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Thursday, April 17, 2008

German whizzkid got it wrong: NASA

Using mind control to make flies sing

The female fly sang the male fly's song when a laser was flashed at it

An Oxford scientist has used mind control to make female flies belt out male love songs, revealing they have a hidden capacity for masculine behaviour.

The research, which suggests that the sexes are not quite so different as they seem, exploits a remote control method that could provide revolutionary insights into behaviour.

Professor Gero Miesenböck of Oxford University is sometimes nicknamed the "lord of the flies" after remarkable work he pioneered in America to use laser light to control fly brains with the flick of a switch. He has now applied his mind control methods to exploring fly sexuality.

Three years ago, he caused a buzz when he showed he could trigger certain actions in flies from a distance by shining light on them. The flies are genetically engineered so that only the brain cells of interest were made responsive to light.

When the laser flashed it activated these brain cells and could make flies jump, walk, fly or, in the present case, produce a 'love song'.

Male fruit flies usually 'sing' to attract females, vibrating one wing to produce a distinctive sound which females like because they then allow copulation.

By tweaking one set of nerve cells thought to control this behaviour, the so called fru neurons, Professor Miesenböck has shown that female fruit flies can be made to 'sing' too.

"You might expect that the brains of the two sexes would be built differently, but that does not seem to be the case," says Prof Miesenböck. "Instead, it appears there is a largely bisexual or 'unisex brain' with a few critical switches that make the difference between male and female behaviour."

"The fact that we could make females vibrate one wing to produce a courtship song - a behaviour never before seen in female flies - shows that the brain circuits for this male behaviour are present in the female brain, even though they are never used for that purpose,' says Miesenböck.

Although the work suggests the circuitry for male behaviour exists in female brains and simply lies dormant, the 'song' was not quite as good as the males'.

"If you look carefully, the females do sound different," he says. "They have a different pitch and rhythm and aren't as well controlled." He thinks those distinctions probably stem from real, if subtle, differences between the male and female brains.

Despite this off key note, the study poses a profound puzzle. "The mystery at the root of our study is the neuronal basis of differences in male and female behaviour. Anatomically, the differences are subtle. How is it that the neural equipment is so similar, but the sexes behave so differently?

The new findings suggest that flies must harbour key nodes or "master switches" that set the whole brain to the male or female mode, according to the researchers. Their next goal is to find those controls.

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Caffeine can get rid of sun damaged skin cells

Coffee, tea, or ... sunscreen? That might one day happen if research into the anti-skin cancer properties of caffeine proves true. As this ScienCentral report explains, research into the effects of caffeine in mice shows it can help get rid of sun damaged skin cells before they become cancerous.

Interviewee: Paul Nghiem,
University of Washington School of Medicine
Length: 1 min 21sec
Produced by Jack Penland
Edited by Charles Young and Chris Bergendorff
Copyright © ScienCentral, Inc.
with additional footage courtesy National Cancer Insititute.

Caffeine As A Jolt

Caffeine is what gives that morning cup of coffee along with tea, and soda, among others, that jolt that helps turn us from pillow-huggers to career ladder-climbers. “You can say many things about caffeine,” says Paul Nghiem, Associate Professor in the University of Washington’s School of Medicine and Fred Hutchinson Cancer Research Center, “including it's the world’s most prevalent drug.”

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US army develops robotic suits

By Rajesh Mirchandani
BBC News, Utah


Rex Jameson, software engineer

On the big screen, films like Robocop, Universal Soldier and forthcoming release Iron Man show man-machines with superhuman powers. But in Utah they are turning science fiction into reality.

We are at a research facility on the outskirts of Salt Lake City, ringed by beautiful snow-capped mountains. Once they held the Winter Olympics here; now they are testing endurance in other ways.

The aluminium limbs gleam in the brilliant sunshine, as the strange metal skeleton hangs from a safety harness at the outdoor testing site. It seems to be treading water; actually its programme is telling it to keep the hydraulic fluid in its joints moving.

Rex Jameson, a software engineer here at laboratories run by Sarcos, the robotics firm which designed the XOS exoskeleton, steps up and into the suit.

Stephen Jacobsen, Sarcos

The lightweight aluminium exoskeleton, called XOS, senses Rex's every move and instantly moves with him; it is almost like a shadow or a second skin. It is designed for agility that can match a human's, but with strength and endurance that far outweigh our abilities.

With the exoskeleton on and fully powered up, Rex can easily pull down weight of more than 90 kilos, more than he weighs.

For the army the XOS could mean quicker supply lines, or fewer injuries when soldiers need to lift heavy weights or move objects around repeatedly. Initial models would be used as workhorses, on the logistics side.

Later models, the army hopes, could go into combat, carrying heavier weapons, or even wounded colleagues.

The XOS in action

There are still problems to solve, not least how to create a mobile power supply that can last an effective length of time.

But the US military expects to take delivery of these early prototypes next year, and hopefully deploy some refined versions within eight years.

It is a long way off before we see robot soldiers that can fly or fire missiles - like in the movies - but the designers are already imagining future versions more reminiscent of Hollywood.

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Evolution: 24 myths and misconceptions

If you think you understand it, you don't know nearly enough about it

It will soon be 200 years since the birth of Charles Darwin and 150 years since the publication of On the Origin of Species, arguably the most important book ever written. In it, Darwin outlined an idea that many still find shocking – that all life on Earth, including human life, evolved through natural selection.

Darwin presented compelling evidence for evolution in On the Origin and, since his time, the case has become overwhelming. Countless fossil discoveries allow us to trace the evolution of today's organisms from earlier forms. DNA sequencing has confirmed beyond any doubt that all living creatures share a common origin. Innumerable examples of evolution in action can be seen all around us, from the pollution-matching pepper moth to fast-changing viruses such as HIV and H5N1 bird flu. Evolution is as firmly established a scientific fact as the roundness of the Earth.

And yet despite an ever-growing mountain of evidence, most people around the world are not taught the truth about evolution, if they are taught about it at all. Even in the UK, the birthplace of Darwin with an educated and increasingly secular population, one recent poll suggests less than half the population accepts evolution.

For those who have never had the opportunity to find out about biology or science, claims made by those who believe in supernatural alternatives to evolutionary theory can appear convincing. Meanwhile, even among those who accept evolution, misconceptions abound.

Most of us are happy to admit that we do not understand, say, the string theory in physics, yet we are all convinced we understand evolution. In fact, as biologists are discovering, its consequences can be stranger than we ever imagined. Evolution must be the best-known yet worst-understood of all scientific theories.

So here is New Scientist's guide to some of the most common myths and misconceptions about evolution.

There are already several good and comprehensive guides out there. But most biologists would probably agree that there can never be too many.

Shared misconceptions:

Everything is an adaptation produced by natural selection

Natural selection is the only means of evolution

Natural selection leads to ever-greater complexity

Evolution produces creatures perfectly adapted to their environment

Evolution always promotes the survival of species

It doesn't matter if people do not understand evolution

"Survival of the fittest" justifies "everyone for themselves"

Evolution is limitlessly creative

Evolution cannot explain traits such as homosexuality

Creationism provides a coherent alternative to evolution

Creationist myths:

Evolution must be wrong because the Bible is inerrant

Accepting evolution undermines morality

Evolutionary theory leads to racism and genocide

Religion and evolution are incompatible

Half a wing is no use to anyone

Evolutionary science is not predictive

Evolution cannot be disproved so is not science

Evolution is just so unlikely to produce complex life forms

Evolution is an entirely random process

Mutations can only destroy information, not create it

Darwin is the ultimate authority on evolution

The bacterial flagellum is irreducibly complex

Yet more creationist misconceptions

Evolution violates the second law of thermodynamics

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April 17, 1970: Houston, We No Longer Have a Problem

Crewmen aboard the USS Iwo Jima hoist the Apollo 13 Command Module aboard ship after successful splashdown in the Pacific. Tragedy had been narrowly averted.
Courtesy NASA

1970: Apollo 13 splashes down in the Pacific Ocean near Samoa, recovering from a barely survivable explosion in space.

Apollo 13 launched from Cape Canaveral on April 11, intended to be the third manned lunar landing. The crew — James A. Lovell Jr., John L. Swigert Jr. and Fred W. Haise Jr. — experienced a slight vibration shortly after launch, but things were going normally until 55 hours, 55 minutes into the flight.

Oxygen tank No. 2 exploded, causing No. 1 to fail and start leaking rapidly. Warning lights started blinking. The astronaut's supplies of air, water, light and electricity were imperiled ... 200,000 miles from Earth.

Swigert radioed Mission Control in Texas: "Houston, we've had a problem here." The the 1995 hit film Apollo 13 used a more dramatic version: "Houston, we have a problem."

NASA had engineered some redundancy into the Apollo systems, but it was an extremely close scrape. The plan now was to scrap the lunar landing, swing around the moon and return home. The crew clambered from the Command Module into the attached Lunar Module as a lifeboat.

Oxygen: There was plenty in the LM, because more oxygen was available from the tanks that would have supplied liftoff from the moon's surface.

Light and electricity: All noncritical systems were turned off, reducing power consumption to one-fifth of normal. But without the heat generated by those systems, the temperature inside the capsule dropped to 38 degrees Fahrenheit. LM power was used to recharge batteries in the CM for eventual re-entry in the Earth's atmosphere.

Water: LM systems needed water for cooling. So the crew conserved water by drinking little and eating only wet foods. They became severely dehydrated, losing about 10 pounds each. But the water lasted.

Carbon dioxide removal: The LM had lithium hydroxide cannisters to remove the CO2 for two men for two days, not three men for four days. Under the guidance of Mission Control, the astronauts attached the CM canisters to the LM system with a pipeline made of plastic bags, cardboard and tape, all of which NASA had placed on board. Kluge city.

Getting home: The navigation system was transfered from CM to LM, but the alignment needed to be checked. Debris from the explosion made it hard for the astronauts to fix upon any distant stars. So NASA instructed the crew to use the nearest one: the sun. Precise navigation was essential, because returning to the Earth at too steep an angle would cause the CM to burn up in the atmosphere. Too tangential an angle could skip the module out into space forever. Fire or ice.

After four days of alternating terror and hope, the three astronauts climbed back to the CM for re-entry an hour before splashdown. Everything worked out.

The Apollo 13 Accident Review Board later determined the cause of the explosion. Improvements to the command module in 1965 raised the permissible voltage to the oxygen-tank heaters from 28 to 65 volts DC. But the heater switches weren't likewise upgraded. The final launch-pad test ran the heaters hot and long. Wires near the heaters were cooked at 1,000 degrees Fahrenheit — enough, it was learned later, to "severely degrade teflon insulation. The thermostatic switches started to open ... and were probably welded shut." NASA also found that other warning signs had been ignored, and the oxygen tank was a potential bomb that became a real bomb.

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The Moon and the Magnetotail

The moon The moon. Credit: NASA Behold the full moon. Ancient craters and frozen lava seas lie motionless under an airless sky of profound quiet. It’s a serene, slow-motion world where even a human footprint may last millions of years. Nothing ever seems to happen there, right?


NASA-supported scientists have realized that something happens every month when the moon gets a lashing from Earth’s magnetic tail.

“Earth’s magnetotail extends well beyond the orbit of the moon and, once a month, the moon orbits through it,” says Tim Stubbs, a University of Maryland scientist working at the Goddard Space Flight Center. “This can have consequences ranging from lunar ‘dust storms’ to electrostatic discharges.”

Yes, Earth does have a magnetic tail. It is an extension of the same familiar magnetic field we experience when using a Boy Scout compass to find our way around Earth’s surface. Our entire planet is enveloped in a bubble of magnetism, which springs from a molten dynamo in Earth’s core. Out in space, the solar wind presses against this bubble and stretches it, creating a long “magnetotail” in the downwind direction.

Anyone can tell when the moon is inside the magnetotail. Just look: “If the moon is full, it is inside the magnetotail,” says Stubbs. “The moon enters the magnetotail three days before it is full and takes about six days to cross and exit on the other side.”

It is during those six days that strange things can happen.

Diagram of Earth's magnetotail Fine particles of dust on the moon's surface can actually float off the ground when they become charged by electrons in Earth's magnetotail. Credit: Tim Stubbs/University of Maryland/GSFC
> Larger image
During the crossing, the moon comes in contact with a gigantic “plasma sheet” of hot charged particles trapped in the tail. The lightest and most mobile of these particles, electrons, pepper the moon’s surface and give the moon a negative charge.

On the moon’s dayside this effect is counteracted to a degree by sunlight: UV photons knock electrons back off the surface, keeping the build-up of charge at relatively low levels. But on the nightside, in the cold lunar dark, electrons accumulate and surface voltages can climb to hundreds or thousands of volts.

Imagine what it feels like to be a sock pulled crackling from a dryer. Astronauts on the moon during a magnetotail crossing might be able to tell you. Walking across the dusty charged-up lunar terrain, the astronauts themselves would gather a load of excess charge. Touching another astronaut, a doorknob, a piece of sensitive electronics -- any of these simple actions could produce an unwelcome discharge. “Proper grounding is strongly recommended,” says Stubbs.

Screen shot of an animation showing Earth's magnetotail Earth's magnetic field responds to the solar wind much like an airport wind sock: It stretches out with its tail pointing downwind. Credit: NASA/Goddard Space Flight Center- Conceptual Image Lab
> Magnetospheric substorm animation
The ground, meanwhile, might leap into the sky. There’s growing evidence that fine particles of moondust might actually float, ejected from the lunar surface by electrostatic repulsion. This could create a temporary nighttime atmosphere of dust ready to blacken spacesuits, clog machinery, scratch faceplates (moondust is very abrasive) and generally make life difficult for astronauts.

Stranger still, moondust might gather itself into a sort of diaphanous wind. Drawn by differences in global charge accumulation, floating dust would naturally fly from the strongly-negative nightside to the weakly-negative dayside. This “dust storm” effect would be strongest at the moon’s terminator, the dividing line between day and night.

Much of this is pure speculation, Stubbs cautions. No one can say for sure what happens on the moon when the magnetotail hits, because no one has been there at the crucial time. “Apollo astronauts never landed on a full moon and they never experienced the magnetotail.”

The best direct evidence comes from NASA’s Lunar Prospector spacecraft, which orbited the moon in 1998-99 and monitored many magnetotail crossings. During some crossings, the spacecraft sensed big changes in the lunar nightside voltage, jumping “typically from -200 V to -1000 V,” says Jasper Halekas of UC Berkeley who has been studying the decade-old data.

Diagram of Earth's magnetotail The moon spends about six days each month inside Earth's magnetic tail, or "magnetotail." Credit: NASA/Steele Hill
> Larger image
“It is important to note,” says Halekas, “that the plasma sheet (where all the electrons come from) is a very dynamic structure. The plasma sheet is in a constant state of motion, flapping up and down all the time. So as the moon orbits through the magnetotail, the plasma sheet can sweep across it many times. Depending on how dynamic things are, we can encounter the plasma sheet many times during a single pass through the magnetotail with encounters lasting anywhere from minutes to hours or even days.”

“As a result, you can imagine how dynamic the charging environment on the moon is. The moon can be just sitting there in a quiet region of the magnetotail and then suddenly all this hot plasma goes sweeping by causing the nightside potential to spike to a kilovolt. Then it drops back again just as quickly.”

The roller coaster of charge would be at its most dizzying during solar and geomagnetic storms. “That is a very dynamic time for the plasma sheet and we need to study what happens then,” he says.

What happens then? Next-generation astronauts are going to find out. NASA is returning to the moon in the decades ahead and plans to establish an outpost for long-term lunar exploration. It turns out they’ll be exploring the magnetotail, too.

More Information:

Earth’s magnetotail isn’t the only source of plasma to charge the moon. Solar wind can provide charged particles, too; indeed, most of the time, the solar wind is the primary source. But when the moon enters the magnetotail, the solar wind is pushed back and the plasma sheet takes over. The plasma sheet is about 10 times hotter than the solar wind and that gives it more "punch" when it comes to altering the charge balance of the moon's surface. Two million degree electrons in the plasma sheet race around like crazy and many of them hit the moon's surface. Solar wind electrons are relatively cool at only 140 thousand degrees, and fewer of them zip all the way down to the shadowed surface of the moon's nightside.
Tony Phillips
NASA's Goddard Space Flight Center

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Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2008 April 17

Messier 63: The Sunflower Galaxy
Credit & Copyright: Tony Hallas

Explanation: A bright spiral galaxy of the northern sky, Messier 63 is about 25 million light-years distant in the loyal constellation Canes Venatici. Also cataloged as NGC 5055, the majestic island universe is nearly 100,000 light-years across, about the size of our own Milky Way. Known by the popular moniker, The Sunflower Galaxy, M63 sports a bright yellowish core and sweeping blue spiral arms, streaked with cosmic dust lanes and dotted with pink star forming regions. But this deep exposure also shows remarkable faint loops and extensions of the galaxy's spiral arms. A dominant member of a known galaxy group, M63's faint extended features could be the result of gravitational interactions with nearby galaxies. M63 also shines across the electromagnetic spectrum and is thought to have undergone bursts of intense star formation.

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NASA Statement on Student Asteroid Calculations

WASHINGTON -- The Near-Earth Object Program Office at NASA's Jet Propulsion Laboratory in Pasadena, Calif., has not changed its current estimates for the very low probability (1 in 45,000) of an Earth impact by the asteroid Apophis in 2036.

Contrary to recent press reports, NASA offices involved in near-Earth object research were not contacted and have had no correspondence with a young German student, who claims the Apophis impact probability is far higher than the current estimate.

This student's conclusion reportedly is based on the possibility of a collision with an artificial satellite during the asteroid's close approach in April 2029. However, the asteroid will not pass near the main belt of geosynchronous satellites in 2029, and the chance of a collision with a satellite is exceedingly remote.

Therefore, consideration of this satellite collision scenario does not affect the current impact probability estimate for Apophis, which remains at 1 in 45,000.

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Dark matter mystery 'solved' - again

It's the experiment dark matter hunters love to hate. But physicists working on the DAMA (DArk MAtter) experiment might have the last laugh later this week. Rumour has it that, later this week, an Italian lab will claim to have found dark matter, at a conference in Venice, Italy.

News of the announcement has spread like wildfire among physicists here at the American Physical Society conference in St Louis, Missouri. What makes the results so controversial is that DAMA scientists have claimed to detect dark matter before, even though other experiments have failed to see it.

Now the experiment has been revamped to make it more sensitive to dark matter and renamed LIBRA. On Wednesday, Rita Bernabei of the University of Rome Tor Vergata, who leads both the DAMA and LIBRA teams, will present the first findings at the NO-VE workshop on neutrino oscillations.

The controversy dates back to 1998 when the DAMA collaboration claimed it had found evidence for particles of dark matter passing through its detector located in an underground laboratory deep within the Gran Sasso mountain, Italy. Dark matter is the invisible, mysterious stuff thought to make up nearly 90% of matter in the universe.

You might think that physicists would be overjoyed at the result. But there was a lot of scepticism. "Extraordinary results require extraordinary evidence," particle physicists would tell me. They simply didn't believe that DAMA had found the leading candidate for dark matter, particles called WIMPs that barely interact with anything.

Part of the reason is that the LIBRA and DAMA teams have always taken a different approach to finding dark matter from other experiments. They assume that the amount of dark matter flooding past our planet depends on the Earth's direction of motion, so it varies with the seasons. So the DAMA team looked for a seasonal variation in its array of sodium iodide detectors. Although the signal was small, it varied just as predicted.

But the original DAMA experiment suffered from much more background noise than other competing experiments - which have not detected dark matter. So physicists assumed that something else must be causing the seasonal variation in the DAMA detector. Perhaps the temperature of the lab was fluctuating, or the detector was picking up the decay of radioisotopes in groundwater which ebbed and flowed with the seasons. Bernabei has always stood by the DAMA result and insisted that the team checked everything they could think of.

Fast forward to today and hunting for dark matter has become extremely popular. There are now around 30 dark matter experiments around the world looking for WIMPS using crystals chilled to a few degrees above absolute zero, giant tanks of ultrapure liquid xenon and even bubble chambers. By using ultrapure materials, freezing them and shielding the detectors from cosmic rays or other radiation, these experiments simply wait for a passing WIMP to leave a signal rather than look for messy seasonal variations.

Several of them have ruled out WIMPs with the properties that DAMA claimed, most recently the COUPP experiment at Fermilab near Chicago. But the DAMA result remains a thorn in the side of dark matter hunters, which is why I think it was right to repeat the experiment using improved technology.

A physicist close to the new LIBRA collaboration says that Bernabei will announce a positive signal for dark matter. If that's true, I reckon the LIBRA result could simply spark another round of controversy, rather than silence the sceptics.

Some scientists might be horrified that I and other bloggers are spreading rumours and speculation about Bernabei's talk. But the beauty of conferences is that you can pick up on the very latest ideas as they emerge. Dark matter research is reaching fever pitch and we should all be able to share the excitement.

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Saturn's Titan: A Mirror Image of Earth Before Life Evolved?

Titans_lakes_1 The Cassini spacecraft observations of Saturn's largest moon, the orange-colored Titan, have given scientists a glimpse of what Earth might have been like before life evolved. They now believe Titan possesses many parallels to Earth, including lakes, rivers, channels, dunes, rain, snow, clouds, mountains and possibly volcanoes.

"Titan is just covered in carbon-bearing material -- it's a giant factory of organic chemicals," according to Ralph Lorenz of Johns Hopkins University Applied Physics Laboratory. "We are carbon-based life, and understanding how far along the chain of complexity towards life that chemistry can go in an environment like Titan will be important in understanding the origins of life throughout the universe."

"When we designed the original tour for the Cassini spacecraft, we really did not know what we would find, especially at Enceladus and Titan," said Dennis Matson, the JPL Cassini project scientist. "This extended tour is responding to these new discoveries and giving us a chance to look for more."

Unlike Earth, Titan's lakes, rivers and rain are composed of methane and ethane, and temperatures reach a chilly minus 180 degrees Celsius (minus 290 degrees Fahrenheit). Although Titan's dense atmosphere limits viewing the surface, Cassini's high-resolution radar coverage and imaging by the infrared spectrometer have given scientists a better look.

Titan has hundreds of times more liquid hydrocarbons than all the known oil and natural gas reserves on Earth, according to new data from NASA's Cassini spacecraft. The hydrocarbons rain from the sky, collecting in vast deposits that form lakes and dunes.

At an eye popping minus 179 degrees Celsius (minus 290 degrees Fahrenheit), Titan has a surface of liquid hydrocarbons in the form of methane and ethane with tholins believed to make up its dunes. The term "tholins," coined by Carl Sagan in 1979, describe the complex organic molecules at the heart of prebiotic chemistry.

Cassini has mapped about 20 percent of Titan's surface with radar. Several hundred lakes and seas have been observed, with each of several dozen estimated to contain more hydrocarbon liquid than Earth's oil and gas reserves. Dark dunes that run along the equator contain a volume of organics several hundred times larger than Earth's coal reserves.

Proven reserves of natural gas on Earth total 130 billion tons, enough to provide 300 times the amount of energy the entire United States uses annually for residential heating, cooling and lighting. Dozens of Titan's lakes individually have the equivalent of at least this much energy in the form of methane and ethane.

"This global estimate is based mostly on views of the lakes in the northern polar regions. We have assumed the south might be similar, but we really don't yet know how much liquid is there," said Lorenz. Cassini's radar has observed the south polar region only once, and only two small lakes were visible. Future observations of that area are planned during Cassini's proposed extended mission.

"We also know that some lakes are more than 10 meters or so deep because they appear literally pitch-black to the radar. If they were shallow we'd see the bottom, and we don't," said Lorenz.

The question of how much liquid is on the surface is an important one because methane is a strong greenhouse gas on Titan as well as on Earth, but there is much more of it on Titan. If all the observed liquid on Titan is methane, it would only last a few million years, because as methane escapes into Titan's atmosphere, it breaks down and escapes into space. If the methane were to run out, Titan could become much colder. Scientists believe that methane might be supplied to the atmosphere by venting from the interior in cryovolcanic eruptions. If so, the amount of methane, and the temperature on Titan, may have fluctuated dramatically in Titan's past.

Cassini's mission originally had been scheduled to end in July 2008. A newly-announced two-year extension will include 60 additional orbits of Saturn and more flybys of its exotic moons. These will include 26 flybys of Titan, seven of Enceladus, and one each of Dione, Rhea and Helene. The extension also includes studies of Saturn's rings, its complex magnetosphere, and the planet itself.

"This extension is not only exciting for the science community, but for the world to continue to share in unlocking Saturn's secrets," said Jim Green, director, Planetary Science Division, NASA Headquarters, Washington. "New discoveries are the hallmarks of its success, along with the breathtaking images beamed back to Earth that are simply mesmerizing."

Based on findings from Cassini, scientists think liquid water may be just beneath the surface of Saturn's moon Enceladus. The small moon, only one-tenth the size of Titan and one-seventh the size of Earth's moon, is one of the highest-priority targets for the extended mission.

Cassini discovered geysers of water-ice jetting from the Enceladus surface. The geysers, which shoot out at a distance three times the diameter of Enceladus, feed particles into Saturn's most expansive ring. In the extended mission, the spacecraft may come as close as 25 kilometers (15 miles) from the moon's surface.

Other activities for Cassini scientists will include monitoring seasons on Titan and Saturn, observing unique ring events, such as the 2009 equinox when the sun will be in the plane of the rings, and exploring new places within Saturn's magnetosphere.

Cassini has returned a daily stream of data from Saturn's system for almost four years. Its travel scrapbook includes nearly 140,000 images, and information gathered during 62 revolutions around Saturn, 43 flybys of Titan and 12 close flybys of the icy moons.

More than 10 years after launch and almost four years after entering into orbit around Saturn, Cassini is a healthy and robust spacecraft. Three of its science instruments have minor ailments, but the impact on science-gathering is minimal. The spacecraft will have enough propellant left after the extended mission to potentially allow a third phase of operations. Data from the extended mission could lay the groundwork for possible new missions to Titan and Enceladus.

Cassini launched Oct. 15, 1997, from Cape Canaveral, Fla., on a seven-year journey to Saturn, traversing 3.5 billion kilometers (2.2 billion miles).

Posted by Casey Kazan, adapted from materials provided by NASA.

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Nasa extends Saturn probe mission

Artist's impression of Cassini spacecraft during Enceladus flyby (Nasa/JPL/SSI)
The extended mission will include further flybys of Saturn's moons

The US space agency (Nasa) has extended the international Cassini-Huygens mission by two years.

The unmanned Cassini-Huygens spacecraft entered orbit around Saturn in 2004 on a mission that was supposed to come to an end in July this year.

The two-year mission extension will encompass some 60 extra orbits of Saturn and more flybys of its moons.

These will include 26 flybys of Titan - its biggest moon - seven of Enceladus, and one each of Dione, Rhea and Helene.

Bob Mitchell, programme manager for Cassini-Huygens at Nasa's Jet Propulsion Laboratory (JPL), in California, commented: "The spacecraft is performing exceptionally well and the team is highly motivated, so we're excited at the prospect of another two years."

Dr Rosaly Lopes, also from JPL, told BBC News: "We're very pleased. We were expecting Nasa to extend Cassini for another two years, we had been told to plan for it, so we had already done a lot of the planning and decided what the tour was going to look like.

"But it's nice to actually have the news out, because you never know up until the point when they sign on the dotted line."

'Earth-like' world

The mission has made stunning discoveries about the Saturn system since it arrived at the ringed planet four years ago.

Its studies of the largest moon, Titan, have provided a glimpse of what Earth might have been like before life evolved. Conditions on the moon are believed to resemble those on our own planet 4.6 billion years ago.

The European Huygens probe was built to explore Titan's atmosphere, weather and its surface. Huygens piggybacked on Cassini, separating from the orbiter in December 2004 to begin its journey to the orange-tinged satellite.

In January 2005, Huygens parachuted through Titan's thick haze and touched down on the surface, and returned data for several hours before succumbing to the cold.

Saturn and its rings (Nasa/JPL/SSI)
The mission has revealed new targets for future exploration

Cassini's observations of the moon from space have revealed Earth-like features such as lakes, rivers, channels, dunes, rain, snow, clouds, mountains and possibly volcanoes.

Unlike Earth, Titan's lakes, rivers and rain are composed of methane and ethane, and temperatures reach a chilling -180C (-290F).

Although Titan's dense atmosphere limits viewing the surface, Cassini's high-resolution radar coverage and imaging by the infrared spectrometer have given scientists a better look.

"We're going to have a lot more Titan flybys," Dr Lopes said of the extended mission.

"These flybys are highly contested because everyone wants to look at Titan with the different instruments, and so the more flybys the better. With radar, it's going to allow us to map much more of the surface."

New tricks

The Enceladus moon, regarded as "just another ball of ice" until Cassini arrived, has now become a high priority for further exploration.

The spacecraft found evidence for geysers of water-ice jetting from the surface.

These geysers, which shoot out at a distance three times the diameter of the moon itself, feed particles into Saturn's outermost ring.

Artist's impression of Huygens probe (Esa)
Huygens is shown on Titan's surface in this artist's impression

In the extended mission, Cassini could come as close as 24km (15 miles) from the moon's surface.

Other activities for Cassini scientists during the extended mission will include monitoring seasons on Titan and Saturn, observing unique ring events - such as the 2009 equinox when the Sun will be in the plane of the rings - and exploring new places within Saturn's magnetic "envelope" - or magnetosphere.

Jim Green, director of Nasa's planetary science division in Washington DC, said the extended mission would allow the science community and the public to continue to share in "unlocking Saturn's secrets".

Nasa said three of the science instruments on Cassini were suffering from minor ailments, but the impact on data gathering was minimal.

The spacecraft will have enough propellant left after the extended mission to potentially allow a third phase of operations.

Science from the extended mission could lay the groundwork for possible new robotic missions to Titan or Enceladus, which are under study by Nasa and the European Space Agency (Esa).

Cassini-Huygens was launched on 15 October 1997, from Cape Canaveral, Florida, taking seven years to make the 3.5 billion km (2.2 billion miles) journey to Saturn.

The Cassini-Huygens mission is a cooperative project between Nasa, Esa and the Italian Space Agency (Asi).

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Pioneer spacecraft mystery may be laid to rest

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What is making NASA's twin Pioneer spacecraft mysteriously drift off course, apparently defying the laws of physics? A rigorous new analysis suggests ordinary heat emission can at least partly explain the wayward probes' strange trajectories.

Pioneer 10 and 11 were launched in the early 1970s and explored the outer solar system. But in 1980, mission scientists noticed that the spacecraft have unexpectedly drifted off course.

Both spacecraft have been pulled a little harder than expected towards the sun, and since their launch, they have drifted off course by hundreds of thousands of kilometres.

Exotic reasons?

Possible explanations for this so-called Pioneer anomaly have included technical problems with the software tracking the spacecraft as well as more exotic reasons, such as a breakdown in our understanding of gravity.

But now the verdict is that a substantial part of the anomaly, at least for Pioneer 11, is due to thermal effects, according to Slava Turyshev of NASA's Jet Propulsion Laboratory in Pasadena, California, US. He described his findings on 13 April at a meeting of the American Physical Society in St Louis, Missouri.

For the past two years, Turyshev and his colleagues have analysed telemetry and tracking data for the spacecraft on hundreds of reels of old magnetic tapes and floppy discs to reconstruct the mission in more detail than ever before. They have also examined archived design documents and talked to mission engineers. "It’s like CSI," says Turyshev.

Uneven heat

The wealth of data has allowed them to build detailed computer models of Pioneer 11, including a thermal model which shows how heat is distributed over the spacecraft. This has revealed that Pioneer 11 gives off heat in certain directions more than others. The uneven heat emission is enough to nudge the spacecraft off course, accounting for 28% to 36% of the anomaly detected when Pioneer 11 was 3750 million kilometres, or 25 times the Earth-sun distance, away from us.

Turyshev suspects that the optical properties of the spacecraft's exterior may have changed during the mission, possibly degrading due to dust hitting the craft and ultraviolet radiation from the sun.

That might make the spacecraft radiate more heat than expected. However, it's not clear yet whether these changes to the spacecraft's exterior could account entirely for its unexpected trajectory.

Turyshev's team is now planning to test the dust theory and he expects to have results in five months' time.

Sputnik’s Legacy - Learn more about humanity’s first 50 years in space in our special report.

German schoolboy, 13, corrects NASA's asteroid figures: paper

This artists rendition released by NASA shows an asteroid belt. A 13-year-old German schoolboy corrected NASAs estimates on the chances of an asteroid colliding with Earth a German newspaper reported Tuesday after spotting the boffins had miscalculat ...
This artist's rendition released by NASA shows an asteroid belt. A 13-year-old German schoolboy corrected NASA's estimates on the chances of an asteroid colliding with Earth, a German newspaper reported Tuesday, after spotting the boffins had miscalculated.

A 13-year-old German schoolboy corrected NASA's estimates on the chances of an asteroid colliding with Earth, a German newspaper reported Tuesday, after spotting the boffins had miscalculated.

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Nico Marquardt used telescopic findings from the Institute of Astrophysics in Potsdam (AIP) to calculate that there was a 1 in 450 chance that the Apophis asteroid will collide with Earth, the Potsdamer Neuerster Nachrichten reported.

NASA had previously estimated the chances at only 1 in 45,000 but told its sister organisation, the European Space Agency (ESA), that the young whizzkid had got it right.

The schoolboy took into consideration the risk of Apophis running into one or more of the 40,000 satellites orbiting Earth during its path close to the planet on April 13 2029.

Those satellites travel at 3.07 kilometres a second (1.9 miles), at up to 35,880 kilometres above earth -- and the Apophis asteroid will pass by earth at a distance of 32,500 kilometres.

If the asteroid strikes a satellite in 2029, that will change its trajectory making it hit earth on its next orbit in 2036.

Both NASA and Marquardt agree that if the asteroid does collide with earth, it will create a ball of iron and iridium 320 metres (1049 feet) wide and weighing 200 billion tonnes, which will crash into the Atlantic Ocean.

The shockwaves from that would create huge tsunami waves, destroying both coastlines and inland areas, whilst creating a thick cloud of dust that would darken the skies indefinitely.

The 13-year old made his discovery as part of a regional science competition for which he submitted a project entitled: "Apophis -- The Killer Astroid."

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Six Things in Expelled That Ben Stein Doesn't Want You to Know...

DEBATING DARWIN: Ben Stein stands in front of a statue of Darwin at The Natural History Museum in London.
Photo by Kelly Engstrom

In the film Expelled: No Intelligence Allowed, narrator Ben Stein poses as a "rebel" willing to stand up to the scientific establishment in defense of freedom and honest, open discussion of controversial ideas like intelligent design (ID). But Expelled has some problems of its own with honest, open presentations of the facts about evolution, ID—and with its own agenda. Here are a few examples—add your own with a comment, and we may add it to another draft of this story. For our complete coverage, see "Expelled: No Intelligence AllowedScientific American's Take.

1) Expelled quotes Charles Darwin selectively to connect his ideas to eugenics and the Holocaust.
When the film is building its case that Darwin and the theory of evolution bear some responsibility for the Holocaust, Ben Stein's narration quotes from Darwin's The Descent of Man thusly:

With savages, the weak in body or mind are soon eliminated. We civilized men, on the other hand, do our utmost to check the process of elimination. We build asylums for the imbecile, the maimed and the sick. Thus the weak members of civilized societies propagate their kind. No one who has attended to the breeding of domestic animals will doubt that this must be highly injurious to the race of man. Hardly anyone is so ignorant as to allow his worst animals to breed.

This is how the original passage in The Descent of Man reads (unquoted sections emphasized in italics):

With savages, the weak in body or mind are soon eliminated; and those that survive commonly exhibit a vigorous state of health. We civilized men, on the other hand, do our utmost to check the process of elimination. We build asylums for the imbecile, the maimed and the sick; we institute poor-laws; and our medical men exert their utmost skill to save the life of every one to the last moment. There is reason to believe that vaccination has preserved thousands, who from a weak constitution would formerly have succumbed to small-pox. Thus the weak members of civilized societies propagate their kind. No one who has attended to the breeding of domestic animals will doubt that this must be highly injurious to the race of man. It is surprising how soon a want of care, or care wrongly directed, leads to the degeneration of a domestic race; but excepting in the case of man himself, hardly anyone is so ignorant as to allow his worst animals to breed.

The producers of the film did not mention the very next sentences in the book (emphasis added in italics):

The aid which we feel impelled to give to the helpless is mainly an incidental result of the instinct of sympathy, which was originally acquired as part of the social instincts, but subsequently rendered, in the manner previously indicated, more tender and more widely diffused. Nor could we check our sympathy, even at the urging of hard reason, without deterioration in the noblest part of our nature. The surgeon may harden himself whilst performing an operation, for he knows that he is acting for the good of his patient; but if we were intentionally to neglect the weak and helpless, it could only be for a contingent benefit, with an overwhelming present evil.

Darwin explicitly rejected the idea of eliminating the "weak" as dehumanizing and evil. Those words falsify Expelled's argument. The filmmakers had to be aware of the full Darwin passage, but they chose to quote only the sections that suited their purposes.

2) Ben Stein's speech to a crowded auditorium in the film was a setup.
Viewers of Expelled might think that Ben Stein has been giving speeches on college campuses and at other public venues in support of ID and against "big science." But if he has, the producers did not include one. The speech shown at the beginning and end was staged solely for the sake of the movie. Michael Shermer learned as much by speaking to officials at Pepperdine University, where those scenes were filmed. Only a few of the audience members were students; most were extras brought in by the producers. Judge the ovation Ben Stein receives accordingly.

3) Scientists in the film thought they were being interviewed for a different movie.
As Richard Dawkins, PZ Myers, Eugenie Scott, Michael Shermer and other proponents of evolution appearing in Expelled have publicly remarked, the producers first arranged to interview them for a film that was to be called Crossroads, which was allegedly a documentary on "the intersection of science and religion." They were subsequently surprised to learn that they were appearing in Expelled, which "exposes the widespread persecution of scientists and educators who are pursuing legitimate, opposing scientific views to the reigning orthodoxy," to quote from the film's press kit.

When exactly did Crossroads become Expelled? The producers have said that the shift in the film's title and message occurred after the interviews with the scientists, as the accumulating evidence gradually persuaded them that ID believers were oppressed. Yet as blogger Wesley Elsberry discovered when he searched domain registrations, the producers registered the URL "" on March 1, 2007—more than a month (and in some cases, several months) before the scientists were interviewed. The producers never registered the URL "". Those facts raise doubt that Crossroads was still the working title for the movie when the scientists were interviewed.

4) The ID-sympathetic researcher whom the film paints as having lost his job at the Smithsonian Institution was never an employee there.
One section of Expelled relates the case of Richard Sternberg, who was a researcher at the Smithsonian Institution's National Museum of Natural History and editor of the journal Proceedings of the Biological Society of Washington. According to the film, after Sternberg approved the publication of a pro-ID paper by Stephen C. Meyer of the Discovery Institute, he lost his editorship, was demoted at the Smithsonian, was moved to a more remote office, and suffered other professional setbacks. The film mentions a 2006 House Committee on Oversight and Government Reform report prepared for Rep. Mark Souder (R–Ind.), "Intolerance and the Politicization of Science at the Smithsonian," that denounced Sternberg's mistreatment.

This selective retelling of the Sternberg affair omits details that are awkward for the movie's case, however. Sternberg was never an employee of the Smithsonian: his term as a research associate always had a limited duration, and when it ended he was offered a new position as a research collaborator. As editor, Sternberg's decision to "peer-review" and approve Meyer's paper by himself was highly questionable on several grounds, which was why the scientific society that published the journal later repudiated it. Sternberg had always been planning to step down as the journal's editor—the issue in which he published the paper was already scheduled to be his last.

The report prepared by Rep. Souder, who had previously expressed pro-ID views, was never officially accepted into the Congressional Record. Notwithstanding the report's conclusions, its appendix contains copies of e-mails and other documents in which Sternberg's superiors and others specifically argued against penalizing him for his ID views. (More detailed descriptions of the Sternberg case can be found on Ed Brayton's blog Dispatches from the Culture Wars and on Wikipedia.)

5) Science does not reject religious or "design-based" explanations because of dogmatic atheism.
Expelled frequently repeats that design-based explanations (not to mention religious ones) are "forbidden" by "big science." It never explains why, however. Evolution and the rest of "big science" are just described as having an atheistic preference.

Actually, science avoids design explanations for natural phenomena out of logical necessity. The scientific method involves rigorously observing and experimenting on the material world. It accepts as evidence only what can be measured or otherwise empirically validated (a requirement called methodological naturalism). That requirement prevents scientific theories from becoming untestable and overcomplicated.

By those standards, design-based explanations rapidly lose their rigor without independent scientific proof that validates and defines the nature of the designer. Without it, design-based explanations rapidly become unhelpful and tautological: "This looks like it was designed, so there must be a designer; we know there is a designer because this looks designed."

A major scientific problem with proposed ID explanations for life is that their proponents cannot suggest any good way to disprove them. ID "theories" are so vague that even if specific explanations are disproved, believers can simply search for new signs of design. Consequently, investigators do not generally consider ID to be a productive or useful approach to science.

6) Many evolutionary biologists are religious and many religious people accept evolution.
Expelled includes many clips of scientists such as Richard Dawkins, Daniel Dennett, William Provine and PZ Myers who are also well known as atheists. They talk about how their knowledge of science confirms their convictions and how in some cases science led them to atheism. And indeed, surveys do indicate that atheism is more common among scientists than in the general population.

Nevertheless, the film is wrong to imply that understanding of evolution inevitably or necessarily leads to a rejection of religious belief. Francisco Ayala of the University of California, Irvine, a leading neuroscientist who used to be a Dominican priest, continues to be a devout Catholic, as does the evolutionary biologist Ken Miller of Brown University. Thousands of other biologists across the U.S. who all know evolution to be true are also still religious. Moreover, billions of other people around the world simultaneously accept evolution and keep faith with their religion. The late Pope John Paul II said that evolution was compatible with Roman Catholicism as an explanation for mankind's physical origins.

During Scientific American's post-screening conversation with Expelled associate producer Mark Mathis, we asked him why Ken Miller was not included in the film. Mathis explained that his presence would have "confused" viewers. But the reality is that showing Miller would have invalidated the film's major premise that evolutionary biologists all reject God.

Inside and outside the scientific community, people will no doubt continue to debate rationalism and religion and disagree about who has the better part of that argument. Evidence from evolution will probably remain at most a small part of that conflict, however.

Have you seen the movie? Add your own notes with a comment.

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Neanderthals speak again after 30,000 years

LONDON (Reuters) - Neanderthals have spoken out for the first time in 30,000 years, with the help of scientists who have simulated their voices using fossil evidence and a computer synthesizer.

Robert McCarthy, an anthropologist at Florida Atlantic University in Boca Raton, used new reconstructions of Neanderthal vocal tracts to work out how they would have sounded, reported on Wednesday.

The conclusion is that Neanderthals spoke, but sounded rather different to us. Specifically, the ancient humans' lacked the "quantal vowel" sounds that underlie modern speech and which provide cues that help speakers understand one another.

By modeling the sounds that a Neanderthal larynx would have made, McCarthy's team engineered the sound of a Neanderthal saying "e." (To listen to McCarthy's simulation of a Neanderthal voice, visit:

In contrast to a modern human "e," the Neanderthal version lacks a quantal hallmark, which helps a listener distinguish the word "beat" from "bit," for instance. (To listen to a simulation of the modern human voice, visit:

McCarthy, who based his reconstructions on 50,000-year-old fossils from France, aims eventually to simulate an entire Neanderthal sentence.

Neanderthals were a dead-end offshoot of the human line who inhabited Europe and parts of west and central Asia. Researchers believe they survived in Europe until the arrival of modern humans about 30,000 years ago.

(Reporting by Ben Hirschler; Editing by Matthew Jones)

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Edward Lorenz, father of chaos theory, dead at 90

WASHINGTON (Reuters) - Edward Lorenz, the father of chaos theory, who showed how small actions could lead to major changes in what became known as the "butterfly effect," died of cancer on Wednesday at the age of 90, the Massachusetts Institute of Technology said.

Lorenz, a meteorologist, figured out in the 1960s that small differences in a dynamic system such as the atmosphere could set off enormous changes. In 1972 he presented a study entitled "Predictability: Does the Flap of a Butterfly's Wings in Brazil Set Off a Tornado in Texas?"

Born in 1917 in West Hartford, Connecticut, Lorenz earned degrees in mathematics from Dartmouth College in 1938, from Harvard University in 1940, and degrees in meteorology from MIT in 1943 and 1948.

While serving as a weather forecaster for the U.S. Army Air Corps in World War Two, he decided to study meteorology.

"As a boy I was always interested in doing things with numbers, and was also fascinated by changes in the weather," Lorenz wrote in an autobiography.

"By showing that certain deterministic systems have formal predictability limits, Lorenz put the last nail in the coffin of the Cartesian universe and fomented what some have called the third scientific revolution of the 20th century, following on the heels of relativity and quantum physics," said Kerry Emanuel, professor of atmospheric science at MIT.

"He was also a perfect gentleman, and through his intelligence, integrity and humility set a very high standard for his and succeeding generations," Emanuel added in a statement.

In 1991, Lorenz won the Kyoto Prize for basic sciences in the field of earth and planetary sciences.

The prize committee said Lorenz "made his boldest scientific achievement in discovering 'deterministic chaos,' a principle which has profoundly influenced a wide range of basic sciences and brought about one of the most dramatic changes in mankind's view of nature since Sir Isaac Newton."

Lorenz, who enjoyed hiking and cross-country skiing, stayed active until two weeks before his death at home in Cambridge, Massachusetts, his family said. He is survived by three children and four grandchildren.

(Reporting by Maggie Fox; Editing by Eric Walsh)

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Up and Then Down

The longest smoke break of Nicholas White’s life began at around eleven o’clock on a Friday night in October, 1999. White, a thirty-four-year-old production manager at Business Week, working late on a special supplement, had just watched the Braves beat the Mets on a television in the office pantry. Now he wanted a cigarette. He told a colleague he’d be right back and, leaving behind his jacket, headed downstairs.

The magazine’s offices were on the forty-third floor of the McGraw-Hill Building, an unadorned tower added to Rockefeller Center in 1972. When White finished his cigarette, he returned to the lobby and, waved along by a janitor buffing the terrazzo floors, got into Car No. 30 and pressed the button marked 43. The car accelerated. It was an express elevator, with no stops below the thirty-ninth floor, and the building was deserted. But after a moment White felt a jolt. The lights went out and immediately flashed on again. And then the elevator stopped.

The control panel made a beep, and White waited a moment, expecting a voice to offer information or instructions. None came. He pressed the intercom button, but there was no response. He hit it again, and then began pacing around the elevator. After a time, he pressed the emergency button, setting off an alarm bell, mounted on the roof of the elevator car, but he could tell that its range was limited. Still, he rang it a few more times and eventually pulled the button out, so that the alarm was continuous. Some time passed, although he was not sure how much, because he had no watch or cell phone. He occupied himself with thoughts of remaining calm and decided that he’d better not do anything drastic, because, whatever the malfunction, he thought it unwise to jostle the car, and because he wanted to be (as he thought, chuckling to himself) a model trapped employee. He hoped, once someone came to get him, to appear calm and collected. He did not want to be scolded for endangering himself or harming company property. Nor did he want to be caught smoking, should the doors suddenly open, so he didn’t touch his cigarettes. He still had three, plus two Rolaids, which he worried might dehydrate him, so he left them alone. As the emergency bell rang and rang, he began to fear that it might somehow—electricity? friction? heat?—start a fire. Recently, there had been a small fire in the building, rendering the elevators unusable. The Business Week staff had walked down forty-three stories. He also began hearing unlikely oscillations in the ringing: aural hallucinations. Before long, he began to contemplate death.

Ask a vertical-transportation-industry professional to recall an episode of an elevator in free fall—the cab plummeting in the shaftway, frayed rope ends trailing in the dark—and he will say that he can think of only one. That would be the Empire State Building incident of 1945, in which a B-25 bomber pilot made a wrong turn in the fog and crashed into the seventy-ninth floor, snapping the hoist and safety cables of two elevators. Both of them plunged to the bottom of the shaft. One of them fell from the seventy-fifth floor with a woman aboard—an elevator operator. (The operator of the other one had stepped out for a cigarette.) By the time the car crashed into the buffer in the pit (a hydraulic truncheon designed to be a cushion of last resort), a thousand feet of cable had piled up beneath it, serving as a kind of spring. A pillow of air pressure, as the speeding car compressed the air in the shaft, may have helped ease the impact as well. Still, the landing was not soft. The car’s walls buckled, and steel debris tore up through the floor. It was the woman’s good fortune to be cowering in a corner when the car hit. She was severely injured but alive.

Traction elevators—the ones hanging from ropes, as opposed to dumbwaiters, or mining elevators, or those lifted by hydraulic pumps—are typically borne aloft by six or eight hoist cables, each of which, according to the national elevator-safety code (and the code determines all), is capable on its own of supporting the full load of the elevator plus twenty-five per cent more weight. Another line, the governor cable, is connected to a device that detects if the elevator car is descending at a rate twenty-five per cent faster than its maximum designed speed. If that happens, the device trips the safeties, bronze shoes that run along vertical rails in the shaft. These brakes are designed to stop the car quickly, but not so abruptly as to cause injury. They work. This is why free falling, at least, is so rare.

Still, elevator lore has its share of horrors: strandings, manglings, fires, drownings, decapitations. An estimated two hundred people were killed in elevators at the World Trade Center on September 11, 2001—some probably in free-fall plunges, but many by fire, smoke, or entrapment and subsequent structural collapse. The elevator industry likes to insist that, short of airplane rammings, most accidents are the result of human error, of passengers or workers doing things they should not. Trying to run in through closing doors is asking for trouble; so is climbing up into an elevator car, or down out of one, when it is stuck between floors, or letting a piece of equipment get lodged in the brake, as happened to a service elevator at 5 Times Square, in Manhattan, four years ago, causing the counterweight to plummet (the counterweight, which aids an elevator’s rise and slows its descent, is typically forty per cent heavier than an empty car) and the elevator to shoot up, at sixty miles an hour, into the beams at the top of the shaft, killing the attendant inside. Loading up an empty elevator car with discarded Christmas trees, pressing the button for the top floor, then throwing in a match, so that by the time the car reaches the top it is ablaze with heat so intense that the alloy (called “babbitt”) connecting the cables to the car melts, and the car, a fireball now, plunges into the pit: this practice, apparently popular in New York City housing projects, is inadvisable.

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