'Heartbeat' of Earth

Lightning flashes in the skies above the Earth about 50 times every second, creating a burst of electromagnetic waves that circle around the planet's atmosphere.

Some of these waves combine and increase in strength, creating something akin to an atmospheric heartbeat that scientists can detect from the ground and use to better understand the makeup of the atmosphere and the weather it generates.

For the first time, scientists have detected this heartbeat — called the Schumann resonance — from space. This detection was surprising because the resonance was thought to be confined to a particular region of the atmosphere, between the ground and a layer of Earth's atmosphere called the ionosphere.

"Researchers didn't expect to observe these resonances in space," said Fernando Simoes, a scientist at NASA's Goddard Space Flight Center in Greenbelt, Md. "But it turns out that energy is leaking out and this opens up many other possibilities to study our planet from above."

Simoes co-authored a study on the detection of this resonance made by the U.S. Air Force's Communications/Navigation Outage Forecast System (C/NOFS) satellite.

   How resonance works

Simoes explains the resonance phenomenon like this: Think of a playground swing. If you push the swing just as it hits the top of its arc, you add speed. Push it backwards in the middle of its swing, and you will slow it down.

When it comes to waves, resonance doesn't occur because of a swing-like push, but because a series of overlapping waves are synchronized such that the crests line up with the other crests and the troughs line up with the other troughs. This naturally leads to a much larger wave than one where the crests and troughs cancel each other out.

The waves created by lightning do not look like the up-and-down waves of the ocean, but they still oscillate with regions of greater energy and lesser energy.

These waves remain trapped inside an atmospheric ceiling created by the lower edge of the ionosphere, which is filled with charged particles and begins about 60 miles (96 kilometers) up into the sky.

The resonance of the lightning-generated waves will only happen in a certain sweet spot where the wave is at least (or twice, three times, etc.) as long as the circumference of Earth.

This is an extremely low-frequency wave that can be as low as 8 Hertz (Hz) — some one-hundred-thousand-times lower than the lowest-frequency radio waves used to send signals to an AM/FM radio.

As this wave flows around Earth, it hits itself again at the perfect spot such that the crests and troughs are aligned, causing the waves to act in resonance and pump up the original signal.

   A new tool

While they'd been predicted in 1952, Schumann resonances weren't reliably measured until the 1960s. Since then, scientists have discovered that variations in the resonances correspond to changes in the seasons, solar activity, activity in Earth's magnetic environment, in water aerosols in the atmosphere and other Earth-bound phenomena.

"There are hundreds, maybe thousands, of studies on this phenomenon and how it holds clues to understanding Earth's atmosphere," said study co-author and Goddard scientist Rob Pfaff. "But they're all based on ground measurements."

The C/NOFS satellite measured them from altitudes of 250-to-500 miles (400–to-800 km). The team found the resonance showing up in almost every orbit C/NOFS made around Earth, which added up to some 10,000 examples.

While models suggest that the resonances should be trapped under the ionosphere, energy has been known to leak through. The findings meant the models will need to be tweaked to account for the leaky boundary, and also that there is a new tool for understanding the ionosphere as well as the electric events in the atmosphere.

"Combined with ground measurements, it provides us with a better way to study lightning, thunderstorms and the lower atmosphere," Simoes said. "The next step is to figure out how best to use that tool from this new vantage point."

More about Schumann Resonance - NASA

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Lab Creates Life With 'Alien' DNA

Organisms carrying beefed-up DNA code could be designed to churn out new drugs that could not otherwise be made

It's alive! Scientists say that they have created the first living organism with synthetic DNA unlike that of any life that has ever existed on Earth.

The first living organism to carry and pass down to future generations an expanded genetic code has been created by American scientists, paving the way for a host of new life forms whose cells carry synthetic DNA that looks nothing like the normal genetic code of natural organisms.

Researchers say the work challenges the dogma that the molecules of life making up DNA are "special". Organisms that carry the beefed-up DNA code could be designed to churn out new forms of drugs that otherwise could not be made, they have claimed.

The latest study moves life beyond the DNA code of G, T, C and A – the molecules or bases that pair up in the DNA helix. Photograph: Scott Camazine /Alamy

"This has very important implications for our understanding of life," said Floyd Romesberg, whose team created the organism at the Scripps Research Institute in La Jolla, California. "For so long people have thought that DNA was the way it was because it had to be, that it was somehow the perfect molecule."

From the moment life gained a foothold on Earth the diversity of organisms has been written in a DNA code of four letters. The latest study moves life beyond G, T, C and A – the molecules or bases that pair up in the DNA helix – and introduces two new letters of life: X and Y.

Romesberg started out with E coli, a bug normally found in soil and carried by people. Into this he inserted a loop of genetic material that carried normal DNA and two synthetic DNA bases. Though known as X and Y for simplicity, the artificial DNA bases have much longer chemical names, which themselves abbreviate to d5SICS and dNaM.

In living organisms, G, T, C and A come together to form two base pairs, G-C and T-A. The extra synthetic DNA forms a third base pair, X-Y, according to the study in Nature.

Romesberg found that when the modified bacteria divided they passed on the natural DNA as expected. But they also replicated the synthetic code and passed that on to the next generation. That generation of bugs did the same.

"What we have now, for the first time, is an organism that stably harbours a third base pair, and it is utterly different to the natural ones," Romesberg said. For now the synthetic DNA does not do anything in the cell. It just sits there. But Romesberg now wants to tweak the organism so that it can put the artificial DNA to good use.

                                                                      Floyd Romesberg

"This is just a beautiful piece of work," said Martin Fussenegger, a synthetic biologist at ETH Zurich. "DNA replication is really the cream of the crop of evolution which operates the same way in all living systems. Seeing that this machinery works with synthetic base pairs is just fascinating."

The possibilities for such organisms are still up for grabs. The synthetic DNA code could be used to build biological circuits in cells which do not interfere with the natural biological function; scientists could make cells which use the DNA to manufacture proteins not known to exist in nature. The development could lead to a vast range of protein-based drugs.

The field of synthetic biology has been controversial in the past. Some observers have raised concerns that scientists could create artificial organisms which could then escape from laboratories and spark an environmental or health disaster.

More than 10 years ago, the scientist Eckard Wimmer, at Stony Brook University, in New York, recreated the polio virus from scratch to highlight the dangers.

Romesberg said that organisms carrying his "unnatural" DNA code had a built-in safety mechanism. The modified bugs could only survive if they were fed the chemicals they needed to replicate the synthetic DNA. Experiments in the lab showed that without these chemicals, the bugs steadily lost the synthetic DNA as they could no longer make it.

                                                     Escherichia coli under the microscope

"There are a lot of people concerned about synthetic biology because it deals with life, and those concerns are completely justified," Romesberg said. "Society needs to understand what it is and make rational decisions about what it wants."

Ross Thyer, at the University of Texas, in Austin, suggested the synthetic DNA could become an essential part of an organism's own DNA. "Human engineering would result in an organism which permanently contains an expanded genetic alphabet, something that, to our knowledge, no naturally occurring life form has accomplished.

"What would such an organism do with an expanded genetic alphabet? We don't know. Could it lead to more sophisticated storage of biological information? More complicated or subtle regulatory networks? These are all questions we can look forward to exploring."

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