The scientists launched 10 flights of small electric aircraft, equipped with cameras and sensors, into the volcanic plume of the Turrialba Volcano near San Jose, Costa Rico, the space agency reported Monday.
The project is intended to improve remote-sensing capabilities of satellites and computer models of volcanic activity, researchers said.
"It is very difficult to gather data from within volcanic eruption columns and plumes because updraft wind speeds are very high and high ash concentrations can quickly destroy aircraft engines," said researcher David Pieri from NASA's Jet Propulsion Laboratory in Pasadena, Calif.
"Such flight environments can be very dangerous to manned aircraft. Volcanic eruption plumes may stretch for miles from a summit vent and detached ash clouds can drift hundreds to thousands of miles from an eruption site."
The Dragon Eye UAVs, formerly used by the U.S. Marine Corps, used in the study weigh 5.9 pounds, have a 3.75-foot wingspan and utilize twin electric engines that ingest little contaminated air, the researchers said.
"This project is great example of how unmanned aircraft can be used for beneficial civilian purposes -- in this case for better understanding Earth system processes and the impact of volcanism on our atmosphere, said Matthew Fladeland of NASA's Ames Research Center at Moffett Field, Calif.
"By taking these retired military tools, we can very efficiently and effectively collect measurements that improve NASA satellite data and aviation safety."
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