A team of researchers from the Sandia National Laboratory has developed simple and cheap solar-powered balloons that can be made for less than USD 50 from conventional building materials. Balloons were launched to a height of more than 20 km to the border with the stratosphere. This region is relatively calm and free from storms, turbulence and commercial air traffic, which means that microphones in this layer of the atmosphere can eavesdrop on the sounds of our planet, both natural and man-made. But scientists were very surprised by what they heard there.
In the stratosphere, balloons collected data using micro-barometers, designed mainly for monitoring volcanoes. Special low-frequency microphones on board are able to capture and record the usual sounds of nature and human activity; however, the team of scientists also caught unidentified sound. The sounds were recorded in the infrasound range, that is, they were at frequencies of 20 Hz and below, well below the range of the human ear. “[In the stratosphere,] there are mysterious infrasound signals that occur a few times per hour on some flights, but the source of these is completely unknown,” Bowman said.
Cheap balloons will explore space
The balloons are cost-effective and easy to manufacture and launch, which allows to collect a huge amount of data by releasing numerous balloons. They are made of painter’s plastic and tape, have a diameter of 7 meters and can be placed on a basketball court. The balloons do not require any energy sources other than sunlight, and can relatively easily rise to a height of 21 kilometers. The balloons were designed to lift scientific cargo into the stratosphere.
In the future, the researchers note, solar-powered balloons can help explore other planets, for example, observe the seismic and volcanic activity of Venus through its thick atmosphere.
Earlier we reported on how the private Spaceship Neptune would offer passengers a lounge area with a bathroom and champagne.
According to Interesting Engineering
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