The 50th Anniversary of the Space Age

October 4, 2007 marked the 50th anniversary of the Space Age when the former Soviet Union launched the Sputnik 1 satellite on Oct. 4, 1957. With the launch of Sputnik, imagination became reality, because space travel was finally possible. The U.S. responded with its own launch of the Explorer 1 on Jan. 31, 1958, about four months after the Sputnik. These events signified our ability, desire, and motivation to explore beyond the boundary of Earth, which made it possible for us to have space explorations on Mars today.

http://www.space.com/news/ap-071004-russia-sputnik.html