There are only a few airplanes (that we know of) that can fly at 70.000 feet or above. The SR71 Blackbird has logged at least one flight at just over 85,000 feet (July, 1976)  and the The X-43A flies at 100,000 feet while still using an air-breathing engine (not a rocket) . But only one plane routinely flies to the edge of space and back, and it’s actually a relic from the 1950’s. Although each plane is periodically stripped completely, x-rayed, and refurbished, the design has remained essentially the same over all these decades. Why? Because it works.
The US Air Force U-2 high-altitude reconnaissance aircraft first flew in 1955 and was developed by Lockheed Martin at the famous Skunk Works site, and built at Area 51. The aircraft provides continuous surveillance day and night and in all weathers. The aircraft can gather surveillance and signals intelligence data in real time and can be deployed anywhere in the world.
The U-2, which is known as the Dragon Lady, can loiter at 70,000ft (21,336m) over the area of operations for several hours and is often described as a glider due to its flight characteristics.
The design has remained essentially unchanged over decades of operational deployment but the reconnaissance systems are constantly upgraded with state-of-the-art and classified systems.
The last U-2 was delivered in 1989 and there are 32 U-2S aircraft in the US Air Force fleet. 
The following video is an excellent documentary on this plane, her crews, and the conditions under which she flies. Let it spark your imagination.