4-D Printing Means Building Things That Build Themselves

H. Jerry Qi, associate professor of mechanical engineering at Colorado University, holds simple models printed using polymers that have "shape memory." The flat piece on the left can reshape itself into a box with the application of heat.

Glenn J. Asakawa/University of Colorado H. Jerry Qi, associate professor of mechanical engineering at Colorado University, holds simple models printed using polymers that have "shape memory." The flat piece on the left can reshape itself into a box with the application of heat.

Glenn J. Asakawa/University of Colorado

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The advent of 3-D printing brought on a number of innovations worthy of news coverage. Printers have created prosthetic hands, action figures, food, even blood vessels, simply by depositing layer after layer of different kinds of ink.

Now a handful of engineers around the world are trying to push the boundaries one step further — by printing objects that can build themselves.

It's called 4-D printing, and the fourth dimension in this case is time. Here's how it works: A 3-D printer with extremely high resolution uses materials that can respond to outside stimuli, like heat or light, as ink. The resulting structure can change, move or even assemble itself after it's been printed.

One team of researchers led by H. Jerry Qi, an associate professor at the University of Colorado Boulder, is using heat and mechanical pressure to transform flat objects into three-dimensional structures. They printed an unfolded box with glassy polymer fibers — a composite material that has "shape memory behavior" — along the folds. They heated it, pulled on the sides and cooled it, and the flat structure responded by folding into a box.

Another team — a collaboration between University of Pittsburgh, University of Illinois at Urbana-Champaign and Harvard University — recently garnered an $855,000 grant from the U.S. Army Research Office to explore how adaptive materials can respond to stimuli like light or temperature.

It's not unlike how the body works, says Professor Anna Balazs at Pittsburgh. It responds continuously, in complex ways, to the world around it.

"The idea is the use the full arsenal of 3-D printing," she says. "It allows complicated objects to morph their structure. You're not just going to print one object, one use."

One potential application? You could make a fabric that changes color in response to light or changes permeability in response to temperature. It could provide a protective layer in the presence of toxic chemicals — that would be particularly useful for soldiers in combat.

Another application, Qi says, is useful in places where traditional manufacturing is impractical — like in space. You could make an instrument that's small and flat and expand it aboard a spacecraft.

You can't make these products at home, at least not yet. The printers are still being tested by individual academic labs, along with the responsive inks. Balazs says integrating the two for reliable commercial use will probably take another three to five years.

Until then, some researchers will be trying, as always, to take technology to the next level.

Skylar Tibbits, who researches self-assembly at MIT, is looking at how construction processes might be simplified by using materials that respond to shaking — or even to sound. His vision is lofty, but he has arguably the most imaginative ideas of 4-D printing research so far.

"Manufacturing could be more like growing," he said in a BBC interview in July. "Maybe the construction sites in the future, we play Beethoven and structures build themselves."

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Another Election?! Relax, This One's To Name A Baby Panda

You can help select a name for the National Zoo's new panda cub.

Abby Wood/Smithsonian's National Zoo You can help select a name for the National Zoo's new panda cub.

Abby Wood/Smithsonian's National Zoo

Fresh off Tuesday's election, another is just around the corner: The National Zoo wants you to help name its new panda cub by casting a vote at Smithsonian.com.

You can vote online (no photo identification required and the balloting continues until Nov. 22).

At NPR, we always strive to ensure that our audience is informed of the candidates — even when they're names for pandas.

The Smithsonian's National Zoo in Washington, D.C., has put forth five possible names for the female cub born this summer — all Chinese names, of course — so we talked to NPR's Beijing correspondent, Anthony Kuhn, for some help in understanding them:

— Bao Bao (??) (bow-BOW) — Precious, treasure. "Bao means treasure and when you say 'Bao Bao,' it usually means baby, as in 'Bao Bao's diapers need changing [or] Bao Bao is hungry,' " Anthony says.

— Ling Hua (??) (ling-HWA) — Darling, delicate flower. "Ling is actually the sound you make when you plink a piece of jade," says Anthony. It also happens to be the name of a wildly popular Chinese pop singer.

— Long Yun (??) (long-YOON) — Long is the Chinese symbol for dragon and "yun" is a pleasing sound, something that rhymes. It translates roughly as "the sound of the dragon," Anthony says, which is meant to be "auspicious, not scary."

— Mulan (??) (moo-LAHN) — Legendary young woman, a smart and brave Chinese warrior from the fifth century — "the legendary woman warrior who dressed as a man to join the army," Anthony says. Also, the name for the magnolia flower in China and the United States.

— Zhen Bao (??) (jen-BAO) — Treasure, valuable. "Zhen Bao is close to Bao Bao," Anthony says. "Zhen also means something precious. So, they are both very close, but it doesn't have the same meaning as baby."

The official naming ceremony at the National Zoo will take place Dec. 1 — when the cub turns 100 days old.

And, if you need a panda fix before then, here's a behind-the-scenes video shot in 2008 by NPR's David Gilkey at the Chengdu Research Base of Giant Panda Breeding.

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As Mirrors Beam Light To Town, Norwegians Share Patch Of Sun

Mirrors erected on a Norwegian mountainside reflect sunlight onto the town below, which is cut off from direct sunlight for about six months a year.

NTB Scanpix/Reuters/Landov Mirrors erected on a Norwegian mountainside reflect sunlight onto the town below, which is cut off from direct sunlight for about six months a year.

NTB Scanpix/Reuters/Landov

The small town of Rjukan has long had to make do without sunlight during the cold Norwegian winters.

But that changed Wednesday, when the town debuted a system of high-tech mirrors to reflect sunlight from neighboring peaks into the valley below.

Rjukan, originally founded 100 years ago as an industrial outpost for the energy company Norsk Hydro, is nestled between several mountains and does not receive direct sunlight from late September to mid-March — nearly six months out of the year.

"Of course, we notice it when the sun is shining," says Karin Ro, who works for the town's tourism office. "We see the sky is blue, and then we see that down in the valley it's darker — it's like on a cloudy day."

People gather in the central square of Rjukan, Norway, on Wednesday to bask in the sun reflected by mirrors on a nearby mountainside.

NTB Scanpix/Reuters/Landov People gather in the central square of Rjukan, Norway, on Wednesday to bask in the sun reflected by mirrors on a nearby mountainside.

NTB Scanpix/Reuters/Landov

Wednesday, residents of Rjukan received their first dose of winter sun down in the valley: A series of reflective panels on a nearby mountainside were put to use for the very first time.

The mirrors are controlled by a computer that directs them to shift along with the sun throughout the day (and to pivot closed during windy weather). They reflect a concentrated beam of light onto the town's central square, creating an elliptical patch of sunlight roughly 600 square meters. When the light appeared, Rjukan residents flocked together.

"People have been sitting there and standing there and taking pictures of each other," Ro tells NPR's Arun Rath. "The town square was totally full. We are not that big of a town, so I think almost all the people in the town were on the town square."

The 3,500 residents cannot all bask in the sun at the same time. Nevertheless, Ro says, the new light supplied by these mirrors feels like more than enough for the town's sun-starved residents.

"It's not very big," she says, "but it is enough when we are sharing."

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Childhood Maltreatment Can Leave Scars In The Brain

Girls are particularly vulnerable to brain changes caused by stress or trauma, researchers say.

Allen Johnson/iStockphoto.com

Maltreatment during childhood can lead to long-term changes in brain circuits that process fear, researchers say. This could help explain why children who suffer abuse are much more likely than others to develop problems like anxiety and depression later on.

Brain scans of teenagers revealed weaker connections between the prefrontal cortex and the hippocampus in both boys and girls who had been maltreated as children, a team from the University of Wisconsin reports in the Proceedings of the National Academy of Sciences. Girls who had been maltreated also had relatively weak connections between the prefrontal cortex the amygdala.

Those weaker connections "actually mediated or led to the development of anxiety and depressive symptoms by late adolescence," says Ryan Herringa, a psychiatrist at the University of Wisconsin and one of the study's authors.

Maltreatment can be physical or emotional, and it ranges from mild to severe. So the researchers asked a group of 64 fairly typical 18-year-olds to answer a questionnaire designed to assess childhood trauma. The teens are part of a larger study that has been tracking children's social and emotional development in more than 500 families since 1994.

The participants were asked how strongly they agreed or disagreed with statements like, "When I was growing up I didn't have enough to eat," or "My parents were too drunk or high to take care of the family," or "Somebody in my family hit me so hard that it left me with bruises or marks."

There were also statements about emotional and sexual abuse. The responses indicated that some had been maltreated in childhood while others hadn't.

All of the participants had their brains scanned using a special type of MRI to measure the strength of connections among three areas of the brain involved in processing fear.

One area is the prefrontal cortex, which orchestrates our thoughts and actions, Herringa says. Another is the amygdala, which is "the brain's emotion and fear center," he says, and triggers the "fight or flight" response when we encounter something scary.

Herringa says messages from the amygdala to the prefrontal cortex are often balanced by input from a third area, the hippocampus, which helps decide whether something is truly dangerous. "So, for example, if you're at home watching a scary movie at night, the hippocampus can tell the prefrontal cortex that you're at home, this is just a movie, that's no reason to go into a full fight or flight response or freak out," Herringa says.

At least that's what usually happens when there's a strong connection between the hippocampus and prefrontal cortex, and the fear circuitry is working correctly.

But Herringa says brain scans showed that in adolescents who had been maltreated as children, the connection with the hippocampus was relatively weak. He says in girls who had been maltreated, the connection with the amygdala was weak, too.

That suggests the fear circuitry wasn't working the way it should, Herringa says. The result seems to explain something he sees in many young patients with anxiety and depression and a history of maltreatment. "These kids seem to be afraid everywhere," he says. "It's like they've lost the ability to put a contextual limit on when they're going to be afraid and when they're not."

The finding that girls have weaker connections to two areas of the brain, not just one, could help explain why they seem to be more sensitive than boys to maltreatment, Herringa says.

The results of the new study are important because they suggest better ways to diagnose and treat mental problems related to maltreatment, says Greg Siegle, a psychologist at the University of Pittsburgh.

"Maltreatment is a disorder where often people are not even aware of the extent of their symptoms," Siegle says. So having an objective test would be "a significant advance," he says.

The study also shows that brain researchers are making some progress in their quest to make mental health care more like physical health care, where objective tests confirm a diagnosis and measure the effectiveness of treatment, Siegle says.

"In psychiatry, in psychology, we very rarely have those tests because we just don't know the biological and brain mechanisms," he says. "This study is starting to get at what mechanisms we should be looking at."

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Forget Barley And Hops: Craft Brewers Want A Taste Of Place

The brewers at Scratch Brewing Company add wild plants like spicebush, goldenseal, wild ginger, chanterelles and wild rose root to their beer to give it the flavor of the Illinois woods.

Aaron Kleidon/Scratch Brewing Company The brewers at Scratch Brewing Company add wild plants like spicebush, goldenseal, wild ginger, chanterelles and wild rose root to their beer to give it the flavor of the Illinois woods.

Aaron Kleidon/Scratch Brewing Company

Last week, Aaron Kleidon went for a walk in the Illinois woods and returned with a bag of lotus seeds. The seeds were bound not for his dinner plate, but for his pint glass.

In a few months, Kleidon will have lotus-flavored beer at the small brewpub Scratch Brewing Company, which he owns with two friends in Ava, Ill. The microbrewery specializes in beers with seeds, leaves, roots, fruits and fungi foraged from a nearby wooded property. The brewers have even made a saison from chanterelle mushrooms.

Why, you may ask, would anyone want to add strange seeds and mushrooms to their beer? The answer is to create a taste of place. It's a concept long recognized by chefs and winemakers, who call it terroir, but is mostly absent from the craft of brewing.

This approach challenges the placelessness of mainstream brewers, who mostly use the same ingredients grown in the same places — barley from the Great Plains and hops from the Pacific Northwest.

"Beer should have a connection with the landscape," says Portland-based beer lover Eric Steen. In 2011, Steen started a program called Beers Made by Walking that invites brewers to go hiking with an eye out for trail-side plants to use in their beers. Steen's beer walks have involved such major breweries as Deschutes and New Belgium, and have resulted in oddities like a sour chokecherry beer, a sage-juniper IPA and a blonde ale brewed with stinging nettles and salmonberries.

Across the country, in backwoods and backyards, there are others searching for ingredients to flavor their beer. This summer, brewers around Washington, D.C., held a tasting event called Foraged Cask, which showcased beers made with unusual additions like mint, mulberries and lavender. And for several years, Chris Haas, head brewer at Desert Edge Brewery in Salt Lake City, has trekked into the local mountains late each summer to collect wild-growing hops.

At Uncommon Brewers in Santa Cruz, Calif., owner Alec Stefansky brews a red ale using maple-scented candy cap mushrooms. Stefansky, who has also experimented with fragrant redwood branches, says using wild, local ingredients in his beer is a way "to make flavors that are uniquely Northern Californian."

For his candy cap beer — called Rubidus Red, after the candy cap's Latin name — Stefansky collects the mushrooms himself each fall and winter. He says that the maple syrup aroma of dried candy caps is so potent that a single cup will do for seven barrels of the beer. What's more, if a person drinks just 2 or 3 pints of Rubidus Red, he or she will begin to smell deliciously like the fungus, according to Stefansky.

"You'll wake up smelling like breakfast," he says.

Imprinting beer with the flavor and scent of the South is a focus at Fullsteam Brewery, in Durham, N.C., founder Sean Lilly Wilson tells The Salt. The brewery features both wild ingredients and those grown on local farms — like hickory-smoked barley, sweet potatoes, local corn grits, figs from neighborhood trees, pawpaw fruits and wild American persimmons.

Brewing with foraged edibles may seem like another eccentric step forward by the ever-innovating craft beer industry, but Steen at Beers Made by Walking says it is actually a step backward.

"Historically, there were all sorts of herbs with flavor and medicinal qualities used in beer," he explains. "So, this is nothing new or special. It's really quite an old tradition."

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Galaxy Quest: Just How Many Earth-Like Planets Are Out There?

This is an artist's illustration of Kepler-62f, a planet in the "habitable zone" of a star that is slightly smaller and cooler than ours. Kepler-62f is roughly 40 percent larger than Earth.

NASA/JPL-Caltech/T. Pyle

A team of planet hunters estimates that about 22 percent of the sun-like stars in our galaxy may have planets about the size of Earth that are bathed in similar amounts of sunlight — and potentially habitable.

That's the conclusion of a new analysis of observations taken by NASA's Kepler Space Telescope, which was launched in 2009 to hunt for potentially habitable Earth-like planets around other stars.

Kepler's goal was to find out if planets like Earth were cosmic rarities or a common occurrence. The telescope continually monitored the brightness of more than 145,000 stars, watching for telltale dips in brightness that might indicate a planet was passing between the star and the telescope.

At a conference to discuss Kepler findings this week, scientists who have combed through the first three years of data say that so far, they've detected indications of 3,538 possible planets, of all different sizes.

Of those planets, 104 are in the so-called habitable zone, where temperatures are mild enough to potentially allow life. Of those, "we're finding about 24 planets that are actually less than twice the size of the Earth," says William Borucki, the principal investigator for the Kepler mission at NASA Ames Research Center. At that size, he says, you might very well expect at least some or many of them to be rocky rather than gaseous.

Earlier this year, however, a critical part of the telescope failed, cutting its work short. Scientists worry that they may not have had enough time to determine how often Earth-like planets orbit sun-like stars.

Now, Erik Petigura and Geoffrey Marcy of the University of California, Berkeley, along with Andrew Howard of the University of Hawaii, have tried to answer that question with an extrapolation that used Kepler data from 42,000 sun-like stars.

They report in the Proceedings of the National Academy of Sciences that they found 603 likely planets, including 10 that are roughly Earth-sized and receive similar amounts of sunlight.

They also checked how well their software could detect Earth twins by creating data for fake planets and seeing how many of these fake planets were picked up or missed.

"You can hope that you are finding all the planets, or you can make guesses about how many planets you are missing, but you really don't know until you subject ... your analysis to a complex and thorough battery of tests," Petigura says.

Other planet hunters have been closely examining the group's work, says Natalie Batalha, Kepler mission scientist at NASA Ames Research Center.

"This is the first time that a team has offered such a number for stars like the sun, based on a thorough detection analysis," says Batalha. "My office was crowded with people, actively talking about the details of the work. The mood was very festive, and the dialogue was very productive."

David Charbonneau of Harvard University says the researchers have "done a careful study, and the results are very interesting."

But he notes that the team did not detect a single planet that is the same size and temperature as Earth. Instead, he points out, the group found planets that are larger and hotter, and used them to calculate the prevalence of more Earth-like worlds.

"The analysis of the Kepler data is by no means finished, and with dedicated effort it may be possible to further clean out the noise and some true Earths may pop out — but for now we have to be satisfied with knowing the population of planets that are broadly Earth-like, but in truth are probably too big and too hot for life," Charbonneau told NPR via email.

Earlier this year, Charbonneau and his colleague Courtney Dressing unveiled a study showing that around 15 percent of small red dwarf stars have a roughly Earth-sized planet in their habitable zones.

Marcy says if you combine that result with this newer study looking at sun-like stars, it suggests that our Milky Way galaxy contains something like 40 billion Earth-sized planets with lukewarm temperatures. "So that's really the stunning number, I think," says Marcy.

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How Pictures Of Infant Boy's Eyes Helped Diagnose Cancer

A milky eye can be a sign of early cancer of the retina.

Courtesy of Bryan Shaw A milky eye can be a sign of early cancer of the retina.

Courtesy of Bryan Shaw

Bryan Shaw never expected to write a research paper about a rare eye cancer.

He's a chemist who works on how metals and proteins interact. But life has a funny way of interrupting the best-laid plans, and now Shaw may be on to a powerful new way to detect retinoblastoma in newborns. Such early detection could mean children with the disease would have a better chance of keeping their eyes and staying alive.

Shaw's scientific odyssey begins in May 2008, when he and his wife, Elizabeth, had a baby boy, Noah. Bryan was a postdoc at Harvard University at the time.

When Noah was 3 months old, Elizabeth noticed that sometimes when she took a flash picture of Noah with their digital camera, she would see a white reflection come back from his eyes instead of the usual red dot. She had read in a parenting magazine that this could be an early sign of retinoblastoma, so naturally as a first-time parent she assumed the worst. As husbands are wont to do, Bryan assured her she was crazy.

But on their next visit to the pediatrician, the doctor dutifully shined a penlight into Noah's eyes, since a white reflection from this simple eye exam can also detect the retinoblastoma tumor. The pediatrician didn't like what she saw, so she sent the Shaws to an ophthalmologist, who confirmed the worst: Noah had tumors in both eyes.

There followed months of chemotherapy, radiation, and ultimately surgery to remove Noah's right eye — and eventually years of checkups.

At first, Shaw says, he was too distraught to think about his son's cancer in scientific terms. But one day when Noah was 2, Bryan was in the waiting room while Noah was getting therapy, and he started thinking about the baby pictures that first revealed the tumor. He wondered if there was a way to track the disease back to the day the tumors first appeared.

He started small, but ultimately he would end up digitizing thousands of pictures he and Elizabeth had taken of Noah, searching for the first sign of leukocoria, as the white-eye condition is technically known.

"It first showed up in a picture taken when Noah was 12 days old," says Shaw. It didn't appear in all the pictures taken around that time. The tumor was small then, and the camera angle had to be just right to get the white reflection. But by 3 months there were days when nearly all the pictures showed signs of leukocoria.

Shaw is now on the faculty of Baylor University in Waco, Texas. He collaborated with the ophthalmologist who treated Noah at the Massachusetts Eye and Ear Infirmary and Noah's oncologists at Dana Farber Cancer Institute to produce a paper published in PLOS ONE.

In addition to pictures of Noah, the paper analyzes family photos from eight other children after they'd been diagnosed with retinoblastoma. The leukocoria is present in all of them.

Using the more than 7,000 pictures Bryan and Elizabeth have taken of Noah, the paper also shows that the amount of leukocoria that the digital cameras can detect increases with the size of his tumor.

Bryan is hoping to get more pictures from families with a child with retinoblastoma. He's also looking for a collaborator who could write software that would automate the process of scanning photos for leukocoria.

The disease is rare — fewer than 12 cases per million children aged 0-4. That works out to about 1 case for every 15,000 live births. Still, Bryan thinks a screening test would help with early detection of the cancer, and might save the vision of kids like Noah.

And speaking of Noah, he's a hoot. His health is good, and the cancers seem to have given up. He likes to draw and sing, and he's anything but shy. He has a prosthesis where his right eye used to be, which makes him look pretty much like any kid his age. And now he has a baby brother Samuel who, happily, doesn't share his disease.

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How To Levitate A Sandwich: 'Modernist Cuisine' Spills Photo Secrets

A previous version of this post incorrectly used the term Modern in describing the book The Photography of Modernist Cuisine.

Food porn or art? That's for you decide.

But one thing is for certain: The jumbo-sized images in The Photography of Modernist Cuisine are truly awesome.

In one, a ham and cheese sandwich levitates in midair. Then, a Weber grill gets sliced in half lengthwise to expose a pink burger cooking on another page. And blueberries and peas balloon to the size of dinner plates and melons.

The latest creation from ex-Microsoft executive Nathan Myhrvold and his team, called The Cooking Lab, is the ultimate coffee table book. It has a wingspan of more than 2 feet, weighs 12 pounds and costs $120.

Want to levitate a grilled ham and cheese in your next Instagram snapshot? The team at The Cooking Lab divulges their photo tricks in their new book.

Courtesy of The Cooking Lab Want to levitate a grilled ham and cheese in your next Instagram snapshot? The team at The Cooking Lab divulges their photo tricks in their new book.

Courtesy of The Cooking Lab Look to the light: In restaurants, find a big window with diffuse, indirect lighting, Nathan Mryhold recommends. "If you have to use flash, use a napkin or menu to bounce the light off it and make it diffuse."Stand up: The angle at which we usually view dinner doesn't produce the best photographs. For food that's flat and wide, shoot the dish from right above. If the food is tall and narrow, get down low and shoot it from the side.Put it on black: Food is most dramatic sitting on white or black, says The Cooking Lab's Chris Hoover. "White can create some weird reflections, but black is quite easy shoot." Place the food black Plexiglass, he says. Then pin a sheet of black velvet on the wall to adsorb the light behind it.Dip your toe into editing: You don't need to buy a sophisticated editing tool, Hoover says. "Just get a basic program, like Adobe Lightroom," he suggests. "It's easy to understand, and there are tutorials on the web."Download an HDR app: For smartphone snapshots, use a high-dynamic range app, like TrueHDR, to capture all the colors and highlights of food.

"There are 600 to 700 big coffee table books on dogs and about 1,500 with naked women," Myhrvold tells The Salt. "But there weren't any with big pictures of food — and no recipes."

And while the images themselves are jaw-dropping, perhaps the best part of the book is that the team shares all the secrets about how the photos are made. Myhrvold's loyal following of mad scientist DIYers are sure to appreciate that.

Myhrvold and his motley crew of chefs, chemists and editors helped build that following when they published a widely celebrated cookbook called Modernist Cuisine: The Art and Science of Cooking a few years ago.

The cookbook offered an inside look at how the world's most avant garde chefs are using technologies and techniques from the lab to change how people eat and enjoy food. Think French fries made extra crispy by blasting them with sound waves or caramelized carrot soup made with a centrifuge to separate out the juice.

The new book features photos from the cookbook — and 278 new ones — in a larger-than-life format. At the back are details about how each photograph was made, from lighting and lenses to editing and stitching images together.

For instance, to get leeks and watermelons to "glow," the team placed thin slices of the produce on clear Plexiglass and then lit them from below. They photographed rice and beans under a microscope to capture the super close-up macros. And to catch a kernel of corn popping, the team filmed more than 5 pounds of popcorn, Myhrovold says. (Who knew that popcorn could rival the grace of a Tchaikovsky ballet?)

But it's the "cutaway" photos that really steal the show. From tomatoes pureeing in a blender to a pork shoulder adsorbing heat in a pressure cooker, Myrhvold and his team offer a glimpse of radical transformations during 14 cooking techniques.

So how did they make the cutaways? Two words: band saw.

To capture the magic of grilling, the team at The Cooking Lab sawed a Weber grill in half and then combined 30 photographs together.

Ryan Matthew Smith/Courtesy of The Cooking Lab To capture the magic of grilling, the team at The Cooking Lab sawed a Weber grill in half and then combined 30 photographs together.

Ryan Matthew Smith/Courtesy of The Cooking Lab

That's right, the Cooking Lab has its own machine shop, and a guy with spiky, red hair literally slices microwave ovens, pots and blenders in half. Then the teams uses toothpicks or sewing needles to hold the cut food into place. A piece of Plexiglass keeps boiling liquids inside the pans.

"We made a hell of mess especially when food was flying through the air," Myrhvold says. The team even started a fire while trying to catch a stir-fry in action. "But the food only had to look good for 1/1000th of the second."

And sometimes they didn't put the food in the air at all but just faked it. For instance, that tossed salad isn't tossed all. Instead pieces of lettuces and dressing are pinned to a black velvet.

All the photos are heavily edited. And many of the images are actually several — even dozens — of photos combined together in Photoshop. For instance, Myrhvold and the team cropped and combined 30 separate photos to capture the burger cooking on the sliced-in-half grill.

That time and effort are worth it, Myhrvold says, because the photographs lure readers into thinking about how cooking works.

"I think a picture may be worth even more than a thousand words," he says. "Nobody is going to read the thousand words anyway."

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How'd They Do That? The Story Of A Giant Rock And A Road Of Ice

The Large Stone Carving is the heaviest stone in the Forbidden City in Beijing. It was believed to have weighed more than 300 tons when it was first transported to the site between 1407 and 1420.

DEA/ W. Buss/De Agostini/Getty Images

Great works of ancient engineering, like the Pyramids or Stonehenge, inspire awe in every beholder. But some onlookers also get inspired to figure out exactly how these structures were made.

Howard Stone, an engineer from Princeton University, had such a moment in Beijing's Forbidden City — a city-within-a-city of palaces and temples built in the 15th and 16th centuries. A carved, 300-ton slab that formed a ramp to one structure particularly caught Stone's eye. "How in the world did it get here?" he wondered.

The distance between the Forbidden City in Beijing (a) and the Dasiwo Quarry in Fangshan (b) is about 43 miles. Double lines on the map represent rivers; single lines represent roads.

PNAS The distance between the Forbidden City in Beijing (a) and the Dasiwo Quarry in Fangshan (b) is about 43 miles. Double lines on the map represent rivers; single lines represent roads.

PNAS

Stone (and no, there will be no puns on his name in this story) is an engineer who studies fluid dynamics. Turns out, that was a lucky thing.

Stone got some of his Chinese colleagues involved. They discovered a 500-year-old document that says the slabs came from a quarry 45 miles away, transported over a road of ice. So Stone set about figuring out what that would have required.

First, why rely on ice? The Chinese had had the wheel for 3,000 years already. "The roads were pretty bumpy and rough," Stone explains, "and one thing ice does is give you a pretty smooth surface."

The document is sketchy about the technique but it does say workers dug wells along the route. That would have provided water to make the ice. It also says the job took 28 days in January — during the depth of winter.

"Given the friction and ... the mass of the rock, ... the temperature conditions in Beijing in the month of January when it was mostly done, what are the typical numbers for people you would need for the dragging?" Stone asked himself. "And is this a plausible number?"

He did some heavy math to see how many people would be required to drag a slab weighing about 120 tons (the weight the document described) over an ice road for 45 miles in 28 days. Everything hinged on the amount of friction that existed between a wooden sledge the rock sat on and the ice beneath the sledge.

A thousand people seemed just too unwieldy a group to drag this block of stone along a road, the engineer thought. But the math said you could do it with about 300 people — if these ice-road workers kept lubricating the ice with water. Doing so would lower the "coefficient of friction" of a wooden sledge-on-ice enough, he figured, so that 300 people could move the slab 20 feet per minute. (Speed skaters understand this phenomenon well — the ability to skate faster when there's a film of water on the ice.)

Sure enough: 20 feet per minute turns out to be fast enough to match the 28 days recorded in the Chinese document for the slab's journey to the Forbidden City.

Writing in the Proceedings of the National Academy of Sciences, Stone says it was an amazing feat. "You had on the order of a month to pull this off at the temperature conditions of Beijing," Stone says. "I think this just says a lot about their ability to engineer, their ability to plan."

The Cape Hatteras Lighthouse in Buxton, N.C., was moved almost 3,000 feet inland on July 9, 1999, to protect it from the advancing ocean.

Bob Jordan/AP The Cape Hatteras Lighthouse in Buxton, N.C., was moved almost 3,000 feet inland on July 9, 1999, to protect it from the advancing ocean.

Bob Jordan/AP

Judging from a carving found in an Egyptian tomb, experts say 172 men were used to transport the 60-ton Statue of Tehuti-Hetep, circa 1880 B.C. Water was used to lubricate the colossus as it slid along wooden planks.

NYPL Digital Gallery Judging from a carving found in an Egyptian tomb, experts say 172 men were used to transport the 60-ton Statue of Tehuti-Hetep, circa 1880 B.C. Water was used to lubricate the colossus as it slid along wooden planks.

NYPL Digital Gallery

Ancient Egyptians pulled off a similar delivery, sliding a 60-ton statue on wooden planks to a temple. They, too, used water to lower the friction. And in 1999, engineers moved North Carolina's Cape Hatteras lighthouse — more than 4,800 tons — more than a half-mile on steel rollers greased with soap.

But the Chinese, Stone believes, appear to be the first to have moved a chunk of mountain along a road of man-made ice.

YearObject, LocationWeight (tons)Distance (mi)MethodLubricantPowerStatue of Tehuti-Hetep, El-Bersheh, EgyptCape Hatteras Lighthouse, North Carolina

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Olympic Torch Relay Headed To Space

Flight Engineer Koichi Wakata of the Japan Aerospace Exploration Agency, left, Soyuz Commander Mikhail Tyurin of the Russian space agency Roscosmos, and Flight Engineer Rick Mastracchio of NASA, hold the Olympic torch that will be flown with them to the International Space Station, during a press conference on Wednesday.

Bill Ingalls/NASA

The Soyuz rocket that launched from Kazakhstan on Wednesday night has some special cargo on board. In addition to three crew members from Japan, Russia and the U.S., the International Space Station-bound probe is carrying an Olympic torch.

Payload specialists Robert Brenton Thirsk, left, and Jean-Jaques Favier hold the Olympic torch they brought to space aboard Space Shuttle Columbia in 1996.

NASA Payload specialists Robert Brenton Thirsk, left, and Jean-Jaques Favier hold the Olympic torch they brought to space aboard Space Shuttle Columbia in 1996.

NASA

As we reported in June, the torch won't be lit — open flame inside the spacecrafts would be dangerous and consume precious oxygen. But Russian cosmonauts Oleg Kotov and Sergey Ryazanskiy will carry the torch outside the station as part of a six-hour spacewalk on Nov. 9.

The Olympic torch will return to Earth on Nov. 10, along with three astronauts currently on board the ISS: Karen Nyberg, Luca Parmitano and Fyodor Yurchikhin.

This year's torch relay is the longest in Olympic history. The 123-day journey, which crisscrosses Russia, will cover more than 40,000 miles and involve more than 14,000 torchbearers.

And this trip isn't the first time an Olympic torch has left the planet — one flew with Space Shuttle Columbia in 1996 before the Atlanta games, and another in 2000 on Space Shuttle Atlantis, before the Sydney Olympics.

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Scientists Estimate 20 Billion Earth-Like Planets In Our Galaxy

An artist's rendition of Kepler-69c, a super-Earth-size planet in the habitable zone of a star like our sun, located about 2,700 light-years from Earth in the constellation Cygnus.

AP An artist's rendition of Kepler-69c, a super-Earth-size planet in the habitable zone of a star like our sun, located about 2,700 light-years from Earth in the constellation Cygnus.

AP

A new study suggests there could be far more Earth-like planets orbiting distant stars than once thought, some of which might even harbor life.

A team of astronomers from the University of California, Berkeley and the University of Hawaii at Manoa, Honolulu, used the Kepler space telescope to survey 42,000 Sun-like stars looking for a telltale dimming caused by an orbiting planet as it crosses between us and the parent star.

While the method is not new, in the past it has tended to favor finding larger planets orbiting close in – lots of so-called "hot Jupiters" that are way too big and/or way too close to their stars to be candidates for life. Kepler's main mission has been to find planets in what astronomers call the "Goldilocks Zone" — not too hot and not too cold and just the right size for life as we know it to evolve.

The team publishing in the latest issue of PNAS looked at how frequently the dimmings took place to determine the orbital period — and therefore the distance from the star — as well as how much light was blocked, which gives an indication of the size of the planet:

"We found 603 planets, 10 of which are Earth size and orbit in the habitable zone, where conditions permit surface liquid water," the team writes. "We find that 22 percent of Sun-like stars harbor Earth-size planets orbiting in their habitable zones. The nearest such planet may be within 12 light-years."

Smithsonian says:

"Over the past 18 years, astronomers have discovered 1038 planets orbiting distant stars. Disappointingly, though, the vast majority don't seem like candidates to support life as we know it—they're either so close to their home star that all water would likely evaporate, or so far away that all of it would freeze, or they're made up of gas instead of rock and more closely resemble our solar system's gas giants than Earth."

Andrew Howard, one of the study's co-authors, enthused at a recent news conference that their 22 percent figure means that "with about 100 billion stars in our Milky Way galaxy, that's about 20 billion such planets. ... That's a few Earth-sized planets for every human being on the planet Earth."

And, that's just in a single galaxy. If the figure for potentially habitable planets derived by the team of scientists is correct, we could take a minor flight of fancy and multiply the 20 billion planets by about 500 billion galaxies in the observable universe for a truly astronomical number – possibly 10 trillion Earth-like planets.

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Space Agencies Of The World, Unite: The U.N.'s Asteroid Defense Plan

This mosaic image from NASA's Dawn spacecraft, captured between 2011 to 2012, shows the giant asteroid Vesta. The mountain at the south pole, seen at the bottom of the image, is more than twice the height of Mount Everest.

NASA

The United Nations General Assembly may approve a plan soon for the world's space agencies to defend the Earth against asteroids.

The plan, introduced last week, is expected to be adopted by the General Assembly in December. It would do two things: create an International Asteroid Warning Network so countries can share what they know about asteroids; and spin up a group of scientists from several countries' space agencies to look for smaller asteroids, as well as make plans to divert them away from the Earth.

The problem here isn't a large asteroid. NASA has already found more than 90 percent of the comets and asteroids larger than 1 kilometer, or 0.6 miles, across — those are the ones big enough to do global damage.

The concern is for the smaller meteoroids — ones that are more than 450 feet across. These can still get through the Earth's atmosphere and rain down on the planet. Although most of the Earth is covered by oceans, an asteroid of this size could destroy several states or an entire city if it lands in the wrong spot.

An international group, formed from discussions at the U.N., would test a strategy to deflect an incoming asteroid by using "a fleet of robot spacecraft to slam into the asteroids," says veteran NASA astronaut Tom Jones. These kamikaze robots would change the direction of the incoming asteroid so it doesn't crash into the Earth.

NASA tried something similar with its 2005 Deep Impact mission, which slammed into a comet to see how the inside differs from the outside.

Jones estimates the cost of a deflection plan would be comparable to the price tag for the Mars Curiosity Rover, which cost $2.5 billion. By working with other space agencies, this cosmic insurance policy would spread this cost around. The plan is for the space agencies to work together, like they have done on the International Space Station, except this project would come with the blessing of the U.N. and the global community.

Jones, who also chairs the Association of Space Explorers' committee on Near-Earth Objects, says the telescopes NASA currently has can't spot these small, but potentially deadly space rocks.

"Those telescopes are not sensitive enough to see distant, small, dark asteroids," Jones says. "The only time they see those is by accident when those asteroids drift past the Earth close by, then you can catch a few of them in your sights."

In 2005, Congress passed legislation asking NASA to find 90 percent of these small asteroids by 2020, but NASA is still working on that. The space agency recently called for the public's help in searching for them, and it brought back a retired spacecraft to spot them. To get closer to this goal, NASA needs special infrared telescopes in space, but the space agency doesn't have the money for them, says Lindley Johnson, program executive for NASA's Near-Earth Object Program, which tracks comets and asteroids in the Earth's neighborhood.

Johnson and Jones both say a plan from the U.N. would enhance what NASA is already doing.

"Here's the biggest of all natural disasters that we're talking about, and it's preventable," Jones says.

Earlier this year, a meteorite hit Chelyabinsk in Russia and injured 1,000 people. "If the people in Chelyabinsk had been warned a day beforehand," Jones says, "they could have been away from the windows or in shelters where almost nobody would have been hurt."

Getting several space agencies and their respective countries on board can also avoid trust problems, Jones says.

"Do you trust the Russians? Do you trust NASA to do a deflection all by itself?" he says. "If they make a mistake halfway through and an asteroid happens to land somewhere else than where we originally thought, who's to blame? We'd rather have that responsibility shared and sanctioned by the U.N. rather than a unilateral approach."

The U.N. member nations that are actively participating include the U.S., the U.K., the countries that are part of the European Space Agency, Russia, Japan, Nigeria and Mexico, says Sergio Camacho-Lara, director of the U.N. Office for Outer Space Affairs.

As the U.N. is the only universal forum for discussing international issues, Camacho-Lara says it is the best way to make sure the world's governments can start thinking about the threat from asteroids. As of now, the resolution is a draft that has been endorsed by several U.N. committees, but Camacho-Lara says in the past 50 years, only four resolutions have reached this point and not been adopted by the General Assembly.

"We will be finding, in the next five, 10 years, another half million or more [asteroids], so the magnitude of the problem is quite a bit larger than what we have right now," Camacho-Lara says. "But the asteroids are there, it's a question of finding them before they actually find us."

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Thanks To Parasites, Moose Are Looking More Like Ghosts

A large bull moose is inspected by a hunter at a weigh station in Maine.

Robert F. Bukaty/AP A large bull moose is inspected by a hunter at a weigh station in Maine.

Robert F. Bukaty/AP

The news for moose is not good across the country's northern tier and in some parts of Canada. A recent and rapid decline of moose populations in many states may be linked to climate change, and to the parasites that benefit from it.

In Minnesota, moose populations have dropped from a high of more than 12,000 two decades ago to fewer than 3,000 now. Moose in some parts of Manitoba have declined by 50 percent and more.

"The colder the weather, the more moose you're going to see," says hunter Nat Rockwell, as he brings a female moose he bagged in New Hampshire's White Mountains to a weigh station.

The 70-year-old tool and die machinist watches as the moose is hoisted and clipped to a scale. She weighs in at 630 pounds. Rockwell asks New Hampshire's moose project leader, Kristine Rines, to check for ticks.

Though most ticks have already abandoned the moose body, Rockwell's concern about ticks is well-placed. Biologists and hunters around the nation say that declines in moose populations have often been accompanied by a surge of infestations of the winter tick. A single moose can carry more than 100,000 of the bloodsuckers.

Sometimes, Rines says, anemic, infested animals are transformed into "ghost moose."

That happens when the moose "have scratched all winter long trying to get the ticks off, and they break their hair all off, and because the hair follicle is broken you see the white inner portion," she says. "And they literally look like ghosts."

One recent year, nearly every moose calf-tracked by New Hampshire biologists died. Rines says several factors are at work. Those include shorter winters, with less snow on the ground. That helps the ticks, which die if they drop off an animal onto snow, but survive and breed if there is bare ground to land on.

Climate change, Rines says, could spell the fate of the moose in New Hampshire. Not only do shorter winters benefit the ticks, they also benefit white-tailed deer, which act as a reservoir for a parasite known as brain worm. That parasite doesn't harm the deer, but it's fatal for moose.

"It might be some of this and some of that, but there is a decline in moose. I've seen it," says Rockwell. Regardless of all the theories floating around, he says something's definitely going on.

"I scouted four days, and there was very little sign of them," he says of a recent moose hunting trip. "So, I believe there's a lot of truth to what the game wardens are saying."

New Hampshire's moose population has dropped by more than a third. The state has cut back the number of hunting permits, from more than 600 a few years ago to fewer than 300 this year.

Such sharp decline could take a toll on economies — and cultures — in states like New Hampshire and Minnesota, where the moose's iconic silhouette appears on many a bumper sticker. In New Hampshire alone, guided moose tours are worth an estimated $115 million a year.

Rockwell's son, Todd, says he's worried that the moose hunt might be suspended altogether here, as it has been in Minnesota.

"I'd hate to see that happen, because it's a good time," he says. "Hopefully, they get it resolved and we can increase the permits in the future."

But with so many factors at work — from changes in climate and land use to public opinion — getting it resolved won't be an easy task.

This winter, biologists in New Hampshire, Minnesota and other states plan high-tech, GPS-guided moose research projects, to get a better handle on just what is going on out in the woods.

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Why Are Pig Farmers Still Using Growth-Promoting Drugs?

In recent years, pork producers have found ways to keep the animals healthy through improved hygiene.

M. Spencer Green/AP In recent years, pork producers have found ways to keep the animals healthy through improved hygiene.

M. Spencer Green/AP

It's one of the most controversial practices in agriculture: feeding small amounts of antibiotics to animals in order to make them grow faster.

But what if the drugs don't even work very well?

There's some good evidence that they don't, at least in pigs. They used to deliver a boost in growth, but that effect has disappeared in recent years or declined greatly.

The reason for this is interesting and even paradoxical.

Researchers think the antibiotics used to work by suppressing low-grade infections. In recent years, however, pork producers found other ways to accomplish the same thing through improved hygiene. This has occurred even while swine operations grow. As a result, the drugs have become largely superfluous — yet many farmers still use them.

To understand how this happened, you have to step back in time, says Steve Dritz, a specialist in swine nutrition at Kansas State University.

Sixty years ago, when antibiotics were new, "people started treating animals, and feeding [the antibiotics], and finding that they had increased growth rates and feed efficiencies," he says. Nursery-age pigs, for instance, grew 12 to 15 percent faster with antibiotics. The animals also needed less feed to reach full weight. Other studies showed similar results in chickens and cattle.

In the 1980s, a new set of studies found similar effects. So the growth-promoting effects of antibiotics became standard practice among meat producers.

Fast forward to the 1990s. Dritz was starting his career as a scientist at Kansas State University, and pork production was changing dramatically. "We instituted this thing called multisite production," says Dritz.

Previously, pigs were born and raised in one barn or in several barns close together. This meant infections could easily pass from one generation to the next, the way that kids share germs between their friends on the playground and their parents at home.

Under the new system, when piglets are weaned, they move to a whole different place. That new site is carefully scrubbed and free of disease.

Craig Rowles, who runs a large swine operation in Carroll, Iowa, shows me one such room. There's not a piglet in sight. "This room just got completely washed and disinfected, and now it's going to sit here and dry for a while," he says.

A whole group of pigs will come in here together, and later they will move out together to yet another site. "That group of pigs will stay together until they go to market," Rowles says.

Craig Rowles raises pigs near Carroll, Iowa. The piglets will enter and leave this room as a group.

Dan Charles/NPR Craig Rowles raises pigs near Carroll, Iowa. The piglets will enter and leave this room as a group.

Dan Charles/NPR

The groups are kept strictly separated from each other. If workers move between the groups, they first have to change their boots.

When farmers adopted multisite production, it cut down on disease — and pigs actually grew faster.

So Dritz wondered whether improved hygiene was delivering exactly the same growth-promoting effect that farmers used to get through antibiotics. If so, did they still need to use the drugs?

Dritz carried out some studies on pigs in these multisite systems, comparing animals that received antibiotics with others that didn't. "Lo and behold, in these studies, there wasn't nearly the magnitude of the growth response," he says.

In the "finishing" stage, the effect of antibiotics disappeared. Younger pigs grew a bit faster with antibiotics, but the effect was smaller than had been observed earlier.

Dritz started telling pork producers that most uses of antibiotics for growth promotion or feed efficiency really did not make sense anymore. Many farmers took his advice. But he was surprised and a little discouraged to see how many did not. They weren't convinced by the evidence.

"It's very hard to change people's perceptions," he says. Even among veterinarians, his professional colleagues, there was reluctance to change. Many continue to recommend using the drugs.

Dritz thinks that this is partly rooted in psychology and the professional culture of veterinary practice. Veterinarians "are action-oriented people, most of them. They want to do something. Not doing something just doesn't seem right, as a professional, you know?"

Once upon a time, this would have been left for farmers and their vets to hash out, but the use of antibiotics on the farm now is the focus of intense controversy. Critics of the meat industry say using these drugs to promote growth is irresponsible because it increases the chances that bacteria will develop resistance to antibiotics, and some of these bacteria can infect humans.

The Food and Drug Administration now says that medically important antibiotics should not be used for this purpose. It is trying to persuade drug companies to stop selling drugs for growth promotion. Within a few years, such uses of antibiotics may no longer be legal.

Among farmers, there's some grumbling about this. But at least for pork producers, dropping the drugs may actually save money.

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Why India's Mars Mission Is So Much Cheaper Than NASA's

A rocket carrying the Mars orbiter lifts off from the island of Sriharikota, India, on Tuesday.

Arun Sankar K/AP A rocket carrying the Mars orbiter lifts off from the island of Sriharikota, India, on Tuesday.

Arun Sankar K/AP

Former NASA Administrator Daniel Goldin pioneered a "faster, better, cheaper" approach to America's space program, but he would have been hard-pressed to deliver a Mars mission for the bargain-basement price of India's first probe to the red planet, which blasted off Tuesday.

"India's Mars mission, with a budget of $73 million, is far cheaper than comparable missions including NASA's $671 million Maven satellite that is expected to set off for Mars later in November," reports The Wall Street Journal, which is among several publications noting the disparity between the cost of U.S. space missions and India's burgeoning program.

Even the project director of India's Mars orbiter mission has been quick to tout his country's frugality in space:

The PSLV-C25, with India's Mars orbiter aboard, prior to Tuesday's launch at the Satish Dhawan Space Centre in southern India.

Indian Space Research Organization (ISRO) The PSLV-C25, with India's Mars orbiter aboard, prior to Tuesday's launch at the Satish Dhawan Space Centre in southern India.

Indian Space Research Organization (ISRO)

"This is less than one-tenth of what the U.S. has spent on their Mars mission Maven," S. Arunan told reporters at a pre-launch news conference last week, according to Al-Jazeera, which added that "the cost-effectiveness of the mission is indeed turning out to be the highlight of the project, almost eclipsing the other aspects."

(Arunan's comments may have been directed partly at the critics of India's space program, who The Washington Post says "wonder why the country is spending $74 million on interplanetary travel while millions of its people remain poor and malnourished.")

In any case, there are some good reasons that India can do it cheaper than the U.S., says David Alexander, director of the Rice Space Institute. It basically boils down to parts and labor.

"I think labor is the biggest factor, as well as the complexity of the mission," Alexander tells NPR. "It takes a whole team of engineers."

Those engineers cost much less in India than they do in the U.S. The mean annual income for an aeronautical engineer in the United States is just under $105,000, according to the Bureau of Labor Statistics. While it's difficult to make direct comparisons, a blog that covers the aerospace industry in India indicates that the higher end of the scale for engineers there is less than $20,000.

Similarly, there's a vast gulf between the pay for electronics engineers. The average electronics engineer in the United States makes a little more than $120,000, according to Salary.com, as opposed to India, where Glassdoor.com says he or she might pull in less than $12,000 a year at a company such as Samsung India.

These figures are approximations — given factors such as the differences in experience levels and fluctuations in currency exchange rates over time — but they give an idea of the disparity. In general, it seems safe to say engineers in India make between one-tenth and one-fifth of what their U.S. counterparts do, in absolute terms.

Alexander says it appears that India's main goal is just getting to Mars, and so the probe is carrying "relatively simple" and therefore not-so-expensive instrumentation, he says.

It's a first try at a very complex mission, one that is orders of magnitude more difficult than India's Chandrayaan-1 probe to the moon five years ago. Mars missions have a history of failure. As Alexander points out, fewer than half of them — launched by the U.S., Russia and the European Space Agency — have been successful.

"What the Indians want to know is: Will it survive? And will it get into orbit?" Alexander says. "I think the hope is that even if it fails, they are going to learn something."

The Associated Press notes that no country has reached Mars on the first try. China's 2011 attempt with Russia to send the Yinghuo-1 probe fizzled when the Russian rocket failed to leave Earth orbit. A 2003 mission by Japan got farther but couldn't get into Mars orbit.

And as Reuters points out, a successful Indian mission will have the effect of "positioning the emerging Asian giant as a budget player in the latest global space race."

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Anode and Cathode

Here's a look at the difference between the anode and cathode of a cell or battery and how you can remember which is which. The anode and cathode are defined by the flow of current. In the general sense, current refers to any movement of electrical charge. However, you should keep in mind the convention that current direction is according to where a positive charge would move, not a negative charge. So, if electrons do the actual moving in a cell, then current runs the opposite direction. Why is it defined this way? Who knows, but that's the standard. Current flows in the same direction as positive charge carriers, for example, when position ions carry the charge. Current flows opposite the direction of negative charge carriers, such as electrons in metals. The cathode is the negatively charged electrode. The cathode attracts cations or positive charge. The cathode is the source of electrons or an electron donor. It may accept positive charge. Because the cathode may generate electrons, which typically are the electrical species doing the actual movement, it may be said that cathodes generate charge or that current moves from the cathode to the anode. This can be confusing, because the direction of current would be defined by the way a positive charge would move. Just remember, any movement of charged particles is current. The anode is the positively charged electrode. The anode attracts electrons or anions. The anode may be a source of positive charge or an electron acceptor.

Remember, charge can flow either from positive to negative or from negative to positive! Because of this, the anode could be positively charged or negatively charged, depending on the situation. The same is true for the cathode.

Remember the cathode attracts cations or the cathode attracts + charge. The anode attracts negative charge.

Electrochemical Cells | Galvanic Cell Example Problem

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Cool Science Trick - Tie Water in Knots

Here's a cool science trick for you to try: tie water in knots: Take an empty carton or jug, such as a milk or orange juice carton or jug. Poke three holes near each other near the bottom of the container. Fill the container with water. You will have three streams of water pouring from the holes. Pinch the streams of water together. They will stick or appear to be tied together! This is caused by the high surface tension of water. Water molecules are cohesive or stick together. The water molecules are in a state of lower energy when they are in contact with each other, so once joined, the water streams tend to run together rather than separate again.Bend Water with Static | Water Factsif(zs>0){if(zSbL250)gEI("spacer").style.height=Math.floor(e[0].height/12)+17.5+'em';else{var zIClns=[];function walkup(e){if(e.className!='entry'){if(e.nodeName=='A'||e.style.styleFloat=='right'||e.style.cssFloat=='right'||e.align=='right'||e.align=='left'||e.className=='alignright'||e.className=='alignleft')zIClns.push(e);walkup(e.parentNode)}}walkup(e[0]);if(zIClns.length){node=zIClns[zIClns.length-1];var clone=node.cloneNode(true);node.parentNode.removeChild(node);getElementsByClassName("entry",gEI("articlebody"))[0].insertBefore(clone,gEI("spacer"))}}}};zSB(2);zSbL=0

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How Carbon Monoxide Detectors Work

Carbon monoxide is an invisible odorless gas that is the leading cause of accidental poisoning deaths in America. Carbon monoxide detectors can alert you to dangerous levels of carbon monoxide. Originally, carbon monoxide detectors were simple opto-chemical detectors that indicated the presence of carbon monoxide by exhibiting a color change when carbon monoxide reacted with a chemical on a white pad, producing a brownish or black color. These detectors do not require an external power source to function, but modern designs use audible alarms to confer a higher level of protection: A opto-chemical or gel sensor interacts with synthetic hemoglobin, darkening in color when carbon monoxide is present and lightening in color when carbon monoxide concentrations are low. A light sensor may be used to detect the change in light levels to sound an alarm. An integrated circuit monitors a sensor, tripping the alarm when concentrations of carbon monoxide are high. The sensor is made from thin wires of semiconducting tin dioxide that rest on an insulating ceramic base. Increasing carbon monoxide concentration reduces the electrical resistance of the sensor, causing the alarm to sound. This is an electrochemical cell that is designed to produce current in relation to the amount of carbon monoxide present in the air. Carbon monoxide is oxidized to carbon dioxide at one electrode while oxygen is consumed at the other electrode. Sulfuric acid is the usual electrolyte that separates the electrodes. The current triggers the alarm or can even be used to quantify the amount of carbon monoxide that is present.

How Carbon Monoxide Detectors Work | What You Need to Know about Carbon Monoxide Detectors

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Hybrid Solar Eclipse of 2013 and the Element Coronium

Here's a picture I took of the hybrid solar eclipse from Uganda on November 3, 2013. Just what is a hybrid solar eclipse? It's a rare type of solar eclipse consists of an annular eclipse that transitions into a total solar eclipse. The eclipse looks like a ring of fire, sparkling with colored beads and jets, that becomes a total solar eclipse, where the sun's corona fans out around a black disc. This happens when the curvature of the Earth intercepts the moon's umbra (shadow), blocking out the entire disc of the sun. The hybrid eclipse was visible in the Atlantic ocean, while I saw a total solar eclipse in Africa.

Scientists observe the solar corona during an eclipse to analyze the chemical composition of the sun. Did you know at one time the sun's corona was believed to contain an element called coronium or newtonium?... Read more

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Make Your Own Guy Fawkes Night Fireworks

Happy Guy Fawkes Night! November 5th is Guy Fawkes Night, an annual celebration in the UK commemorating the day that Guy Fawkes, a member of the Gunpowder Plot, was arrested while guarding explosives hidden beneath the House of Lords. People lit bonfires to celebrate King James I survival of the plot, eventually leading to a public day of thanksgiving, which of course, is celebrated by lighting FIRE, usually in the form of bonfires and fireworks.

Alas, I am American, but I support my friends across the pond in their evening of burnination. Here are some fun projects for you:

Make Homemade Fireworks
Apply the Thermite Reaction to Light a Bonfire
How To Color Fire
How To Breathe Fire
Gunpowder Facts and History

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On This Day in Science History - November 4 - X-10 Reactor

On November 4, 1943, the X-10 nuclear reactor began operations. This reactor was the first reactor built to produce plutonium for the Manhattan Project. The reactor consisted of a 24 foot cube of graphite slabs surrounded by a thick concrete radiation shield. There were 1,248 horizontal holes drilled into the graphite to hold slugs of uranium fuel. These slugs would remain in the reactor to emit and absorb neutrons to convert uranium-238 into plutonium-239. After a period of time, operators would push an new uranium slug into the hole and shove the plutonium rich slug out the back for processing. The plutonium would be extracted and sent on to the Los Alamos facility.

The X-10 reactor was shut down in 1963 and declared a National Historical Landmark in 1965. The reactor face is still open to the public and a must see to anyone who visits Oak Ridge National Laboratory. Find out what else occurred on this day in science history.

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On This Day in Science History - November 5 - Léon Teisserenc de Bort

November 5th is L?on Teisserenc de Bort's birthday. He was a French meteorologist best known for the discovery of the layer in the atmosphere known as the stratosphere. He was a pioneer of the unmanned weather balloons carrying instruments to collect and record data such as temperature, pressure and wind speed. Typically, as you increase altitude, the temperature falls rather quickly. He discovered a boundary layer of the atmosphere approximately 7 miles up where the temperature would stop decreasing and would remain constant as the altitude increased. He concluded there were two regions of the atmosphere. The first 7 miles was called the troposphere ("sphere of change" in Greek) where the weather was constantly changing and stirring up the different gases in air because of the temperature differences in the air. After 7 miles, he reasoned the gases in the air would layer themselves, heaviest to lightest in strata. He named this section the stratosphere.

Find out what else occurred on this day in science history.

Follow About.com Chemistry on Facebook or Twitter.

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On This Day in Science History - November 6 - Yeast Fermentation

November 7th marks the passing of Swedish biochemist, Hans von Euler-Chelpin. He was awarded the 1929 Nobel Prize in Chemistry with Arthur Harden for their investigations into the process of fermentation and yeast enzymes.

Brewers use yeast to convert glucose (sugar) into carbon dioxide and ethyl alcohol. People have been using yeast for centuries for fermentation but the process was not fully understood. Eduard Buchner identified the yeast enzyme called zymase when he removed all cells from the yeast and still managed to produce fermentation. He would win the 1907 Nobel Prize for this discovery. Harden later showed zymase was made up of two different varieties and Euler-Chelpin discovered the complementary enzyme, cozymase that was responsible for the production of carbon dioxide in the process.

Find out what else occurred on this day in science history.

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On This Day in Science History - November 7 - Tacoma Narrows Bridge

On November 7, 1940, the bridge spanning Puget Sound across the Tacoma Narrows in Washington state dramatically collapsed. The bridge opened on July 1, 1940 as the third longest suspension bridge in the world. Almost immediately, the bridge was nicknamed "Gallopin' Gertie" because of its sway due to the wind. The state hired an engineer to propose methods to settle Gertie's galloping tendencies. They concluded their study on November 2, 1940 and recommended a couple of options to fix the problem. Unfortunately, the bridge didn't wait for the repairs.

On the morning of November 7, the winds were pretty strong and the bridge swayed more than usual. As the wind speed built up during the morning, the swaying approached the resonant frequency of the bridge itself. The bridge span began to jump and sway until it ripped itself apart at 11:00. Because of the long period of time it took to reach the breaking point, local camera shop owner Barney Elliott was able to film the collapse. This film is still shown to students of architecture, physics and engineering.

There was only one casualty to the collapse. The man in the film running from his car was named Leonard Coatsworth. Mr. Coatsworth attempted to cross the bridge but abandoned his car and daughter's cocker spaniel Tubby. Tubby would not leave the car even when others attempted to rescue him and went down with the bridge.

Find out what else occurred on this day in science history.

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Why Is Water a Polar Molecule?

Water (H2O) is a polar solvent and each water molecule exhibits polarity. Do you know why?

Water is polar because of the difference in electronegativity between hydrogen and oxygen. The highly electronegative oxygen atom attracts electrons or negative charge to it, making the region around the oxygen more negative than the areas around the two hydrogen atoms.

However, the molecule would not be polar if H2O was linear like, for example, carbon dioxide, CO2. Each water molecule is bent so that the positive portions of the molecule (the hydrogen atoms) are flexed away from the two filled orbitals of the oxygen.

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