Orbiting Vehicle 1-9, launched 11 December 1966 along with OV1-10, was the ninth satellite in the OV1 series of the United States Air Force's Orbiting Vehicle program. OV1-9 recorded low frequency radio emissions and particle radiation in Earth's exosphere; the satellite also collected data on the impact of long-term radiation on biological samples and tissue equivalents. OV1-9 returned the first proof that Earth has an electric field.

Orbiting Vehicle 1-10, launched 11 December 1966 along with OV1-9, was the tenth satellite in the OV1 series of the United States Air Force's Orbiting Vehicle program. Designed to observe atmospheric airglow, X-ray and cosmic radiation, OV1-10 returned significant data on the Sun as well as on geophysical phenomena in Earth's magnetic field. OV1-10 reentered Earth's atmosphere on 30 November 2002.