geology of mars

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Evidence of Martian life could be hard to find in some meteorite blast sites

Scientists in their preliminary findings suggest signs of life from under Mars’ surface may not survive in rocks excavated by some meteorite impacts.

Scientists analysing samples from Mars’ surface have so far not conclusively detected organic compounds that are indigenous to Mars, which would be indicators of past or present life. The inconclusive results mean that researchers are now suggesting that a good place to find these organic compounds would be deep underground - from rocks that have been blasted to the surface by meteor impacts. This is because such rocks have been sheltered from the Sun’s harmful radiation and from chemical processes on the surface that would degrade organic remains.

Now, a team of scientists from Imperial College London and the University of Edinburgh has replicated meteorite blasts in the lab. The aim of the study was to see if organic compounds encased in rock could survive the extreme conditions associated with them being blasted to the surface of Mars by meteorites. The study, published today in Scientific Reports, suggests that rocks excavated through meteorite impacts may incorrectly suggest a lifeless early Mars, even if indicators of life were originally present.

In the study the team replicated blast impacts of meteorites of around 10 metres in size. The researchers found that the types of organic compounds found in microbial and algal life - long chain hydrocarbon-dominated matter- were destroyed by the pressures of impact. However, the types of organic compounds found in plant matter - dominated by aromatic hydrocarbons - underwent some chemical changes, but remained relatively resistant to impact pressures. Meteorites often contain organic matter not created by life, which have some similarities in their organic chemistry to land plants. The team infer that they also should also be resistant to blast impacts.

Their study could help future missions to Mars determine the best locations and types of blast excavated rocks to examine to find signs of life. For example, it may be that meteorite impacts of a certain size may not destroy organic compounds or scientists may need to concentrate on rocks excavated from a certain depth.

Professor Mark Sephton, co-author of the research from the Department of Earth Science and Engineering at Imperial College London, said: “We’ve literally only scratched the surface of Mars in our search for life, but so far the results have been inconclusive. Rocks excavated through meteorite impacts provide scientists with another unique opportunity to explore for signs of life, without having to resort to complicated drilling missions. Our study is showing us is that we may need to be nuanced in our approach to the rocks we choose to analyse.”
Dr Wren Montgomery, co-author of the study from the Department of Earth Science and Engineering, added: “The study is helping us to see that when organic matter is observed on Mars, no matter where, it must be considered whether the sample could have been affected by the pressures associated with blast impacts. We still need to do more work to understand what factors may play an important role in protecting organic compounds from these blast impacts. However, we think some of the factors may include the depths at which the rock records are buried and the angles at which meteorites hit the Martian surface.”

Previous in situ analyses of the Martian terrain have found inconclusive evidence for the existence organic compounds - so far only finding chlorinated organic matter. The issue for scientists has been that it is not easy to look at simple chlorine-containing organic molecules and determine the origin of the organic compound components.

NASA’s Viking landers in 1976 detected chlorine-containing organic compounds, but they were thought to be chemical left-overs from cleaning procedures of Viking’s equipment before it left Earth. Later, the Phoenix Mission in 2008 discovered chlorine-containing minerals on the Martian surface, but no organic compounds. In 2012 the Mars Science Laboratory Mission detected chlorinated organic matter, but they thought that the analysis process, which involved heating chlorine containing minerals and carbonaceous material together, was producing chlorine-containing organic compounds. Working out whether the source of the carbon found on Mars was carried once again from Earth or was indigenous to Mars remains frustratingly difficult for scientists.

The team carried out their research by subjecting the different types of organic matter to extreme pressure and temperature in a piston cylinder device. They then did a chemical analysis using pyrolysis-gas chromatography mass spectrometry.

The next steps will see the team investigating a broader range of pressures and temperatures, which would help them understand the likely effects of a greater range of meteorite impacts. This would enable them to identify the specific conditions under which organic material may escape the destructive effects of blasts - even when excavated from deep underground by violent events. This could help future Mars missions further refine the types and locations of rocks that they can analyse for signs of past or present life.

NASA’s Curiosity Rover Sharpens Paradox of Ancient Mars

Fast Facts:
› Curiosity rover findings add to a puzzle about ancient Mars because the same rocks that indicate a lake was present also indicate there was very little carbon dioxide in the air to help keep a lake unfrozen.
› No carbonate has been found definitively in rock samples analyzed by Curiosity.
› A new study calculates how much carbon dioxide could have been in the ancient atmosphere without resulting in carbonate detectable by the rover: not much.

Mars scientists are wrestling with a problem. Ample evidence says ancient Mars was sometimes wet, with water flowing and pooling on the planet’s surface. Yet, the ancient sun was about one-third less warm and climate modelers struggle to produce scenarios that get the surface of Mars warm enough for keeping water unfrozen.

A leading theory is to have a thicker carbon-dioxide atmosphere forming a greenhouse-gas blanket, helping to warm the surface of ancient Mars. However, according to a new analysis of data from NASA’s Mars rover Curiosity, Mars had far too little carbon dioxide about 3.5 billion years ago to provide enough greenhouse-effect warming to thaw water ice.

The same Martian bedrock in which Curiosity found sediments from an ancient lake where microbes could have thrived is the source of the evidence adding to the quandary about how such a lake could have existed. Curiosity detected no carbonate minerals in the samples of the bedrock it analyzed. The new analysis concludes that the dearth of carbonates in that bedrock means Mars’ atmosphere when the lake existed – about 3.5 billion years ago – could not have held much carbon dioxide.

“We’ve been particularly struck with the absence of carbonate minerals in sedimentary rock the rover has examined,” said Thomas Bristow of NASA’s Ames Research Center, Moffett Field, California. “It would be really hard to get liquid water even if there were a hundred times more carbon dioxide in the atmosphere than what the mineral evidence in the rock tells us.” Bristow is the principal investigator for the Chemistry and Mineralogy (CheMin) instrument on Curiosity and lead author of the study being published this week in the Proceedings of the National Academy of Sciences.

Curiosity has made no definitive detection of carbonates in any lakebed rocks sampled since it landed in Gale Crater in 2012. CheMin can identify carbonate if it makes up just a few percent of the rock. The new analysis by Bristow and 13 co-authors calculates the maximum amount of carbon dioxide that could have been present, consistent with that dearth of carbonate.

In water, carbon dioxide combines with positively charged ions such as magnesium and ferrous iron to form carbonate minerals. Other minerals in the same rocks indicate those ions were readily available. The other minerals, such as magnetite and clay minerals, also provide evidence that subsequent conditions never became so acidic that carbonates would have dissolved away, as they can in acidic groundwater.

The dilemma has been building for years: Evidence about factors that affect surface temperatures – mainly the energy received from the young sun and the blanketing provided by the planet’s atmosphere – adds up to a mismatch with widespread evidence for river networks and lakes on ancient Mars. Clues such as isotope ratios in today’s Martian atmosphere indicate the planet once held a much denser atmosphere than it does now. Yet theoretical models of the ancient Martian climate struggle to produce conditions that would allow liquid water on the Martian surface for many millions of years. One successful model proposes a thick carbon-dioxide atmosphere that also contains molecular hydrogen. How such an atmosphere would be generated and sustained, however, is controversial.

The new study pins the puzzle to a particular place and time, with an on-the-ground check for carbonates in exactly the same sediments that hold the record of a lake about a billion years after the planet formed.

For the past two decades, researchers have used spectrometers on Mars orbiters to search for carbonate that could have resulted from an early era of more abundant carbon dioxide. They have found far less than anticipated.

“It’s been a mystery why there hasn’t been much carbonate seen from orbit,” Bristow said. “You could get out of the quandary by saying the carbonates may still be there, but we just can’t see them from orbit because they’re covered by dust, or buried, or we’re not looking in the right place. The Curiosity results bring the paradox to a focus. This is the first time we’ve checked for carbonates on the ground in a rock we know formed from sediments deposited under water.”

The new analysis concludes that no more than a few tens of millibars of carbon dioxide could have been present when the lake existed, or it would have produced enough carbonate for Curiosity’s CheMin to detect it. A millibar is one one-thousandth of sea-level air pressure on Earth. The current atmosphere of Mars is less than 10 millibars and about 95 percent carbon dioxide.

“This analysis fits with many theoretical studies that the surface of Mars, even that long ago, was not warm enough for water to be liquid,” said Robert Haberle, a Mars-climate scientist at NASA Ames and a co-author of the paper. “It’s really a puzzle to me.”

Researchers are evaluating multiple ideas for how to reconcile the dilemma.

“Some think perhaps the lake wasn’t an open body of liquid water. Maybe it was liquid covered with ice,” Haberle said. “You could still get some sediments through to accumulate in the lakebed if the ice weren’t too thick.”

A drawback to that explanation is that the rover team has sought and not found in Gale Crater evidence that would be expected from ice-covered lakes, such as large and deep cracks called ice wedges, or “dropstones,” which become embedded in soft lakebed sediments when they penetrate thinning ice.

If the lakes were not frozen, the puzzle is made more challenging by the new analysis of what the lack of a carbonate detection by Curiosity implies about the ancient Martian atmosphere.

“Curiosity’s traverse through streambeds, deltas, and hundreds of vertical feet of mud deposited in ancient lakes calls out for a vigorous hydrological system supplying the water and sediment to create the rocks we’re finding,” said Curiosity Project Scientist Ashwin Vasavada of NASA’s Jet Propulsion Laboratory, Pasadena, California.

“Carbon dioxide, mixed with other gases like hydrogen, has been the leading candidate for the warming influence needed for such a system. This surprising result would seem to take it out of the running.”

When two lines of scientific evidence appear irreconcilable, the scene may be set for an advance in understanding why they are not. The Curiosity mission is continuing to investigate ancient environmental conditions on Mars.

It is managed by JPL, a division of Caltech in Pasadena, for NASA’s Science Mission Directorate, Washington. Curiosity and other Mars science missions are a key part of NASA’s Journey to Mars, building on decades of robotic exploration to send humans to the Red Planet in the 2030s

IMAGE….View of Yellowknife Bay Formation, with Drilling Sites This mosaic of images from Curiosity’s Mast Camera (Mastcam) shows geological members of the Yellowknife Bay formation, and the sites where Curiosity drilled into the lowest-lying member, called Sheepbed, at targets “John Klein” and “Cumberland.” The scene has the Sheepbed mudstone in the foreground and rises up through Gillespie Lake member to the Point Lake outcrop. These rocks record superimposed ancient lake and stream deposits that offered past environmental conditions favorable for microbial life. Rocks here were exposed about 70 million years ago by removal of overlying layers due to erosion by the wind.
The 50-centimeter scale bars at different locations in the image are about 20 inches long. The lower scale bar is about 26 feet (8 meters) away from where Curiosity was positioned when the view was recorded. The upper scale bar is about 98 feet (30 meters) from the rover’s location. The scene is a portion of a 111-image mosaic acquired during the 137th Martian day, or sol, of Curiosity’s work on Mars (Dec. 24, 2012). The foothills of Mount Sharp are visible in the distance, upper left, southwest of camera position.

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Scientists To Plan Missions And Explore Mars Through Holograms 

For planetary scientists, a hologram of a distant planet might be the next best thing to being there. While NASA’s goal to send astronauts to Mars sometime in the 2030s is still a long time off, researchers will start setting their feet down on a data-based three-dimensional representation of the red planet later this year.

In other words, the first iteration of a NASA science holodeck is here.

It was just yesterday that Microsoft announced its HoloLens, what the company bills as a powerful holographic computing headset. “For the first time ever, Microsoft HoloLens brings high-definition holograms to life in your world, where they integrate with your physical places, spaces, and things,” the company says.

While many applications for virtual and augmented reality systems have already been identified thanks to projects like Google Glass and Oculus Rift, the U.S. space agency is sounding vocal support for the science applications of HoloLens from the get-go.

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Mars Rover Views Spectacular Layered Rock Formations

The layered geologic past of Mars is revealed in stunning detail in new color images returned by NASA’s Curiosity Mars rover, which is currently exploring the “Murray Buttes” region of lower Mount Sharp.

The new images arguably rival photos taken in U.S. National Parks.
Curiosity took the images with its Mast Camera (Mastcam) on Sept. 8.

The rover team plans to assemble several large, color mosaics from the multitude of images taken at this location in the near future.

“Curiosity’s science team has been just thrilled to go on this road trip through a bit of the American desert Southwest on Mars,” said Curiosity Project Scientist Ashwin Vasavada, of NASA’s Jet Propulsion Laboratory, Pasadena, California.

The Martian buttes and mesas rising above the surface are eroded remnants of ancient sandstone that originated when winds deposited sand after lower Mount Sharp had formed.

“Studying these buttes up close has given us a better understanding of ancient sand dunes that formed and were buried, chemically changed by groundwater, exhumed and eroded to form the landscape that we see today,” Vasavada said.

The new images represent Curiosity’s last stop in the Murray Buttes, where the rover has been driving for just over one month. As of this week, Curiosity has exited these buttes toward the south, driving up to the base of the final butte on its way out. In this location, the rover began its latest drilling campaign (on Sept. 9). After this drilling is completed, Curiosity will continue farther south and higher up Mount Sharp, leaving behind these spectacular formations.

Curiosity landed near Mount Sharp in 2012. It reached the base of the mountain in 2014 after successfully finding evidence on the surrounding plains that ancient Martian lakes offered conditions that would have been favorable for microbes if Mars has ever hosted life. Rock layers forming the base of Mount Sharp accumulated as sediment within ancient lakes billions of years ago.

On Mount Sharp, Curiosity is investigating how and when the habitable ancient conditions known from the mission’s earlier findings evolved into conditions drier and less favorable for life.

IMAGE 1….This view from the Mast Camera (Mastcam) in NASA’s Curiosity Mars rover shows an outcrop with finely layered rocks within the “Murray Buttes” region on lower Mount Sharp.
The buttes and mesas rising above the surface in this area are eroded remnants of ancient sandstone that originated when winds deposited sand after lower Mount Sharp had formed. Curiosity closely examined that layer – called the “Stimson formation” – during the first half of 2016, while crossing a feature called “Naukluft Plateau” between two exposures of the Murray formation. The layering within the sandstone is called “cross-bedding” and indicates that the sandstone was deposited by wind as migrating sand dunes.
The image was taken on Sept. 8, 2016, during the 1454th Martian day, or sol, of Curiosity’s work on Mars.


IMAGE 2….This view from the Mast Camera (Mastcam) in NASA’s Curiosity Mars rover shows a sloping hillside within the “Murray Buttes” region on lower Mount Sharp. The rim of Gale Crater, where the rover has been active since landing in 2012, is visible in the distance, through the dusty haze.
The image was taken on Sept. 8, 2016, during the 1454th Martian day, or sol, of Curiosity’s work on Mars.


IMAGE 3….This view from the Mast Camera (Mastcam) in NASA’s Curiosity Mars rover shows sloping buttes and layered outcrops within the “Murray Buttes” region on lower Mount Sharp.
The buttes and mesas rising above the surface are eroded remnants of ancient sandstone that originated when winds deposited sand after lower Mount Sharp had formed. Curiosity closely examined that layer – called the “Stimson formation” – during the first half of 2016, while crossing a feature called “Naukluft Plateau” between two exposures of the Murray formation. The layering within the sandstone is called “cross-bedding” and indicates that the sandstone was deposited by wind as migrating sand dunes.
The image was taken on Sept. 8, 2016, during the 1454th Martian day, or sol, of Curiosity’s work on Mars.


IMAGE 4….This view from the Mast Camera (Mastcam) in NASA’s Curiosity Mars rover shows finely layered rocks within the “Murray Buttes” region on lower Mount Sharp.
The buttes and mesas rising above the surface in this area are eroded remnants of ancient sandstone that originated when winds deposited sand after lower Mount Sharp had formed. Curiosity closely examined that layer – called the “Stimson formation” – during the first half of 2016, while crossing a feature called “Naukluft Plateau” between two exposures of the Murray formation. The layering within the sandstone is called “cross-bedding” and indicates that the sandstone was deposited by wind as migrating sand dunes.
The image was taken on Sept. 8, 2016, during the 1454th Martian day, or sol, of Curiosity’s work on Mars.


IMAGE 5….This view from the Mast Camera (Mastcam) in NASA’s Curiosity Mars rover shows a hillside outcrop with layered rocks within the “Murray Buttes” region on lower Mount Sharp.
The buttes and mesas rising above the surface in this area are eroded remnants of ancient sandstone that originated when winds deposited sand after lower Mount Sharp had formed. Curiosity closely examined that layer – called the “Stimson formation” – during the first half of 2016, while crossing a feature called “Naukluft Plateau” between two exposures of the Murray formation. The layering within the sandstone is called “cross-bedding” and indicates that the sandstone was deposited by wind as migrating sand dunes.
The image was taken on Sept. 8, 2016, during the 1454th Martian day, or sol, of Curiosity’s work on Mars.
Malin Space Science Systems, San Diego, built and operates the rover’s Mastcam. NASA’s Jet Propulsion Laboratory, a division of Caltech in Pasadena, manages the Mars Science Laboratory Project for NASA’s Science Mission Directorate, Washington. JPL designed and built the project’s Curiosity rover.

Starry dunes

Sandy formations of this type develop when there is no single dominant wind direction, a multiplicity of them combining instead to shape the landform. This process is not confined to our planet, as these examples, which could easily be in the Rub al Khali (the Empty Quarter) of the Arabian Peninsula, were actually snapped on the next planet out from the sun, namely Mars.

Loz

Image credit: NASA