Wednesday 31 December 2014
"ATTEMPT NO LANDING THERE" --New NASA Mission to Europa will Ignore Arthur C Clarke's Warning (2014 Most Popular)
NASA is ignoring Arthur C Clarke's warning to avoid exploring Juipter's moon, Europa. In 2010: Odyssey Two, a 1982 the science fiction novel by Arthur C. Clarke, the Earth mission returns to the Jupiter system to explore beneath the ice of Europa, nine years after the failure of the Discovery One mission. As Jupiter is about to transform into a new star, Lucifer, David Bowman returns to Discovery to give HAL a last order to carry out. HAL begins repeatedly broadcasting the message: ALL THESE WORLDS ARE YOURS EXCEPT EUROPA ATTEMPT NO LANDING THERE. The space agency has announced funding early development of an unusual mission to Europa as it looks toward future space exploration of planets and moons that may contain both water and extraterrestrial life.
The Europa mission proposal aims to create a gravitational map of the moon’s icy surface that many researchers suspect hides an alien ocean beneath. That map would then allow the mission’s “mothership” — a cubesat the size of several Rubik’s cubes stuck together — to deploy possibly hundreds of tiny chipsats to regions of Europa’s surface where liquid water is coming out.
The “two missions in one” concept — using cheap, expendable chipsats that represent tiny spacecraft-on-a-chip systems — could allow the mission to react quickly to new events happening on Europa’s surface, unlike more expensive missions sent to the moon and Mars in the past that just carried one large lander or robotic rover.
Based on new evidence from Europa, astronomers hypothesize that chloride salts bubble up from the icy moon’s global liquid ocean and reach the frozen surface where they are bombarded with sulfur from volcanoes on Jupiter’s innermost large moon Io. The new findings propose answers to questions that have been debated since the days of NASA’s Voyager and Galileo missions. The illustration of Europa avove (foreground), Jupiter (right) and Io (middle) is an artist’s concept.
“Let’s say we go to Europa, measure the moon’s gravity using the spacecraft’s quantum inertial sensors, and we find a cool new place with liquid water coming out of surface or near surface,” said Brett Streetman, principal investigator at the Draper Laboratory in Cambridge, Mass. “Instead of waiting for a new mission to be funded so we can bring a robotic lander the next time, now we can respond to things happening on the planet and send chipsats down right away.”
NASA’s Innovative Advanced Concepts (NIAC) Program recently awarded $100,000 to the Draper Laboratory, a not-for-profit research and development laboratory, to work out the concept for how such a mission could explore Europa and other moons or planets on the fly.
Each chipsat may only carry a few sensors capable of detecting the presence of certain chemical elements, but the lack of moving parts means the chipsats have a good chance of surviving impact upon landing on Europa’s surface.
Streetman and John West, program manager at the Draper Laboratory, have been refining the chipsat idea alongside Mason Peck, a mechanical and aerospace professor at Cornell University and former chief technologist for NASA. Draper Laboratory has also been developing a new gravitational sensor that could create a density map of Europa which would reveal the moon’s internal structure and differentiate icy or liquid parts of the moon based on their density. NASA previously used a similar gravitational sensor concept in its GRAIL mission that involved looking at the moon’s gravitational effects on the distance between twin spacecraft orbiting as a pair.
But instead of using two spacecraft, the Draper Laboratory developed cold atom sensing as a technology capable of acting as a gravitational sensor. Cold atom sensing uses a combination of magnets and laser beams to trap atoms and then measure the effect of gravity on the atom’s positions.
“We have a tabletop model working in the lab, but to my knowledge no one has deployed this technology in any field use that we know of,” West said.
This reprojection of the official USGS Europa basemap is centered at the estimated source region for potential plumes that might have been detected using the Hubble Space Telescope. The view is centered at -65 degrees latitude, 183 degrees longitude. (Credit: NASA/JPL-Caltech/SETI Institute)
Such technology could fit within a spacecraft made of several cubesats — small cubic satellites about 4 inches long on each side. The Draper Laboratory team estimates that their Europa mission mothership could range in size from three to six cubesats.
Most cubesats launch as low-cost missions that piggyback on the rocket rides of bigger missions. But the proposed Europa mission would likely need its own dedicated rocket to launch it on the proper trajectory to reach Jupiter’s moon. Still, Draper Laboratory hopes that using low-cost cubesats could make for a cheaper space mission than past planetary missions costing hundreds of millions or billions of dollars.
If Draper Laboratory can come up with a feasible mission proposal, the researchers could also apply for a second phase of NIAC funding from NASA worth about $400,000. The lab does not plan to produce spacecraft hardware during this first phase, but it does already have sample devices and prototypes for both the chipsats and the gravitational sensor.
Streetman and West chose Europa as their proposed destination because the icy moon has long intrigued researchers with the possibility of liquid water lurking beneath the frozen surface. They hope their miniaturized mission’s flexibility will speed up the process of surveying and then exploring the moon’s mysteries sometime in the next decade or two.
“Every time we go there we find cool stuff we didn’t expect to find,” Streetman said. “And we always leave with more questions than answers.”
This proposal isn’t the only idea to consider smaller robotic explorers for Europa. Another concept from NASA’s Jet Propulsion Laboratory in California and Uppsala University in Sweden suggested using a small robotic submarine the size of two soda cans to look for signs of alien life in Europa’s ocean.
Over the centuries, Europa, has provided an abundance of mysteries. These culminated in what may have been a literal explosion in December 2012, when a cloud of water vapor was seen 20 miles over its south pole. This eruption was tiny on the cosmic scale, but enormous in its importance to astrobiology.
Outside of Earth, Europa may be the most hospitable home for life inside the Solar System. Four billion years of tidal heating and a liquid ocean may have given rise to something we can identify as life. A man-made satellite in the Jovian system could potentially capture traces of that life in the water vapor shooting from Europa’s surface. Yet, in spite of the exciting science, a dedicated mission to Jupiter hasn’t launched in a generation.
Though Europa was discovered more than 400 years ago, it wasn’t until deep space satellites came along that we had our first good look at one of the most luminous objects in the Solar System. Between 1973 and 1993, eight satellites flew past Europa. Each dispelled some of the uncertainties surrounding this mysterious body orbiting 390.4 million miles (628.3 million kilometers) away.
The first arrived in 1973. The Pioneer 10 satellite sent back the first close-up photograph of that bright moon. Europa reflects back into space 64 percent of the light that falls on its surface. By contrast, Earth’s light reflectivity, or albedo, is 33 percent. Venus’ is 76 percent. In other words, Europa’s brightness falls somewhere between Earth’s liquid oceans and Venus’ constant cloud cover.
But what creates the brightness? With the Sun 2,000 times further away, Europa probably isn’t covered in liquid water the way that the Earth is. As for clouds, Europa is slightly smaller than our Moon. It lacks the gravity to maintain a substantial atmosphere. A planet coated in solid ice would explain Pioneer’s observations, but it doesn't account for one big effect: Jupiter’s tidal force. Europa’s proximity to Jupiter means that it might very well be heated from the inside out, melting some of the ice at least near the center.
Shortly before the arrival of the next satellite into the Jovian system, another suggestion was made: Europa might have three layers. In this model, the innermost core would be silica. The outermost core would be ice. The pressure of being slung around Jupiter every 3.5 days might generate enough tidal heating to maintain a liquid ocean in between. If this model were true, even though the third layer is solid, Jupiter’s tidal forces might be strong enough to crack the ice shell covering of Europa as it moves rapidly around the gas giant.
Thanks to Pioneer, Voyager and Galileo, we had learned more in three decades than in the preceding five centuries. The brightness of the ice was known to be the result of continual surface renewal. The enormous cracks, sometimes referred to as “flexi”, appear to originate when the solid ice shell flexes as Jupiter pulls on Europa. In a nod towards the three-layer-model, Galileo’s measurements also indicated that a large, salt water ocean might well exist beneath the ice shell. While all this was being discovered half a billion miles away, things were being uncovered in our own backyard that made the possibility of Europa’s oceans even more exciting.
In 1977, hydrothermal vents teeming with life were discovered deep within Earth’s oceans. This was the first proof that life could thrive in the absence of light, using heat as a source of chemical power. This led to the current understanding that life can prosper as long as there is heat and water. With a probable ocean and definite heat source, Europa suddenly became a leading candidate in the search for habitability.
Tuesday 30 December 2014
"At the Edge of the Cosmic Ocean" --Human Tracks on Mars (Best of 2014)
“Exploration is in our nature. We began as wanderers, and we are wanderers still. We have lingered long enough on the shores of the cosmic ocean. We are ready at last to set sail for the stars," Carl Sagan, Cosmos. In February 2014, Curiosity’s MastCam instrument took this picture of rover tracks across a dune located in an area dubbed “Dingo Gap.”
"Given the recent Curiosity findings, past Martian life seems possible, and we should begin the difficult endeavor of seeking the signs of life," says Jack Mustard, chairman of the Science Definition Team and a professor at the Geological Sciences at Brown University. "However, no matter what we learn, we would make significant progress in understanding the circumstances of early life existing on Earth and the possibilities of extraterrestrial life."
Credit: NASA/JPL-Caltech/MSSS
« A 2014 Best Image --Phantom Light from 200 Billion Outcast Stars in Pandora's Galaxy Cluster | Main
A 2014 Best Image --Phantom Light from 200 Billion Outcast Stars in Pandora's Galaxy Cluster
NASA’s Hubble Space Telescope has picked up the faint, ghostly glow of stars ejected from ancient galaxies that were gravitationally ripped apart several billion years ago. The mayhem happened 4 billion light-years away, inside an immense collection of nearly 500 galaxies nicknamed “Pandora’s Cluster,” also known as Abell 2744. The Hubble team estimates that the combined light of about 200 billion outcast stars contributes approximately 10 percent of the cluster’s brightness.
The scattered stars are no longer bound to any one galaxy, and drift freely between galaxies in the cluster. By observing the light from the orphaned stars, Hubble astronomers have assembled forensic evidence that suggests as many as six galaxies were torn to pieces inside the cluster over a stretch of 6 billion years.
“The Hubble data revealing the ghost light are important steps forward in understanding the evolution of galaxy clusters,” said Ignacio Trujillo of The Instituto de AstrofÃsica de Canarias (IAC), Santa Cruz de Tenerife, Spain. “It is also amazingly beautiful in that we found the telltale glow by utilizing Hubble’s unique capabilities.”
Computer modeling of the gravitational dynamics among galaxies in a cluster suggests that galaxies as big as our Milky Way Galaxy are the likely candidates as the source of the stars. The doomed galaxies would have been pulled apart like taffy if they plunged through the center of a galaxy cluster where gravitational tidal forces are strongest. Astronomers have long hypothesized that the light from scattered stars should be detectable after such galaxies are disassembled. However, the predicted “intracluster” glow of stars is very faint and was therefore a challenge to identify.
“The results are in good agreement with what has been predicted to happen inside massive galaxy clusters,” said Mireia Montes of the IAC, lead author of the paper published in the Oct. 1 issue of the Astrophysical Journal.
Because these extremely faint stars are brightest at near-infrared wavelengths of light, the team emphasized that this type of observation could only be accomplished with Hubble’s infrared sensitivity to extraordinarily dim light.
Hubble measurements determined that the phantom stars are rich in heavier elements like oxygen, carbon, and nitrogen. This means the scattered stars must be second or third-generation stars enriched with the elements forged in the hearts of the universe’s first-generation stars. Spiral galaxies – like the ones believed to be torn apart -- can sustain ongoing star formation that creates chemically-enriched stars.
Weighing more than 4 trillion solar masses, Abell 2744 is a target in the Frontier Fields program. This ambitious three-year effort teams Hubble and NASA’s other Great Observatories to look at select massive galaxy clusters to help astronomers probe the remote universe. Galaxy clusters are so massive that their gravity deflects light passing through them, magnifying, brightening, and distorting light in a phenomenon called gravitational lensing. Astronomers exploit this property of space to use the clusters as a zoom lens to magnify the images of far-more-distant galaxies that otherwise would be too faint to be seen.
Montes’ team used the Hubble data to probe the environment of the foreground cluster itself. There are five other Frontier Fields clusters in the program, and the team plans to look for the eerie “ghost light” in these clusters, too.
The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA's Goddard Space Flight Center in Greenbelt, Maryland, manages the telescope. The Space Telescope Science Institute (STScI) in Baltimore conducts Hubble science operations. STScI is operated for NASA by the Association of Universities for Research in Astronomy, Inc., in Washington.
Saturday 27 December 2014
"Biggest Explosion Since the Big Bang" --From a Supermassive Black Hole a Billion Times the Mass of Our Sun
The cavities shown in the image of galaxy cluster MS0735 above were created by jets of charged particles ejected at nearly light speed from a supermassive black hole weighing nearly a billion times the mass of our Sun lurking in the nucleus of the bright central galaxy. The jets displaced more than one trillion solar masses worth of gas. The power required to displace the gas exceeded the power output of the Sun by nearly ten trillion times in the past 100 million years.
MS0735 is ocated about 2.6 billion light-years away in the constellation Camelopardus. The image represents three views of the region that astronomers have combined into one photograph. The optical view of the galaxy cluster, taken by the Hubble Space Telescope's Advanced Camera for Surveys in February 2006, shows dozens of galaxies bound together by gravity.
Diffuse, hot gas with a temperature of nearly 50 million degrees permeates the space between the galaxies. The gas emits X-rays, seen as blue in the image taken with the Chandra X-ray Observatory in November 2003. The X-ray portion of the image shows enormous holes or cavities in the gas, each roughly 640,000 light-years in diameter -- nearly seven times the diameter of the Milky Way. The cavities are filled with charged particles gyrating around magnetic field lines and emitting radio waves shown in the red portion of image taken with the Very Large Array telescope in New Mexico in June 1993.
Thursday 25 December 2014
Best Wishes for the Holidays! (The Christmas Tree Star Cluster)
The Cone Nebula, part of a much larger star-forming complex, is at bottom with inverted Christmas Tree cluster NGC 2264 above the cone; the bright star just above the cone is the tree topper and the very bright star at the top of the image is the center of the tree trunk. The Fox Fur Nebula is at the top right corner.
The Snowflake nebula is in the middle which shows up better on the infrared image. The cone's shape comes from a dark absorption nebula consisting of cold molecular hydrogen and dust in front of a faint emission nebula containing hydrogen ionized by S Monocerotis, the brightest star of NGC 2264. The faint nebula is approximately seven light-years long, and is 2,700 light-years away from Earth.
Image credit: NASA/Hubble Space Telescope
« Image of the Day: A Colossal Galaxy Almost as Old as the Universe | Main
Wednesday 24 December 2014
Image of the Day: A Colossal Galaxy Almost as Old as the Universe
“AzTEC-3 is a massive galaxy that already contains billions of stars at this early epoch, but has the potential to form many more by present day. It produces a thousand times more stars each year than what our own Milky Way galaxy produces,” says Dominik Riechers, Cornell assistant professor of astronomy. “Think about a star factory that puts out 50 billion objects the mass of our sun.
Our Milky Way galaxy forms one star the mass of Earth’s own sun each year. Massive AzTEC-3, the second-most-distant one of its kind known to humanity, produces about five of our suns each Earth day, churning out a total of 1,800 solar masses annually. Such ancient massive star-bursting galaxies can be found by astronomers using modern, mountaintop telescopes like the National Science Foundation-funded Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile. This exceptional galaxy, which at present day is only slightly younger than the 13.8 billion-year-old universe, is named after the AzTEC-millimeter-wave camera on the James Clerk Maxwell Telescope – through which it was initially found.
“These things are just humongous,” said Dominik Riechers, Cornell assistant professor of astronomy. “That’s why we call them ‘monsters.’ Essentially, thanks to telescopes like the ALMA, we’re looking back in time to the childhood, the toddler years of the universe, and are trying to discern how these galaxies form.”
Squinting close to the beginning of time, Riechers, discovered an association of gas-rich galaxies near the infancy of cosmic time. It’s an early epoch – some 12.7 billion years ago – telling a tale that revolves around an exceptionally dusty galaxy called AzTEC-3.
The NASA image at the top of the page shows the formation of a galaxy during the first 2bn years of the universe. The supercomputer-generated image displays hydrogen gas in grey, young stars appearing in blue, and older stars as red. The simulation reveals that gas flows into galaxies along filaments akin to cosmic bendy, or swirly, straws.
AzTEC-3, together with its gang of calmer galaxies may represent the best evidence yet that large galaxies grow from the merger of smaller ones in the early Universe, a process known as hierarchical merging.
New ALMA (Atacama Large Millimeter/submillimeter Array) data reveals that AzTEC-3 is a very compact, highly disturbed galaxy that is bursting with new stars at close to its theoretically predicted maximum limit and is surrounded by a population of more normal, but also actively star-forming galaxies," said Riechers, lead author of a new paper published today on Nov. 10 in the Astrophysical Journal. "This particular grouping of galaxies represents an important milestone in the evolution of our Universe: the formation of a galaxy cluster and the early assemblage of large, mature galaxies."
In the early Universe, starburst galaxies like AzTEC-3 were forming new stars at a monstrous pace fueled by the enormous quantities of star-forming material they devoured and by merging with other adolescent galaxies. Over billions of years, these mergers continued, eventually producing the large galaxies and clusters of galaxies we see in the Universe today.
Evidence for this hierarchical model of galaxy evolution has been mounting, but these latest ALMA data show a strikingly clear picture of the all-important first steps along this process when the Universe was only 8 percent of its current age.
"One of the primary science goals of ALMA is the detection and detailed study of galaxies throughout cosmic time," said Chris Carilli, an astronomer with the National Radio Astronomy Observatory in Socorro, New Mexico. "These new observations help us put the pieces together by showing the first steps of a galaxy merger in the early Universe."
AzTEC-3, which is located in the direction of the constellation Sextans, is what astronomers refer to as a submillimeter galaxy, since it shines brightly in that portion of the spectrum, but is remarkably dim at optical and infrared wavelengths. This is due to light from its stars being absorbed by dust in the star-forming environments of the galaxy and then re-emitted by the dust at far-infrared wavelengths. As this light travels across the cosmos, it becomes stretched due to the expansion of the Universe, so by the time it arrives at Earth, the far-infrared light has shifted to the submillimeter/millimeter portion of the spectrum.
New ALMA observations suggest that AzTEC-3 recently merged with another young galaxy and that the whole system represents the first steps toward forming a galaxy cluster. ALMA, with its remarkable sensitivity and high resolving power, was able to observe this system at these wavelengths in unprecedented detail. It also was able to study, for the first time, the star-forming gas in three additional, extremely distant members of an emerging galactic protocluster.
The ALMA data revealed that the three smaller, more normal galaxies are indeed producing stars from their gas at a relatively calm and steady pace. Unlike its neighbors, however, AzTEC-3 is burning through star-forming fuel at breakneck speed. Indeed, AzTEC-3 appears to form more new stars each day than our Milky Way galaxy forms in an entire year -- outpacing the normal galaxies in its proximity by about a factor of 100.
The researchers also observed very little rotation in AzTEC-3's dust and gas -- suggesting that something had disrupted its motion. Taken together, these two characteristics are strong indications that AzTEC-3 recently merged with another galaxy.
"AzTEC-3 is currently undergoing an extreme, but short-lived event," said Riechers. "This is perhaps the most violent phase in its evolution, leading to a star formation activity level that is very rare at its cosmic epoch."
New ALMA observations suggest that AzTEC-3 recently merged with another young galaxy and that the whole system represents the first steps toward forming a galaxy cluster. The astronomers believe that AzTEC-3 and the other nearby galaxies appear to be part of the same system, but are not yet gravitationally bound into a clearly defined cluster. This is why the astronomers refer to them collectively as a protocluster.
The starburst galaxy was originally observed with and named after the AzTEC millimeter-wavelength camera, which was installed at the time on the James Clerk Maxwell Telescope, a single-dish radio telescope located on Mauna Kea, Hawaii. Only with ALMA has it become possible to understand the nature of this exceptional galaxy and those in its immediate environment.
Image of the Day: A Colossal Galaxy Almost as Old as the Universe
“AzTEC-3 is a massive galaxy that already contains billions of stars at this early epoch, but has the potential to form many more by present day. It produces a thousand times more stars each year than what our own Milky Way galaxy produces,” says Dominik Riechers, Cornell assistant professor of astronomy. “Think about a star factory that puts out 50 billion objects the mass of our sun.
Our Milky Way galaxy forms one star the mass of Earth’s own sun each year. Massive AzTEC-3, the second-most-distant one of its kind known to humanity, produces about five of our suns each Earth day, churning out a total of 1,800 solar masses annually. Such ancient massive star-bursting galaxies can be found by astronomers using modern, mountaintop telescopes like the National Science Foundation-funded Atacama Large Millimeter/submillimeter Array (ALMA) telescope in Chile. This exceptional galaxy, which at present day is only slightly younger than the 13.8 billion-year-old universe, is named after the AzTEC-millimeter-wave camera on the James Clerk Maxwell Telescope – through which it was initially found.
“These things are just humongous,” said Dominik Riechers, Cornell assistant professor of astronomy. “That’s why we call them ‘monsters.’ Essentially, thanks to telescopes like the ALMA, we’re looking back in time to the childhood, the toddler years of the universe, and are trying to discern how these galaxies form.”
Squinting close to the beginning of time, Riechers, discovered an association of gas-rich galaxies near the infancy of cosmic time. It’s an early epoch – some 12.7 billion years ago – telling a tale that revolves around an exceptionally dusty galaxy called AzTEC-3.
The NASA image at the top of the page shows the formation of a galaxy during the first 2bn years of the universe. The supercomputer-generated image displays hydrogen gas in grey, young stars appearing in blue, and older stars as red. The simulation reveals that gas flows into galaxies along filaments akin to cosmic bendy, or swirly, straws.
AzTEC-3, together with its gang of calmer galaxies may represent the best evidence yet that large galaxies grow from the merger of smaller ones in the early Universe, a process known as hierarchical merging.
New ALMA (Atacama Large Millimeter/submillimeter Array) data reveals that AzTEC-3 is a very compact, highly disturbed galaxy that is bursting with new stars at close to its theoretically predicted maximum limit and is surrounded by a population of more normal, but also actively star-forming galaxies," said Riechers, lead author of a new paper published today on Nov. 10 in the Astrophysical Journal. "This particular grouping of galaxies represents an important milestone in the evolution of our Universe: the formation of a galaxy cluster and the early assemblage of large, mature galaxies."
In the early Universe, starburst galaxies like AzTEC-3 were forming new stars at a monstrous pace fueled by the enormous quantities of star-forming material they devoured and by merging with other adolescent galaxies. Over billions of years, these mergers continued, eventually producing the large galaxies and clusters of galaxies we see in the Universe today.
Evidence for this hierarchical model of galaxy evolution has been mounting, but these latest ALMA data show a strikingly clear picture of the all-important first steps along this process when the Universe was only 8 percent of its current age.
"One of the primary science goals of ALMA is the detection and detailed study of galaxies throughout cosmic time," said Chris Carilli, an astronomer with the National Radio Astronomy Observatory in Socorro, New Mexico. "These new observations help us put the pieces together by showing the first steps of a galaxy merger in the early Universe."
AzTEC-3, which is located in the direction of the constellation Sextans, is what astronomers refer to as a submillimeter galaxy, since it shines brightly in that portion of the spectrum, but is remarkably dim at optical and infrared wavelengths. This is due to light from its stars being absorbed by dust in the star-forming environments of the galaxy and then re-emitted by the dust at far-infrared wavelengths. As this light travels across the cosmos, it becomes stretched due to the expansion of the Universe, so by the time it arrives at Earth, the far-infrared light has shifted to the submillimeter/millimeter portion of the spectrum.
New ALMA observations suggest that AzTEC-3 recently merged with another young galaxy and that the whole system represents the first steps toward forming a galaxy cluster. ALMA, with its remarkable sensitivity and high resolving power, was able to observe this system at these wavelengths in unprecedented detail. It also was able to study, for the first time, the star-forming gas in three additional, extremely distant members of an emerging galactic protocluster.
The ALMA data revealed that the three smaller, more normal galaxies are indeed producing stars from their gas at a relatively calm and steady pace. Unlike its neighbors, however, AzTEC-3 is burning through star-forming fuel at breakneck speed. Indeed, AzTEC-3 appears to form more new stars each day than our Milky Way galaxy forms in an entire year -- outpacing the normal galaxies in its proximity by about a factor of 100.
The researchers also observed very little rotation in AzTEC-3's dust and gas -- suggesting that something had disrupted its motion. Taken together, these two characteristics are strong indications that AzTEC-3 recently merged with another galaxy.
"AzTEC-3 is currently undergoing an extreme, but short-lived event," said Riechers. "This is perhaps the most violent phase in its evolution, leading to a star formation activity level that is very rare at its cosmic epoch."
New ALMA observations suggest that AzTEC-3 recently merged with another young galaxy and that the whole system represents the first steps toward forming a galaxy cluster. The astronomers believe that AzTEC-3 and the other nearby galaxies appear to be part of the same system, but are not yet gravitationally bound into a clearly defined cluster. This is why the astronomers refer to them collectively as a protocluster.
The starburst galaxy was originally observed with and named after the AzTEC millimeter-wavelength camera, which was installed at the time on the James Clerk Maxwell Telescope, a single-dish radio telescope located on Mauna Kea, Hawaii. Only with ALMA has it become possible to understand the nature of this exceptional galaxy and those in its immediate environment.
A Gorgeous Island Universe --How Our Milky Way Would Look from 50-Million Light Years
The e gorgeous island universe spiral galaxy NGC 7331, about 50 million light-years distant in the northern constellation Pegasus is a visual analog to our own Milky Way. The galaxy was recognized early on as a spiral nebula and is actually one of the brighter galaxies not included in Charles Messier's famous 18th century catalog. The most prominent background galaxies are about one tenth the apparent size of NGC 7331 and so lie roughly ten times farther away. Their close alignment on the sky with NGC 7331 occurs just by chance. Seen through faint foreground dust clouds lingering above the plane of Milky Way, this visual grouping of galaxies is known as the Deer Lick Group.
Tuesday 23 December 2014
Image of the Day: The Dark Kilometer-High Cliffs of Comet Churyumov–Gerasimenko
These amazing cliffs were discovered to be part of the dark nucleus of Comet Churyumov–Gerasimenko (CG) by Rosetta, a robotic spacecraft launched by ESA which began orbiting the comet in early August. The ragged cliffs, as featured here, were imaged by Rosetta about two weeks ago. Although towering about one kilometer high, the low surface gravity of Comet CG would likely make a jump from the cliffs, by a human, survivable. At the foot of the cliffs is relatively smooth terrain dotted with boulders as large as 20 meters across. Data from Rosetta indicates that the ice in Comet CG has a significantly different deuterium fraction -- and hence likely a different origin -- than the water in Earth's oceans. The Rosetta spacecraft is scheduled to continue to accompany the comet as it makes its closest approach to the Sun in 2015 August.
Monday 22 December 2014
New Milky Way Neighbor Discovered --"May Be a Huge Number of Dwarf Galaxies Out There"
The Milky Way, the galaxy we live in, is part of a cluster of more than 50 galaxies that make up the ‘Local Group’, a collection that includes the famous Andromeda galaxy and many other far smaller objects. Now a Russian-American team have added to the canon, finding a tiny and isolated dwarf galaxy almost 7 million light years away.
The image above is a negative image of the galaxy, KKs 3, made using the Advanced Camera for Surveys on the Hubble Space Telescope. The core of the galaxy is the right hand dark object at the top centre of the image, with its stars spreading out over a large section around it. (The left hand of the two dark objects is a much nearer globular star cluster.)
“Finding objects like Kks3 is painstaking work, even with observatories like the Hubble Space Telescope," said
Team member Prof Dimitry Makarov, also of the Special Astrophysical Observatory. "But with persistence, we’re slowly building up a map of our local neighbourhood, which turns out to be less empty than we thought. It may be that are a huge number of dwarf spheroidal galaxies out there, something that would have profound consequences for our ideas about the evolution of the cosmos.”
The team, led by Prof Igor Karachentsev of the Special Astrophysical Observatory in Karachai-Cherkessia, Russia, found the new galaxy, named KKs3, using the Hubble Space Telescope Advanced Camera for Surveys (ACS) in August 2014. Kks3 is located in the southern sky in the direction of the constellation of Hydrus and its stars have only one ten-thousandth of the mass of the Milky Way.
Kks3 is a ‘dwarf spheroidal’ or dSph galaxy, lacking features like the spiral arms found in our own galaxy. These systems also have an absence of the raw materials (gas and dust) needed for new generations of stars to form, leaving behind older and fainter relics. In almost every case, this raw material seems to have been stripped out by nearby massive galaxies like Andromeda, so the vast majority of dSph objects are found near much bigger companions.
Isolated objects must have formed in a different way, with one possibility being that they had an early burst of star formation that used up the available gas resources. Astronomers are particularly interested in finding dSph objects to understand galaxy formation in the universe in general, as even HST struggles to see them beyond the Local Group. The absence of clouds of hydrogen gas in nebulae also makes them harder to pick out in surveys, so scientists instead try to find them by picking out individual stars.
For that reason, only one other isolated dwarf spheroidal, KKR 25, has been found in the Local Group, a discovery made by the same group back in 1999.
The team will continue to look for more dSph galaxies, a task that will become a little easier in the next few years, once instruments like the James Webb Space Telescope and the European Extremely Large Telescope begin service.
Their results appear in Monthly Notices of the Royal Astronomical Society.
Sunday 21 December 2014
“There have been 10,000 Generations Before Us --Ours Could be the First to Discover Extraterrestrial Life” --NASA (2014 Most Viewed)
In 1960, the astronomer Francis Drake pointed a radio telescope located in Green Bank, West Virginia, toward two Sun-like stars 11 light years away. His hope: to pick up a signal that would prove intelligent life might be out there. Fifty years have gone by since Drake’s pioneering SETI experiment, and we’ve yet to hear from the aliens.mmBut thanks to a host of discoveries, the idea that life might exist beyond Earth now seems more plausible than ever. For one, we’ve learned that life can thrive in the most extreme environments here on Earth — from deep-sea methane seep and Antarctic sea ice to acidic rivers and our driest deserts.
We’ve also found that liquid water isn’t unique to our planet. Saturn’s moon Enceladus and Jupiter’s moons Ganymede and Europa harbor large oceans beneath their icy surfaces. Even Saturn’s largest moon, Titan, could spawn some kind of life in its lakes and rivers of methane-ethane. And then there’s the discovery of exoplanets, with more than 1800 alien worlds beyond our Solar System identified so far. In fact, astronomers estimate there may be a trillion planets in our galaxy alone, one-fifth of which may be Earth-like. As Carl Sagan famously said: “The Universe is a pretty big place. If it’s just us, seems like an awful waste of space.”
Now some scientists believe the hunt for life beyond Earth may well pay off in our lifetimes. “There have been 10,000 generations of humans before us. Ours could be the first to know,” said SETI astronomer Seth Shostak.
But what happens once we do? How would we handle the discovery? And what would be its impact on society? This daunting question was the focus of a conference organized last September by the NASA Astrobiology Institute and the Library of Congress. For two days, a group of scientists, historians, philosophers and theologians from around the world explored how we might prepare for the inevitable discovery of life — microbial or intelligent — elsewhere in our Universe. The symposium was hosted by Steven J. Dick, the second annual Chair in Astrobiology at the Library of Congress. The video presentations can be viewed here.
Of course, the impact of discovery will depend on the specific scenario. In a talk titled “Current Approaches to Finding Life Beyond Earth, and What Happens If We Do,” Shostak described three ways — or three “horse races” — for finding life in space. First, we could find it nearby, in our Solar System. NASA’s Curiosity Rover is currently surveying the Martian surface for signs of past or present life. And Europa Clipper, a mission to Jupiter’s icy moon, is now under consideration. Second, we could “sniff it out” of the atmosphere of an exoplanet, using telescopes to look for gases such as methane and oxygen that might hint at a biosphere. The James Webb Space Telescope, to be launched in 2018, will be able to carry out that kind of work.
Finding life in our Solar System, which likely would be microbial, might not have as great an impact as hearing from an intelligent civilization far away. We’d have to worry about issues like contamination. We might also discover some alternative biochemistry, perhaps uncovering new insights about the nature of life. But that kind of discovery wouldn’t affect us as much as the prospect of communicating with intelligent life.
Then again it’d take hundreds, if not thousands of years for a signal to travel back and forth, Shostak pointed out. So that third scenario would only teach us a very few things right away, such as their location or what kind of star they orbit. However, picking a signal might have other tantalizing implications about the nature of alien intelligence.
Several researchers, including Shostak, put forward the following premise: “That once a society creates the technology that could put them in touch with the cosmos, they are only a few hundred years away from changing their paradigm from biology to artificial intelligence.” The idea is based on the so-called “time scale argument” or “short window observation.” Many researchers predict we’ll have developed a strong artificial intelligence by 2050 here on Earth — about a hundred years after the invention of computers, or a hundred and fifty years after the invention of radio communication. “The point is that, going from inventing radios to inventing thinking machines is very short — a few centuries at most,” Shostak said. “The dominant intelligence in the cosmos may well be non-biological.”
In a talk titled “Alien Minds,” Susan Schneider, a philosophy professor at the University of Connecticut, explored that idea further. The concept of “whole brain emulation” is becoming increasingly popular among certain researchers, she explained. So are other far-fetched sounding ideas like “mind uploading” and “immortally.” So, to her, a civilization capable of radio communication would likely be “super-intelligent” by the time we hear from them.
According to the "short window observation" idea, a civilization capable of radio communication would likely have developed artificial intelligence by the time we hear from them. She also argued that alien super-intelligence would be conscious in principle, since the neural code is akin to a computational code, and thoughts could well be embedded in a silicon-based substrate. A silicon-based intelligence would also have tremendous implications for long distance space travel. But again, a recurring theme throughout the conference was to be aware of our anthropocentric tendencies. There’s been a huge gap between microbial life and intelligent life on Earth, and even intelligent life has even evolved on a spectrum.
Lori Marino, a neuroscientist and current director of the Kimela Center for Animal Advocacy, argued as such in a talked titled “The Landscape of Intelligence.” We have a lot to learn from other intelligent beings here on Earth (such as dolphins) before even thinking about communicating with aliens.
Ultimately, the greatest implications might be philosophical. Whether it turns out to be microbial, complex or intelligent, finding life elsewhere will raise intriguing questions about our place in the cosmos. A couple of presentations, by theologian Robin Lovin and Vatican astronomer Guy Consolmagno, even addressed the potential impact on the world’s religions. But what if we don’t find anything soon, or even at all?
The search itself can give us a sense of direction, and help us forge a planetary identity, argued the philosopher Clement Vidal in a talk titled “Silent Impact.” And if we’re truly alone, then we should start taking better care of life here on Earth, and contemplate our duty of colonization, he added. The search itself can help us forge a planetary identity, said philosopher Clement Vidal. In the meantime, astrobiology can help narrow the gap between the sciences and humanities, as many presenters emphasized. And it can be a step toward integrating our knowledge across a wide range of disciplines.
So, how do we prepare for something we know so little about? We do so “by continuing to do good science, but also by realizing that science is not metaphysically neutral,” concluded the conference host Steven Dick. “We prepare by continuing to question our assumptions about the nature of life and intelligence.”
Friday 19 December 2014
NASA's Venus "Cloud" Mission --"Did It Once have Ancient Oceans?"
The conditions on Venus are hard to describe. Many planetary scientists say "Start by imagining Hell and work up from there." It's an environment where words like "over 500 degrees Celsius" get thrown around, and it's flat-out crushed every probe we've sent into it. Even worse, there's almost no water.
But recently, NASA's Langeley Research Center has proposed a High Altitude Venus Operational Concept (or HAVOC), the proposed space balloons would sit at roughly 50 kilometers above Venus, with astronauts living in a cloud city, subject to about 85% Earth gravity, and the temperature peaks below 80°C — still higher than you could find anywhere on Earth, but low enough that NASA scientists can deal with it via the super-materials of modern astrophysics. On average, Venus is less than half Mars’ distance from Earth, while its thick atmosphere would both protect astronauts from intense radiation and allow enough solar radiation through to make solar power a real option. The Langeley team argues that we ought to focus on the upper atmosphere of Venus, and not the surface of Mars, for our first manned mission to an alien world.
The Venus mission would occur in five stages: robotic exploration, a 1-month orbiting mission, a 1-month atmospheric mission, a 1-year atmospheric mission, and finally a semi-permanent installation with rotating crew. This would be far easier to keep going than a Mars missions since, first of all, it’s so much closer, and since docking with a cloud facility wouldn’t require as much fuel/power as landing and taking off from the surface of Mars.
Venus was created at about the same time as Earth, in about the same place, and it's roughly the same size - it would therefore have started with the same materials as us, drawn together from the same region of the planet forming dust left over from the sun. But Venus now has only 0.001% of our water content, and a couple of flybys by the Venus Express may have revealed the reason.
In 2008, the probe discovered hydrogen and oxygen streaming off the night side of the planet in a 2:1 ratio, which you might recognize as the ratio in H20. It seems that what little water Venus has left is being blasted apart in the atmosphere by the solar wind, a vast stream of charged particles blown out by the sun. Venus Express has passed by the dayside and measured almost three hundred kilograms of hydrogen a day being lost into space. It hasn't found any oxygen yet, but the search continues.
"Venus today has a thick atmosphere that contains very little water, but we think the planet started out with an ocean's worth of water," said John T. Clarke of Boston University.
Scientists are still trying to determine whether water existed on the surface of Venus or only high up the atmosphere, where temperatures were cooler. If the surface temperature stayed below the boiling point of water long enough, rivers might have once flowed on the planet. Venus may have even had ice.
The key to figuring out how much water Venus once had lies in how much hydrogen and deuterium, a heavier version of hydrogen, remain in the atmosphere. Both can combine with oxygen to make water, either in the familiar H2O form or the rarer hydrogen, deuterium and oxygen form, called HDO. (Very small amounts of D2O also form.)
Intense UV light from the sun has broken apart nearly all of the water molecules in Venus' atmosphere. Because the regular hydrogen atoms in the water are lighter, they escape into space more quickly than the heavier deuterium ones. By comparing the amount of deuterium now in the atmosphereto the amount of hydrogen, researchers can estimate how much water disappeared from Venus and how quickly it happened.
Early estimates, made from data collected by NASA's 1978 Pioneer Venus spacecraft and other observations, indicated Venus could have had enough ancient water to cover the whole globe with 23 feet (7 meters) of liquid. But it turns out that the amounts of hydrogen and deuterium can vary at different heights in Venus' atmosphere, which could change the calculations.
Data gathered from European Space Agency’s Venus Express is invaluable to climate scientists modeling Earth’s climate to predict its future. The climate of our two neighbors is in stark contrast to Earth with Venus is a cloudy inferno and Mars is a frigid desert.
Astrobiologist David Grinspoon believes that scientists should look at our neighboring planets to help understand the perils of global warming. “It seems that both Mars and Venus started out much more like Earth and then changed. They both hold priceless climate information for Earth."
Climate scientists believe that Venus experienced a runaway greenhouse effect as the Sun gradually heated up. Astronomers believe that the young Sun was dimmer than the present-day Sun by 30 percent. Over the last 4 thousand million years, it has gradually brightened. During this increase, Venus’s surface water evaporated and entered the atmosphere.
“Water vapor is a powerful greenhouse gas and it caused the planet to heat-up even more. This is turn caused more water to evaporate and led to a powerful positive feedback response known as the runaway greenhouse effect,” says Grinspoon.
As Earth warms in response to manmade greenhouse gases, it risks the same fate. Reconstructing the climate of the past on Venus can give scientists a better understanding of how close our planet is to such a catastrophe. However, determining when Venus passed the point of no return is not easy. Maybe that's where a NASA HAVOC mission come is.
Thursday 18 December 2014
Mars' Mount Sharp Mystery -- Proof of a Lake Tens of Millions of Years Old?
"We are making headway in solving the mystery of Mount Sharp," said Curiosity Project Scientist John Grotzinger of the California Institute of Technology. "Where there's now a mountain, there may have once been a series of lakes."
Observations by NASA’s Curiosity Rover indicate Mars' Mount Sharp was built by sediments deposited in a large lake bed over tens of millions of years. This suggests ancient Mars maintained a climate that could have produced long-lasting lakes at many locations on the Red Planet.
"If our hypothesis for Mount Sharp holds up, it challenges the notion that warm and wet conditions were transient, local, or only underground on Mars,” said Ashwin Vasavada, Curiosity deputy project scientist at NASA's Jet Propulsion Laboratory in Pasadena. “A more radical explanation is that Mars' ancient, thicker atmosphere raised temperatures above freezing globally, but so far we don't know how the atmosphere did that."
This evenly layered rock photographed by the Mast Camera (Mastcam) on NASA's Curiosity Mars Rover on Aug. 7, 2014, shows a pattern typical of a lake-floor sedimentary deposit not far from where flowing water entered a lake. Image Credit: NASA/JPL-Caltech/MSSS
Why this layered mountain sits in a crater has been a challenging question for researchers. Mount Sharp stands about 3 miles (5 kilometers) tall, its lower flanks exposing hundreds of rock layers. The rock layers – alternating between lake, river and wind deposits -- bear witness to the repeated filling and evaporation of a Martian lake much larger and longer-lasting than any previously examined close-up.
Curiosity currently is investigating the lowest sedimentary layers of Mount Sharp, a section of rock 500 feet (150 meters) high dubbed the Murray formation. Rivers carried sand and silt to the lake, depositing the sediments at the mouth of the river to form deltas similar to those found at river mouths on Earth. This cycle occurred over and over again.
"The great thing about a lake that occurs repeatedly, over and over, is that each time it comes back it is another experiment to tell you how the environment works," Grotzinger said. "As Curiosity climbs higher on Mount Sharp, we will have a series of experiments to show patterns in how the atmosphere and the water and the sediments interact. We may see how the chemistry changed in the lakes over time. This is a hypothesis supported by what we have observed so far, providing a framework for testing in the coming year."
After the crater filled to a height of at least a few hundred yards and the sediments hardened into rock, the accumulated layers of sediment were sculpted over time into a mountainous shape by wind erosion that carved away the material between the crater perimeter and what is now the edge of the mountain.
On the 5-mile (8-kilometer) journey from Curiosity’s 2012 landing site to its current work site at the base of Mount Sharp, the rover uncovered clues about the changing shape of the crater floor during the era of lakes.
This image from Curiosity's Mastcam shows inclined beds of sandstone interpreted as the deposits of small deltas fed by rivers flowing down from the Gale Crater rim and building out into a lake where Mount Sharp is now. It was taken March 13, 2014, just north of the "Kimberley" waypoint. Image Credit: NASA/JPL-Caltech/MSSS
"We found sedimentary rocks suggestive of small, ancient deltas stacked on top of one another," said Curiosity science team member Sanjeev Gupta of Imperial College in London. "Curiosity crossed a boundary from an environment dominated by rivers to an environment dominated by lakes."
Despite earlier evidence from several Mars missions that pointed to wet environments on ancient Mars, modeling of the ancient climate has yet to identify the conditions that could have produced long periods warm enough for stable water on the surface.
NASA's Mars Science Laboratory Project uses Curiosity to assess ancient, potentially habitable environments and the significant changes the Martian environment has experienced over millions of years. This project is one element of NASA's ongoing Mars research and preparation for a human mission to the planet in the 2030s.
"Knowledge we're gaining about Mars' environmental evolution by deciphering how Mount Sharp formed will also help guide plans for future missions to seek signs of Martian life," said Michael Meyer, lead scientist for NASA's Mars Exploration Program.
NASA's Kepler Mission 2.0 Spies a New Super-Earth
"Like a phoenix rising from the ashes, Kepler has been reborn and is continuing to make discoveries. Even better, the planet it found is ripe for follow-up studies," says Andrew Vanderburg of the Harvard-Smithsonian Center for Astrophysics (CfA). The report of the Kepler spacecraft's death was greatly exaggerated. Despite a malfunction that ended its primary mission in May 2013, Kepler is still alive and working. The evidence comes from the discovery of a new super-Earth using data collected during Kepler's "second life."
NASA's Kepler spacecraft detects planets by looking for transits, when a 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 a steady pointing.
Kepler's primary mission came to an end when the second of four reaction wheels used to stabilize the spacecraft failed. Without at least three functioning reaction wheels, Kepler couldn't be pointed accurately.
Rather than giving up on the plucky spacecraft, a team of scientists and engineers developed an ingenious strategy to use pressure from sunlight as a virtual reaction wheel to help control the spacecraft. The resulting second mission, K2, promises to not only continue Kepler's search for other worlds, but also introduce new opportunities to observe star clusters, active galaxies, and supernovae.
Due to Kepler's reduced pointing capabilities, extracting useful data requires sophisticated computer analysis. Vanderburg and his colleagues developed specialized software to correct for spacecraft movements, achieving about half the photometric precision of the original Kepler mission.
Kepler's new life began with a 9-day test in February 2014. When Vanderburg and his colleagues analyzed that data, they found that Kepler had detected a single planetary transit.
They confirmed the discovery with radial velocity measurements from the HARPS-North spectrograph on the Telescopio Nazionale Galileo in the Canary Islands. Additional transits were weakly detected by the Microvariability and Oscillations of STars (MOST) satellite.
The newfound planet, HIP 116454b, has a diameter of 20,000 miles, two and a half times the size of Earth. HARPS-N showed that it weighs almost 12 times as much as Earth. This makes HIP 116454b a super-Earth, a class of planets that doesn't exist in our solar system. The average density suggests that this planet is either a water world (composed of about three-fourths water and one-fourth rock) or a mini-Neptune with an extended, gaseous atmosphere.
This close-in planet circles its star once every 9.1 days at a distance of 8.4 million miles. Its host star is a type K orange dwarf slightly smaller and cooler than our sun. The system is 180 light-years from Earth in the constellation Pisces.
Since the host star is relatively bright and nearby, follow-up studies will be easier to conduct than for many Kepler planets orbiting fainter, more distant stars.
"HIP 116454b will be a top target for telescopes on the ground and in space," says Harvard astronomer and co-author John Johnson of the CfA.
The research paper reporting this discovery has been accepted for publication in The Astrophysical Journal.
Wednesday 17 December 2014
An Alien Water World --"Could It be Habitable?" Asks MIT Team
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.The more extreme the tilt, the less habitable a planet may be or so the thinking has gone.
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."
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.
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."
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."
"Search for Earth's Deep Life" --Ancient, Hydrogen-Rich Waters Discovered Deep Underground
A team of scientists has mapped the location of hydrogen-rich waters found trapped kilometres beneath Earth's surface in rock fractures in Precambrian rocks make up over 70% of the surface of the Earth's crust in Canada, South Africa and Scandinavia.
The team says their findings provide a "global network of sites" with hydrogen-rich waters that can be targeted in the search for deep life over coming years. They also point to the implications for life on Mars. The Red Planet has ancient rocks with hydrogen-producing potential, so could also host microbial life: "If the ancient rocks of Earth are producing this much hydrogen, it may be that similar processes are taking place on Mars," Sherwood Lollar, a geoscientist at University of Toronto's Department of Earth Sciences, said.
Scientists said the water is found in the oldest rocks on Earth – Precambrian Shield rocks. Findings showed they have a chemistry similar to water found near deep sea vents, meaning they could support microbes living in isolation. The study, to be published in Nature on December 18, includes data from 19 different mine sites that were explored by Lollar, senior research associate Georges Lacrampe-Couloume, and colleagues at Oxford and Princeton universities.
"This represents a quantum change in our understanding of the total volume of Earth's crust that may be habitable,"
lead author Lollar said. "Until now, none of the estimates of global hydrogen production sustaining deep microbial populations had included a contribution from the ancient continents." She said the terrain represents a "sleeping giant", with the huge area a "source of possible energy for life".
The authors explain that understanding how much hydrogen is produced is key to understanding the amount of Earth's habitable subsurface. Deep in gold mines and under the sea, hydrothermal vents release geothermally heated waters that are hydrogen rich. They host complex microbial communities nurtured by the chemicals dissolved in the fluid.
Origin of Earth's Oceans --"From Plate Tectonics or Icy Comets?"
The relationship between Earth's plate tectonics and surface water is one of the great mysteries in the geosciences. But a 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,” Wendy Panero, associate professor of earth sciences at Ohio State. “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.”
The 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.
“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.
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.
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.
Confirmed! NASA Makes First Detection of Organic Matter at Mars' Gale Crater (VIDEO)
"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?"
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.
The team responsible for the Sample Analysis at Mars (SAM) instrument suite on NASA's Curiosity rover made the first definitive detection of organic molecules at Mars --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.
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".
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.
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 about 875 degrees Celsius (around 1,600 degrees Fahrenheit) 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 Caltech, 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."
NASA's Mars Science Laboratory Project is using Curiosity to assess ancient habitable environments and major changes in Martian environmental conditions. NASA's Jet Propulsion Laboratory in Pasadena, California, a division of Caltech, built the rover and manages the project for NASA's Science Mission Directorate in Washington.
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The same goes to the staff of DG: A very happy and exciting one. Thanks for all your work over the years; it was always a joy to flip through the pages ;-)
Posted by: Ted | December 31, 2014 at 10:15 AM