Comet rain took life's ingredients to Jupiter's moons

Dust made from pulverised comets may have seeded Jupiter's moons with the raw ingredients for life. That includes Europa, which is thought to harbour a liquid ocean beneath its icy crust.

Jupiter has two kinds of natural satellites: large spherical moons and smaller lumpy bodies that follow elongated orbits. Chemical analysis of the irregular bodies suggests they are made of the same stuff as asteroids and comets. This means they are probably rich in the carbon-containing compounds that are key to life on Earth.

It is thought that a gravitational reshuffling of the planets some 4 billion years ago shook up distant belts of space rocks and sent many of them hurtling towards the sun. Some got caught in Jupiter's orbit and became the irregular satellites. The objects frequently collided as they settled into their new orbits, creating dust as fine as coffee grounds.

Blanketed moons

Models say that Jupiter should have captured about 70 million gigatonnes of rocky material, but less than half that amount remains as irregular moons. "So what happened to all the stuff?" asks William Bottke of the Southwest Research Institute in Boulder, Colorado.

His team ran simulations of the irregular moons' evolution and found that their ground-up material would have fallen towards Jupiter, dragged by gravity and blown by the solar wind. About 40 per cent of it would have hit Jupiter's four largest moons. Most of this landed on Callisto (Icarus, doi.org/kff). The rest hit Ganymede and then Europa.

That's roughly consistent with images from the Galileo spacecraft, which show dark material on Ganymede and Callisto. "Callisto literally looks like it's buried in dark debris," says Bottke, while Ganymede has a lot of similarities but less dark stuff on its surface.

Sinking carbon

But the surface of Europa is relatively clean. Cracks cover the moon's crust, which suggests it has cycled material from deeper inside, so the carbon-rich debris may have been incorporated into the ice and even made it into the ocean, says Bottke. "Would it be important in Europa's ocean? It's hard to say," he says. "But it is kind of interesting to think about."

Bottke's calculations only set a lower limit on the amount of carbon-rich material that could have ended up in Europa's ocean, says Cynthia Phillips of the SETI Institute in Mountain View, California, who studies Europa.

"This could potentially be an even larger source of astrobiologically interesting material for the ocean layer than the authors of this paper estimate," she says.

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66-year-old man arrested for alleged outrage of modesty

SINGAPORE: Police have arrested a 66-year-old male suspect for a case of outrage of modesty.

Police were notified of the case on Friday evening when an 11-year-old victim reported that he was kissed and touched inappropriately by an unknown man in the vicinity of Yishun Street 11.

Following the report, officers from Ang Mo Kio Police Division conducted extensive follow-up and managed to establish the identity of the 66-year-old suspect.

The suspect was arrested an hour from the time of the report.

The suspect will be charged in Court on Saturday for three counts of Outrage of Modesty under Section 354(2) of the Penal Code, Chapter 224, which carries an imprisonment term of up to five years and caning.

- CNA/xq

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Why We Walk … and Run … And Walk Again to Get Where We're Going

You have to get to a bus stop to catch the once-an-hour express ... or to a restaurant to meet a friend ... or to a doctor's office. You've got maybe a half a mile to cover and you're worried you'll be late. You run, then you stop and walk, then run some more.

But wait. Wouldn't it be better to run the whole way?

Not necessarily.

A new study by an assistant professor of mechanical engineering at Ohio State University tests the theory that people subconsciously mix walking and running so they get where they need to. The idea is that "people move in a manner that minimizes energy consumption," said the professor, Manoj Srinivasan.

Srinivasan asked 36 subjects to cover 400 feet (122 meters), a bit more than the length of a football field. He gave them a time to arrive at the finish line and a stopwatch. If the deadline was supertight, they ran. If they had two minutes, they walked. And if the deadline was neither too short nor too far off, they toggled between walking and running.

The takeaway: Humans successfully make the walk-run adjustment as they go along, based on their sense of how far they have to go. "It's not like they decide beforehand," Srinivasan said. (Get tips, gear recommendations, and more in our Running Guide.)

The Best Technique for "the Twilight Zone"

"The mixture of walking and running is good when you have an intermediate amount of time," he explained. "I like to call it 'the Twilight Zone,' where you have neither infinite time nor do you have to be there now."

That ability to shift modes served ancient humans well. "It's basically an evolutionary argument," Srinivasan said. A prehistoric human seeking food would want to move in a way that conserves some energy so that if food is hard to find, the hunter won't run out of gas—and will still be able to rev it up to escape predators.

The study, published on January 30 in the Journal of the Royal Society Interface, doesn't answer that question of how we make such adjustments.

Runners: Take a Break if You Need It

The mix of walking and running is also something that nonelite marathoners are familiar with. Covering 26.2 miles might take less of a toll if the runner stops running from time to time, walks a bit, then resumes a jogging pace. "You use less energy overall and also give yourself a bit of a break," Srinivasan noted. (Watch: An elite marathoner on her passion for running.)

One take-home lesson is: Runners, don't push it all the time. A walk-run mix will minimize the energy you expend.

Lesson two: If you're a parent walking with your kid, and the kid lags behind, then runs to catch up, then lags again, the child isn't necessarily trying to annoy you. Rather, the child is perhaps exhibiting an innate ability to do the walk-run transition.

Potential lesson three: The knowledge that humans naturally move in a manner that minimizes energy consumption might be helpful in designing artificial limbs that feel more natural and will help the user reduce energy consumption.

The big question for Manoj Srinivasan: Now that he has his walk-run theory, does he consciously switch between running and walking when he's trying to get somewhere? "I must admit, no," he said. "When I want to get somewhere, I just let the body do its thing." But if he's in a rush, he'll make a mad dash.

"Talk to you tomorrow," he signed off in an email to National Geographic News. "Running to get to teaching now!"

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Nightmare Ends: Passengers Leave Disabled Ship

After five days without power in the Gulf of Mexico, the more than 4,200 people aboard the Carnival Triumph returned home to the U.S., with many of them telling their horror stories for the first time.

Passengers began to disembark the damaged ship around 10:15 p.m. CT Thursday in Mobile, Ala. The last passenger disembarked the ship at 1 a.m. local time, according to Carnival's Twitter handle.

Passenger Brandi Dorsett was thankful to be home, especially for her mother who was with her on the ship. Dorsett said she wasn't pleased with the doctor on staff.

"My mother is a diabetic and they would not even come to the room because she cannot walk the stairs to help her with insulin. She hasn't had insulin in three days," Dorsett said.

Click Here for Photos of the Stranded Ship at Sea

The Carnival Triumph departed Galveston, Texas, last Thursday and lost power Sunday after a fire in the engine room disabled the vessel's propulsion system and knocked out most of its power.

After power went out, passengers texted ABC News that sewage was seeping down the walls from burst plumbing pipes, carpets were wet with urine, and food was in short supply. Reports surfaced of elderly passengers running out of critical heart medicine and others on board squabbling over scarce food.

"It's degrading. Demoralizing and then they want to insult us by giving us $500," Veronica Arriaga said after disembarking the ship.

Passengers were already being given a full refund for the cruise, transportation expenses and vouchers for another cruise. Carnival Cruise Lines is now boosting that offer to include another $500 per person.

As the ship docked, passengers lined the decks of the Triumph, waving and whistling to those on shore. "Happy V-Day" read a homemade sign made for the Valentine's Day arrival and another, more starkly: "The ship's afloat, so is the sewage."

AP Photo/John David Mercer

Girl Disembarks Cruise Ship, Kisses the Ground Watch Video

Carnival CEO Gerry Cahill: 'I Want to Apologize' Watch Video

Carnival Cruise Ship Passengers Line Up for Food Watch Video

WATCH: Carnival CEO Gerry Cahill Apologizes to Passengers

Some still aboard chanted, "Let me off, let me off!" and "Sweet Home Alabama."

Kendall Jenkins was one of many passengers that were photographed kissing the ground when they exited the ship. Jenkins, like many passengers, created makeshift beds out of lounge chairs on the ship's deck after the raw sewage smell became too much to contend with.

"We kind of camped out by our lifeboat. We would have nightmares about Titanic basically happening," passenger Kendall Jenkins told ABC News Radio.

"I am just so blessed to be back home," she added.

Cruise Ship Newlyweds Won't Be Spending Honeymoon on a Boat

Approximately 100 buses were waiting to take passengers on the next stage of their journey. Passengers had the option to take a bus ride to New Orleans or Galveston, Texas, where the ill-fated ship's voyage began. From there, passengers will take flights home, which Carnival said they would pay for.

Inside the buses, Carnival handed out bags of food that included French fries, chicken nuggets, honey mustard barbecue sauce and apples.

Deborah Knight, 56, decided to stay in Mobile after the arduous journey was over rather than board a bus for a long ride. Her husband Seth drove in from Houston and they checked in at a downtown Mobile hotel.

"I want a hot shower and a daggum Whataburger," said Knight.

She said she was afraid to eat the food on board and had gotten sick while on the ship.

For 24-year-old Brittany Ferguson of Texas, not knowing how long passengers had to endure their time aboard was the worst part.

"I'm feeling awesome just to see land and buildings," Ferguson said, who was in a white robe given to her aboard. "The scariest part was just not knowing when we'd get back," she told The Associated Press.

Carnival president and CEO Gerry Cahill praised the ship's crew and told reporters that he was headed on board to apologize directly to its passengers shortly before the Carnival Triumph arrived in Mobile.

"I know the conditions on board were very poor," Cahill said Thursday night. "I know it was very difficult, and I want to apologize again for subjecting our guests for that. ... Clearly, we failed in this particular case."

Luckily no one was hurt in the fire they triggered the power outage, but many passengers aboard the 900 foot colossus said they smelled smoke and were living in fear.

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Mosh pit physics could aid disaster planning

Metalheads in mosh pits act like atoms in a gas. That's the conclusion of the first study of the collective motion of people at a rock concert.

The finding could add to the realism of computer-generated crowd scenes in films and games.; More importantly, it could help architects design buildings that ease the flow of chaotic crowds in an emergency.

Research into how humans behave in crowds had mostly been limited to fairly organised situations, like pedestrians forming lanes when walking on the street. But when Jesse Silverberg, a graduate student at Cornell University in Ithaca, New York, took his girlfriend to her first heavy metal concert a few years ago, he witnessed a different and surprising form of crowd behaviour.

"I didn't want to put her in harm's way, so we stood off to the side," he says. "I'm usually in the mosh pit, but for the first time I was off to the side and watching. I was amazed at what I saw."

Metal fans' favoured dance style is called moshing and mostly involves bodies slamming into each other. Silverberg wondered if the mathematical laws that describe group behaviour in flocks of birds or schools of fish could apply to moshers as well.

Like a random gas

Together with another grad student and two physics professors at Cornell, he pulled videos of mosh pits off YouTube and used software developed for analysing particles in a fluid to track the moshers' motions. They found that the dancers' speeds had the same statistical distribution as the speeds of particles in a gas. Such particles move around freely, interacting only when they bounce off one another.

"This presented a bit of a mystery," Silverberg says. What makes a crowd of people with independent decision-making powers behave like a random gas?

To investigate, the team simulated a mosh pit with a few basic rules: the virtual moshers bounce off each other when they collide (instead of sticking or sliding through each other); they can move independently; and they can flock, or follow each other, to varying degrees. Finally, the team added a certain amount of statistical noise to the simulated moshers' movements – "to mimic the effects of the inebriants that the participants typically use", says co-author Matthew Bierbaum.

They found that by tweaking their model parameters – decreasing noise or increasing the tendency to flock, for instance – they could make the pit shift between the random-gas-like moshing and a circular vortex called a circle pit, which is exactly what they saw in the YouTube videos of real mosh pits. Their simulation is available online.

"These are collective behaviours that you wouldn't have predicted based on the previous literature on collective motion in humans," Silverberg says. "That work was geared at pedestrians, but what we're seeing is fundamentally different."

"The fact that human beings are very complex creatures, and yet we can develop a lifeless computer simulation that mimics their behaviour, really tells us that we're understanding something new about the behaviour of crowds that we didn't understand before," says co-author James Sethna.

Lane formation

The team also found a third mosh-pit mode that they hadn't seen on YouTube, which they call lane formation. "If you increase the flocking or decrease the density of the simulated moshers, the active participants can break down the circle and just stream through the crowd," Bierbaum says. "I'd be excited to see this, but it would have to be at a very large venue, so that the ends didn't collide with each other to form a circle pit."

Although the project was mostly for fun, the researchers think it could have real-world implications for crowd animators and architects.

"When you have earthquakes or buildings on fire, people tend to panic when they escape. We don't have a good way of experimentally seeing what's going on," Silverberg says. "By going to these heavy-metal concerts, we're able to ethically and safely observe how humans behave in these unusual excited states."

"That's how we justify it after the fact, by talking about safety," Sethna adds.

The correlation between moshers and random gases "seems very fitting to me", says Jon Freund, drummer in Ithaca-based metal band Thirteen South. "It's kind of the same thing – a pure expression of energy that's just random."

But he says knowing the physics behind it won't change how he moshes – mostly because these days he stays out of the pit. "I'm a hide-on-the-stage-and-play-my-drums mosher," he admits. "I don't want to get hit in the head."

Silverberg notes that the study's main limitation was the quality of the data. "YouTube videos are typically shaky and taken from a poor viewing angle," he says. What's more, staff at venues "tend to baulk when you walk in with a camera". He hopes to convince at least one venue to let him film with a camera suspended over the crowd. "There really is so much to do and so much we don't know yet. It's really just beginning."

Journal reference: arxiv.org/abs/1302.1886

If you would like to reuse any content from New Scientist, either in print or online, please contact the syndication department first for permission. New Scientist does not own rights to photos, but there are a variety of licensing options available for use of articles and graphics we own the copyright to.

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Athletics: Pistorius charged with murder

PRETORIA - South Africa's Olympic sprint star Oscar "Blade Runner" Pistorius has been charged with the Valentine's Day murder of his model girlfriend, police confirmed Thursday ahead of his expected court appearance.

"I can confirm that a suspect has been charged, he has been charged with murder," said Lieutenant-Colonel Katlego Mogale. Officials said there was no other suspect in the case.

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Researchers develop a more accurate car navigation system

Researchers say new navigation system can be installed on any vehicle, including a Volkswagen Touareg.

(Credit:
Josh Miller/CNET)

Driverless cars could get a big boost from a new system that researchers say will increase the accuracy of in-car satellite navigation systems by 90 percent.

Researchers say the system combines conventional GPS signals with data from sensors such as accelerometers and gyroscopes to determine a vehicle's position within six feet of its location, a dramatic reduction from the current margin of error of 50 feet. The system can be installed inexpensively in any vehicle, say researchers at Spain's Universidad Carlos III de Madrid, where the system was developed.

"We have managed to improve the determination of a vehicle's position in critical cases by between 50 and 90 percent, depending on the degree of the signals' degradation and the time that is affecting the degradation on the GPS receiver," David Martín, a researcher at the Systems Intelligence Laboratory, said in a statement describing the project.

The system aims to tackle the greatest challenge faced by conventional GPS systems in urban settings: loss or disruption of satellite signal due to interference created by buildings, trees, and tunnels. The new system uses contextual information and an algorithm that eliminates deviations caused by degradation or loss of signal from satellites.

The researchers have installed a prototype system on an "intelligent
car" with the goal of capturing and interpreting all the information available while driving a car. The team sees applications of the system in driverless car systems currently under development by Google and a handful of automakers.

"Future applications that will benefit from the technology that we are currently working on will include cooperative driving, automatic maneuvers for the safety of pedestrians, autonomous vehicles or cooperative collision warning systems," the team said.

Ultimately, the team hopes to develop a system that harnesses the sensors built in to smartphones, such an accelerometer, a gyroscope, a magnetometer, and GPS, as well as taking advantage of communications tools such as Wi-Fi, Bluetooth, and GSM.

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Are Honeybees Losing Their Way?

A single honeybee visits hundreds, sometimes thousands, of flowers a day in search of nectar and pollen. Then it must find its way back to the hive, navigating distances up to five miles (eight kilometers), and perform a "waggle dance" to tell the other bees where the flowers are.

A new study shows that long-term exposure to a combination of certain pesticides might impair the bee's ability to carry out its pollen mission.

"Any impairment in their ability to do this could have a strong effect on their survival," said Geraldine Wright, a neuroscientist at Newcastle University in England and co-author of a new study posted online February 7, 2013, in the Journal of Experimental Biology.

Wright's study adds to the growing body of research that shows that the honeybee's ability to thrive is being threatened. Scientists are still researching how pesticides may be contributing to colony collapse disorder (CCD), a rapid die-off seen in millions of honeybees throughout the world since 2006.

"Pesticides are very likely to be involved in CCD and also in the loss of other types of pollinators," Wright said. (See the diversity of pollinating creatures in a photo gallery from National Geographic magazine.)

Bees depend on what's called "scent memory" to find flowers teeming with nectar and pollen. Their ability to rapidly learn, remember, and communicate with each other has made them highly efficient foragers, using the waggle dance to educate others about the site of the food source.

Watch as National Geographic explains the waggle dance.

Their pollination of plants is responsible for the existence of nearly a third of the food we eat and has a similar impact on wildlife food supplies.

Previous studies have shown certain types of pesticides affect a bee's learning and memory. Wright's team wanted to investigate if the combination of different pesticides had an even greater effect on the learning and memory of honeybees.

"Honeybees learn to associate floral colors and scents with the quality of food rewards," Wright explained. "The pesticides affect the neurons involved in these behaviors. These [affected] bees are likely to have difficulty communicating with other members of the colony."

The experiment used a classic procedure with a daunting name: olfactory conditioning of the proboscis extension reflex. In layman's terms, the bee sticks out its tongue in response to odor and food rewards.

For the experiment, bees were collected from the colony entrance, placed in glass vials, and then transferred into plastic sandwich boxes. For three days the bees were fed a sucrose solution laced with sublethal doses of pesticides. The team measured short-term and long-term memory at 10-minute and 24-hour intervals respectively. (Watch of a video of a similar type of bee experiment.)

This study is the first to show that when pesticides are combined, the impact on bees is far worse than exposure to just one pesticide. "This is particularly important because one of the pesticides we used, coumaphos, is a 'medicine' used to treat Varroa mites [pests that have been implicated in CCD] in honeybee colonies throughout the world," Wright said.

The pesticide, in addition to killing the mites, might also be making honeybees more vulnerable to poisoning and effects from other pesticides.

Stephen Buchmann of the Pollinator Partnership, who was not part of Wright's study, underscored how critical pollinators are for the world. "The main threat to pollinators is habitat destruction and alteration. We're rapidly losing pollinator habitats, natural areas, and food—producing agricultural lands that are essential for our survival and well being. Along with habitat destruction, insecticides weaken pollinators and other beneficial insects."

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'Blade Runner' Charged With Murder of Girlfriend

Oscar Pistorius, the Olympic and Paralympic athlete known as the "blade runner," was taken into custody in South Africa today and charged with the murder of his girlfriend, who was fatally shot at his home.

Police in the South African capital of Pretoria received a call around 3 a.m. Thursday that there had been a shooting at the home of 26-year-old Pistorius, Lt. Col. Katlego Mogale told the Associated Press. When police arrived at the scene they found paramedics trying to revive 29-year-old Reeva Steenkamp, the AP reported.

At a press conference early Thursday police said that a 26-year-old man, whom they have not named, was arrested and has requested to be taken to court immediately. Police in South Africa do not name suspects in crimes until they have appeared in court.

RELATED: 'Blade Runner' Oscar Pistorius Faster Than a Horse

AP Photo/Matt Dunham, File

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Mogale said that the woman died at the house, and a 9 mm pistol was recovered at the scene and a murder case opened against Pistorius, the AP reported.

Police said this morning that there are no other suspects in the shooting, and that Pistorius is currently at the police station.

The precise circumstances surrounding the incident are unclear. Local reports say he may have mistaken her for a burglar, according to the AP.

Police said that they have heard reports of an argument or shouting at the apartment complex, and that the only two people on the premises were Steenkamp and Pistorius.

Police confirmed there have previously been incidents of a domestic nature at the home of Pistorius.

Pistorius, a sprint runner, had double below the knee amputations, and part of his legs have been replaced with carbon fiber blades. In 2012 he became the first double leg amputee to participate in the Olympics, competing in the men's 400 meter race. He also competed in the Paralympics, where he won gold medals in the men's 400 meter race, in what became a Paralympics record. He also took the silver in the 200 meter race.

Steenkamp, according to her Twitter bio, is a law graduate and model. On Wednesday she tweeted, "What do you have up your sleeve for your love tomorrow??? #getexcited #ValentinesDay."

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Night-vision rat becomes first animal with sixth sense

Douglas Heaven, reporter

The latest bionic superhero is a rat: its brain hooked up to an infrared detector, it's become the first animal to be given a sixth sense.

Developed by Miguel Nicolelis and colleagues at Duke University in Durham, North Carolina, the system connects a head-mounted sensor to a brain region that normally processes touch sensations from whiskers. As shown in this video, the rat's brain is tricked when infrared light is detected, giving it a new sense organ. "Instead of seeing, the rats learned how to touch the light," says Nicolelis.

Even though the touch-processing brain area acquires a new role, the team found that it continues to process touch sensations from whiskers, somehow dividing its time between both types of signal. "The adult brain is a lot more plastic than we thought," says Nicolelis.

The finding could lead to new brain prostheses that restore sight in humans with a damaged visual cortex. By bypassing the damaged part of the brain altogether, it might be possible to wire up a video camera to a part of the brain that processes touch, letting people "touch" what the camera sees.

According to Nicolelis, it could also lead to superhero powers for humans. "It could be X-rays, radio waves, anything," he says. "Superman probably had a prosthetic device that nobody knew of."

If you enjoyed this post,watch a robot and human swap brains to learn teamwork or see a body-sharing robot that lets you experience another place.

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