Chinese Plan to Pull an Asteroid into Orbit Around Earth

Last week Chinese scientists wanted to divert an asteroid away from Earth. This week, they want to pull one into orbit around the Earth. What’s possible objections could anyone have to this idea?

The notion stems from a phenomenon the researchers from Tsinghua University in Beijing noticed from time to time with Jupiter. Every now and then our solar systems biggest planet pulls in an object from space, which orbits the planet for a time before jetting off into interplanetary space again.

We could do something similar with a number of near earth objects (NEOs) that will pass near Earth in the coming years and decades. None of these objects will pass close enough to be naturally captured by Earth’s gravity, but a few will come so close that a small nudge in the right direction would put them in orbit--likely a temporary orbit--around Earth.

The idea isn’t simply to flirt with cataclysmic danger, but to bring a small object (they suggest a 10-meter object called 2008EA9 that will pass nearby in 2049) into a loop around the Earth so we can study it closely for a few years. If we can get the art of capturing asteroids orbitally down to a science, we could use it to temporarily make asteroids into Earth-bound satellites (orbiting at about twice the distance of the moon), mine them for minerals, and then send them on their ways.

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Posted in: Chinese Plan to Pull an Asteroid into Orbit Around Earth,danger,earth,idea,interplanetary,objects

Acoustic Cloaking Device Lets Sound Travel Around Objects

A new type of acoustic cloak would allow sound waves to travel around an object unimpeded, and could be used to build better concert halls, quiet spaces and noise-shielding head gear, researchers say.

Much like an optical invisibility cloak works to fool light waves, an acoustic cloak would allow sound waves to travel around an object like water flowing around a smooth rock in a stream. To the sound wave, whose wave form would propagate without obstruction, it would seem as though nothing is present. A noise-canceling system, on the other hand, would create an exact opposite wave form to cancel out the sound wave.

A wave-form-preserving cloak would be useful for objects trying to evade sonar, because it would appear there is nothing for sound waves to hit and bounce back. But it would also have applications in areas where you’d want sound to be preserved or channeled, like a concert hall.

A team of researchers from Valencia, Spain, propose a system of cylinders that work together to allow sound waves to travel uninterrupted. Their design involves 120 separate 15-millimeter cylinders arranged around an object to be cloaked, in this case another cylinder measuring 22.5 centimeters in diameter. A high-pitched sound wave, at 3061 hertz in this case, would maintain its original wave-front pattern as it moved around the object. To the sound waves, then, the 22.5-cm cylinder would be invisible (unhearable?)

The cloak only works in a narrow operating band, but a different frequency would just require a different cylinder setup, according to the researchers. It could conceivably be scaled up to a wide range of frequencies, to create better acoustics in concert halls, quieter public parks and even helmets that protect the ears from loud noises, according to the American Institute of Physics. The system is described in the AIP journal Applied Physics Letters.

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Posted in: device,objects,sound,travel

Static Electricity Still A mistery

Static Electricity Don't try explaining this to children. We don't even fully understand it yet. Just call it "magic."

 Today in the Things We Thought We Understood But Really Don’t file, a Northwestern University researcher has upended what was previously thought to be a pretty good understanding of how static electricity works. Static electricity goes beyond the usual theory that it's a simple imbalance of charges caused by the exchange of ions, the researchers’ paper says. Rather, it is the result of anactual transfer of material.

             Static electricity has been under investigation for a few millennia now, with research dating back to the ancient Greeks. But the Northwestern team wasn’t convinced that everything was as it seemed. So they applied Kelvin probe force microscopy to the problem, which allowed them to see the varying levels of charge distributed unevenly across the surface of objects.

           What they found is that these charges are far less uniform than previously thought, and that clumps of positive and negative charge are strewn unevenly across surfaces. It’s these clumps that are transferred between objects when they come in contact, not just the charges. 

           In normal human language, that means that when you rub a balloon on your hair to make it stand up, there is a small exchange of matter--tiny bits of balloon actually adhere to the hair, disrupting the electrical patchwork on the balloon and causing that strange attraction between it and other objects that we all know as static electricity.

          That matter exchange is proven pretty definitively by this research, but like most discoveries, this one begets more questions. Why do these negative and positive clumps exist, and does knowing that they do exist fully explain the static phenomenon? Scientists still aren’t sure. And that, boys and girls, is why we never stop learning.

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Posted in: charges,electricity,objects,static,surfaces