ASSET (spacecraft)

ASSET, the Aerothermodynamic Elastic Structural Systems Environmental Tests program, was a series of small unmanned United States Air Force spaceplane test vehicles. It began in 1960 as one part of the Dyna-Soar project and was intended to flight test materials, heat shields and structures on subscale models before full-scale crewed flights. After Dyna-Soar was cancelled in 1963, the flights continued. There were six launches between 18 September 1963 and 23 February 1965, using surplus Thor missiles for the 4,000 meter per second flights and Thor-Delta boosters for the 6,000 meter per second flights. The vehicles flew suborbital trajectories to a recovery zone near Ascension Island. Two variants flew: the aerodynamic elastic vehicle and the aerothermodynamic structural test vehicle used for heat shield trials. Some observers have argued that its bi-conic shape with a low swept wing made it closer to a Winged Gemini concept than to a true model of the X-20.