SERT (Space Electric Rocket Test)
Early NASA suborbital and orbital tests of the performance
of electron-bombardment ion engines.
SERT 1 flew on a 30-minute suborbital mission, launched by a Scout X-4 from
Wallops Island, on Jul. 20, 1964. SERT 2, which also studied how prolonged
operation of such engines affect other spacecraft systems, entered a 1,040km-high
orbit on Feb. 4, 1970, having been launched by an LT Thor-Agena D from Vandenberg
AFB. The two engines on SERT 2 ran, on and off, for about a decade.