Explorer (S-55)

S-55 was an American satellite launched by NASA on 30 June 1961 as part of the Explorers program. Explorer (S-55), also known as Meteoroid Sat A, was launched using a Scout_X-1 rocket from the Wallops Flight Facility. Its mission was to evaluate the launch vehicle, and investigate micro meteoroid impact and penetration. The mission failed because the third stage failed to ignite and the spacecraft did not achieve orbit.