Vanguard II is an Earth orbiting satellite and the first weather satellite. It was designed to measure cloud-cover distribution over the daylight portion of its orbit for a period of 19 days and to provide information on the density of the atmosphere. February 17, 1959 at 15:55 UTC · Launch Successful Vanguard — US Navy, to Medium Earth Orbit Launch Complex 18A, Cape Canaveral SFS, FL, USA The world's 33rd orbital launch attempt, and 2nd of 1959. Data: Launch Library 2, The Space Devs. Image by NASA (NASA Image and Media Guidelines) via The Space Devs.