The Radio Astronomy Explorer B (RAE-B) mission was the second of a pair of RAE satellites. It was placed into lunar orbit to provide radio astronomical measurements of the planets, the sun, and the galaxy over the frequency range of 25 kHz to 13.1 MHz.

Explorer 35, also known as the Anchored Interplanetary Monitoring Platform (AIMP-E or AIMP-6) was designed to study interplanetary space phenomena, particularly the solar wind, the interplanetary magnetic field, dust distribution near the Moon, the lunar gravitational field, the weak lunar ionosphere, and the radiation environment.