The USAF ASSET research program was the first phase of the Spacecraft Technology and Advanced Re-entry Tests (START) involving the testing of an unmanned subscale reentry vehicle.

The ASSET vehicles were built by McDonnell Aircraft Corp. Six were launched on Thor boosters rockets during 1963-1965. The McDonnell ASSET vehicle had a maximum speed of Mach 25. Only one of the six ASSET vehicles (ASV-3) was recovered following the test flights above the Atlantic Ocean and it is on display at the Museum of the USAF.

Lessons learned from the ASSET program eventually found their way to the Space Shuttle Orbiter.