Some of them were involved in the expanding scientific assault upon space. Others were hoping to develop lighter, simpler, or more versatile aircraft to fly in the same realm as the X-15, and wanted it as a testing ground for their ideas. Because of these various interests, the X-15 program began to take on a new character. Some of these experiments change the X-15 from a research airplane to a kind of space probe, such as Vanguard or Pioneer. Other experiments are pertinent to the development of supersonic transports and Mach 10 aircraft.
Several tests are underway and many more are planned.
Another study will include tests of heat exchangers under weightless conditions to verify performance analysis. A new type of supersonic decelerator for the recovery of payloads from space will also be evaluated. The X-15 program is also capable of opening some windows in the atmosphere that shrouds the Earth. Satellites are thoroughly exploring the region above 100 miles. Balloon-borne instruments continue to probe the region below 20 miles.