Thursday, November 29, 2007

New Findings Underscore an Earth-Venus Kinship

From the NY Times:

"Other than the hellish heat, a crushing carbon dioxide atmosphere and corrosive clouds of sulfuric acid, Venus is a lot like Earth, scientists said yesterday.

In a news conference at the Paris headquarters of the European Space Agency, the scientists, working on the agency’s Venus Express mission, played up the Venus-as-Earth’s-twin angle in presenting their newest findings, including signs of lightning, surprising swings of temperature and additional evidence that Venus could have once had oceans the size of Earth’s.

“They’re really twins which are just separated at birth,” said Dmitri Titov, the mission’s science coordinator. “The key question is why those twins are so different.”

Understanding the dynamics and history of Venus’s turbulent atmosphere could lead to a better understanding of the role that heat-trapping gases like carbon dioxide play in shaping the climate of planets including Earth.

Eight scientific articles describing the observations of Venus Express, the first spacecraft to visit the planet in more than a decade, appear in today’s issue of the journal Nature.

Venus is about the same size and mass as Earth, and of roughly the same composition. And before the space age, planetary scientists imagined an Earth-like environment, perhaps even tropical jungles, obscured by Venus’s perpetual cloud cover. But in 1958, when astronomers measured intense microwaves emanating from the planet, they first got a hint that it was not as lush as they had imagined.

Subsequent visits by spacecraft confirmed that the surface temperatures exceed 800 degrees Fahrenheit, hot enough to melt tin and lead. Although Venus is closer to the Sun than is Earth, the clouds reflect much of the sunlight, and the high temperatures largely result from the heat-trapping effects of an atmosphere that is almost pure carbon dioxide and about 100 times as dense as Earth’s.

Scientists imagine that Venus formed with much liquid water, just like Earth, but that because it is closer to the Sun, with sunlight twice as intense as on Earth, the water began to evaporate. Water vapor, also a greenhouse gas, trapped heat.

“That heats up the surface and leads to more evaporation,” said David Grinspoon of the Denver Museum of Nature & Science. “It’s a powerful feedback.”

The evaporation accelerated until all the liquid water had turned into a thick atmosphere of water vapor. As the water molecules floated in the air, scientists hypothesize, ultraviolet rays from the Sun broke them apart into hydrogen and oxygen atoms. Chemical reactions with minerals in the rocks transformed the oxygen into carbon dioxide. The hydrogen, the lightest of atoms, escaped into outer space.

Measurements from Venus Express, which arrived at the planet last year, support that hypothesis, looking at amounts of hydrogen remaining in the atmosphere compared with concentrations of deuterium, a heavier version of hydrogen. The heavier deuterium would escape more slowly into space, and Venus Express detected a deuterium-to-hydrogen ratio 150 times as high as on Earth, a finding that agreed with earlier measurements. What was surprising, though, was that the deuterium concentration turned out to be 2.5 times as high in the upper atmosphere as near the ground.

“We haven’t completely figured out what it means yet,” Dr. Grinspoon said. “Once we crack this mystery, this will be an important clue to this overall question of the history of water.”

In other measurements, Venus Express detected the bursts of radio waves known as “whistlers,” which, at least on Earth, are generated by lightning, and also found large temperature swings, up to 70 degrees Fahrenheit, between the daytime and nighttime sides of Venus.

The much thicker atmosphere would have been expected to minimize the temperature differences, said Andrew P. Ingersoll, a professor of planetary science at the California Institute of Technology who wrote a commentary in Nature to accompany the scientific papers.

Dr. Ingersoll said he remained skeptical of lightning despite earlier observations by space probes and Earth telescopes. The clouds of Venus are much different from those that produce thunderstorms on Earth. “They’re more like smog in L.A.,” he said. “It’s really just a haze of sulfuric acid. That kind of cloud, at least on Earth, doesn’t produce electrical charge. And thus it’s a little puzzling to have lightning.”

Friday, November 16, 2007

Led by Robots, Roaches Abandon Instincts

"Many a mother has said, with a sigh, “If your friends jumped off a cliff, would you jump, too?”

The answer, for cockroaches at least, may well be yes. Researchers using robotic roaches were able to persuade real cockroaches to do things that their instincts told them were not the best idea.

This experiment in bug peer pressure combined entomology, robotics and the study of ways that complex and even intelligent patterns can arise from simple behavior. Animal behavior research shows that swarms working together can prosper where individuals might fail, and robotics researchers have been experimenting with simple robots that, together, act a little like a swarm.

“We decided to join the two approaches,” said José Halloy, a biology researcher at the Free University of Brussels and lead author of a paper describing the research in today’s issue of the journal Science.

Dr. Halloy and his colleagues worked with roaches because their societies are simple, egalitarian and democratic, with none of the social stratification seen in some other insect societies — no queen bees, no worker ants. “Cockroaches are not like that,” Dr. Halloy said. “They live all together.”

They also have weak eyes, which allowed the researchers to create a robotic roach that resembles a miniature golf cart more than an insect. In the roach world, however, looking right is not as important as smelling right, and the scientists doused the machines with eau de cockroach sex hormones.

They set up a cockroach arena one yard in diameter. Two six-inch-wide plastic discs were suspended over it, providing the dark shelters that cockroaches prefer to congregate in. But one disc was darker and a more likely cockroach hangout.

When 16 cockroaches were placed in the arena, they naturally gravitated toward the darker disc, following what the researchers believe is an internal calculation of the amount of light and the number of other roaches, finding comfort in company.

Dr. Halloy then replaced four of the cockroaches with four robots equipped with sensors to measure light and the proximity of other robots. When the robots emulated the real roaches, the group continued to seek the dark and crowded place.

When the four robotic roaches were reprogrammed to prefer the lighter disc, however, the real roaches followed them about 60 percent of the time, in essence deferring their own judgment as the preference grew more popular. (The other 40 percent of the time, the robotic roaches succumbed to peer pressure and headed for the darkest place.)

“It’s a cascade of imitation, so a small effect can become quite large,” said Stephen Pratt, a professor of life sciences at Arizona State University. “This one is a real step forward. They’ve developed these theories about what kinds of individual behavior rules would have to follow to generate a collective intelligence. I thought it was very gratifying they could get the roaches to do what they normally would not do.”

The scientists plan to extend their research to higher animals. The next creation: a robotic chicken, which will look a little like a ball on tank treads with loudspeakers. Newly hatched chicks, which bond to the first thing they see, will do so with the robot as if it were their mother. The researchers say they hope to explore the chicks’ behavior with the false mother as leader.

The current research did not test whether the robots could lead the cockroaches to something they really disliked, like broad daylight or insecticide. The results also apply only to cockroaches, Dr. Halloy said. “We are not interested in people,” he said."

My question is...why did the programmed roaches follow the real roaches 40 percent of the time????

Tuesday, November 13, 2007

Wow! Japan’s moon probe updates Earthrise

"A Japanese moon probe has replicated the famous Apollo-era "Earthrise" photograph with modern high-definition imaging.

The Kaguya spacecraft, also called Selene, has been orbiting 62 miles (100 kilometers) above the moon since Oct. 18.

The new Earthrise image shows our blue world floating in the blackness of space. Released on Tuesday, it is a still shot taken from video made by the craft's high-definition television camera.


A second image, taken from a different location in the lunar orbit, has been dubbed "Earthset." A related series of still images shows our planet setting beyond the lunar horizon.

In the Earthset image, Earth appears upside-down; visible are Australia and Asia. A region near the moon's south pole is seen in the foreground."


Dylan videos

The uninvited guest: Chinese sub pops up in middle of U.S. Navy exercise, leaving military chiefs red-faced

From the U.K.'s Daily Mail...

"When the U.S. Navy deploys a battle fleet on exercises, it takes the security of its aircraft carriers very seriously indeed.

At least a dozen warships provide a physical guard while the technical wizardry of the world's only military superpower offers an invisible shield to detect and deter any intruders.

That is the theory. Or, rather, was the theory.

A Chinese Song class submarine, like the one that surfaced by the U.S.S. Kitty Hawk

American military chiefs have been left dumbstruck by an undetected Chinese submarine popping up at the heart of a recent Pacific exercise and close to the vast U.S.S. Kitty Hawk - a 1,000ft supercarrier with 4,500 personnel on board.

By the time it surfaced the 160ft Song Class diesel-electric attack submarine is understood to have sailed within viable range for launching torpedoes or missiles at the carrier.

According to senior Nato officials the incident caused consternation in the U.S. Navy.

The Americans had no idea China's fast-growing submarine fleet had reached such a level of sophistication, or that it posed such a threat.

One Nato figure said the effect was "as big a shock as the Russians launching Sputnik" - a reference to the Soviet Union's first orbiting satellite in 1957 which marked the start of the space age.

The incident, which took place in the ocean between southern Japan and Taiwan, is a major embarrassment for the Pentagon.

The Kitty Hawk carries 4,500 personnel

The lone Chinese vessel slipped past at least a dozen other American warships which were supposed to protect the carrier from hostile aircraft or submarines.

And the rest of the costly defensive screen, which usually includes at least two U.S. submarines, was also apparently unable to detect it.

According to the Nato source, the encounter has forced a serious re-think of American and Nato naval strategy as commanders reconsider the level of threat from potentially hostile Chinese submarines.

It also led to tense diplomatic exchanges, with shaken American diplomats demanding to know why the submarine was "shadowing" the U.S. fleet while Beijing pleaded ignorance and dismissed the affair as coincidence.

Analysts believe Beijing was sending a message to America and the West demonstrating its rapidly-growing military capability to threaten foreign powers which try to interfere in its "backyard".

The People's Liberation Army Navy's submarine fleet includes at least two nuclear-missile launching vessels.

Its 13 Song Class submarines are extremely quiet and difficult to detect when running on electric motors.

Commodore Stephen Saunders, editor of Jane's Fighting Ships, and a former Royal Navy anti-submarine specialist, said the U.S. had paid relatively little attention to this form of warfare since the end of the Cold War.

He said: "It was certainly a wake-up call for the Americans.

"It would tie in with what we see the Chinese trying to do, which appears to be to deter the Americans from interfering or operating in their backyard, particularly in relation to Taiwan."

In January China carried a successful missile test, shooting down a satellite in orbit for the first time."

Saturday, November 10, 2007

Holiday cards and the lost art of letter writing

"I’ve always been a writer. Not just out here in public, where everyone and anyone can read me, but privately, in the comfort of my home, at my desk, or curled up on my my sofa, lap tray, pens, paper and postage stamps in place. I am a letter writer. A compulsive letter writer.

It’s a compulsion that manifests itself in the months leading up to Christmas, months when I haul out my once finely honed Palmer penmanship - once done with Parker fountain pen, inkwell and blotters - taught in grueling detail by the nuns at the French Catholic school of my childhood. Honed further still by my mother, whose penchant for cards, notes, letters and postcards were unrivaled in our neighborhood. I get it from her. And her mother and father before her."

Read the full article here.