Shrinking moon may explain lunar quakes

The moon has shrunk in the past billion years, and may still be shrinking today, triggering moonquakes and making the moon a more active body than previously thought.

The shrinkage has wrinkled parts of the moon's surface like a raisin, creating pinched formations called lobate scarps.

Apollo astronauts imaged some of these wrinkles near the moon's equator 40 years ago. Now, new images from NASA's Lunar Reconnaissance Orbiter (LRO) have revealed 14 more. Some of these lie near the poles, showing that the scarps occur all over the moon's surface.

Thomas Watters of the Smithsonian Institution in Washington, DC, and colleagues say the wrinkles likely formed as the moon cooled and contracted.

The features are surprisingly recent, having formed no more than 1 billion years ago. That estimate is based on the fact that they partly destroyed some pre-existing small craters that seem to be no more than 1 billion years old. "The moon may still be geologically and tectonically active and still shrinking today," Watters said in a teleconference with reporters on Thursday.

Growing pains

If so, the wrinkles might still be growing, and the contraction might have triggered some of the moonquakes recorded by seismometers placed on the moon in the 1970s by NASA astronauts, he said.

He and his colleagues are planning to see if the wrinkles have grown in the past few decades by comparing LRO images with those taken by Apollo astronauts.

The team calculates that the moon's diameter has shrunk by just 200 metres in the last billion years, suggesting the amount of recent cooling has been relatively small, he says. Mercury also has wrinkles, but they are "humungous", suggesting it has experienced much more cooling in its lifetime than the moon, he said.

The moon's rate of cooling is affected by its interior structure and composition, so the new data might teach us something about the moon's innards, said Patrick McGovern of the Lunar and Planetary Institute in Houston, Texas, who was not involved in the study.

Journal reference: Science, DOI: 10.1126/science.1189590

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A Car for the Modern Fred Flintstone

Fred Flintstone could only dream of such a car. The HumanCar Imagine PS, a four-seater vehicle that uses hand cranks, can take on hills at 30 miles per hour, exceed 60 mph on flat terrain and is expected to hit the market next year.

The vehicle has electric plug-in capabilities, so it can still run if only one person is operating the hand-crank in a rowing-like motion (see the video showing the action, below). When four people are all rowing, it can run on human power alone. This thing is truly a "human-electric" hybrid. The chassis is adaptable, and can work with different kinds of batteries and technology in the future without requiring an entirely new vehicle.

Getting it going looks a little bit like those wind-up toys: a few front-to-back pulls on the two-hand crank and it's ready to take off. Despite the physical requirement, the company says online that a senior citizen in decent shape could handle it and paraplegics have made suggestions on adaptability. The sleek vehicle could use a larger windshield, although there is apparently an all-weather shell available. Airbags are on the list to be included in future models. In the meantime, I'd probably wear a helmet while driving it.

Others have been hard at work on human powered cars, too. The American Society ASME runs an annual international Human Powered Vehicle Challenge, where students build aerodynamic vehicles. Next month teams will compete in Venezuela. Based on speed-endurance events that took place this year, the vehicles' top speeds are closing in on 20 miles per hour.

Higher speeds make the Imagine PS impressive. I can hardly get any miles per hour going uphill on a bike. Zooming uphill using my own energy looks so much more enjoyable. The car will cost $15,500 when it goes on sale next year, according to the HumanCar site. Potential owners can put down a refundable $50 placeholder for when the vehicles become available. So far, the company says it has 100 pre-orders and that production will begin when they reach 800.

Source <news.discovery.com>

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Invisibility Cloak Made From Silk

For thousands of years people have worn shimmering silk to stand out in a crowd. Within the next few years people could wear silk to become invisible in a a crowd.

For the first time ever, scientists have created an invisibility cloak made from silk, and coated in gold.

The new metamaterial, as invisibility cloaks and their kin are technically called, only works on relatively long terahertz waves (a region of the electromagnetic spectrum between radio and infrared light), but the Boston-area scientists who developed the technology think that silk could work as an invisibility cloak at much smaller wavelengths, even in the visible range.

The research could lead to a wide range of optically unique materials for use in biomedicine or defense.

"This is an unusual angle for a metamaterial because of silk's ability to interface with the human body," something that no other metamaterial is currently capable of, said Fiorenzo Omenetto, a scientist at Tufts University who, along with colleagues at Boston University, helped develop the silk-based metamaterial and detail their new research in the journal Advanced Materials.

"On the sensing side it gives you a platform that is very adaptable."

Invisibility cloaks, along with their optically exotic cousins, perfect absorbers and perfect reflectors and others, belong to a special class of materials known as metamaterials. Unlike most materials, which derive optical properties like color from their chemical make up, metamaterials derive their properties from the physical structure.

A curly cue, or short spiral, is a common metamaterial structure. Scientists call them split ring resonators, or SSRs. Usually scrawled into metals, SSR can give ordinary materials extraordinary abilities, like absorbing or reflecting all the specific wavelengths of light, or bending a wavelength around an object.

To create their silk-based metamaterial, the Tufts and Boston University scientists, including Richard Averitt, started with a one-centimeter-square piece of silkworm silk. (In another recent paper, Omenetto's colleague and another co-author of the Advanced Material's paper, David Kaplan of Tufts, created silk-producing bacteria.) Onto that tiny piece of dielectric silk they stenciled 10,000 gold resonators.

Ordinarily when silk is exposed to terahertz waves they pass straight through it. When the new silk metamaterial was subjected to T-rays the scientists detected a resonance.

A metamaterial that works in the terahertz range is nothing new. But, unlike other metamaterials, silk is biocompatable -- the human body won't reject silk-based implants the way it does with most other materials. The scientists implanted the patterned silk into a muscle, and still detected a resonance.

The new silk research is "interesting," said Douglas Werner, a metamaterial scientist at Pennsylvania State University. "There is a lot of interest in using flexible substrates for metamaterials, and silk is a good candidate for that."

The potential applications of silk-based invisibility are huge. Omenetto and his colleagues at Tufts aren't even focused on Harry Potter or Star Trek-style invisibility materials, although he says that is one potential application.

Their main focus is in biomedical applications. One of the first biomedical uses could be as an implantable glucose sensor for diabetics. As the level of glucose changes inside the body, it changes the silk. Then as the silk changes, do does the metamaterial printed on the silk. That change would then be relayed to the person's cell phone; no needle prick necessary.

Silk-based invisibility would also allow doctors and radiologists to cloak various organs or tissues and see through them, said Omenetto, getting a better image of the organs or tissues usually hidden behind.

Source <news.discovery.com>

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Brazil air force to record UFO sightings

Brazil's government has ordered its air force to officially record any sighting of unidentified flying objects.A government decree said all military and civilian pilots as well as air traffic controllers should register any UFO sightings with the national aerospace defence command.

The information will be stored in the national archives in Rio de Janeiro.It will be made available to researchers, including those seeking evidence of extraterrestrial life.Anything unusual that is seen, photographed or video filmed in Brazil's air space will now have to be reported and catalogued.

But the air force said it would limit itself to collecting information, and would not be chasing UFOs."Air force command does not have a specialized structure to carry out scientific experiments on these phenomena and will limit itself to recording any events" the air force said in a statement."Any unexplained atmospheric event is worthy of at least being keep track of"

There have been several reports of UFOs in Brazil in recent decades.In 1986, air force jets were scrambled to investigate unidentified objects in the skies above Sao Paulo, but the phenomenon was never fully explained.And in 1977 the Amazon town of Vigia asked for military help after some residents said they had been attacked by extra-terrestrials.One anonymous air traffic controller told the Brazilian newspaper O Dia that sightings had been reported at the highest level."I have heard of ministers and even a president who said they had seen a UFO", he said.

Brazilian UFO watchers have welcomed the decision to make such information public in future.

Source <www.bbc.com>

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