Gliders are light aircraft that fly with no engine. They are pulled by a powered plane into the sky and set free to fly on air currents. They soar on wind currents called "mountain waves." That is why their wings are longer than ordinary planes.

　　The aerospace company Airbus Group recently completed the first flight of a glider it calls Perlan 2. The Perlan Project intends to use gliders to take measurements in the stratosphere. Scientists believe weather in the stratosphere affects the Earth's climate more than they thought before.

　　Airbus plans to send Perlan 2 to an altitude of 27 kilometers next year. That is higher than the records set by the U-2 and SR-71 spy planes.

　　Jim Payne is the chief pilot of Perlan 2.

　　"We're not a thousand percent sure that the mountain wave will go that high, but all the meteorologists tell us that it does, so we're going to go out and find out."

　　Ed Warnock is the chief executive officer of the Perlan Project.

　　He says the project intends to discover how fast moving winds at altitudes between 10 and 50 kilometers influence the earth's climate.

　　"It turns out some of the biggest waves in the world -- vertical movements -- exist in the stratosphere. We're going to go and study those waves. Those waves change weather and they change climate, and we are going to study how do they do that."

　　Stratospheric winds may also influence commercial air traffic. Many airplanes fly at high altitudes to reduce fuel consumption.

　　The air density, or thickness, at those altitudes is similar to the atmosphere on the planet Mars. This may lead to future aircraft designs that could someday fly through the skies of the Red Planet.

　　I'm Jonathan Evans.

　　VOA's George Putic wrote this story from Washington. Jonathan Evans adapted it for Learning English. Kathleen Struck was the editor.