Scientists have long thought that the burning up of space junk in Earth’s atmosphere creates air pollution that can affect the planet’s climate. Now, for the first time, they’ve managed to detect the presence of these pollutants in the air high above our planet.
A team of researchers flew high-altitude NASA aircraft over Alaska and the U.S. mainland to sample the chemical composition of the thin air in the stratosphere, the second-lowest layer of Earth’s atmosphere, which extends from about 6 miles to 30 miles (10 to 50 kilometers) above the planet’s surface.
The planes, NASA’s WB-57
and ER-2 aircraft, allowed the researchers to reach altitudes of up to 11.8 miles (19 km), which is about five miles (9 km) above the cruising altitude of commercial airliners.
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Sensitive sensors in the nosecones of the planes analyzed the chemical compounds diluted in the thin, pristine stratospheric air, which is out of reach of Earth-based air pollution sources. The researchers found traces of lithium, aluminum, copper and lead in the sampled air. The detected concentrations of these compounds were much higher than what could be caused by natural sources, such as the evaporation of cosmic dust and meteorites upon their encounter with the atmosphere. In fact, the concentrations of these pollutants reflected the ratio of chemical compounds present in alloys used in satellite manufacturing, the researchers said in a statement.
“We are finding this human-made material in what we consider a pristine area of the atmosphere,” Dan Cziczo, a professor of Earth, atmospheric, and planetary sciences at Purdue University in Indiana and one of the authors of the study, said in the statement. “And if something is changing in the stratosphere — this stable region of the atmosphere — that deserves a closer look.”
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