Nasa Solar Wind Mission encounters 'SLAMS' waves

Earth is surrounded by a giant magnetic bubble called the magnetosphere. 

As it travels through space, a complex system of charged particles from the sun and magnetic structures piles up in front of it. 

Scientists wish to better understand this area in front of the bow shock, known as the foreshock, as it can help explain how energy from the rest of space makes its way past this boundary into the magnetosphere. Nasa Solar Wind Mission.

Credit: NASA/GSFC 

As Earth moves around the sun, it travels surrounded by a giant bubble created by its own magnetic fields, called the magnetosphere.

As the magnetosphere plows through space, it sets up a standing bow wave or bow shock, much like that in front of a moving ship.

Just in front of this bow wave lies a complex, turbulent system called the foreshock. Conditions in the foreshock change in response to solar particles streaming in from the sun, moving magnetic fields and a host of waves, some fast, some slow, sweeping through the region.

To tease out what happens at that boundary of the magnetosphere and to better understand how radiation and energy from the sun can cross it and move closer to Earth, NASA launches spacecraft into this region to observe the changing conditions.

From 1998 to 2002, NASA's Wind spacecraft traveled through this foreshock region in front of Earth 17 times, providing new information about the physics there.

"I stumbled on some cool squiggles in the data," says Lynn Wilson, who is deputy project scientist for Wind at NASA's Goddard Space Flight Center in Greenbelt, Md.

"They turned out to be a special kind of magnetic pulsations called short large amplitude magnetic structures, (SLAMS)."

SLAMS are waves with a single, large peak, a little like giant rogue waves that can develop in the deep ocean.

By studying the region around the SLAMS and how they propagate, the Wind data showed SLAMS may provide an improved explanation for what accelerates narrow jets of charged particles back out into space, away from Earth.

Tracking how any phenomenon catalyzes the movement of other particles is one of the crucial needs for modeling this region.

In this case, understanding just how a wave can help initiate a fast-moving beam might also help explain what causes incredibly powerful rays that travel from other solar systems across interstellar space toward Earth.

Wilson and his colleagues published a paper on these results in the Journal of Geophysical Research online on March 6, 2013.

The material pervading this area of space – indeed all outer space – is known as plasma. Plasma is much like a gas, but each particle is electrically charged so movement is governed as much by the laws of electromagnetics as it is by the fundamental laws of gravity and motion we more regularly experience on Earth.

"One of the unique things about space weather is how little things can have big effects," says David Sibeck, a space scientist at Goddard who is a co-author on the paper.

"An event might seem small and just generate local turbulence, but it can have profound effects downstream.

The front of the magnetosphere is right in the line between sun and Earth, so it's a crucial place to understand which small things can lead to big results."

Since the 1970s, researchers have known that particles seem to be reflecting off the magnetosphere, creating intense particle jets called field aligned ion beams, but it's not been clear how.

Now, the Wind data helps provide a more detailed snapshot of how they form, as it travels through a slew of SLAMS and the ion beams.

The scientists' job was to map where these events happen in space and time and to try to determine which events initiate which.

Wilson says that the solar wind constantly moves toward Earth's bow shock and then reflects off it.

"What happens to Earth's magnetic field depends on what's happening here at the front of the bow shock," says Sibeck.

"And what's happening there is dramatic. It's going to affect how much energy moves into the magnetosphere. Once inside the magnetosphere, it can create powerful solar storms and impact communications and GPS satellites that we depend on daily."

Venice: Curly Pasta shaped Radiowaves to solve congestion

A group of Italian and Swedish researchers appears to have solved the problem of radio congestion by cleverly twisting radio waves into the shape of fusilli pasta, allowing a potentially infinite number of channels to be broadcast and received.

the researchers have demonstrated this in real-life conditions by beaming two twisted radio waves across the waters of Venice.

Their results have been reported today, Friday 2 March, in the Institute of Physics and German Physical Society's New Journal of Physics and are accompanied by a video abstract that gives an excellent insight into the authors' work.

As the world continues to adapt in the digital age, the introduction of new mobile smartphones, wireless internet and digital TVs means the number of radio frequency bands available to broadcast information gets smaller and smaller.

"You just have to try sending a text message at midnight on New Year's Eve to realise how congested the bands are," said lead author Dr Fabrizio Tamburini.

The researchers, from the University of Padova, Italy, and the Angstrom Laboratory, Sweden, devised a solution to this by manipulating waves so that they can hold more than one channel of information.

In addition to increasing the quantity of information being passed around our planet, this new discovery could also help lend an insight into objects far out in our galaxy. Black holes, for example, are constantly rotating and as waves pass them, they are forced to twist in line with the black hole.

According to Tamburini, analysing the incoming waves from the supermassive black hole at the centre of the Milky Way, Sagittarius A, could help astronomers obtain crucial information about the rotation of this "million-solar mass monster."

More information: "Encoding many channels on the same frequency through radio vorticity: first experimental test" Tamburini F et al 2012 New J. Phys. 14 033001 - http://iopscience. … 3001/article

Gravity defying Robotic Insect

Winged flight, or simply fly-by-wire? (Image: South West News Service / Rex Features)

CREATING a free-flying robotic insect is the dearest wish of many an engineer because such a machine would have great potential in surveillance and in seeking out trapped people in search-and-rescue situations. But a curious effect might upset their plans.

Last year, a team at Harvard University released a video demonstration of a robotic fly they had developed, showing it flapping its wings and levitating up a pair of guide wires.

Fly by Wires

But Michele Milano of Arizona State University in Tempe wondered whether the wing motion was entirely responsible for giving the robot lift, or whether some other force was involved. "The video showed that the guide wires were vibrating significantly when the wings beat," he told New Scientist.

Lift without Wings

To find out if these vibrations played a role in the fly's upward motion, his team built a vibrating model "insect" with no wings. The balsa-wood contraption consisted of a motor with an off-centre weight on its spindle that produced vibrations, and four metal tubes through which vertical guide wires were threaded (see Diagram). When they set the motor running, the team discovered that the model moved up the wires despite having no wings. They've dubbed it the "flying brick".

Traveling waves

The researchers suspect that the vibrating motor sets off traveling waves in the guide wires, rather like those produced by plucking guitar strings. Each vibration cycle produces a kink in the wires above the model, which forces the model to travel upwards.

Movements of up to 5 centimetres were seen, depending on the wires' tension and the diameters of both the wires and the tubular connectors. The greatest "flight" effect was achieved when the vibration frequency matched the resonant frequency of the wires (IEEE Transactions in Robotics, vol 25, p 426).