Scientists Yell at Clouds, Also Shoot Lasers at Them

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Could satellites perform better if we ... cleared tubes in the sky using powerful lasers? Researchers from the U.S. and Switzerland say this evil genius-like strategy could improve optical data transmission by reducing cloud interference. The results, they say, are the “fiberless” counterpart to fiber—the way wireless revolutionized wired internet.

 

The major proposed use case for so-called fiberless fiber is for objects in space to transmit and receive messages from Earth. But it could also revolutionize what we think of as satellite internet and any other communication that’s beamed to and from satellites every day. While NASA engineers built an existing station in 2013, without “weather control,” they had to build multiple stations in order to cast the best odds of a successful transmission. Wired reports:

 

“uccessful downlinks through Earth’s atmosphere depend on the weather. Like a mob of tiny shadow puppets, cloud and fog droplets will dim and scatter the laser’s signal. To beat the clouds during the LLCD mission, NASA engineers had to build three receiver sites on Earth, of which two were usually in the line of sight between the spacecraft and the moon.”

 

The theory is simple: instead of waiting for a cloud to clear, use a rapidly pulsing laser to ensure a clear route through the cloud. The laser pulses are intensely powerful and cause rapid chemical changes within the molecules of fog or cloud, and the clear path is created by a sonic boom on the molecular level. Unlike a classic punch cloud made by an aircraft, the process is finely tuned and “brighter than 10 trillion suns,” Wired reports.

 

For now, demonstrations are limited to very small scale, but researchers say they’re prepared to clear channels up to 100 meters long, which can then be chained. Different lasers have shown promise in reaching lengths into the kilometers. Researcher Malte Schröder colloquially calls the process “weather control,” but the paper describing his team’s work has the technical term: molecular quantum wakes.

 

Previous work on clearing fog in this way used powerful photon beams (lasers) to turn the foggy air into plasma, which generated the shockwave that cleared the channel. “However, for practical applications like free-space optical communication (FSO), channels of multi-centimeter diameters over kilometer ranges are required, which is extremely challenging for a plasma based method,” the team writes:

 

“Here we report a radically different approach, based on quantum control. We demonstrate that fog clearing can also be achieved by producing molecular quantum wakes in air, and that neither plasma generation nor filamentation are required.”

 

By carefully controlling the photon pulses, the researchers can harness “rotational heating” that has the same effect as the plasma version. “[N]either ionization nor filamentation are required to produce a fog clearing acoustic wave, as they can be substituted by quantum controlled rotational heating in air,” they conclude.

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