- Earth’s Atmosphere May Have Alien Origin
- T. Rex Skeleton Can Finally Be Ogled by the Public
- Data Nerds Hack NASA (In a Good Way)
- New NASA Sky Mapper to Hunt Stars, Galaxies, Near-Earth Asteroids
- Mediterranean Is Scary Laboratory of Ocean Futures
Posted: 10 Dec 2009 07:53 PM PST
Isotopic analyses of the gases krypton and xenon suggest that much of Earth's atmosphere came from outer space, not inner space.
Krypton and xenon appear in Earth's atmosphere — and in the universe as a whole — only in trace amounts. Detailed analyses of the gases provide clues about where those atmospheric components originated, says Greg Holland, an isotope geochemist at the University of Manchester in England. Those analyses, reported in the Dec. 11 Science, suggest that those gases, as well as many others now cloaking our planet, arrived via comets or were swept up from nearby gas clouds during the late stages of Earth's formation.
Some scientists have proposed that the gases in Earth's atmosphere originated within the planet, says Holland. According to those arguments, the atmosphere either seeped out of the Earth as the planet gradually cooled or were expelled from the crust when large numbers of asteroids pummeled the planet and melted its surface around 3.9 billion years ago. But new isotopic evidence gathered by Holland and his colleagues suggests that those scenarios probably aren't right.
The researchers analyzed samples of gas pulled from a natural reservoir of carbon dioxide that lies several hundred meters below northeastern New Mexico. There, Holland explains, krypton and xenon that originate deep within the Earth — gases that presumably accumulated when the planet coalesced billions of years ago — mix with small amounts of atmospheric krypton and xenon carried downward by rainfall and groundwater.
Ratios of isotopes of krypton and xenon present in the geologic reservoir don't match the ratios seen in today's atmosphere. In particular, heavier isotopes of each gas appear in larger proportions in the subterranean samples than they do in the atmosphere. So it's unlikely that large amounts of these atmospheric gases came from within the Earth, the team argues.
Analyses also show that if the geologic gas samples weren't tainted by atmospheric krypton and xenon, the isotope ratios measured for those gases would match the ratios seen in meteorites. That's another sign that neither the planet nor meteorites were the source of the isotopically light xenon and krypton in today's atmosphere, Holland notes.
Instead, he and his colleagues propose, the krypton and xenon now present in the air — and many other atmospheric components as well — may be remnants of gas clouds swept up by the newly forming Earth. Or, they suggest, the gases may have been delivered to Earth by comets, in which the proportions of light isotopes for xenon and krypton are relatively higher.
"This is an important piece of work, and an extremely interesting contribution to studies of how the atmosphere evolved," says Robert Pepin, an astrophysicist at the University of Minnesota in Minneapolis. But the team's results aren't unambiguous, he notes. The krypton and xenon in today's atmosphere may, for example, be a mix of isotopically light gases delivered by comets and the heavier versions originating within the Earth.
Posted: 10 Dec 2009 04:28 PM PST
The 40-foot long Tyrannosaurus rex that failed to sell at a Las Vegas auction in October has finally found a home in an Oregon museum.
Though the skeleton, one of the most complete ever found, was purchased by a private buyer, it will be on display at the Oregon Museum of Science and Industry in Portland beginning Dec. 17 through summer 2010.
"It is a truly unique and magnificent specimen that has opened new doors to scientific discovery about the life of the Tyrannosaurus rex," said OMSI president Nancy Stueber in a press release. "We're pleased to offer visitors the rare opportunity to view its real bones up close."
Known as Samson, the 66-million year old fossil was discovered in South Dakota in 1987. Because the skull was largely intact when it was found, it is perhaps the finest T.rex skull ever unearthed. The fossil contains 60 percent of the original bones, 170 in all, making it the third most complete T. rex specimen in the world.
Bonhams & Butterfields auction house estimated the dinosaur was worth between $2 million and $8 million, but bidders failed to meet the owner's specified minimum sale price at the October auction. The most complete skeleton, known as Sue, went for $8 million at auction to the Chicago Field Museum. Samson's new owner paid an undisclosed sum.
Image: Bonhams & Butterfields
Posted: 10 Dec 2009 04:06 PM PST
A bunch of data nerds from inside and outside NASA will gather at a house in Cupertino, California called the Rainbow Mansion this Saturday to hack through the agency's data jungles.
The event isn't NASA-sponsored. None of the bureaucracy is involved at all. Instead, the event is being coordinated by a small group of people who just love the space program and want to help open up the agency's troves of information.
"If we can build cool prototypes and demos and proofs-of-concept, other people will see that it's not that hard," said the event's co-host Jessy Cowan-Sharp, a NASA contractor and proprietor of OpenNASA.com. "Maybe then it will be adopted inside NASA."
The event is just one of dozens this weekend being promoted by the Sunlight Foundation as part of its Great American Hackathon. Each one is being organized by volunteers who want to make government data easier to access and more useful to the public. In Pittsburgh, the hackers will be working on making stimulus spending easier to understand. In Boston, the Massachusetts Department of Transportation data will be the focus.
Over the past several years, NASA has made considerable efforts to open itself up to the public. The agency's public relations officials make extensive use of social media networks. Raw images from NASA missions like Cassini also make their way to the web. Many NASA datasets are available on the web and technical reports stretching back a decade have their own server too.
But while NASA has made considerable strides, many of these tools are still hard to find and use.
The challenge for Hackathon events dealing with complex data is how to pick a small enough bite to chew.
"How do you identify a project that's doable in a day?" Cowan-Sharp asked.
The NASA data event will be kicked off by a quick introduction by Cowan-Sharp and her co-host, Robbie Schingler, on how they get useful stuff done in short periods of time. They run a site dedicated to developing microsoftware called TinyApps. Their motto: "Never spend more than 4 hours on a first release."
Unlike a lot of Sunlight events, which focus on making data more publicly accessible, the NASA-focused event will also look at ways of making data flow better within the agency itself.
"We're a bunch of government contractors and civil servants," Cowan-Sharp said. "For us, the question is not just how can we take stuff outside of government, but how can we use these data sources to help each other collaborate."
Posted: 10 Dec 2009 12:33 PM PST
Veteran astronomer Ned Wright is already considered pretty smart. But soon he'll be getting wise.
That's WISE as in Wide-field Infrared Survey Explorer, the NASA spacecraft set for launch on December 11 that will provide the most comprehensive examination of the sky ever recorded in infrared radiation. Wright, of the University of California, Los Angeles, leads the $320 million robotic mission, which for at least nine months will map the sky in four bands of infrared wavelengths. These wavelengths, ranging from 3.3 micrometers to 23 micrometers, are absorbed by Earth's atmosphere and can't be seen from the ground.
The mission is expected to catalog hundreds of millions of infrared-emitting bodies, including hundreds of dim, previously unknown asteroids and comets that cross Earth's orbit. WISE will also give a detailed census of thousands of failed stars, called brown dwarfs, and millions of distant galaxies that glow unusually brightly at infrared wavelengths.
WISE is expected to dramatically boost the number of known debris disks—composed of pulverized rocky remnants of planet formation—around young stars and to turn up more of the dusty cocoons that serve as birth sites for stars. Dust will be easily detected because it absorbs the visible and ultraviolet light from these hatchlings and reradiates the light in the infrared.
The craft is also likely to find the nearest known brown dwarfs — Jupiter-sized balls of gas that are not quite massive enough to keep burning like stars do. Wright calculates that WISE may find as many as 100 brown dwarfs within a mere 20 light-years of Earth. By imaging hundreds of thousands of asteroids in the main belt between the orbits of Mars and Jupiter, WISE will provide the first complete census of the number and sizes of these rocky bodies and new information about their composition, Wright says.
"I'm very excited because we're going to be seeing parts of the universe that we haven't seen before," he notes.
Wright views the mission as the successor to the Infrared Astronomical Satellite, which in 1983 became the first craft to survey the entire sky in the infrared. WISE is 500 times more sensitive than IRAS was at the mid-infrared wavelengths of 12 micrometers and 23 micrometers, meaning that the new craft will record much fainter infrared sources and pinpoint their locations with much greater accuracy.
Researchers still use data generated by the now-defunct IRAS to guide high-resolution observations by large infrared telescopes. In the same way, WISE, which relies on a relatively small 40-centimeter telescope, is expected to provide an avalanche of data to help target searches by much larger telescopes, such as the recently launched European Space Agency's Herschel telescope and especially the James Webb Space Telescope, the proposed infrared successor to the Hubble Space Telescope.
"IRAS was the gift that just kept on giving, and I think WISE will do the same," comments Charles Beichman of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "When you make a breakthrough of hundreds to thousands in sensitivity, great things will follow. When you do that over the whole sky, it will be referenced for decades to come."
The craft will settle into a polar orbit around Earth, allowing WISE to sweep out a circle that will slowly precess, or change its angle of inclination. That orbit will enable WISE, which takes a snapshot every 11 seconds, to scan the entire sky in six months. The craft will then begin a second, partial scan of the sky that will last three months.
A tank of hydrogen ice will keep WISE chilled to 15 degrees above absolute zero, reducing infrared emissions from the craft that could interfere with detection of faint infrared sources from space. Wright expects the first images to be released a few months after launch, but he says the first detailed maps won't be available until sometime around April 2011.
Posted: 10 Dec 2009 10:52 AM PST
Warmed, overfished and polluted, the small Mediterranean Sea is giving scientists a look at what the future may hold for the rest of Earth's oceans — and it's not pretty.
Beneath its surface, a transformation is taking place. Food webs are shrinking, with rich ecosystems that supported valuable commercial fisheries giving way to barrens dominated by jellyfish and tiny invertebrates. Mass die-offs and disease are now common.
"The predicted effects of climate change are being met in the Mediterranean. The results are more obvious and dramatic, but the drivers are the same all over the world," said Pierre Chevaldonné, a University of the Mediterranean biologist.
Chevaldonné is a co-author of a review of more than 100 studies on the Mediterranean's changing ecological dynamics. Published last Monday in Trends in Ecology and Evolution, it describes the convergence of climate change and human impacts in waters that had been stable since the time of Aristotle.
During the latter half of the 20th century, the Mediterranean's deep northern regions, a traditional source of cold waters that flowed south into warmer basin currents, warmed by one-fifth of a degree Fahrenheit. Shallow northwest waters — an intermediate zone more productive than any other region of the Mediterranean — warmed by 1.8 degrees Fahrenheit. Some of the warming was expected, but it appears to have accelerated in the last 20 years, as the unusually hot 1990s coincided with natural cycles.
With that overheated decade came anomalies in surface temperature and rainfall. These appear to have disrupted deep-water hydrology, changing its composition and currents. That disruption has now rippled to the western shallows. Compounding the problem, runaway population growth has packed 132 million people around the sea's rim, with habitat destruction, pollution and fishing pressure increasing apace.
The effects of these interacting stresses make the Mediterranean a model system for the rest of Earth's oceans, which are also overfished and, in many regions, warming at comparable or greater rates. Scientists say warming will continue for decades even if greenhouse gas emissions soon fall to a fraction of current levels. And though it will take longer for disruption to become visible in those larger waters, the lessons are the same.
"It's difficult to know exactly what's going to happen elsewhere, but the principles can be extrapolated," said Marta Call, a Dalhousie University marine biologist who has modeled the interactions of Mediterranean species. In a paper published last year in Ecosystems, she and her colleagues described Mediterranean food webs as "in an advanced state of degradation."
Degradation in the Mediterranean has taken place on multiple levels. Many large fish species, including top-level predators like sharks and tuna, have been fished to functional extinction. A few still swim, but they no longer have the same ecological role. Coll's models and other research on predator interactions suggest that they helped stabilize food webs, and their absence now leaves other species prone to wild fluctuations.
Mass die-offs of dozens of invertebrate species are now common in the northeast. They're stressed by rising temperatures and vulnerable to disease, and the most common invasive species are not new predators, but microbes. Most strikingly, soft corals that once carpeted the northwest seafloor, forming a literal underwater forest, have in many areas been wiped out altogether. Replacing them is what Chevaldonné calls "lawns" of algae and short-lived invertebrates.
The prevailing dynamic is what scientists call "brittleness," or a decline in "robustness." Historically complex food webs cannot find balance. In their place have emerged simpler food webs dominated by species that Coll and her colleagues characterize as "unpalatables" and "detritus" — algae, invertebrates and jellyfish. There are still some fish, but they're relatively few in number, and small. Much of the Mediterranean catch is now processed and sold as animal feed.
"In terms of biomass and production, the Mediterranean is basically impoverished," said Coll.
These conditions probably represent a transitional period for the Mediterranean, though it's likely a one-way transition. Neither Chevaldonné nor Coll claims to know exactly what the sea's next stable ecological configuration will look like, but this may be a preview, just as the Mediterranean may be a preview of the profound shifts likely elsewhere.
"In the future, we may get only jellyfish. Then we'll find a way of consuming jellyfish," Coll said. "The problem is, do we want that?"
Images: 1) In some regions of the Mediterranean, traditional food webs have collapsed, and the new ones are dominated by bacteria, small invertebrates and jellyfish./jetzt_ist_immer/Flickr.
Citations: "Climate change effects on a miniature ocean: the highly diverse, highly impacted Mediterranean Sea." Christophe Lejeusne, Pierre Chevaldonne, Christine Pergent-Martini, Charles F. Boudouresque and Thierry Perez. Trends in Ecology and Evolution, published online, Dec. 1, 2009.
"Structural Degradation in Mediterranean Sea Food Webs: Testing Ecological Hypotheses Using Stochastic and Mass-Balance Modelling." By Marta Coll, Heike K. Lotze, and Tamara N. Romanuk. Ecosystems, Vol. 11 No. 6, Sept. 2008.
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