Meteorites yield clues to Martian early atmosphere - Sulphur

A microscope reveals colorful augite crystals in this 1.3 billion-year-old meteorite from Mars, which researchers studied to understand the red planet's atmospheric history. 

Credit: James Day

Geologists who analyzed 40 meteorites that fell to Earth from Mars unlocked secrets of the Martian atmosphere hidden in the chemical signatures of these ancient rocks.

Their study, published April 17 in the journal Nature, shows that the atmospheres of Mars and Earth diverged in important ways very early in the 4.6 billion year evolution of our solar system.

The results will help guide researchers' next steps in understanding whether life exists, or has ever existed, on Mars and how water—now absent from the Martian surface—flowed there in the past.

Heather Franz

Heather Franz, a former University of Maryland (UMD) research associate who now works on the Curiosity rover science team at the NASA Goddard Space Flight Center, led the study with James Farquhar, co-author and UMD geology professor.

The researchers measured the sulfur composition of 40 Mars meteorites—a much larger number than in previous analyses. Of more than 60,000 meteorites found on Earth, only 69 are believed to be pieces of rocks blasted off the Martian surface.

The meteorites are igneous rocks that formed on Mars, were ejected into space when an asteroid or comet slammed into the red planet, and landed on Earth.

James Farquhar

The oldest meteorite in the study is about 4.1 billion years old, formed when our solar system was in its infancy. The youngest are between 200 million and 500 million years old.

Studying Martian meteorites of different ages can help scientists investigate the chemical composition of the Martian atmosphere throughout history, and learn whether the planet has ever been hospitable to life.

Mars and Earth share the basic elements for life, but conditions on Mars are much less favourable, marked by an arid surface, cold temperatures, radioactive cosmic rays, and ultraviolet radiation from the Sun.

Still, some Martian geological features were evidently formed by water – a sign of milder conditions in the past.

Scientists are not sure what conditions made it possible for liquid water to exist on the surface, but greenhouse gases released by volcanoes likely played a role.

Sulphur, which is plentiful on Mars, may have been among the greenhouse gases that warmed the surface, and could have provided a food source for microbes.

Because meteorites are a rich source of information about Martian sulphur, the researchers analyzed sulfur atoms that were incorporated into the rocks.

In the Martian meteorites, some sulphur came from molten rock, or magma, which came to the surface during volcanic eruptions.

Volcanoes also vented sulphur dioxide into the atmosphere, where it interacted with light, reacted with other molecules, and settled on the surface.

The team's work has yielded the most comprehensive record of the distribution of sulphur isotopes on Mars.

In effect, they have compiled a database of atomic fingerprints that provide a standard of comparison for sulphur-containing samples collected by NASA's Curiosity rover and future Mars missions.

This information will make it much easier for researchers to zero in on any signs of biologically produced sulphur, Farquhar said.

More information: Isotopic links between atmospheric chemistry and the deep sulphur cycle on Mars, Nature, DOI: 10.1038/nature13175

MAVEN: Mars atmosphere could give clues to its past water loss - Video

NASA's Mars MAVEN mission (arriving 21 September 2014) will detect and measure how the solar wind interacts with the Red Planet’s atmosphere, giving clues to where its water went and why.

Credit: NASA / GSFC

Dwarf galaxies provide clues to origin of supermassive black holes

Dwarf galaxy NGC 4395, about 13 million light-years from Earth, known to harbour a black hole some 300,000 times more massive than the Sun. 

It is a prototypical example of a small galaxy once thought to be too small to contain such a black hole. 

Credit: David W. Hogg, Michael R. Blanton, and the Sloan Digital Sky Survey Collaboration; NRAO/AUI/NSF.

Pouring through data from a large sky survey, astronomers have found more than 100 small, dwarf galaxies with characteristics indicating that they harbor massive black holes feeding on surrounding gas.

The discovery confounds a common assumption that only much larger galaxies hold such monsters and may help resolve the question of how such black holes originated and grew in the early universe.

Amy Reines

"We've shown that even small galaxies can have massive black holes and that they may be more common than previously thought," said Amy Reines, of the National Radio Astronomy Observatory (NRAO).

"This is really exciting because these little galaxies hold the clues to the origin of the first 'seeds' of supermassive black holes in the early universe," she said. Reines and her colleagues presented their findings to the American Astronomical Society's meeting in Washington, DC.

Black holes are concentrations of mass so dense that not even light can escape their gravitational pull.

Nearly all "full-sized" galaxies are known to have supermassive black holes, millions or billions of times more massive than the Sun, at their cores.

Until recently, however, smaller galaxies were thought not to harbor massive black holes.

Marla Geha

Reines, along with Jenny Greene of Princeton University and Marla Geha of Yale University, analyzed data from the Sloan Digital Sky Survey and found more than 100 dwarf galaxies whose patterns of light emission indicated the presence of massive black holes and their feeding process.

"The galaxies are comparable in size to the Magellanic Clouds, dwarf satellite galaxies of the Milky Way," Geha said.

"Previously, such galaxies were thought to be too small to have such massive black holes," she added.

In the nearby universe, astronomers have found a direct relationship between the mass of a galaxy's central black hole and a "bulge" in its center.

This indicates that the black holes and the bulges may have affected each others' growth.

NASA Cassini: Clues about Saturn's moon Titan

This coloured mosaic from NASA's Cassini mission shows the most complete view yet of Titan's northern land of lakes and seas. 

Saturn's moon Titan is the only world in our solar system other than Earth that has stable liquid on its surface. 

The liquid in Titan's lakes and seas is mostly methane and ethane. 

Credit: NASA/JPL-Caltech/ASI/USGS

NASA's Cassini spacecraft is providing scientists with key clues about Saturn's moon Titan, and in particular, its hydrocarbon lakes and seas.

Titan is one of the most Earth-like places in the solar system, and the only place other than our planet that has stable liquid on its surface.

Cassini's recent close flybys are bringing into sharper focus a region in Titan's northern hemisphere that sparkles with almost all of the moon's seas and lakes.

Scientists working with the spacecraft's radar instrument have put together the most detailed multi-image mosaic of that region to date.

The image includes all the seas and most of the major lakes. Some of the flybys tracked over areas that previously were seen at a different angle, so researchers have been able to create a flyover of the area around Titan's largest and second largest seas, known as Kraken Mare and Ligeia Mare, respectively, and some of the nearby lakes.

"Learning about surface features like lakes and seas helps us to understand how Titan's liquids, solids and gases interact to make it so Earth-like," said Steve Wall, acting radar team lead at NASA's Jet Propulsion Laboratory in Pasadena, Calif.

"While these two worlds aren't exactly the same, it shows us more and more Earth-like processes as we get new views."

Moon's Aitken Basin: Ancient crater could hold clues about moon's mantle

Red areas on the topographic image indicate high elevations, and blue or purple areas indicate low elevation. 

The South Pole Aitken basin could hold clues about the composition of the Moon's mantle. 

Credit: NASA/GSFC

Researchers from Brown University and the University of Hawaii have found some mineralogical surprises in the Moon's largest impact crater.

Data from the Moon Mineralogy Mapper that flew aboard India's Chandrayaan-1 lunar orbiter shows a diverse mineralogy in the subsurface of the giant South Pole Aitken basin.

The differing mineral signatures could be reflective of the minerals dredged up at the time of the giant impact 4 billion years ago, the researchers say.

If that's true, then the South Pole Aitken (SPA) basin could hold important information about the Moon's interior and the evolution of its crust and mantle.

The study, led by Brown graduate student Dan Moriarty, is published in online early view in the Journal of Geophysical Research: Planets.

At 2,500 kilometers across, the SPA is the largest impact basin on the Moon and perhaps the largest in the solar system.

Impacts of this size turn tons of solid rock into molten slush. It has been assumed generally that the melting process would obliterate any distinct signatures of pre-existing mineralogical diversity through extensive mixing, but this latest research suggests that might not be the case.

The study looked at smaller craters within the larger SPA basin made by impacts that happened millions of years after the giant impact that formed the basin.

Those impacts uncovered material from deep within the basin, offering important clues about what lies beneath the surface.

Specifically, the researchers looked at the central peaks of four craters within the basin. Central peaks form when material under the impact zone rebounds, forming an upraised rock formation in the middle of the crater. The tops of those peaks represent pristine material from below the impact zone.

Moon Mineralogy Mapper

Using Moon Mineralogy Mapper data, the researchers looked at the light reflected from each of the four central peaks. The spectra of reflected light give scientists clues about the makeup of the rocks.

The spectra showed substantial differences in composition from peak to peak. Some crater peaks were richer in magnesium than others.

One of the four craters, located toward the outer edge of the basin, contained several distinct mineral deposits within its own peak, possibly due to sampling a mixture of both upper and lower crust or mantle materials.

The varying mineralogy in these central peaks suggests that the SPA subsurface is much more diverse than previously thought.

"Previous studies have suggested that all the central peaks look very similar, and that was taken as evidence that everything's the same across the basin," Moriarty said.

"We looked in a little more detail and found significant compositional differences between these central peaks."

"The Moon Mineralogy Mapper has very high spatial and spectral resolution. We haven't really been able to look at the Moon in this kind of detail before."

The next step is figuring out where that diversity comes from.

New Star's 'Snow Line' Reveals Clues About Planet Formation

Astronomers have identified the point where carbon monoxide (CO) freezes in the disk around a sunlike star — information that could help them understand how planets form.

A team of international scientists has calculated the CO "snow line" for a star called TW Hydrae, determining that the gas solidifies at about the distance of the orbit of Neptune, where it could help feed the formation of the outer edges of the system.

"The CO snow line is interesting, not only because CO is abundant in the disks, but its snow line is the most accessible to direct observations due to its low freeze-out temperature — it's farther away from the star," said principal investigator Chunhua Qi of the Harvard-Smithsonian Center for Astrophysics.

"It could mark the starting point where smaller icy bodies, like comets, and dwarf planets, like Pluto, would begin to form."

Volatiles like carbon monoxide freeze at a range of temperatures, and each can have its own impact on the growth of orbiting bodies.

The location of the snow lines for volatiles can affect planetary formation. 

Recent research has indicated the water snow line, shown here, lies farther out than previously suspected.

Credit: NASA, ESA, and A. Feild (STScI)

Tracer ions
Stars form when a disk of dust and gas collapses in on itself due to gravity. The remaining material continues to orbit the newly formed object in a disk of material.

As dust and gas particles pass through the disk, scientists say, they come together to form larger and larger clumps that can eventually grow into planets. Frozen volatiles help this process along.

"The snow line provides more sticky solid grains, and enhances the planet formation efficiency and grain growth," Qi told reporters.

But determining the location of these grains can be a challenge. Emission from volatiles along the outside of the disk can make it difficult for scientists to image the telltale signs of frozen compounds.

To locate the region of the disk where CO freezes, Qi and his team utilized a new technique. Using the Atacama Large Millimeter Array (ALMA) in Chile, they searched for the ion diazenylium (N2H+), rather than the hard-to-find carbon monoxide, around TW Hydrae, which lies 176 light-years from Earth.

"N2H+ is easily destroyed in the presence of CO gas, and is abundant where CO has frozen out," Qi said.

The new technique should be helpful for studying the CO snow lines of other stars, which will provide more insight into how outer solar-system objects form.

"As long as the disk is gas-rich, so that there should be enough N2H+, we can use this ion to image the CO snow line," Qi said.

NASA Mars Rover Opportunity examines clay clues in rock Esperance

The pale rock in the upper center of this image, about the size of a human forearm, includes a target called "Esperance," which was inspected by NASA's Mars Exploration Rover Opportunity.

Data from the rover's Alpha Particle X-ray Spectrometer (APXS) indicate that Esperance's composition is higher in aluminum and silica, and lower in calcium and iron, than other rocks Opportunity has examined in more than nine years on Mars.

Preliminary interpretation points to clay mineral content due to intensive alteration by water. 

Image Credit: NASA/JPL-Caltech/Cornell/Arizona State Univ.

NASA's senior Mars rover, Opportunity, is driving to a new study area after a dramatic finish to 20 months on "Cape York" with examination of a rock intensely altered by water.

The fractured rock, called "Esperance," provides evidence about a wet ancient environment possibly favorable for life.

Steve Squyres

The mission's principal investigator, Steve Squyres of Cornell University, Ithaca, N.Y., said, "Esperance was so important, we committed several weeks to getting this one measurement of it, even though we knew the clock was ticking."

The mission's engineers at NASA's Jet Propulsion Laboratory, Pasadena, Calif., had set this week as a deadline for starting a drive toward "Solander Point," where the team plans to keep Opportunity working during its next Martian winter.

"What's so special about Esperance is that there was enough water not only for reactions that produced clay minerals, but also enough to flush out ions set loose by those reactions, so that Opportunity can clearly see the alteration," said Scott McLennan of the State University of New York, Stony Brook, a long-term planner for Opportunity's science team.

This map of a portion of the western rim of Endeavour Crater on Mars shows the area where NASA's Mars Exploration Rover Opportunity worked for 20 months, "Cape York," in relation to the area where the rover team plans for Opportunity to spend its sixth Martian winter, "Solander Point."

This rock's composition is unlike any other Opportunity has investigated during nine years on Mars—higher in aluminum and silica, lower in calcium and iron.

The next destination, Solander Point, and the area Opportunity is leaving, Cape York, both are segments of the rim of Endeavour Crater, which spans 14 miles (22 kilometers) across.

The planned driving route to Solander Point is about 1.4 miles (2.2 kilometers).

Cape York has been Opportunity's home since the rover arrived at the western edge of Endeavour in mid-2011 after a two-year trek from a smaller crater.

"Based on our current solar-array dust models, we intend to reach an area of 15 degrees northerly tilt before Opportunity's sixth Martian winter," said JPL's Scott Lever, mission manager.

Scott McLennan

"Solander Point gives us that tilt and may allow us to move around quite a bit for winter science observations."

Northerly tilt increases output from the rover's solar panels during southern-hemisphere winter.

Daily sunshine for Opportunity will reach winter minimum in February 2014. The rover needs to be on a favourable slope well before then.

This mosaic of four frames shot by the microscopic imager on the robotic arm of NASA's Mars Exploration Rover Opportunity shows a rock target called "Esperance" after some of the rock's surface had been removed by Opportunity's rock abrasion tool, or RAT. 

Credit: NASA/JPL-Caltech /Cornell /USGS

The first drive away from Esperance covered 81.7 feet (24.9 meters) on May 14.

Three days earlier, Opportunity finished exposing a patch of the rock's interior with the rock abrasion tool.

The team used a camera and spectrometer on the robotic arm to examine Esperance.

JPL's Scott Lever, mission manager

The team identified Esperance while exploring a portion of Cape York where the Compact Reconnaissance Spectrometer for Mars (CRISM) on NASA's Mars Reconnaissance Orbiter (MRO) had detected a clay mineral.

Clays typically form in wet environments that are not harshly acidic.

For years, Opportunity had been finding evidence for ancient wet environments that were very acidic.

The CRISM findings prompted the rover team to investigate the area where clay had been detected from orbit.

There, they found an outcrop called "Whitewater Lake," containing a small amount of clay from alteration by exposure to water.

"There appears to have been extensive, but weak, alteration of Whitewater Lake, but intense alteration of Esperance along fractures that provided conduits for fluid flow," Squyres said.

"Water that moved through fractures during this rock's history would have provided more favourable conditions for biology than any other wet environment recorded in rocks Opportunity has seen."

Canada: Billion-year-old water could hold clues to life on Mars

A UK-Canadian team of scientists has discovered ancient pockets of water, which have been isolated deep underground for billions of years and contain abundant chemicals known to support life.

This water could be some of the oldest on the planet and may even contain life.

Not just that, but the similarity between the rocks that trapped it and those on Mars raises the hope that comparable life-sustaining water could lie buried beneath the red planet's surface.

The findings, published in Nature today, may force us to rethink which parts of our planet are fit for life, and could reveal clues about how microbes evolve in isolation.

Researchers from the universities of Manchester, Lancaster, Toronto and McMaster analysed water pouring out of boreholes from a mine 2.4 kilometres beneath Ontario, Canada.

They found that the water is rich in dissolved gases like hydrogen, methane and different forms – called isotopes – of noble gases such as helium, neon, argon and xenon. Indeed, there is as much hydrogen in the water as around hydrothermal vents in the deep ocean, many of which teem with microscopic life.

The hydrogen and methane come from the interaction between the rock and water, as well as natural radioactive elements in the rock reacting with the water.

These gases could provide energy for microbes that may not have been exposed to the sun for billions of years.

The crystalline rocks surrounding the water are thought to be around 2.7 billion years old but no-one thought the water could be the same age, until now.

Using ground-breaking techniques developed at the University of Manchester, the researchers show that the fluid is at least 1.5 billion years old, but could be significantly older.

Chris Ballentine

NERC-funded Professor Chris Ballentine of the University of Manchester, co-author of the study, and project director, says: 'We've found an interconnected fluid system in the deep Canadian crystalline basement that is billions of years old, and capable of supporting life. Our finding is of huge interest to researchers who want to understand how microbes evolve in isolation, and is central to the whole question of the origin of life, the sustainability of life, and life in extreme environments and on other planets.'

Before this finding, the only water of this age was found trapped in tiny bubbles in rock and is incapable of supporting life but the water found in the Canadian mine pours from the rock at a rate of nearly two litres per minute.

It has similar characteristics to far younger water flowing from a mine 2.8 kilometres below ground in South Africa that was previously found to support microbes.

Greg Holland

Ballentine and his colleagues don't yet know if the underground system in Canada sustains life, but Dr Greg Holland of Lancaster University, lead author of the study says: 'Our Canadian colleagues are trying to find out if the water contains life right now. What we can be sure of is that we have identified a way in which planets can create and preserve an environment friendly to microbial life for billions of years. This is regardless of how inhospitable the surface might be, opening up the possibility of similar environments in the subsurface of Mars.'

Professor Ballentine, based in Manchester's School of Earth, Atmospheric and Environmental Sciences, adds: 'While the questions about life on Mars raised by our work are incredibly exciting, the ground-breaking techniques we have developed at Manchester to date ancient waters also provide a way to calculate how fast methane gas is produced in ancient rock systems globally. The same new techniques can be applied to characterise old, deep groundwater that may be a safe place to inject carbon dioxide.'

David Willetts, Minister for Universities and Science, says: 'This is excellent pioneering research. It gives new insight into our planet. It has also developed new technology for carbon capture and storage projects. These have the potential for growth, job creation and our environment.'

More information: 
Deep fracture fluids isolated in the crust since the Precambrian era, by G. Holland, B. Sherwood Lollar, L. Li, G. Lacrampe-Couloume, G. F. Slater & C. J. Ballentine, in Nature, 16 May 2013. dx.doi.org/10.1038/nature12127

Has NASA's Curiosity Rover Found Clues to Life's Building Blocks on Mars?

This patch of windblown sand and dust downhill from a cluster of dark rocks is the 'Rocknest' site studied by NASA’s Mars rover Curiosity. 

The Rocknest patch is about 8 feet by 16 feet (1.5 meters by 5 meters) and may contain perchlorate salts. Image added April 1, 2013.

CREDIT: NASA/JPL-Caltech/MSSS

NASA's Mars rover Curiosity just might be the latest in a long line of Mars-exploring robots to discover the building blocks for primitive life on the Red Planet.

The Curiosity rover may have gathered evidence for the presence of perchlorates in Rocknest — a sand patch inside the rover's Gale Crater landing site on the Red Planet, scientists say. If so, it shores up the case that the material may well be globally distributed on Mars.

Not only can perchlorates, which are a class of salts, serve as an energy source for potential Martian microorganisms, they are also a sensitive marker of past climate and can lead to the formation of liquid brines under current conditions on the planet.

The possibility that perchlorates are widespread on Mars was detailed in a March 18 presentation at the 44th annual Lunar and Planetary Science Conference in The Woodlands, Texas.


Curiosity's possible detection
The possible detection of perchlorates at Curiosity’s Gale crater site was spotlighted by Doug Archer, a scientist with the Astromaterials Research and Exploration Science Directorate of NASA's Johnson Space Center in Houston. He is focused on the habitability of various Martian environments over time. [The Search for Life on Mars

Archer pointed to the rover’s Sample Analysis at Mars (SAM) instrument suite that recently ran four samples from Rocknest. That area was selected as the source of the first samples analyzed because it is representative of both windblown material in the Gale Crater and the planet's globally distributed dust, he said.

"When we heated this up, we saw a large oxygen release at the same time we saw the release of these chlorinated hydrocarbons," Archer said, thus making a strong case for the presence of perchlorate salts in Rocknest's soil.

NASA ATTREX: Climate Change Clues In The Stratosphere

ATTREX is one of the first investigations in NASA's new Venture-class series of low- to moderate-cost projects.

Starting this month, NASA will send a remotely piloted research aircraft as high as 65,000 feet over the tropical Pacific Ocean to probe unexplored regions of the upper atmosphere for answers to how a warming climate is changing Earth.

The first flights of the Airborne Tropical Tropopause Experiment (ATTREX), a multi-year airborne science campaign with a heavily instrumented Global Hawk aircraft, will take off from and be operated by NASA's Dryden Flight Research Center at Edwards Air Force Base in California.

The Global Hawk is capable of making 30-hours of continuous flight.

Water vapour and ozone in the stratosphere can have a large impact on Earth's climate. The processes that drive the rise and fall of these compounds, especially water vapor, are not well understood.

This limits scientists' ability to predict how these changes will influence global climate in the future. ATTREX will study moisture and chemical composition in the upper regions of the troposphere, the lowest layer of Earth's atmosphere.

The tropopause layer between the troposphere and stratosphere, 8 miles to 11 miles above Earth's surface, is the point where water vapour, ozone and other gases enter the stratosphere.

Studies have shown even small changes in stratospheric humidity may have significant climate impacts. Predictions of stratospheric humidity changes are uncertain because of gaps in the understanding of the physical processes occurring in the tropical tropopause layer.

ATTREX will use the Global Hawk to carry instruments to sample this layer near the equator off the coast of Central America.

"The ATTREX payload will provide unprecedented measurements of the tropical tropopause," said Eric Jensen, ATTREX principal investigator at NASA's Ames Research Center in Moffett Field, Calif.

"This is our first opportunity to sample the tropopause region during winter in the northern hemisphere when it is coldest and extremely dry air enters the stratosphere."

Led by Jensen and project manager Dave Jordan of Ames, ATTREX scientists installed 11 instruments in the Global Hawk.

The instruments include remote sensors for measuring clouds, trace gases and temperatures above and below the aircraft, as well as instruments to measure water vapor, cloud properties, meteorological conditions, radiation fields and numerous trace gases around the aircraft.

Orion Nebula Gives Clues To Origin Of Life On Earth

What is intriguing is that amino acids in several meteorites show enantiomeric excesses of the same handedness as that seen in biological amino acids. Therefore, the process that produced the handedness of amino acids in the meteorites may provide clues to how homochirality developed in life forms on Earth. The larger question becomes how enantiomeric excesses can be produced and under what conditions.

How did life on Earth begin? One hypothesis is that terrestrial life began when organics were delivered from outer space during the early, heavy bombardment phase of Earth's development. We know that several meteorites (e.g., Murchison) have amino acids with properties similar to those seen in biological amino acids, the building blocks of life.

An international team of astronomers led by Fukue and Tamura of the National Astronomical Observatory of Japan conducted research on the properties of light in a massive star-forming region (BN/KL nebula) of the Orion Nebula and have investigated a process that may have played a role in the development of life on Earth.

The origin of what is technically called "biomolecular homochirality" is a longstanding mystery and an important one to solve, since it characterizes most life forms on Earth.

Chirality refers to the handedness of an image or phenomenon, which is not identical to the mirror image of its counterpart, much as the right and left hands are similar in structure but are opposites and thus not the same.

Homochirality means that a group of molecules exhibit the same handedness. Therefore, biomolecular homochirality indicates an organic group of molecules that are characterized by the same handedness. Terrestrial living material displays homochirality and consists almost exclusively of one enantiomer, L-amino acid, one of a pair of amino acids.

What is intriguing is that amino acids in several meteorites show enantiomeric excesses of the same handedness as that seen in biological amino acids. Therefore, the process that produced the handedness of amino acids in the meteorites may provide clues to how homochirality developed in life forms on Earth. The larger question becomes how enantiomeric excesses can be produced and under what conditions.