A US military sounding rocket. The most successful sounding rocket of the space age, it could lift 45 kg of scientific instruments to an altitude of 121 km. Aerobee was developed by the Office of Naval Research and the Applied Physics Laboratory of Johns Hopkins University, and produced by Aerojet General for the US military. The many versions included the Aerobee-Hi and Aerobee 350. When the programme ended in 1985, 1 058 rockets had been launched. The second-stage motor of the Vanguard rocket was based on the Aerobee-Hi.