ASSET, or Aerothermodynamic Elastic Structural Systems Environmental Tests was an experimental US space project involving the testing of an uncrewed sub-scale reentry vehicle.

Begun in 1960, ASSET was originally designed to verify the superalloy heat shield of the X-20 Dyna-Soar prior to full-scale crewed flights. The vehicle's biconic shape and low delta wing were intended to represent Dyna-Soar's forward nose section, where the aerodynamic heating would be the most intense; in excess of an estimated 2200 °C (4000 °F) at the nose cap.

Following the X-20 Dyna-Soar programs' cancellation in December 1963, completed ASSET vehicles were used in reentry heating and structural investigations with hopes that data gathered would be useful for the development of future space vehicles, such as the Space Shuttle.

Based on the results of the ASSET program, McDonnell proposed Winged Gemini, a Gemini spacecraft version capable of landing on a runway.

Built by McDonnell, each vehicle was launched on a suborbital trajectory from Cape Canaveral's Pad 17B at speeds of up to 6000 m/s before making a water landing in the South Atlantic near Ascension Island.

Originally, a Scout launch vehicle had been planned for the tests, but this was changed after a large surplus of Thor and Thor-Delta missiles (returned from deployment in the United Kingdom) became available.

Of the six vehicles built, only one was successfully recovered and is currently on display at the National Museum of the United States Air Force in Dayton, Ohio.