The Perlan Project is making engineless gliders that ride on airwaves from mountain ranges.  These gliders will fly up to 90,000 feet, much higher than normal airplanes today.  Their second glider is being tested in Nevada before it will be shipped to Argentina.  The glider has a moderately sized cabin and very long wings giving it the ability to smoothly catch the airwaves that are produced by mountain ranges.  The Perlan 2 will be brought to southern Patagonia where it will attempt to break the record and fly 90,000 feet, where the air is so thin that it is said to be more like flying on Mars than on Earth.  The glider is said to help us learn about flight on Mars.  This may lead to discoveries on new planets and even discoveries of new planets.  

http://news.discovery.com/space/private-spaceflight/glider-to-surf-the-sky-to-the-edge-of-space-160516.htm