Bárðarbunga Volcano, September 4 2014. Source: Wikipedia

Bárðarbunga Volcano, September 4 2014. Source: Wikipedia

New research into an Icelandic eruption has shed light on how the Earth’s crust forms, according to a paper published this week in Nature.

When the Bárðarbunga volcano, which is buried beneath Iceland’s Vatnajökull ice cap, reawakened in August 2014, scientists had a rare opportunity to monitor how the magma flowed through cracks in the rock away from the volcano.

The molten rock forms vertical sheet-like features known as dykes, which force the surrounding rock apart.

Study co-author Professor Andy Hooper from the Centre for Observation and Modelling of Earthquakes, volcanoes and Tectonics (COMET) at the University of Leeds explained: “New crust forms where two tectonic plates are moving away from each other. Mostly this happens beneath the oceans, where it is difficult to observe.

“However, in Iceland this happens beneath dry land. The events leading to the eruption in August 2014 are the first time that such a rifting episode has occurred there and been observed with modern tools, like GPS and satellite radar.”

Although it has a long history of eruptions, Bárðarbunga has been increasingly restless since 2005. There was a particularly dynamic period in August and September this year, when more than 22,000 earthquakes were recorded in or around the volcano in just four weeks, due to stress being released as magma forced its way through the rock.

Using GPS and satellite measurements, the team were able to track the path of the magma for over 45km before it reached a point where it began to erupt, and continues to do so to this day. The rate of dyke propagation was variable and slowed as the magma reached natural barriers, which were overcome by the build-up of pressure, creating a new segment.

The dyke grows in segments, breaking through from one to the next by the build up of pressure. This explains how focused upwelling of magma under central volcanoes is effectively redistributed over large distances to create new upper crust at divergent plate boundaries, the authors conclude.

As well as the dyke, the team found ‘ice cauldrons’ – shallow depressions in the ice with circular crevasses, where the base of the glacier had been melted by magma. In addition, radar measurements showed that the ice inside Bárðarbunga’s crater had sunk by 16m, as the volcano floor collapsed.

COMET PhD student Karsten Spaans from the University of Leeds, a co-author of the study, added: “Using radar measurements from space, we can form an image of caldera movement occurring in one day. Usually we expect to see just noise in the image, but we were amazed to see up to 55cm of subsidence.”

Like other liquids, magma flows along the path of least resistance, which explains why the dyke at Bárðarbunga changed direction as it progressed.  Magma flow was influenced mostly by the lie of the land to start with, but as it moved away from the steeper slopes, the influence of plate movements became more important.

Summarising the findings, Professor Hooper said: “Our observations of this event showed that the magma injected into the crust took an incredibly roundabout path and proceeded in fits and starts.

“Initially we were surprised at this complexity, but it turns out we can explain all the twists and turns with a relatively simple model, which considers just the pressure of rock and ice above, and the pull exerted by the plates moving apart.”

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Study Hints that Ancient Earth Made Its Own Water—Geologically

Evidence that rock circulating in the mantle feeds world’s oceans even today

Blue Marble: Earth from Space

Blue Marble: Earth from Space

A new study is helping to answer a longstanding question that has recently moved to the forefront of earth science: Did our planet make its own water through geologic processes, or did water come to us via icy comets from the far reaches of the solar system?

The answer is likely “both,” according to researchers at The Ohio State University— and the same amount of water that currently fills the Pacific Ocean could be buried deep inside the planet right now.

At the American Geophysical Union (AGU) meeting on Wednesday, Dec. 17, they report the discovery of a previously unknown geochemical pathway by which the Earth can sequester water in its interior for billions of years and still release small amounts to the surface via plate tectonics, feeding our oceans from within.

In trying to understand the formation of the early Earth, some researchers have suggested that the planet was dry and inhospitable to life until icy comets pelted the earth and deposited water on the surface.

Wendy Panero, associate professor of earth sciences at Ohio State, and doctoral student Jeff Pigott are pursuing a different hypothesis: that Earth was formed with entire oceans of water in its interior, and has been continuously supplying water to the surface via plate tectonics ever since.

Researchers have long accepted that the mantle contains some water, but how much water is a mystery. And, if some geological mechanism has been supplying water to the surface all this time, wouldn’t the mantle have run out of water by now?

Because there’s no way to directly study deep mantle rocks, Panero and Pigott are probing the question with high-pressure physics experiments and computer calculations.

This plate tectonics diagram from the Byrd Polar and Climate Research Center shows how mantle circulation delivers new rock to the crust via mid-ocean ridges. New research suggests that mantle circulation also delivers water to the oceans.

This plate tectonics diagram from the Byrd Polar and Climate Research Center shows how mantle circulation delivers new rock to the crust via mid-ocean ridges. New research suggests that mantle circulation also delivers water to the oceans.

“When we look into the origins of water on Earth, what we’re really asking is, why are we so different than all the other planets?” Panero said. “In this solar system, Earth is unique because we have liquid water on the surface. We’re also the only planet with active plate tectonics. Maybe this water in the mantle is key to plate tectonics, and that’s part of what makes Earth habitable.”

Central to the study is the idea that rocks that appear dry to the human eye can actually contain water—in the form of hydrogen atoms trapped inside natural voids and crystal defects. Oxygen is plentiful in minerals, so when a mineral contains some hydrogen, certain chemical reactions can free the hydrogen to bond with the oxygen and make water.

Stray atoms of hydrogen could make up only a tiny fraction of mantle rock, the researchers explained. Given that the mantle is more than 80 percent of the planet’s total volume, however, those stray atoms add up to a lot of potential water.

In a lab at Ohio State, the researchers compress different minerals that are common to the mantle and subject them to high pressures and temperatures using a diamond anvil cell—a device that squeezes a tiny sample of material between two diamonds and heats it with a laser—to simulate conditions in the deep Earth. They examine how the minerals’ crystal structures change as they are compressed, and use that information to gauge the minerals’ relative capacities for storing hydrogen. Then, they extend their experimental results using computer calculations to uncover the geochemical processes that would enable these minerals to rise through the mantle to the surface—a necessary condition for water to escape into the oceans.

In a paper now submitted to a peer-reviewed academic journal, they reported their recent tests of the mineral bridgmanite, a high-pressure form of olivine. While bridgmanite is the most abundant mineral in the lower mantle, they found that it contains too little hydrogen to play an important role in Earth’s water supply.

Another research group recently found that ringwoodite, another form of olivine, does contain enough hydrogen to make it a good candidate for deep-earth water storage. So Panero and Pigott focused their study on the depth where ringwoodite is found—a place 325-500 miles below the surface that researchers call the “transition zone”—as the most likely region that can hold a planet’s worth of water. From there, the same convection of mantle rock that produces plate tectonics could carry the water to the surface.

One problem: If all the water in ringwoodite is continually drained to the surface via plate tectonics, how could the planet hold any in reserve?

For the research presented at AGU, Panero and Pigott performed new computer calculations of the geochemistry in the lowest portion of the mantle, some 500 miles deep and more. There, another mineral, garnet, emerged as a likely water-carrier—a go-between that could deliver some of the water from ringwoodite down into the otherwise dry lower mantle.

If this scenario is accurate, the Earth may today hold half as much water in its depths as is currently flowing in oceans on the surface, Panero said—an amount that would approximately equal the volume of the Pacific Ocean. This water is continuously cycled through the transition zone as a result of plate tectonics.

“One way to look at this research is that we’re putting constraints on the amount of water that could be down there,” Pigott added.

Panero called the complex relationship between plate tectonics and surface water “one of the great mysteries in the geosciences.” But this new study supports researchers’ growing suspicion that mantle convection somehow regulates the amount of water in the oceans. It also vastly expands the timeline for Earth’s water cycle.

“If all of the Earth’s water is on the surface, that gives us one interpretation of the water cycle, where we can think of water cycling from oceans into the atmosphere and into the groundwater over millions of years,” she said. “But if mantle circulation is also part of the water cycle, the total cycle time for our planet’s water has to be billions of years.”

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Curiosity Detects Methane and Organic Molecules in Gale Crater

self-portrait of NASA's Mars Curiosity Rover includes a sweeping panoramic view of its current location in the Yellowknife Bay region of the Red Planet's Gale Crater.

This self-portrait of NASA’s Mars Curiosity Rover includes a sweeping panoramic view of its location in the Yellowknife Bay region of Gale Crater. The impressive mosaic was constructed using frames from the rover’s Mars Hand Lens Imager (MAHLI) and Mastcam. Credit: NASA, JPL-Caltech, MSSS – Panorama by Andrew Bodrov

NASA’s Curiosity rover has made two of its most important observations on Mars since arriving on the planet in 2012. The rover measured a spike in levels of the organic chemical methane in the local atmosphere of its research site. Additionally, Curiosity detected other organic molecules in drill samples from a mudstone that once sat at the bottom of the lake that filled Gale crater in Mars’ ancient past.

The results were published in the journal Sciencexpress, and announced at the 2014 Fall Meeting of the American Geophysical Union (AGU).


Credit: American Geophysical Union (AGU) on UStream
 

The Scent of Methane

Methane has previously been detected in the martian atmosphere by Earth-based telescopes and orbital missions at the red planet. However, methane levels measured by Curiosity at Gale crater have shown only a small fraction of methane in the air.

The new measurements showed a tenfold increase in local methane levels. The methane was short-lived and decreased to previous levels shortly after it appeared.

“This temporary increase in methane – sharply up and then back down – tells us there must be some relatively localized source,” said Curiosity science team member, Sushil Atreya of the University of Michigan, in a recent press release from NASA JPL. “There are many possible sources, biological or non-biological, such as interaction of water and rock.”

This graphic shows tenfold spiking in the abundance of methane in the Martian atmosphere surrounding NASA's Curiosity Mars rover, as detected by a series of measurements made with the Tunable Laser Spectrometer (TLS) instrument in the rover's Sample Analysis at Mars (SAM) laboratory suite. Credit: NASA/JPL-Caltech

This graphic shows tenfold spiking in the abundance of methane in the Martian atmosphere surrounding NASA’s Curiosity Mars rover, as detected by a series of measurements made with the Tunable Laser Spectrometer (TLS) instrument in the rover’s Sample Analysis at Mars (SAM) laboratory suite. Credit: NASA/JPL-Caltech

Methane is important because it is an organic molecule often produced by life on Earth. However, methane is not proof of life because it can also be produced by many different processes that do not involve living organisms. Even so, the finding proves that present-day Mars is an active world.

“At this point, we don’t know the origin of this methane,” said Danny Glavin in a recent NASA interview. “It could be biological from, maybe methanogenic bacteria deep in the subsurface releasing methane. But there are non-biological explanations as well, such as water-rock interactions in the subsurface that could also produce the methane signals that we’re seeing.”

NASA's Mars rover Curiosity drilled into this rock target, "Cumberland," during the 279th Martian day, or sol, of the rover's work on Mars (May 19, 2013) and collected a powdered sample of material from the rock's interior. Analysis of the Cumberland sample using laboratory instruments inside Curiosity will check results from "John Klein," the first rock on Mars from which a sample was ever collected and analyzed. The two rocks have similar appearance and lie about nine feet (2.75 meters) apart. Curiosity used the Mars Hand Lens Imager (MAHLI) camera on the rover's arm to capture this view of the hole in Cumberland on the same sol as the hole was drilled. The diameter of the hole is about 0.6 inch (1.6 centimeters). The depth of the hole is about 2.6 inches (6.6 centimeters). Credit: NASA/JPL-Caltech/MSSS

NASA’s Mars rover Curiosity drilled into this rock target, “Cumberland,” during the 279th Martian day, or sol, of the rover’s work on Mars (May 19, 2013) and collected a powdered sample of material from the rock’s interior. Analysis of the Cumberland sample using laboratory instruments inside Curiosity will check results from “John Klein,” the first rock on Mars from which a sample was ever collected and analyzed. The two rocks have similar appearance and lie about nine feet (2.75 meters) apart. Curiosity used the Mars Hand Lens Imager (MAHLI) camera on the rover’s arm to capture this view of the hole in Cumberland on the same sol as the hole was drilled. The diameter of the hole is about 0.6 inch (1.6 centimeters). The depth of the hole is about 2.6 inches (6.6 centimeters). Credit: NASA/JPL-Caltech/MSSS

Drilling Organics

The second of Curiosity’s big discoveries came when the rover drilled into a rock dubbed “Cumberland.” Samples from the mudstone were analyzed by Curiosity’s SAM instrument, which then provided the first definitive detection of organic molecules on the martian surface.

Previous data gathered by Curiosity has shown that Gale crater was once filled with a lake of liquid water that persisted for long periods of time. Cumberland sat on the lake bed of this ancient body of water.

Data graphed here are examples from the Sample Analysis at Mars (SAM) laboratory's detection of Martian organics in a sample of powder that the drill on NASA's Curiosity Mars rover collected from a rock target called "Cumberland." Credit: NASA/JPL-Caltech

Data graphed here are examples from the Sample Analysis at Mars (SAM) laboratory’s detection of Martian organics in a sample of powder that the drill on NASA’s Curiosity Mars rover collected from a rock target called “Cumberland.” Credit: NASA/JPL-Caltech

In the Cumberland samples, Curiosity found molecules that are not common on Earth, including chlorinated alkanes and chlorobenzene, which was the most abundant molecule detected. On our planet, chlorobenzene is used in manufacturing, but does not occur naturally.

Astrobiologists have been hunting for organic material on Mars for decades. Organic molecules are typically built from atoms of carbon, hydrogen and oxygen, and they are often referred to as the ‘building blocks’ for life as we know it. However, this does not indicate that the martian organic molecules are connected to life.

There is not enough information to determine whether or not the martian organics found by Curiosity are biological or non-biological in origin. Many non-biological processes on Mars could have produced them, including the delivery of materials by meteorites or geological reactions in the rock.

This graphic offers comparisons between the amount of an organic chemical named chlorobenzene detected in the "Cumberland" rock sample and amounts of the same compound in samples from three other Martian surface targets analyzed by NASA's Curiosity Mars rover. Credit: NASA/JPL-Caltech

This graphic offers comparisons between the amount of an organic chemical named chlorobenzene detected in the “Cumberland” rock sample and amounts of the same compound in samples from three other Martian surface targets analyzed by NASA’s Curiosity Mars rover. Credit: NASA/JPL-Caltech

“Although at this point in the mission we can’t conclude that there was definitive life on Mars, the SAM discoveries have really shown us that all of the basic ingredient for life were there, including complex organic compounds, the building blocks of life,” said Glavin.

The findings raise hope that chemical evidence of ancient life could one day be found on Mars. Determining the origins of the newly discovered organics could help solve the age-old question of whether or not Mars was once a living world.

“We think life began on Earth around 3.8 billion years ago, and our result shows that places on Mars had the same conditions at that time – liquid water, a warm environment, and organic matter,” said Caroline Freissinet in a press release from NASA’s Goddard Space Flight Center. Freissinet is the lead author of an additional paper that has been submitted to the Journal of Geophysical Research-Planets.


Need To Know: Sample Analysis at Mars Findings. Credit: NASA Goddard (YouTube)
 

Astrobiology and SAM

Curiosity’s SAM instrument is one of the most complex analytical chemistry laboratories ever delivered to another planet. One of SAM’s most important astrobiological goals is to search for evidence of ancient habitable environments in Gale crater that could have supported life in Mars’ past.

For more information about astrobiology-related sessions at the 2014 Fall Meeting of the American Geophysical Union, check out this handy pdf of abstracts collated by the NASA Astrobiology Program: http://astrobiology.nasa.gov/articles/2014/12/14/astrobiology-related-sessions-at-agu/

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Life on an aquaplanet

Study finds an exoplanet, tilted on its side, could still be habitable if covered in ocean.

Illustration: Christine Daniloff/MIT

Illustration: Christine Daniloff/MIT

Nearly 2,000 planets beyond our solar system have been identified to date. Whether any of these exoplanets are hospitable to life depends on a number of criteria. Among these, scientists have thought, is a planet’s obliquity — the angle of its axis relative to its orbit around a star.

Earth, for instance, has a relatively low obliquity, rotating around an axis that is nearly perpendicular to the plane of its orbit around the sun. Scientists suspect, however, that exoplanets may exhibit a host of obliquities, resembling anything from a vertical spinning top to a horizontal rotisserie. The more extreme the tilt, the less habitable a planet may be — or so the thinking has gone.

Now scientists at MIT have found that even a high-obliquity planet, with a nearly horizontal axis, could potentially support life, so long as the planet were completely covered by an ocean. In fact, even a shallow ocean, about 50 meters deep, would be enough to keep such a planet at relatively comfortable temperatures, averaging around 60 degrees Fahrenheit year-round.

David Ferreira, a former research scientist in MIT’s Department of Earth, Atmospheric and Planetary Sciences (EAPS), says that on the face of it, a planet with high obliquity would appear rather extreme: Tilted on its side, its north pole would experience daylight continuously for six months, and then darkness for six months, as the planet revolves around its star.

“The expectation was that such a planet would not be habitable: It would basically boil, and freeze, which would be really tough for life,” says Ferreira, who is now a lecturer at the University of Reading, in the United Kingdom. “We found that the ocean stores heat during summer and gives it back in winter, so the climate is still pretty mild, even in the heart of the cold polar night. So in the search for habitable exoplanets, we’re saying, don’t discount high-obliquity ones as unsuitable for life.”

The tilt of Mars' axis varies over a 124,000-year cycle. A steeper tilt means a generally warmer climate; a slight tilt a colder one. Courtesy of NASA

The tilt of Mars’ axis varies over a 124,000-year cycle. A steeper tilt means a generally warmer climate; a slight tilt a colder one. Courtesy of NASA

Details of the group’s analysis are published in the journal Icarus. The paper’s co-authors are Ferreira; Sara Seager, the Class of 1941 Professor in EAPS and MIT’s Department of Physics; John Marshall, the Cecil and Ida Green Professor in Earth and Planetary Sciences; and Paul O’Gorman, an associate professor in EAPS.

Tilting toward a habitable exoplanet

Ferreira and his colleagues used a model developed at MIT to simulate a high-obliquity “aquaplanet” — an Earth-sized planet, at a similar distance from its sun, covered entirely in water. The three-dimensional model is designed to simulate circulations among the atmosphere, ocean, and sea ice, taking into the account the effects of winds and heat in driving a 3000-meter deep ocean. For comparison, the researchers also coupled the atmospheric model with simplified, motionless “swamp” oceans of various depths: 200 meters, 50 meters, and 10 meters.

The researchers used the detailed model to simulate a planet at three obliquities: 23 degrees (representing an Earth-like tilt), 54 degrees, and 90 degrees.

For a planet with an extreme, 90-degree tilt, they found that a global ocean — even one as shallow as 50 meters — would absorb enough solar energy throughout the polar summer and release it back into the atmosphere in winter to maintain a rather mild climate. As a result, the planet as a whole would experience spring-like temperatures year round.

“We were expecting that if you put an ocean on the planet, it might be a bit more habitable, but not to this point,” Ferreira says. “It’s really surprising that the temperatures at the poles are still habitable.”

A runaway “snowball Earth”

In general, the team observed that life could thrive on a highly tilted aquaplanet, but only to a point. In simulations with a shallower ocean, Ferreira found that waters 10 meters deep would not be sufficient to regulate a high-obliquity planet’s climate. Instead, the planet would experience a runaway effect: As soon as a bit of ice forms, it would quickly spread across the dark side of the planet. Even when this side turns toward the sun, according to Ferreira, it would be too late: Massive ice sheets would reflect the sun’s rays, allowing the ice to spread further into the newly darkened side, and eventually encase the planet.

“Some people have thought that a planet with a very large obliquity could have ice just around the equator, and the poles would be warm,” Ferreira says. “But we find that there is no intermediate state. If there’s too little ocean, the planet may collapse into a snowball. Then it wouldn’t be habitable, obviously.”

Darren Williams, a professor of physics and astronomy at Pennsylvania State University, says past climate modeling has shown that a wide range of climate scenarios are possible on extremely tilted planets, depending on the sizes of their oceans and landmasses. Ferreira’s results, he says, reach similar conclusions, but with more detail.

“There are one or two terrestrial-sized exoplanets out of a thousand that appear to have densities comparable to water, so the probability of an all-water planet is at least 0.1 percent,” Williams says. “The upshot of all this is that exoplanets at high obliquity are not necessarily devoid of life, and are therefore just as interesting and important to the astrobiology community.”

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Rosetta Orbiter to Swoop Down On Comet in February

From the location where it came to rest after bounces, the Philae lander of the European Space Agency's Rosetta mission captured this view of a cliff on the nucleus of comet 67P/Churyumov-Gerasimenko. Copyright: ESA/Rosetta/Philae/CIVA

From the location where it came to rest after bounces, the Philae lander of the European Space Agency’s Rosetta mission captured this view of a cliff on the nucleus of comet 67P/Churyumov-Gerasimenko. Copyright: ESA/Rosetta/Philae/CIVA

The European Space Agency’s orbiting Rosetta spacecraft is expected to come within four miles (six kilometers) of the surface of comet 67P/Churyumov-Gerasimenko in February of next year. The flyby will be the closest the comet explorer will come during its prime mission.

“It is the earliest we could carry it out without impacting the vitally important bound orbits that are currently being flown,” said Matt Taylor, the Rosetta project scientist from the European Space Research and Technology Center, Noordwijk, the Netherlands. “As the comet becomes more and more active, it will not be possible to get so close to the comet. So this opportunity is very unique.”

This mosaic of images from the navigation camera on the European Space Agency's Rosetta spacecraft shows the nucleus of comet 67P/Churyumov-Gerasimenko as it appeared at 5 a.m. UTC on Dec. 17, 2014 (9 p.m. PST on Dec. 16). Credit: ESA/Rosetta/NAVCAM

This mosaic of images from the navigation camera on the European Space Agency’s Rosetta spacecraft shows the nucleus of comet 67P/Churyumov-Gerasimenko as it appeared at 5 a.m. UTC on Dec. 17, 2014 (9 p.m. PST on Dec. 16). Credit: ESA/Rosetta/NAVCAM

The low flyby will be an opportunity for Rosetta to obtain imagery with a resolution of a few inches (tens of centimeters) per pixel. The imagery is expected to provide information on the comet’s porosity and albedo (its reflectance). The flyby will also allow the study of the processes by which cometary dust is accelerated by the cometary gas emission.

“Rosetta is providing us with a grandstand seat of the comet throughout the next year. This flyby will put us track side — it’s going to be that close,” said Taylor.

The Rosetta orbiter deployed its Philae lander to one spot on the comet’s surface in November. Philae obtained the first images taken from a comet’s surface and will provide analysis of the comet’s possible primordial composition.

Comets are time capsules containing primitive material left over from the epoch when our sun and its planets formed. Rosetta will be the first spacecraft to witness at close proximity how a comet changes as it is subjected to the increasing intensity of the sun’s radiation. Observations will help scientists learn more about the origin and evolution of our solar system and the role comets may have played in seeding Earth with water, and perhaps even life.

This graphic depicts the position of the Philae lander of the European Space Agency's Rosetta mission in the context of topographic modeling of the surface of comet 67P/Churyumov-Gerasimenko's nucleus. Copyright: ESA/Rosetta/Philae/CNES/FD

This graphic depicts the position of the Philae lander of the European Space Agency’s Rosetta mission in the context of topographic modeling of the surface of comet 67P/Churyumov-Gerasimenko’s nucleus. Copyright: ESA/Rosetta/Philae/CNES/FD

Rosetta is a European Space Agency mission with contributions from its member states and NASA. The Jet Propulsion Laboratory, Pasadena, California, a division of the California Institute of Technology in Pasadena, manages the U.S. contribution of the Rosetta mission for NASA’s Science Mission Directorate in Washington.

JPL also built the MIRO instrument and hosts its principal investigator, Samuel Gulkis. The Southwest Research Institute (San Antonio and Boulder) developed the Rosetta orbiter’s IES and Alice instruments, and hosts their principal investigators, James Burch (IES) and Alan Stern (Alice).

For more information on the U.S. instruments aboard Rosetta, visit: http://rosetta.jpl.nasa.gov

More information about Rosetta is available at: http://www.esa.int/rosetta

 

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NASA’s Kepler Reborn, Makes First Exoplanet Find of New Mission

This artist's concept shows the first planet discovered by NASA's Kepler spacecraft during its K2 mission, a "super Earth" called HIP 116454b. The planet has a diameter of 20,000 miles, weighs 12 times as much as Earth and orbits its star once every 9.1 days. Credit: David A. Aguilar (CfA)

This artist’s concept shows the first planet discovered by NASA’s Kepler spacecraft during its K2 mission, a “super Earth” called HIP 116454b. The planet has a diameter of 20,000 miles, weighs 12 times as much as Earth and orbits its star once every 9.1 days.
Credit: David A. Aguilar (CfA)

NASA’s planet-hunting Kepler spacecraft makes a comeback with the discovery of the first exoplanet found using its new mission — K2.

The discovery was made when astronomers and engineers devised an ingenious way to repurpose Kepler for the K2 mission and continue its search of the cosmos for other worlds.

“Last summer, the possibility of a scientifically productive mission for Kepler after its reaction wheel failure in its extended mission was not part of the conversation,” said Paul Hertz, NASA’s astrophysics division director at the agency’s headquarters in Washington. “Today, thanks to an innovative idea and lots of hard work by the NASA and Ball Aerospace team, Kepler may well deliver the first candidates for follow-up study by the James Webb Space Telescope to characterize the atmospheres of distant worlds and search for signatures of life.”

Lead researcher Andrew Vanderburg, a graduate student at the Harvard-Smithsonian Center for Astrophysics in Cambridge, Massachusetts, studied publicly available data collected by the spacecraft during a test of K2 in February 2014. The discovery was confirmed with measurements taken by the HARPS-North spectrograph of the Telescopio Nazionale Galileo in the Canary Islands, which captured the wobble of the star caused by the planet’s gravitational tug as it orbits.

The newly confirmed planet, HIP 116454b, is 2.5 times the diameter of Earth and follows a close, nine-day orbit around a star that is smaller and cooler than our sun, making the planet too hot for life as we know it. HIP 116454b and its star are 180 light-years from Earth, toward the constellation Pisces.

Kepler’s onboard camera detects planets by looking for transits — when a distant star dims slightly as a planet crosses in front of it. The smaller the planet, the weaker the dimming, so brightness measurements must be exquisitely precise. To enable that precision, the spacecraft must maintain steady pointing. In May 2013, data collection during Kepler’s extended prime mission came to an end with the failure of the second of four reaction wheels, which are used to stabilize the spacecraft.

The artistic concept shows NASA's planet-hunting Kepler spacecraft operating in a new mission profile called K2. Using publicly available data, astronomers have confirmed K2's first exoplanet discovery proving Kepler can still find planets. Image Credit: NASA Ames/JPL-Caltech/T Pyle

The artistic concept shows NASA’s planet-hunting Kepler spacecraft operating in a new mission profile called K2. Using publicly available data, astronomers have confirmed K2’s first exoplanet discovery proving Kepler can still find planets. Image Credit: NASA Ames/JPL-Caltech/T Pyle

Rather than giving up on the stalwart spacecraft, a team of scientists and engineers crafted a resourceful strategy to use pressure from sunlight as a “virtual reaction wheel” to help control the spacecraft. The resulting K2 mission promises to not only continue Kepler’s planet hunt, but also to expand the search to bright nearby stars that harbor planets that can be studied in detail and better understand their composition. K2 also will introduce new opportunities to observe star clusters, active galaxies and supernovae.

Small planets like HIP 116454b, orbiting nearby bright stars, are a scientific sweet spot for K2 as they are good prospects for follow-up ground studies to obtain mass measurements. Using K2’s size measurements and ground-based mass measurements, astronomers can calculate the density of a planet to determine whether it is likely a rocky, watery or gaseous world.

“The Kepler mission showed us that planets larger in size than Earth and smaller than Neptune are common in the galaxy, yet they are absent in our solar system,” said Steve Howell, Kepler/K2 project scientist at NASA’s Ames Research Center in Moffett Field, California. “K2 is uniquely positioned to dramatically refine our understanding of these alien worlds and further define the boundary between rocky worlds like Earth and ice giants like Neptune.”

Since the K2 mission officially began in May 2014, it has observed more than 35,000 stars and collected data on star clusters, dense star-forming regions, and several planetary objects within our own solar system. It is currently in its third campaign.

The research paper reporting this discovery has been accepted for publication in The Astrophysical Journal.

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How NASA Curiosity Instrument Made First Detection of Organic Matter on Mars

This self-portrait of NASA's Mars rover Curiosity combines dozens of exposures taken by the rover's Mars Hand Lens Imager on Feb. 3, 2013 plus three exposures taken May 10, 2013 to show two holes (in lower left quadrant) where Curiosity used its drill on the rock target "John Klein". Image Credit: NASA/JPL-Caltech/MSSS

This self-portrait of NASA’s Mars rover Curiosity combines dozens of exposures taken by the rover’s Mars Hand Lens Imager on Feb. 3, 2013 plus three exposures taken May 10, 2013 to show two holes (in lower left quadrant) where Curiosity used its drill on the rock target “John Klein”. Image Credit: NASA/JPL-Caltech/MSSS

The team responsible for the Sample Analysis at Mars (SAM) instrument suite on NASA’s Curiosity rover has made the first definitive detection of organic molecules at Mars. Organic molecules are the building blocks of all known forms of terrestrial life, and consist of a wide variety of molecules made primarily of carbon, hydrogen, and oxygen atoms.

However, organic molecules can also be made by chemical reactions that don’t involve life, and there is not enough evidence to tell if the matter found by the team came from ancient Martian life or from a non-biological process. Examples of non-biological sources include chemical reactions in water at ancient Martian hot springs or delivery of organic material to Mars by interplanetary dust or fragments of asteroids and comets.

The surface of Mars is currently inhospitable to life as we know it, but there is evidence that the Red Planet once had a climate that could have supported life billions of years ago. For example, features resembling dry riverbeds and minerals that only form in the presence of liquid water have been discovered on the Martian surface. The Curiosity rover with its suite of instruments including SAM was sent to Mars in 2011 to discover more about the ancient habitable Martian environment by examining clues in the chemistry of rocks and the atmosphere.

The organic molecules found by the team were in a drilled sample of the Sheepbed mudstone in Gale crater, the landing site for the Curiosity rover. Scientists think the crater was once the site of a lake billions of years ago, and rocks like mudstone formed from sediment in the lake. Moreover, this mudstone was found to contain 20 percent smectite clays. On Earth, such clays are known to provide high surface area and optimal interlayer sites for the concentration and preservation of organic compounds when rapidly deposited under reducing chemical conditions.

While the team can’t conclude that there was life at Gale crater, the discovery shows that the ancient environment offered a supply of reduced organic molecules for use as building blocks for life and an energy source for life. Curiosity’s earlier analysis of this same mudstone revealed that the environment offered water and chemical elements essential for life and a different chemical energy source.

“We think life began on Earth around 3.8 billion years ago, and our result shows that places on Mars had the same conditions at that time – liquid water, a warm environment, and organic matter,” said Caroline Freissinet of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “So if life emerged on Earth in these conditions, why not on Mars as well?” Freissinet is lead author of a paper on this research submitted to the Journal of Geophysical Research-Planets.

Daniel Glavin of NASA’s Goddard Space Flight Center discusses the discovery of organic matter on Mars and other recent results from the MSL Curiosity rover. Image Credit: NASA Goddard

The organic molecules found by the team also have chlorine atoms, and include chlorobenzene and several dichloroalkanes, such as dichloroethane, dichloropropane and dichlorobutane. Chlorobenzene is the most abundant with concentrations between 150 and 300 parts-per-billion. Chlorobenzene is not a naturally occurring compound on Earth. It is used in the manufacturing process for pesticides (insecticide DDT), herbicides, adhesives, paints and rubber. Dichloropropane is used as an industrial solvent to make paint strippers, varnishes and furniture finish removers, and is classified as a carcinogen.

It’s possible that these chlorine-containing organic molecules were present as such in the mudstone. However, according to the team, it’s more likely that a different suite of precursor organic molecules was in the mudstone, and that the chlorinated organics formed from reactions inside the SAM instrument as the sample was heated for analysis. Perchlorates (a chlorine atom bound to four oxygen atoms) are abundant on the surface of Mars. It’s possible that as the sample was heated, chlorine from perchlorate combined with fragments from precursor organic molecules in the mudstone to produce the chlorinated organic molecules detected by SAM.

In 1976, the Gas Chromatograph Mass Spectrometer instrument on NASA’s Viking landers detected two simple chlorinated hydrocarbons after heating Martian soils for analysis (chloromethane and dichloromethane). However they were not able to rule out that the compounds were derived from the instrument itself, according to the team. While sources within the SAM instrument also produce chlorinated hydrocarbons, they don’t make more than 22 parts-per-billion of chlorobenzene, far below the amounts detected in the mudstone sample, giving the team confidence that organic molecules really are present on Mars.

The SAM instrument suite was built at NASA Goddard with significant elements provided by industry, university, and national and international NASA partners.

SAM's three instruments are visible in this view taken before installation of its side panels: the tunable laser spectrometer (TLS) at lower left, the quadrupole mass spectrometer (QMS) at upper right, and the gas chromatograph (GC) at lower right. Image Credit: NASA

SAM’s three instruments are visible in this view taken before installation of its side panels: the tunable laser spectrometer (TLS) at lower left, the quadrupole mass spectrometer (QMS) at upper right, and the gas chromatograph (GC) at lower right. Image Credit: NASA

For this analysis, the Curiosity rover sample acquisition system drilled into a mudstone and filtered fine particles of it through a sieve, then delivered a portion of the sample to the SAM laboratory. SAM detected the compounds using its Evolved Gas Analysis (EGA) mode by heating the sample up to around 1,600 degrees Fahrenheit (about 875 degrees Celsius) and then monitoring the volatiles released from the sample using a quadrupole mass spectrometer, which identifies molecules by their mass using electric fields.

SAM also detected and identified the compounds using its Gas Chromatograph Mass Spectrometer (GCMS) mode. In this mode, volatiles are separated by the amount of time they take to travel through a narrow tube (gas chromatography – certain molecules interact with the sides of the tube more readily and thus travel more slowly) and then identified by their signature mass fragments in the mass spectrometer.

The first evidence for elevated levels of chlorobenzene and dichloroalkanes released from the mudstone was obtained on Curiosity Sol 290 (May 30, 2013) with the third analysis of the Cumberland sample at Sheepbed. The team spent over a year carefully analyzing the result, including conducting laboratory experiments with instruments and methods similar to SAM, to be sure that SAM could not be producing the amount of organic material detected.

“The search for organics on Mars has been extremely challenging for the team,” said Daniel Glavin of NASA Goddard, a co-author on the paper. “First, we need to identify environments in Gale crater that would have enabled the concentration of organics in sediments. Then they need to survive the conversion of sediment to rock, where pore fluids and dissolved substances may oxidize and destroy organics. Organics can then be destroyed during exposure of rocks at the surface of Mars to intense ionizing radiation and oxidants. Finally, to identify any organic compounds that have survived, we have to deal with oxychlorine compounds and possibly other strong oxidants in the sample which will react with and combust organic compounds to carbon dioxide and chlorinated hydrocarbons when the samples are heated by SAM.”

As part of Curiosity’s plan for exploration, an important strategic goal was to sample rocks that represent different combinations of the variables thought to control organic preservation.

“The SAM and Mars Science Laboratory teams have worked very hard to achieve this result,” said John Grotzinger of the California Institute of Technology in Pasadena, Mars Science Laboratory’s Project Scientist. “Only by drilling additional rock samples in different locations, and representing different geologic histories were we able to tease out this result. At the time we first saw evidence of these organic molecules in the Cumberland sample it was uncertain if they were derived from Mars, however, additional drilling has not produced the same compounds as might be predicted for contamination, indicating that the carbon in the detected organic molecules is very likely of Martian origin.”

Size, duration were like modern climate change

Banded sedimentary rocks in the Willwood formation in Wyoming were sampled to look into the past. Credit: Scott Wing

Banded sedimentary rocks in the Willwood formation in Wyoming were sampled to look into the past. Credit: Scott Wing

The rate at which carbon emissions warmed Earth’s climate almost 56 million years ago resembles modern, human-caused global warming much more than previously believed, but involved two pulses of carbon to the atmosphere, researchers have found.

The findings mean that the so-called Paleocene-Eocene thermal maximum, or PETM, can provide clues to the future of modern climate change.

The good news: Earth and most species survived.

The bad news: It took millennia to recover from the episode, when temperatures rose by 5 to 8 degrees Celsius (9 to 15 degrees Fahrenheit).

“There is a positive note in that the world persisted, it did not go down in flames, it has a way of self-correcting and righting itself,” says University of Utah geochemist Gabe Bowen, lead author of a paper published today in the journal Nature Geoscience. “However, in this event it took almost 200,000 years before things got back to normal.”

Using continental drilling boreholes from the Bighorn Basin of Wyoming, “these researchers have revealed for the first time that two rapid carbon release events occurred in the beginning of the PETM about 55.5 million years ago, the warmest period for the past 65 million years on Earth,” says Yusheng (Chris) Liu, program director in the National Science Foundation’s (NSF) Division of Earth Sciences, which funded the research.

Carbonate or limestone in the sediment cores revealed the amount of carbon stored long ago. Credit: Bianca Maibauer

Carbonate or limestone in the sediment cores revealed the amount of carbon stored long ago. Credit: Bianca Maibauer

Bowen and colleagues report that carbonate or limestone nodules in Wyoming sediment cores show that the global warming episode 55.5 million to 55.3 million years ago involved the average annual release of a minimum of 0.9 petagrams (1.98 trillion pounds) of carbon to the atmosphere, and probably much more over shorter periods.

That’s “within an order of magnitude of, and may have approached, the 9.5 petagrams (20.9 trillion pounds) per year associated with modern anthropogenic carbon emissions,” the researchers write in their paper.

Since 1900, human burning of fossil fuels has emitted an average of 3 petagrams per year–even closer to the rate 55.5 million years ago. Each past pulse of carbon emissions lasted no more than 1,500 years. Previous conflicting evidence indicated that the carbon release lasted anywhere from less than a year to tens of thousands of years.

The new research shows that atmospheric carbon levels returned to normal within a few thousand years after the first pulse, probably as carbon dissolved in the ocean.

200,000 years for conditions to normalize

After the second pulse, it took up to 200,000 years for conditions to normalize.

The research also ruled as unlikely some theorized causes of the warming episode, including an asteroid impact, slow melting of permafrost, burning of organic-rich soil or drying out of a major seaway.

Instead, the findings suggest that more likely causes included melting of seafloor methane ices known as clathrates, or volcanism that heated organic-rich rocks and released methane.

“The Paleocene-Eocene thermal maximum has stood out as a striking, but contested, example of how 21st-century-style atmospheric carbon dioxide buildup can affect climate, environments and ecosystems worldwide,” says Bowen.

“This new study tightens the link. Carbon release back then looked a lot like human fossil-fuel emissions today, so we might learn a lot about the future from changes in climate, plants and animal communities 55.5 million years ago.”

Sediment cores were drilled in Bighorn Basin, then sectioned for further study. Credit: Bianca Maibauer

Sediment cores were drilled in Bighorn Basin, then sectioned for further study. Credit: Bianca Maibauer

Bowen cautioned, however, that global climate already was much warmer than today’s when the Paleocene-Eocene warming began, and there were no icecaps, “so this happened out on a different playing field than what we have today.”

Paper co-author Scott Wing, a paleobiologist at the Smithsonian Institution in Washington, D.C., adds, “This study gives us the best idea yet of how quickly this vast amount of carbon was released at the beginning of the global warming event we call the Paleocene-Eocene thermal maximum.

“The answer is just a few thousands of years or less. That’s important because it means the ancient event happened at a rate more like human-caused global warming than we ever realized.”

Bowen and Wing conducted the study with University of Utah geologists Bianca Maibauer and Amy Steimke; Mary Kraus of the University of Colorado, Boulder; Ursula Rohl and Thomas Westerhold of the University of Bremen, Germany; Philip Gingerich of the University of Michigan; and William Clyde of the University of New Hampshire.

Effects of the Paleocene-Eocene warming 

Bowen says that previous research has shown that during the Paleocene-Eocene warming period, there was “enhanced storminess in some areas and increased aridity in other places. We see continent-scale migration of animals and plants, and ranges shifting.”

A rainbow appears over an NSF-funded geologic research drilling site in Wyoming's Bighorn Basin. Credit: Elisabeth Denis

A rainbow appears over an NSF-funded geologic research drilling site in Wyoming’s Bighorn Basin. Credit: Elisabeth Denis

First, “we see only a little bit of extinction–some groups of deep-sea foraminifera, one-celled organisms, that go extinct at the start of this event. Not much else went extinct. Then “we see the first wave of modern mammals showing up, including ancestral primates and hoofed animals,” he adds. Oceans became more acidic, as they are now.

“We look through time recorded in those rocks, and this warming event stands out, and everything happens together,” Bowen says. “We can look back in Earth’s history and say this is how this world works, and it’s totally consistent with the expectation that carbon dioxide change today will be associated with these other sorts of change.”

The Paleocene-Eocene thermal maximum also points to the possibility of runaway climate change enhanced by feedbacks.

“The fact we have two releases may suggest that the second one was driven by the first,” perhaps, for example, if the first warming raised ocean temperatures enough to melt massive amounts of frozen methane, Bowen says.

Drilling into Earth’s past

The study is part of a major drilling project aimed at understanding the 56-million-year-old warming episode. The researchers drilled long, core-shaped, sediment samples from two boreholes at Polecat Bench in northern Wyoming’s Bighorn Basin, east of Cody and just north of Powell.

“This site has been excavated for more than 100 years by paleontologists studying fossil mammals,” Bowen says.

Paleobiologist Scott Wing holds a core sample drilled from the Willwood formation. Credit: William Clyde

Paleobiologist Scott Wing holds a core sample drilled from the Willwood formation. Credit: William Clyde

The Paleocene-Eocene warming is recorded in the banded, tan and red rock and soil layers of the Willwood formation, in round, gray to brown-gray carbonate nodules in those rocks.

By measuring carbon isotope ratios in the nodules, the researchers found that during each 1,500-year carbon release, the ratio of carbon-13 to carbon-12 in the atmosphere declined, indicating two large releases of carbon dioxide or methane, both greenhouse gases from plant material.

The decline was three parts per thousand for the first pulse and 5.7 parts per thousand for the second. Previous evidence from seafloor sediments elsewhere is consistent with two Paleocene-Eocene carbon pulses, which “means we don’t think this is something unique to northern Wyoming,” Bowen says. “We think it reflects a global signal.”

What caused the prehistoric warming?

The double-barreled carbon release at the Paleocene-Eocene time boundary pretty much rules out an asteroid or comet impact because such a catastrophe would have been “too quick” to explain the 1,500-year duration of each carbon pulse, Bowen says.

Another theory: oxidation of organic matter–as permafrost thawed, as peaty soils burned, or as a seaway dried up–may have caused the Paleocene-Eocene warming. But that would have taken tens of thousands of years, far slower than what the study found. Volcanoes releasing carbon gases also would have been too slow.

Bowen says the two relatively rapid carbon releases–about 1,500 years each–are more consistent with warming oceans or an undersea landslide triggering the melting of frozen methane on the seafloor and large emissions to the atmosphere, where it became carbon dioxide within decades.

Another possibility is a massive intrusion of molten rock that heated overlying organic-rich rocks and released a lot of methane.

Contamination of Impacted Meteorites Can Happen Quickly

Scott Sandford next to a cryovacuum systems that helps reveal the chemistry that produces organic compounds of astrobiological interest. Credit: NASA Ames/Sandford

Scott Sandford next to a cryovacuum systems that helps reveal the chemistry that produces organic compounds of astrobiological interest. Credit: NASA Ames/Sandford

A team of scientists has published the results of an investigative survey into the Sutter’s Mill meteorite that landed in California in 2012.

The results reveal that the meteorite contained a number of features associated with minerals such as olivines, phyllosilicates, carbonates, and possibly pyroxenes, as well as organics.

However, a key conclusion of the paper, and one that is likely to be of keen interest to astrobiologists, is confirmation that meteorites can become contaminated by Earth-based organics very quickly. That means scientists must be extra vigilant in identifying and assessing the effects of terrestrial organic contamination of meteoritic samples.

Infrared Spectroscopy

The paper, “Mid-infrared Study of Stones from the Sutter’s Mill Meteorite,” was published online in the March, 2014 issue of the journal Meteoritics and Planetary Science. It provides a detailed overview of the mineral composition of the meteorite, which fell in northern California on April 22, 2012.

Scott Sandford of NASA’s Ames Research Center looks into the sample chamber of one of the cryovacuum systems to study the chemical processes that can happen in space. Credit: NASA Ames/ Sandford

Scott Sandford of NASA’s Ames Research Center looks into the sample chamber of one of the cryovacuum systems to study the chemical processes that can happen in space. Credit: NASA Ames/ Sandford

Several fragments of the meteorite were recovered, four of them shortly after the fall, and others several days later after a heavy rainstorm. The research team used infrared spectroscopy, employing several different analytical devices to obtain spectra from very small samples. The spectra from the samples were then compared those of “standard materials,” which refer to previously identified and characterized mineral standards. For example, the spectra of the carbonates in the Sutter’s Mill meteorite samples were compared against the spectra of “mineral standards” of the carbonates calcite and dolomite.

“This sort of spectral matching is a way to identify an unknown,” says Scott Sandford, a co-author of the paper and a space scientist at the NASA Ames Research Center. “Good spectral matches suggest possible identifications, while bad matches eliminate them. Most of the spectra are dominated by minerals that are consistent with the identification of this meteorite as a carbonaceous chondrite.”

Carbonaceous chondrites are counted amongst the most primitive of all known meteorites and comprise about 3 percent of all the meteorites collected on Earth. They are of particular importance to astrobiologists because of the insights they provide into the early history of the Solar System.

Indigenous Organics

The research team hoped that the analysis of the meteorite samples would detect the spectral features of the “indigenous organics” that arrived with the original meteorite, as opposed to organic contaminates that got onto the samples after they landed on the ground. Although the team saw “clear” evidence of contamination on some of the samples, Sandford says there were a few places where it was “possible” that the team detected “organics original to the meteorite,” but admits that the matter is “in no way proven by the data.”

“[M]uch of the discussion in our paper associated with organics is devoted to addressing the caution that must be applied to searching for organics in this meteorite using spectral techniques, since the presence of organic contamination and abundant carbonate minerals makes spectral searches very difficult,” adds Sandford.

For him, this difficulty was caused by a combination of two different factors. To begin with, even though some of the team’s samples were collected fairly rapidly, there was evidence that bacterial contamination was present “in at least one of the samples.”

Scott Sandford on an Antarctic expedition to collect meteorites. Credit: NASA Ames/Sandford

Scott Sandford on an Antarctic expedition to collect meteorites. Credit: NASA Ames/Sandford

Secondly, many of the samples contained abundant carbonate minerals, which made it much more difficult to detect the spectral signatures of certain types of organic materials.

As Sandford explains, this is because carbonate minerals produce a series of characteristic bands in the infrared spectrum, some strong, some weak. Some of these weak bands happen to land right on top of one of the spectral positions where particular types of organic compounds, known as aliphatic hydrocarbons, also typically produce features. Aliphatic hydrocarbons include molecules such as ethane, propane and butane.

“This is unfortunate, since it can cause considerable spectral confusion that makes it difficult to detect organics if they are present,” adds Sandford.

A Note of Caution

In Sandford’s view, both of these points serve as “cautionary items” for the astrobiology community.

The photon energies associated with the part of the infrared spectrum investigated by the team are generally not large enough to excite individual electrons, but are often high enough to induce the vibration of highly stable covalently bonded atoms and groups.

One way of thinking about this is to picture the covalent bonds in molecules not as stiff rods or poles of the type found in molecule construction kits, but rather as rigid springs that can be bent or stretched. These types of vibrations, or vibrational modes, are often assigned descriptive names, including bending, scissoring, rocking, wagging, twisting and stretching. The research team analysing the Sutter’s Mill meteorite concentrated on one such mode, known as the C-H stretching mode.

The recover team of the Stardust comet sample return mission collects the recovered capsule, which has been bagged to minimized contamination of the returned samples. Sandford is on the far right. Credit: NASA Ames/Sandford

The recover team of the Stardust comet sample return mission collects the recovered capsule, which has been bagged to minimized contamination of the returned samples. Sandford is on the far right. Credit: NASA Ames/Sandford

“Because of the structure of carbonate minerals, one of their vibrational modes can be mistaken for organics if only the C-H stretching region is examined and you’re not cautious,” he says.

Sandford adds:

“I’d say that use of IR spectroscopy in the C-H stretching region clearly needs to be used with caution, particularly in samples that may contain carbonates.”

Constant Vigilance

In light of the investigations carried out by the team, Sandford concludes that the broader astrobiological community “must always be vigilant” when assessing the effects of terrestrial contamination of any samples collected.

Scott Sandford shows a sample of aerogel, the world’s lowest density solid material, from the comet Wild-2. Credit: NASA Ames/Sandford

Scott Sandford shows a sample of aerogel, the world’s lowest density solid material, from the comet Wild-2. Credit: NASA Ames/Sandford

Although he is pessimistic about the prospects of astrobiologists ever finding signs of extinct life in meteorites, he believes that studies of this kind will continue to be a fruitful area of research into the detection of prebiotic organics.

“I don’t think that there are many people who are trying to detect life in meteorites. Most of us are trying to detect prebiotic organics in meteorites — that is, molecules that may have played a role in helping life get started on Earth. While there are some folks that think they’ve detected signs of extinct life in meteorites, I have not so far found their arguments to be very compelling,” he says.

Scientists using NASA data released new insights into the hidden plumbing of melt water flowing through the Greenland Ice Sheet as well as the most detailed picture ever of how the ice sheet moves toward the sea. Image Credit: NASA/Michael Studinger

Scientists using NASA data released new insights into the hidden plumbing of melt water flowing through the Greenland Ice Sheet as well as the most detailed picture ever of how the ice sheet moves toward the sea. Image Credit: NASA/Michael Studinger

For years NASA has tracked changes in the massive Greenland Ice Sheet. This week scientists using NASA data released the most detailed picture ever of how the ice sheet moves toward the sea and new insights into the hidden plumbing of melt water flowing under the snowy surface.

The results of these studies are expected to improve predictions of the future of the entire Greenland ice sheet and its contribution to sea level rise as researchers revamp their computer models of how the ice sheet reacts to a warming climate.

“With the help of NASA satellite and airborne remote sensing instruments, the Greenland Ice Sheet is finally yielding its secrets,” said Tom Wagner, program scientist for NASA’s cryosphere program in Washington. “These studies represent new leaps in our knowledge of how the ice sheet is losing ice. It turns out the ice sheet is a lot more complex than we ever thought.”

University at Buffalo geophysicist Beata Csatho led an international team that produced the first comprehensive study of how the ice sheet is losing mass based on NASA satellite and airborne data at nearly 100,000 locations across Greenland. The study found that the ice sheet shed about 243 gigatons of ice per year from 2003-09, which agrees with other studies using different techniques. The study was published today in the Proceedings of the National Academy of Sciences.

The study suggests that current ice sheet modeling is too simplistic to accurately predict the future contribution of the Greenland ice sheet to sea level rise, and that current models may underestimate ice loss in the near future.

This animation (from March 2014) portrays the changes occurring in the surface elevation of the Greenland Ice Sheet since 2003 in three drainage areas: the southeast, the northeast and the Jakobshavn regions. In each region, the time advances to show the accumulated change in elevation, 2003-2012.Image Credit: NASA’s Goddard Space Flight Center

The project was a massive undertaking, using satellite and aerial data from NASA’s ICESat spacecraft, which measured the elevation of the ice sheet starting in 2003, and the Operation IceBridge field campaign that has flown annually since 2009. Additional airborne data from 1993-2008, collected by NASA’s Program for Arctic Regional Climate Assessment, were also included to extend the timeline of the study.

Current computer simulations of the Greenland Ice Sheet use the activity of four well-studied glaciers — Jakobshavn, Helheim, Kangerlussuaq and Petermann — to forecast how the entire ice sheet will dump ice into the oceans. The new research shows that activity at these four locations may not be representative of what is happening with glaciers across the ice sheet. In fact, glaciers undergo patterns of thinning and thickening that current climate change simulations fail to address, Csatho says.

As a step toward building better models of sea level rise, the research team divided Greenland’s 242 glaciers into 7 major groups based on their behavior from 2003-09.

“Understanding the groupings will help us pick out examples of glaciers that are representative of the whole,” Csatho says. “We can then use data from these representative glaciers in models to provide a more complete picture of what is happening.”

The team also identified areas of rapid shrinkage in southeast Greenland that today’s models don’t acknowledge. This leads Csatho to believe that the ice sheet could lose ice faster in the future than today’s simulations would suggest.

Surface elevation changes over the entire Greenland Ice Sheet have been mapped in detail by NASA’s ICESat satellite (gray path lines) and Operation IceBridge airborne campaigns (purple path lines). Image Credit: NASA

Surface elevation changes over the entire Greenland Ice Sheet have been mapped in detail by NASA’s ICESat satellite (gray path lines) and Operation IceBridge airborne campaigns (purple path lines). Image Credit: NASA

In separate studies presented today at the American Geophysical Union annual meeting in San Francisco, scientists using data from Operation IceBridge found permanent bodies of liquid water in the porous, partially compacted firn layer just below the surface of the ice sheet. Lora Koenig at the National Snow and Ice Data Center in Boulder, Colorado, and Rick Forster at the University of Utah in Salt Lake City, found signatures of near-surface liquid water using ice-penetrating radar.

Across wide areas of Greenland, water can remain liquid, hiding in layers of snow just below the surface, even through cold, harsh winters, researchers are finding. The discoveries by the teams led by Koenig and Forster mean that scientists seeking to understand the future of the Greenland ice sheet need to account for relatively warm liquid water retained in the ice.

Although the total volume of water is small compared to overall melting in Greenland, the presence of liquid water throughout the year could help kick off melt in the spring and summer. “More year-round water means more heat is available to warm the ice,” Koenig said.

Koenig and her colleagues found that sub-surface liquid water are common on the western edges of the Greenland Ice Sheet. At roughly the same time, Forster used similar ground-based radars to find a large aquifer in southeastern Greenland. These studies show that liquid water can persist near the surface around the perimeter of the ice sheet year round.

Another researcher participating in the briefing found that near-surface layers can also contain masses of solid ice that can lead to flooding events. Michael MacFerrin, a scientist at the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder, and colleagues studying radar data from IceBridge and surface based instruments found near surface patches of ice known as ice lenses more than 25 miles farther inland than previously recorded.

Ice lenses form when firn collects surface meltwater like a sponge. When this shallow ice melts, as was seen during July 2012, they can release large amounts of water that can lead to flooding. Warm summers and resulting increased surface melt in recent years have likely caused ice lenses to grow thicker and spread farther inland. “This represents a rapid feedback mechanism. If current trends continue, the flooding will get worse,” MacFerrin said.

Venus Express Goes Gently Into the Night

Visualisation of the Venus Express aerobraking manoeuvre. Copyright ESA–C. Carreau

Visualisation of the Venus Express aerobraking manoeuvre. Copyright ESA–C. Carreau

ESA’s Venus Express has ended its eight-year mission after far exceeding its planned life. The spacecraft exhausted its propellant during a series of thruster burns to raise its orbit following the low-altitude aerobraking earlier this year.

Since its arrival at Venus in 2006, Venus Express had been on an elliptical 24‑hour orbit, traveling 66 000 km above the south pole at its furthest point and to within 200 km over the north pole on its closest approach, conducting a detailed study of the planet and its atmosphere.

However, after eight years in orbit and with propellant for its propulsion system running low, Venus Express was tasked in mid-2014 with a daring aerobraking campaign, during which it dipped progressively lower into the atmosphere on its closest approaches to the planet.

Normally, the spacecraft would perform routine thruster burns to ensure that it did not come too close to Venus and risk being lost in the atmosphere. But this unique adventure was aimed at achieving the opposite, namely reducing the altitude and allowing an exploration of previously uncharted regions of the atmosphere.

The campaign also provided important experience for future missions – aerobraking can be used to enter orbit around planets with atmospheres without having to carry quite so much propellant.

Venus Express aerobraking. Copyright ESA–C. Carreau

Venus Express aerobraking. Copyright ESA–C. Carreau

Between May and June 2014, the lowest point of the orbit was gradually reduced to about 130–135 km, with the core part of the aerobraking campaign lasting from 18 June to 11 July.

After this month of ‘surfing’ in and out of the atmosphere at low altitudes, the lowest point of the orbit was raised again through a series of 15 small thruster burns, such that by 26 July it was back up to about 460 km, yielding an orbital period of just over 22 hours.

The mission then continued in a reduced science phase, as the closest approach of the spacecraft to Venus steadily decreased again naturally under gravity.

Under the assumption that there was some propellant still remaining, a decision was taken to correct this natural decay with a new series of raising manoeuvres during 23–30 November, in an attempt to prolong the mission into 2015.

However, full contact with Venus Express was lost on 28 November. Since then the telemetry and telecommand links had been partially re-established, but they were very unstable and only limited information could be retrieved.

“The available information provides evidence of the spacecraft losing attitude control most likely due to thrust problems during the raising manoeuvres,” says Patrick Martin, ESA’s Venus Express mission manager.

“It seems likely, therefore, that Venus Express exhausted its remaining propellant about half way through the planned manoeuvres last month.”

Venus. Copyright ESA/MPS/DLR/IDA, M. Pérez-Ayúcar & C. Wilson

Venus. Copyright ESA/MPS/DLR/IDA, M. Pérez-Ayúcar & C. Wilson

Unlike cars and aircraft, spacecraft are not equipped with fuel gauges, so the time of propellant exhaustion for any satellite – especially after such a long time in space – is difficult to predict. The end could not be predicted but was not completely unexpected either.

Without propellant, however, it is no longer possible to control the attitude and orient Venus Express towards Earth to maintain communications. It is also impossible to raise the altitude further, meaning that the spacecraft will naturally sink deeper into the atmosphere over the coming weeks.

“After over eight years in orbit around Venus, we knew that our spacecraft was running on fumes,” says Adam Williams, ESA’s acting Venus Express spacecraft operations manager.

“It was to be expected that the remaining propellant would be exhausted during this period, but we are pleased to have been pushing the boundaries right down to the last drop.”

“During its mission at Venus, the spacecraft provided a comprehensive study of the planet’s ionosphere and atmosphere, and has enabled us to draw important conclusions about its surface,” says Håkan Svedhem, ESA’s Venus Express project scientist.

Venus has a surface temperature of over 450°C, far hotter than a normal kitchen oven, and its atmosphere is an extremely dense, choking mixture of noxious gases.

Is Venus volcanically active? Copyright ESA/AOES

Is Venus volcanically active? Copyright ESA/AOES

One highlight from the mission is the tantalising hint that the planet may well be still geologically active today. One study found numerous lava flows that must have been created no more than 2.5 million years ago – just yesterday on geological timescales – and possibly even much less than that.

Indeed, measurements of sulphur dioxide in the upper atmosphere have shown large variations over the course of the mission. Although peculiarities in the atmospheric circulation may produce a similar result, it is the most convincing argument to date of active volcanism.

Even though the conditions on the surface of Venus are extremely inhospitable today, a survey of the amount of hydrogen and deuterium in the atmosphere suggests that Venus once had a lot of water in the atmosphere, which is now mostly gone, and possibly even oceans of water like Earth’s.

Also just like Earth, the planet continues losing parts of its upper atmosphere to space: Venus Express measured twice as many hydrogen atoms escaping out of the atmosphere as oxygen atoms. Because water is made of two hydrogen atoms and one oxygen atom, the observed escape indicates that water is being broken up in the atmosphere.

Studies of the planet’s ‘super-rotating’ atmosphere – it whips around the planet in only four Earth-days, much faster than the 243 days the planet takes to complete one rotation about its axis – also turned up some intriguing surprises. When studying the winds, by tracking clouds in images, average wind speeds were found to have increased from roughly 300 km/h to 400 km/h over a period of six Earth years.

Venus, southern hemisphere. Copyright ESA/VIRTIS-VenusX IASF-INAF, Observatoire de Paris (R.Hueso, Univ. Bilbao)

Venus, southern hemisphere. Copyright ESA/VIRTIS-VenusX IASF-INAF, Observatoire de Paris (R.Hueso, Univ. Bilbao)

At the same time, a separate study found that the rotation of the planet had slowed by 6.5 minutes since NASA’s Magellan measured it before completing its five-year mission at Venus 20 years ago. However, it remains unknown if there is a direct relationship between the increasing wind speeds and the slowing rotation.

“While the science collection phase of the mission is now complete, the data will keep the scientific community busy for many years to come,” adds Håkan.

“Venus Express has been part of our family of spacecraft in orbit since it was launched in 2005,” says Paolo Ferri, Head of ESA Mission Operations.

“It has been an exciting experience to operate this marvellous spacecraft in the Venus environment. The scientific success of the mission is a great reward for the work done by the operations teams and makes us more proud than sad in this moment of farewell.”

“While we are sad that this mission is ended, we are nevertheless happy to reflect on the great success of Venus Express as part of ESA’s planetary science programme and are confident that its data will remain important legacy for quite some time to come,” says Martin Kessler, Head of ESA Science Operations.

“The mission has continued for much longer than its planned lifetime and it will now soon go out in a blaze of glory.”

“Venus Express was an important element of the scientific programme of ESA and, even though mission operations are ending, the planetary science community worldwide will continue to benefit from more than eight years of Venus Express data and major discoveries which foster the knowledge of terrestrial planets and their evolution,” says Alvaro Giménez, ESA’s Director of Science and Robotic Exploration.

The Structure and Nonfunction of RNA

An artist's rendering of a Ribonucleic Acid (RNA) molecule.

Credit: Nicolle Rager Fuller, National Science Foundation

An artist’s rendering of a Ribonucleic Acid (RNA) molecule.

Credit: Nicolle Rager Fuller, National Science Foundation

By studying how the structural components of RNA interact, and how the molecule performs the remarkable feat of self-assembling, scientists have uncovered new details about the chemical evolution of RNA.

Ribonucleic acid (RNA) exist in every living cells and plays numerous roles in living organisms. It’s most well-known duties are to help transport information and to participate in regulating how and when genes are expressed. RNA is believed to be one of the key molecules necessary for life as we know it.


The “RNA World” Hypothesis – Jack Szostak (Harvard/HHMI) Credit: iBioEducation(YouTube)
Previous studies have shown that RNA is an ancient molecule, and may have been present on Earth as long as life itself. Because of this, scientists have long wondered if RNA played a role in life’s origins on our planet. This is the basis for the theory of the ‘RNA world.’ In this proposed scenario, RNA would have functioned not only as a carrier of information in cells, but also as a catalyst for the reactions that keep cells alive.

Ramanarayanan Krishnamurthy. Associate Professor of Chemistry at the The Scripps Research Institute. Credit: The Scripps Research Institute

Lead author Ramanarayanan Krishnamurthy of the Department of Chemistry at Scripps Research Institute. Credit: The Scripps Research Institute

In recent decades, many studies have shown that RNA can perform a number of additional functions in cells. Studying the details of RNA’s structure and how it assembles can help shed light on whether or not its role in cellular reactions has changed over time.

There are many nuances in how structural components of RNA ultimately assemble into a molecule. The ways in which they assemble determine whether or not the molecule is capable of participating in certain reactions. Sometimes, the molecule assembles in such a way that it is rendered useless, or nonfuctional. These nonfunctional RNA molecules are what the research team turned to for their study. By comparing nonfunctional RNA molecules to functional ones, scientists were able to uncover new clues about how RNA molecules could have evolved over time at the chemical level.

The study, “RNA as an Emergent Entity: An Understanding Gained Through Studying its Nonfunctional Alternatives,” was supported by the National Science Foundation (NSF) and the NASA Astrobiology Program under the NSF/NASA Center for Chemical Evolution.

NASA Rover Finds Active and Ancient Organic Chemistry on Mars

The first definitive detection of Martian organic chemicals in material on the surface of Mars came from analysis by NASA's Curiosity Mars rover of sample powder from this mudstone target, "Cumberland." Image credit: NASA/JPL-Caltech/MSSS

The first definitive detection of Martian organic chemicals in material on the surface of Mars came from analysis by NASA’s Curiosity Mars rover of sample powder from this mudstone target, “Cumberland.” Image credit: NASA/JPL-Caltech/MSSS

NASA’s Mars Curiosity rover has measured a tenfold spike in methane, an organic chemical, in the atmosphere around it and detected other organic molecules in a rock-powder sample collected by the robotic laboratory’s drill.

“This temporary increase in methane — sharply up and then back down — tells us there must be some relatively localized source,” said Sushil Atreya of the University of Michigan, Ann Arbor, a member of the Curiosity rover science team. “There are many possible sources, biological or non-biological, such as interaction of water and rock.”

Researchers used Curiosity’s onboard Sample Analysis at Mars (SAM) laboratory a dozen times in a 20-month period to sniff methane in the atmosphere. During two of those months, in late 2013 and early 2014, four measurements averaged seven parts per billion. Before and after that, readings averaged only one-tenth that level.

Curiosity also detected different Martian organic chemicals in powder drilled from a rock dubbed Cumberland, the first definitive detection of organics in surface materials of Mars. These Martian organics could either have formed on Mars or been delivered to Mars by meteorites.

This graphic shows the Tunable Laser Spectrometer, one of the tools within the Sample Analysis at Mars laboratory on NASA's Curiosity Mars rover. Image credit: NASA/JPL-Caltech

This graphic shows the Tunable Laser Spectrometer, one of the tools within the Sample Analysis at Mars laboratory on NASA’s Curiosity Mars rover. Image credit: NASA/JPL-Caltech

Organic molecules, which contain carbon and usually hydrogen, are chemical building blocks of life, although they can exist without the presence of life. Curiosity’s findings from analyzing samples of atmosphere and rock powder do not reveal whether Mars has ever harbored living microbes, but the findings do shed light on a chemically active modern Mars and on favorable conditions for life on ancient Mars.

“We will keep working on the puzzles these findings present,” said John Grotzinger, Curiosity project scientist of the California Institute of Technology in Pasadena. “Can we learn more about the active chemistry causing such fluctuations in the amount of methane in the atmosphere? Can we choose rock targets where identifiable organics have been preserved?”

Researchers worked many months to determine whether any of the organic material detected in the Cumberland sample was truly Martian. Curiosity’s SAM lab detected in several samples some organic carbon compounds that were, in fact, transported from Earth inside the rover. However, extensive testing and analysis yielded confidence in the detection of Martian organics.

Identifying which specific Martian organics are in the rock is complicated by the presence of perchlorate minerals in Martian rocks and soils. When heated inside SAM, the perchlorates alter the structures of the organic compounds, so the identities of the Martian organics in the rock remain uncertain.

This illustration portrays possible ways methane might be added to Mars' atmosphere (sources) and removed from the atmosphere (sinks). Image credit: NASA/JPL-Caltech/SAM-GSFC/Univ. of Michigan

This illustration portrays possible ways methane might be added to Mars’ atmosphere (sources) and removed from the atmosphere (sinks). Image credit: NASA/JPL-Caltech/SAM-GSFC/Univ. of Michigan

“This first confirmation of organic carbon in a rock on Mars holds much promise,” said Curiosity Participating Scientist Roger Summons of the Massachusetts Institute of Technology in Cambridge.

“Organics are important because they can tell us about the chemical pathways by which they were formed and preserved. In turn, this is informative about Earth-Mars differences and whether or not particular environments represented by Gale Crater sedimentary rocks were more or less favorable for accumulation of organic materials. The challenge now is to find other rocks on Mount Sharp that might have different and more extensive inventories of organic compounds.”

Researchers also reported that Curiosity’s taste of Martian water, bound into lakebed minerals in the Cumberland rock more than three billion years ago, indicates the planet lost much of its water before that lakebed formed and continued to lose large amounts after.

SAM analyzed hydrogen isotopes from water molecules that had been locked inside a rock sample for billions of years and were freed when SAM heated it, yielding information about the history of Martian water. The ratio of a heavier hydrogen isotope, deuterium, to the most common hydrogen isotope can provide a signature for comparison across different stages of a planet’s history.

“It’s really interesting that our measurements from Curiosity of gases extracted from ancient rocks can tell us about loss of water from Mars,” said Paul Mahaffy, SAM principal investigator of NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and lead author of a report published online this week by the journal Science

This illustration portrays some of the reasons why finding organic chemicals on Mars is challenging. Image credit: NASA/JPL-Caltech

This illustration portrays some of the reasons why finding organic chemicals on Mars is challenging. Image credit: NASA/JPL-Caltech

The ratio of deuterium to hydrogen has changed because the lighter hydrogen escapes from the upper atmosphere of Mars much more readily than heavier deuterium. In order to go back in time and see how the deuterium-to-hydrogen ratio in Martian water changed over time, researchers can look at the ratio in water in the current atmosphere and water trapped in rocks at different times in the planet’s history.

Martian meteorites found on Earth also provide some information, but this record has gaps. No known Martian meteorites are even close to the same age as the rock studied on Mars, which formed about 3.9 billion to 4.6 billion years ago, according to Curiosity’s measurements.

The ratio that Curiosity found in the Cumberland sample is about one-half the ratio in water vapor in today’s Martian atmosphere, suggesting much of the planet’s water loss occurred since that rock formed.

However, the measured ratio is about three times higher than the ratio in the original water supply of Mars, based on the assumption that supply had a ratio similar to that measured in Earth’s oceans. This suggests much of Mars’ original water was lost before the rock formed.

The results of the Curiosity rover investigation into methane detection and the Martian organics in an ancient rock were discussed at a news briefing Tuesday at the American Geophysical Union’s convention in San Francisco. The methane results are described in a paper published online this week in the journal Science by NASA scientist Chris Webster of JPL, and co-authors.

A report on organics detection in the Cumberland rock by NASA scientist Caroline Freissenet, of Goddard, and co-authors, is pending publication.

For copies of the new Science papers about Mars methane and water, visit: http://go.nasa.gov/1cbk35X

Underground microbes are social creatures, new study shows.

Underground microbes are social creatures, new study shows.

Oil reservoirs are scattered deep inside the Earth like far-flung islands in the ocean, so their inhabitants might be expected to be very different, but a new study led by Dartmouth College and University of Oslo researchers shows these underground microbes are social creatures that have exchanged genes for eons.

The study, which was led by researchers at Dartmouth College and the University of Oslo, appears in the ISME Journal. A PDF is available on request.

The findings shed new light on the “deep biosphere,” or the vast subterranean realm whose single-celled residents are estimated to be roughly equal in number and diversity to all the microbes inhabiting the surface’s land, water and air. Deep microbial research may also help scientists to better understand life’s early evolution on Earth and aid the search for life on Mars and other planets.

Some scientists support a “burial and isolation” scenario in which bacteria living in oil reservoirs are descendants of isolated bacterial communities buried with sediments that over time became oil reservoirs. “Instead, our analysis supports a more complex ‘colonization’ view, where bacteria from subsurface and marine populations have been continuously migrating into the oil reservoirs and influencing their genetic composition since ancient times,” says co-author Olga Zhaxybayeva, an assistant professor at Dartmouth.

Since the 1980s, a growing number of microbial life forms have been discovered deep underground, but many questions remain, including when and how these microorganisms came to inhabit places where temperatures and pressure are extreme and nutrients and energy can be scarce. Microorganisms are the oldest form of life on Earth and continue to play a crucial role in the planet’s ecosystem. Those bacteria dwelling underground live not off sunlight energy but the Earth’s inner heat, chemicals and nutrients.

In their new paper, researchers asked a number of questions, including: do buried bacteria adapt to living in oil reservoirs as they form from sediments? Do bacteria evolve in isolation, or do they migrate to oil reservoirs and exchange genes with surrounding bacteria, including surface ones introduced through drilling fluids used in oil production?

The researchers analyzed 11 genomes of Thermotoga, an ancient lineage of heat-loving bacteria, taken from oil reservoirs in the North Sea and Japan and from hot water vents on the ocean floor near the Kuril Islands north of Japan, Italy and the Azores, an island chain west of Portugal. They also analyzed Thermotoga community DNA from the environment (so-called metagenomes) from North America and Australia that are available in public databases.

The results reveal extensive gene flow across all the sampled environments, suggesting the bacteria do not stay isolated in the oil reservoirs but instead have long migrated to and colonized the reservoirs and contributed to their genetic make-up.

“The pathway of the gene flow remains to be explained, but we hypothesize that a lot of the gene flow may happen within the subsurface,” says co-author Camilla Nesbø, a researcher at Centre for Ecological and Evolutionary Synthesis at the University of Oslo.

Zhaxybayeva and Nesbø’s previous research showed that Thermotoga and its close relatives have exchanged small pieces of genome with Archaea, an ancient single-celled life form different from bacteria, and with another distant group of bacteria, Firmicutes.

NASA’s MAVEN mission is observing the upper atmosphere of Mars to help understand climate change on the planet. MAVEN entered its science phase on Nov. 16, 2014. Image Credit: NASA's Goddard Space Flight Center

NASA’s MAVEN mission is observing the upper atmosphere of Mars to help understand climate change on the planet. MAVEN entered its science phase on Nov. 16, 2014. Image Credit: NASA’s Goddard Space Flight Center

Early discoveries by NASA’s newest Mars orbiter are starting to reveal key features about the loss of the planet’s atmosphere to space over time.

The findings are among the first returns from NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) mission, which entered its science phase on Nov. 16. The observations reveal a new process by which the solar wind can penetrate deep into a planetary atmosphere. They include the first comprehensive measurements of the composition of Mars’ upper atmosphere and electrically charged ionosphere. The results also offer an unprecedented view of ions as they gain the energy that will lead to their to escape from the atmosphere.

“We are beginning to see the links in a chain that begins with solar-driven processes acting on gas in the upper atmosphere and leads to atmospheric loss,” said Bruce Jakosky, MAVEN principal investigator with the Laboratory for Atmospheric and Space Physics at the University of Colorado, Boulder. “Over the course of the full mission, we’ll be able to fill in this picture and really understand the processes by which the atmosphere changed over time.”

On each orbit around Mars, MAVEN dips into the ionosphere – the layer of ions and electrons extending from about 75 to 300 miles above the surface. This layer serves as a kind of shield around the planet, deflecting the solar wind, an intense stream of hot, high-energy particles from the sun.

Scientists have long thought that measurements of the solar wind could be made only before these particles hit the invisible boundary of the ionosphere. MAVEN’s Solar Wind Ion Analyzer, however, has discovered a stream of solar-wind particles that are not deflected but penetrate deep into Mars’ upper atmosphere and ionosphere.

This computer-generated view depicts part of Mars at the boundary between darkness and daylight. Image credit: NASA/JPL-Caltech

This computer-generated view depicts part of Mars at the boundary between darkness and daylight. Image credit: NASA/JPL-Caltech

Interactions in the upper atmosphere appear to transform this stream of ions into a neutral form that can penetrate to surprisingly low altitudes. Deep in the ionosphere, the stream emerges, almost Houdini-like, in ion form again. The reappearance of these ions, which retain characteristics of the pristine solar wind, provides a new way to track the properties of the solar wind and may make it easier to link drivers of atmospheric loss directly to activity in the upper atmosphere and ionosphere.

MAVEN’s Neutral Gas and Ion Mass Spectrometer is exploring the nature of the reservoir from which gases are escaping by conducting the first comprehensive analysis of the composition of the upper atmosphere and ionosphere. These studies will help researchers make connections between the lower atmosphere, which controls climate, and the upper atmosphere, where the loss is occurring.

The instrument has measured the abundances of many gases in ion and neutral forms, revealing well-defined structure in the upper atmosphere and ionosphere, in contrast to the lower atmosphere, where gases are well-mixed. The variations in these abundances over time will provide new insights into the physics and chemistry of this region and have already provided evidence of significant upper-atmospheric “weather” that has not been measured in detail before.

New insight into how gases leave the atmosphere is being provided by the spacecraft’s Suprathermal and Thermal Ion Composition (STATIC) instrument. Within hours after being turned on at Mars, STATIC detected the “polar plume” of ions escaping from Mars. This measurement is important in determining the rate of atmospheric loss.

As the satellite dips down into the atmosphere, STATIC identifies the cold ionosphere at closest approach and subsequently measures the heating of this charged gas to escape velocities as MAVEN rises in altitude. The energized ions ultimately break free of the planet’s gravity as they move along a plume that extends behind Mars.

MAVEN spacecraft in orbit

MAVEN spacecraft in orbit

The MAVEN spacecraft and its instruments have the full technical capability proposed in 2007 and are on track to carry out the primary science mission. The MAVEN team delivered the spacecraft to Mars on schedule, launching on the very day in 2013 projected by the team 5 years earlier. MAVEN was also delivered well under the confirmed budget established by NASA in 2010.

The team’s success can be attributed to a focused science mission that matched the available funding and diligent management of resources. There were also minimal changes in requirements on the hardware or science capabilities that could have driven costs. It also reflects good coordination between the principal investigator; the project management at NASA’s Goddard Space Flight Center; the Mars Program Office at NASA’s Jet Propulsion Laboratory in Pasadena, California; and the Mars Exploration Program at NASA Headquarters.

The entire project team contributed to MAVEN’s success to date, including the management team, the spacecraft and science-instrument institutions, and the launch-services provider.

“The MAVEN spacecraft and its instruments are fully operational and well on their way to carrying out the primary science mission,” said Jim Green, director of NASA’s Planetary Science Division at NASA Headquarters in Washington. “The management team’s outstanding work enabled the project to be delivered on schedule and under budget.”