What differences might an airport runway and landing differences have on Mount Everest for airplanes at 30,000ft? The drawn line in the pictures is about 2 miles. This would be practical for hand gliding, skiing, base jumping, shortcut to the top, and other exotic fun.
At 90,000 feet, the Perlan 2 must be engineered to fly in less than 3% of normal air density and at temperatures of -70°C. The mission will harvest invaluable data for scientists worldwide to help update and improve existing climate models.
30,000 feet is just an appetizer for this awesome glider. The gliders will start at low alititude being towed by planes, then coast upwards as gliders do. They are not fast moving craft and landing at altitude should poise no particular difficulty. Ideally the landing strip is over a cliff, so on returning the glider can just fall over the edge of clif and glide away.
30,000 feet is above the service ceiling of most aircraft: helicopters tend to top out around 10,000-15,000 feet, piston-engine aircraft are usually limited to 25,000 or so, and even turboprops rarely venture that high. The only aircraft that could theoretically operate out of your airport are turbofan-powered jets.
So let's say you wanted to land a Boeing 737 at your high-altitude airport: how fast would it be going? Boeing doesn't publish performance charts for altitudes that high, but we can estimate based on known performance.
There's a useful measurement called "calibrated air speed": it's a measure of how much air is moving past the airplane, so it's independent of things like altitude and temperature. The target landing CAS of a 737 is roughly 150 knots, and we can use standard correction formulas to figure out what the true speed is at 30,000 feet and average temperatures. Turns out, in order to land in calm air, your 737 is going slightly over 240 knots across the ground -- a bit faster than the wheels are rated for.