- Clear Spring Skies Emerge on Titan
- Life on Earth May Have Had an Icy Start
- LHC Detects Evidence of New Physics
- Video: How the Red Sea Could Have Parted
- Video: Shark-Finning Puts Species on Verge of Extinction
Posted: 21 Sep 2010 03:30 PM PDT
Spring on Saturn's moon Titan looks to be sunny and mostly cloud-free, according to a new analysis of data from the Cassini spacecraft.
Titan is the only body in the solar system other than Earth known to have liquid lakes, clouds and perhaps even rain. But instead of water, frigid Titan's lakes and clouds are made of liquid hydrocarbons like ethane and methane.
While Earth's northern hemisphere is moving into autumn, Titan's northern hemisphere has been shifting from winter to spring for most of the six years Cassini has been there. A full year on Saturn — and therefore on all its moons — lasts 30 Earth years, and each season lasts about seven years.
Throughout the northern winter, Titan's poles were shrouded in heavy clouds. But as the seasons changed, the clouds cleared, says planetary scientist Sebastian Rodriguez of the University of Paris Diderot.
"Over the past six years, we've found that clouds appear clustered in three distinct latitude regions of Titan: large clouds at the north pole, patchy cloud at the south pole and a narrow belt around 40 degrees south," Rodriguez said in a press release. "However, we are now seeing evidence of a seasonal circulation turnover on Titan — the clouds at the south pole completely disappeared just before the equinox and the clouds in the north are thinning out."
Rodriguez and colleagues presented the first long-term study of Titan's weather that includes the spring equinox, which occurred in August 2009, at the European Planetary Science Congress in Rome on September 22.
The team used more than 2000 images from Cassini's VIMS (Visual and Infrared Mapping Spectrometer) instrument to analyze the moon's cloud patterns. They found that in the winter, north polar clouds of ethane form 18 to 30 miles up in the lower portion of Titan's atmosphere by a constant influx of ethane and small particles from an upper layer. In the southern hemisphere, clouds are produced by air humid with methane upwelling from the surface.
Thanks to a mission extension, Cassini will continue to study Saturn and its moons until operating until May 2017, a few months past Saturn's northern summer solstice. This will let scientists observe seasonal changes all the way through from mid-winter to mid-summer in the northern hemisphere.
"We have learned a lot about Titan's climate since Cassini arrived at Saturn, but there is still a great deal to learn," Rodriguez said. "With the new mission extension, we will have the opportunity to answer some of the key questions about the meteorology of this fascinating moon."
Images: 1) Clouds in Titan's atmosphere between July 2004 and April 2010. Black areas are cloud-free and yellow are fully covered. 2) Left: A flyby of Titan on May 12, 2008 shows a large cloud capping Titan's north pole. Right: Another flyby on December 12, 2009 shows a band of clouds at 40 degrees south, but the north pole is cloud-free. Credit: NASA/JPL/University of Arizona/University of Nantes/ University of Paris Diderot
Posted: 21 Sep 2010 12:43 PM PDT
Cracks in ice could have served as a safe environment — much like a cell — for the first life on Earth to replicate and evolve.
A new study adds plausibility to the 'RNA World' hypothesis that argues life began with a single stranded molecule capable of self-replication.
"I always thought that the idea of an RNA world was exciting, but that RNA was a perverse choice of primordial material because it was hard to imagine chemical conditions under which they could survive on the early earth," said biologist Philipp Holliger of MRC Laboratory of Molecular Biology in the United Kingdom, who led a study in Nature Communications Sept. 21.
"What we've found is that RNA would have been much happier in the ice than in hot hydrothermal vents, where it would have lasted only a few seconds," Holliger said.
Holliger was inspired to study how RNA replicates in icy conditions by a 2004 study that found when nucleotides — the building blocks of genetic code — are frozen in ice, they spontaneously assemble into random strands of RNA.
If nucleotides were present in the ice on early Earth, they could have formed uncountable combinations of these random genetic strands, many of which would have been meaningless. But a few of the strands might have contained the right genetic code to begin self-replication.
Over time, the replicating RNA strands would have mutated and changed with some of them surviving better than others, beginning the long chain of evolution towards more complex organisms.
By testing the process out in beakers, adding water, salts, RNA building blocks, and ribosomes — an RNA-derived molecule that serves as a center for the further RNA replication — Holliger found that liquid pockets ice would have served as an essential container for this process to occur. The cold would have also kept the molecules from degrading.
"It's like the tortoise and the hare problem," Holliger said. "The tortoise is slower, but it keeps on going, rather than falling apart. One thing that was available at the beginning of the Earth was time."
A decade ago, this theory might have been dismissed because the early Earth was thought to be so hot and volcanic that ice couldn't form. But more recently there has been evidence that the climate may have been more temperate, with areas of ice on the poles and at high altitudes, Holliger said.
If the theory of an ice RNA world is correct, it could dramatically change our search for life elsewhere in the universe.
"Ice is literally everywhere," Holliger said . "If we can conceive of life arising and maybe thriving in ice it would considerably broaden the places to look for life, both extant and extinct."
Posted: 21 Sep 2010 12:17 PM PDT
After nearly 6 months of smashing particles, the Large Hadron Collider has seen signs of something entirely new. Pairs of charged particles produced when two beams of protons collide seem to be associated with each other even after they fly apart.
"It is a small effect, but it is very interesting in itself," said physicist Guido Tonelli, spokesperson for the LHC's CMS experiment. Tonelli and colleagues announced the results in a seminar at CERN September 21 and in a paper submitted to the Journal of High Energy Physics.
The LHC finally got up and running in March after more than a year of false starts. Beams of protons were smashed together in the 17-mile-long ring at energies of 7 teraelectronvolts (TeV) — three times the energy that had been achieved before.
When two protons collide, they produce a flurry of smaller, short-lived charged particles that fly away from each other at certain angles and speeds. The CMS (Compact Muon Solenoid) experiment at the LHC detects the path each of these particles takes. Physicists can then use those tracks to reconstruct what happened at the heart of the collision, like reassembling shards of glass from a broken window.
In the new experiment, the CMS team took data on the charged particles produced in hundreds of thousands of collisions. The team observed the angles the particles' paths took with respect to each other, and calculated something called a "correlation function" to determine how intimately the particles are linked after they separate. The plot of the data ends up looking like a topographical map of a mountain surrounded by lowlands and a long ridge behind it.
In the most basic case (below, left), the data looked exactly like the physicists expected it to. But in cases where at least 110 charged particles were produced, the team saw a funny ridge-like structure extending away from the mountain peak (below, right).
That ridge essentially means that particles in some pairs are flying away from each other at close to the speed of light along one axis, but are oriented along the same angle in the other axis.
It's as if two particles somehow talked to each other when they were produced, the physicists said. This phenomenon has never been seen before in proton-proton collisions, though it resembles something seen at RHIC (the Relativistic Heavy Ion Collider) at Brookhaven National Laboratory in New York. That effect was interpreted to be from the creation of hot dense matter shortly after the collisions.
The CMS team collected the data in mid-July, and spent the rest of the summer trying to blame it on an error or artifact of the data.
"We are here today because we didn't succeed to kill it," Tonelli said. As far as the team can tell, the effect is real.
But where it comes from, nobody knows. There are a lot of possible explanations, and the team is not ready to choose one yet.
"This is a subtle effect, and careful work is required to establish its physical origin," said MIT physicist Gunther Roland at the seminar at CERN. "So fire away."
Images: 1) Image of a 7 TeV proton-proton collision in CMS producing more than 100 charged particles. 2) The correlation functions for "minimum bias" collisions (left) and for collisions that produced at least 110 charged particles (right); the new ridge is indicated with an arrow. Credit: CERN/CMS Collaboration
Posted: 21 Sep 2010 12:07 PM PDT
Biblical accounts of the Red Sea's parting are hydrologically plausible, suggest computer simulations of sustained winds in a coastal lagoon where the Nile met the Mediterranean 3,000 years ago.
Under steady 60-mph winds, "the ocean model produces an area of exposed mud flats where the river mouth opens into the lake," wrote National Center for Atmospheric Research oceanographers Carl Drews and Weiqing Han in an August 30 Public Library of Science One study. "These mud flats represent the area of crossing, and the crossing party would observe water to their left and right."
In the Book of Exodus, Moses is described as leading Israelite slaves in flight from Egypt, arriving at the Red Sea's shores just ahead of pursuing armies. At that point, "Moses stretched out his hand over the sea; and the Lord caused the sea to go back by a strong east wind all that night, and made the sea dry land, and the waters were divided."
Han and Drews, who hosts a website dedicated to the compatibility of science and Christian faith, don't consider the Exodus narrative to be literally true, but rather "an interesting and ancient story of uncertain origin." Others have been similarly intrigued, suggesting that a rare phenomenon called wind setdown could have created dry passage across the Red Sea's narrow northern tip. A wind setdown is essentially the flip side of a storm surge; when strong, steady winds cause water to rise dramatically in some areas, it necessarily drops in others.
In 1879, theologian Samuel Bartlett proposed a setdown location at a shallow inlet near of Suez, used by Arabs to cross the Red Sea at low tide. More recently, Russian researchers Naum Voltzinger and Alexei Androsov calculated that a 74-mph wind could have exposed an underwater reef near what is now the Suez Canal.
In the new study, Han and Drews determined that the depressions in the reef would have stayed underwater. They propose a different location, 75 miles north of the reef and just south of the Mediterranean, in what is now known as the Kedua Gap. The area is now dry, but historical reconstructions suggest an ancient branch of the Nile once flowed into a lagoon there.
After using satellite measurements and archaeological records to create a model of local hydrogeography, the researchers ran simulations that found 12 hours of 60-mph easterly winds would have exposed a dry passage, 2 miles long and 3 miles wide, out of Egypt.
When the winds stopped blowing, the waters would surge back, appearing in the researchers' words "as an advancing wall of churning water" — or, per Exodus, "the waters returned, and covered the chariots, and the horsemen, and all the host of Pharaoh that came into the sea after them; there remained not so much as one of them."
"If a crossing actually took place here, any debris field of military artifacts should be found to the north of the gap," wrote Han and Drews.
Video: Tim Scheitlin and Ryan McVeigh, NCAR. Image: Nicolas Poussin, The Crossing of the Red Sea./Wikimedia Commons.
Citation: "Dynamics of Wind Setdown at Suez and the Eastern Nile Delta." By Carl Drews and Weiqing Han. Public Library of Science One, Vol. 5 No. 8, Augusts 30, 2010.
Posted: 21 Sep 2010 04:00 AM PDT
It's estimated that as many as a million sharks a year are killed just for their fins.
Shark-finning is a cruel practice. Sharks are caught on long lines, or in nets, regardless of size or species. The shark is often stabbed or clubbed, to be less of a threat to the fisherman. The shark's fins are then cut off and the shark is thrown back into the water, alive, to be eaten by other fish as it sinks to the bottom.
Shark-finning has increased over the past decade for a number of reasons, including increasing demand for shark-fin soup and traditional cures, improved fishing technology and improved market economics, according to the conservation group Shark Water.
Shark fins go for big money. A single dried fin can fetch up to $300.
A growing Asian middle class now has access to shark-fin soup, a dish once reserved for royalty. Cities like Shanghai have multistory shopping centers dedicated to fish and animal sales, which include bin after bin of shark fins.
Local Asian markets in the United States and Europe supply shark fins to eager customers. And shark fins are increasingly found in other products such as energy drinks, pet supplies, makeup, vitamins and homeopathic medicines.
Consequently, many species of shark may already be on the way to extinction, which could be bad news for the entire ocean ecosystem. According to the National Shark Research Consortium, "Sharks are involved in several steps of this web including feeding on the sick and dying, and feeding on
Laws have been enacted to protect the shark in Hawaii, the Maldives and Palou, which have no–shark-finning zones, The conservation group Sea Shepherd is using new strategies, including sniffer dogs, to fight shark-finning in the Galapogos.
Scientists are backing up these efforts. Marine biologist Mahmood Shivji of the Guy Harvey Research Institute at Nova Southeastern University in Fort Lauderdale, Florida, is using DNA to help law enforcement agencies convict smugglers, and his research has shown that hammerheads from the Atlantic Ocean end up in Hong Kong seafood markets.
In the video at the top of this page, Wired speaks to scientists and conservation groups about the severity of the situation and what is being done to fight back.
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