The Echo 2 spacecraft was a 41-m balloon of aluminum foil-mylar laminate. Echo 2 was designed as a rigidized passive communications spacecraft for testing propagation, tracking, and communication techniques. January 25, 1964 at 13:59 UTC · Launch Successful Thor SLV-2 Agena B — United States Air Force, to Low Earth Orbit Space Launch Complex 2E, Vandenberg SFB, CA, USA The world's 297th orbital launch attempt, and 4th of 1964. Data: Launch Library 2, The Space Devs.