https://perlanproject.org/missions wrote:
<<From 1992-98, NASA test pilot Einar Enevoldson collected evidence on a weather phenomenon that no one at the time even knew existed:
stratospheric mountain waves. Like huge ocean waves, these waves of air are kicked off by strong winds blowing over the tops of high mountain ranges like the Andes. These waves of air then shoot straight up towards space. As a pilot, Einar quickly figured out that you can use a glider to ride those waves all the way up to near space. And he set out to prove it. This became The Perlan Project.
In 1998 meteorologist Dr. Elizabeth Austin teamed up with Einar and expanded upon his findings proving that
it is the stratospheric polar night jet and the polar vortex that are factors in sustaining these mountain waves allowing them to reach up to 130,000 feet (39,624 metres).
In 1999 Steve Fossett, the record-setting aviator, sailor, adventurer and first person to fly solo non-stop around the world in a balloon, decided to fund Perlan Mission I and became one of its pilots. On August 30, 2006 Steve Fossett and Einar Enevoldson flew (Perlan Mission I) a modified DG-505m aircraft (Perlan 1), to 50,722 ft (15,460 m) breaking the previous record by 1,662 ft (507 m).
And they could have gone even higher!
The problem was that their pressure suits expanded so much inside the cabin that they could not move the flight controls and safely control the aircraft anymore. Therefore, they came down, and quickly decided they needed a custom glider with a pressurized cabin.
Based on the complete success of Perlan Mission I, proving Enevoldson’s thesis, Steve agreed to fund Perlan Mission II, building a pressurized cabin for a special sailplane to fly to 90,000 feet (27,432 meters).
On September 3, 2007, Steve Fossett disappeared while flying over the Sierra Nevada Mountains and his death was eventually confirmed. At the time of Steve’s passing, the structural and aerodynamic design of the fuselage of Perlan 2 had been completed, along with the aerodynamic design of the entire sailplane (glider). Unfortunately, both Steve Fossett and the funding for completion of Perlan Mission II were lost.>>