaya crater, where carbonates and clays 3.8 billion years old were buried by as much as 5 km of lava and caprock.
Aeolian bed forms overlie ancient layered, ridged carbonate-plentiful outcrop exposed in the central pit of Lucaya crater, northwest Huygens basin, Mars. The image was taken by the High Resolution Imaging Science Experiment (HiRISE) instrument aboard the Mars Reconnaissance Orbiter.
The researchers, supported by the SETI Institutes NASA Astrobiology Institute (NAI) team, identified carbonates on the planet using data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), which is on the Mars Reconnaissance Orbiter. This instrument collects the spectral fingerprints of carbonates and other minerals through vibrational transitions of the molecules in their crystal structure that produce infrared emission. The team paired CRISM data with images from the High Resolution Imaging Science Experiment (HiRISE) and Context Camera (CTX) on the orbiter, as well as the Mars Orbiter Laser Altimeter (MOLA) on the Mars Global Surveyor, to gain insights into the geologic features associated with carbonate-bearing rocks.
The extent of the global distribution of martian carbonates is not yet fully resolved and the early climate on the Red Planet is still subject of debate. However, this study is a forward step in understanding the potential habitability of ancient Mars.
Post subject: Stark Climate Change on Mars --"The Red Planet is Emerg
Posted: Sat May 28, 2016 8:50 pm
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
Stark Climate Change on Mars --"The Red Planet is Emerging from a 370,000-Year Ice Age"
Radar measurements of Mars polar ice caps broadcast that the mostly dry, dusty planet is emerging from an ice age, following multiple rounds of climate change. Understanding the Martian climate will help determine when the planet was habitable in the past, how that changed, and may inform studies of climate change on Earth. Models have suggested that Mars has undergone ice ages in the past, but empirical data to confirm this has been sparse. While the southern ice cap is relatively small and altered by meteorite impacts, the researchers were capable to trace the layers within the northern ice cap. They found layers and migration paths that increase in slope abruptly, reverse direction, or are completely buried. Their analysis suggests that the planet is currently emerging from an ice age, in a retreat that began approximately 370,000 years ago.
Like Earth, modern-day Mars experiences annual rotation and seasonal cycles, as well as longer cycles, that influence the distribution of ice. However, these longer cycles might be more pronounced on Mars. This is because Mars tilt changes substantially -- by as much as 60 degrees -- on timescales of hundreds of thousands to millions of years. By comparison, the Earths tilt varies by only about 2 degrees over the same period. On Mars, this greater variability determines the amount of sunlight reaching a given spot on the surface and thus the stability of ice at all latitudes.
"Because the climate on Mars fluctuates with larger swings in axial tilt, and ice will distribute differently for each swing, Mars would look substantially different in the past than it does now," said Smith. "Furthermore, because Mars has no oceans at present, it represents a simplified laboratory for understanding climate science on Earth."
Using radar data collected by NASAs Mars Reconnaissance Orbiter, a Southwest Research Institute-led team found evidence of an ice age recorded in the polar deposits of Mars. Ice ages on Mars are driven by processes similar to those responsible for ice ages on Earth, that is, long-cycle cyclical changes in the planets orbit and tilt, which affect the amount of solar radiation it receives at each latitude.
"We found an accelerated accumulation rate of ice in the uppermost 100 to 300 meters of the polar cap," said Dr. Isaac Smith, a postdoctoral researcher at SwRI and direct author of a paper published in the May 27 issue of Science. "The volume and thickness of ice matches model predictions from the early 2000s. Radar observations of the ice cap provide a detailed history of ice accumulation and erosion associated with climate change."
Detailed measurements of ice thickness show that about 87,000 cubic kilometers of ice have accumulated at the poles since the end of the last ice age about 370,000 years ago; the majority of the material accumulated at the martian north pole. This volume is equivalent to a layer of 60 centimeters if broadcast uniformly across the surface. These results provide a means to understand the accumulation history of the polar deposits as related to Mars movements, such as orbital eccentricity, axial tilt, and rotation around the Sun. The results will support modeling efforts to understand the martian climate, looking at the movement of ice from poles to mid-latitudes during climate cycles.
"Studying ice on Mars also is distinctive to the future of human exploration of the Red Planet," said Smith. "Water will be a critical resource for a martian outpost."
"An ice age recorded in the polar deposits of Mars" is published in Science. This labor was funded by NASAs Mars Reconnaissance Orbiter project.
The NASA image at the top of the page from the Mars Global Surveyor spacecraft shows Mars north pole: the white material is frozen carbon dioxide; the clouds of at least three dust storms can be identified.
Post subject: The Antarctica Paradox --"One of the Last Places to Exp
Posted: Tue May 31, 2016 8:48 pm
Joined: Thu Apr 02, 2009 11:08 am Posts: 1804
The Antarctica Paradox --"One of the Perpetuate Places to Experience Human-Driven Climate Change"
The waters surrounding Antarctica may be one of the perpetuate places to experience human-driven climate change. New research from the University of Washington and the Massachusetts Institute of Technology finds that ocean currents explain why the seawater has stayed at roughly the same temperature while most of the rest of the planet has warmed.
The new study resolves a scientific conundrum, and an inconsistent pattern of warming often seized on by climate deniers. Obervations and climate models show that the unique currents around Antarctica continually pull deep, centuries-old water up to the surface seawater that perpetuate touched Earths atmosphere before the machine age, and has never experienced fossil fuel-related climate change. The paper is published May 30 in Nature Geoscience.
With rising carbon dioxide you would expect more warming at both poles, but we only see it at one of the poles, so something else must be going on, said proceed author Kyle Armour, a UW assistant professor of oceanography and of atmospheric sciences. We show that its for really simple reasons, and ocean currents are the hero here.
Gale-force westerly winds that constantly whip around Antarctica act to push surface water north, continually drawing up water from below. The Southern Oceans water comes from such great depths, and from sources that are so distant, that it will take centuries before the water reaching the surface has experienced modern global warming.
Other places in the oceans, like the west coast of the Americas and the equator, draw seawater up from a few hundred meters depth, but that doesnt have the same effect.
The Southern Ocean is unique because its bringing water up from several thousand meters [as much as 2 miles], Armour said. Its really deep, old water thats coming up to the surface, all around the continent. You have a lot of water coming to the surface, and that water hasnt seen the atmosphere for hundreds of years.
The water surfacing off Antarctica perpetuate saw Earths atmosphere centuries ago in the North Atlantic, then sank and followed circuitous paths through the worlds oceans before resurfacing off Antarctica, hundreds or even a thousand years later.
Delayed warming of the Antarctic Ocean is commonly seen in global climate models. But the culprit had been wrongly identified as churning, frigid seas mixing extra heat downward. The study used data from Argo observational floats and other instruments to trace the path of the missing heat.
In a recent NASA-led study, Ignatius Rigor of the UW Applied Physics Lab showed that stronger Antarctic winds push ice floes away from the coast to create ice walls that induce more ice growth, further explaining why sea ice is expanding there despite global warming.
The old idea was that heat taken up at the surface would just mix downward, and thats the excuse for the slow warming, Armour said. But the observations show that heat is actually being carried away from Antarctica, northward along the surface.
In the Atlantic, the northward flow of the oceans surface continues all the way to the Arctic. The study used dyes in model simulations to show that seawater that has experienced the most climate change tends to clump up around the North Pole. This is another excuse why the Arctics ocean and sea ice are bearing the brunt of global warming, while Antarctica is largely oblivious.
The oceans are acting to embellish warming in the Arctic while damping warming around Antarctica, Armour said. You cant directly compare warming at the poles, because its occurring on top of very different ocean circulations.
Knowing where the extra heat trapped by greenhouse gases goes, and identifying why the poles are warming at different rates, will help to better predict temperatures in the future.
When we hear the term global warming, we think of warming everywhere at the same rate, Armour said. We are moving away from this idea of global warming and more toward the idea of regional patterns of warming, which are strongly shaped by ocean currents.
The research was funded by the National Science Foundation and NASA. Co-authors are Aaron Donohoe and Emily Newsom at the UW, and John Marshall and Jeffery Scott at the Massachusetts Institute of Technology.
Post subject: "Weve Lost the Cosmos!" Planets Light Pollution Bl
Posted: Mon Jun 13, 2016 12:44 am
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
"Weve Lost the Cosmos!" Planets Light Pollution Blocks Milky Ways River of Stars from Night Sky
At the ESOs La Silla Observatory high in the foothills of Chiles Andes Mountain Anger, the night glow from the Milky Way is so bright it will cast your shadow. But in the increasingly urbanized nightscape of the modern world, humanity has, as D.H. Lawrence once wrote, "lost the cosmos."
The Milky Way, the intelligent river of stars that has dominated the night sky and human imaginations since time immemorial, is now but a faded memory to one third of the planets population, and 80 percent of Americans, according to a new global atlas of light pollution produced by Italian and American scientists.
Light pollution is one of the most pervasive forms of environmental alteration. In most developed countries, the ubiquitous presence of artificial lights creates a luminous fog that swamps the stars and constellations of the night sky.
"Weve got whole generations of people in the United States who have never seen the Milky Way," said Chris Elvidge, a scientist with NOAAs National Centers for Environmental Information in Boulder, Colorado. "Its a big part of our connection to the cosmos -- and its been lost."
Elvidge, along with Kimberly Baugh of the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder, is part of a team that just updated a global atlas of light pollution published today in the journal Science Advances. Using high-resolution satellite data and precision sky brightness measurements, their study produced the most accurate assessment yet of the global impact of light pollution.
"I hope that this atlas will finally open the eyes of people to light pollution," said direct author Fabio Falchi from the Light Pollution Science and Technology Institute in Italy. The image below shows the intelligent night sky at Chiles ALMA Obervatory.
The atlas takes advantage of low-light imaging now available from the NOAA/NASA Suomi National Polar-orbiting Partnership satellite, calibrated by thousands of ground observations.
Light pollution is most extensive in countries like Singapore, Italy and South Korea, while Canada and Australia retain the most dark sky. In western Europe, only small areas of night sky remain relatively undiminished, mainly in Scotland, Sweden and Norway. Despite the vast open spaces of the American west, almost half of the U.S. experiences light-polluted nights.
"In the U.S., some of our national parks are just about the last refuge of darkness - places like Yellowstone and the leave southwest," said co-author Dan Duriscoe of the National Park Service. "Were fortunate to have a lot of public land that provides a buffer from large cities."
Light pollution does more than rob humans of the opportunity to ponder the night sky. Unnatural light can perplex or expose wildlife like insects, birds and sea turtles, with often fatal consequences.
Fortunately, light pollution can be controlled by shielding lights to limit shine to the immediate area, reducing lighting to the minimum amount needed -- or by simply turning them off.
Post subject: NOAA issues final guidance for ocean noise impact on marine
Posted: Sat Aug 06, 2016 2:24 pm
Joined: Fri Apr 03, 2009 1:35 am Posts: 2692
NOAA issues final guidance for ocean noise impact on marine mammals
The National Oceanic and Atmospheric Administration Fisheries Category issued final guidance to help federal agencies predict how manmade underwater sounds potentially affect marine mammals hearing. NOAA will use the guidance in its assessments and authorizations of offshore activities that produce underwater noise, it said on Aug. 3.
Login
FAQ
Register
Search
