Pioneer A to E (Pioneer 6 to 9 after launch) were a series of five solar-orbiting, spin-stabilized, solar-cell and battery-powered satellites designed to obtain measurements of interplanetary phenomena from widely separated points in space on a continuing basis. December 16, 1965 at 07:31 UTC · Launch Successful Thor Delta E — United States Air Force, to Heliocentric N/A Space Launch Complex 17A, Cape Canaveral SFS, FL, USA The world's 509th orbital launch attempt, and 116th of 1965. Data: Launch Library 2, The Space Devs. Image by NASA (NASA Image and Media Guidelines) via The Space Devs.