It is important to note that these early spacecraft were representative of the state of the art in just the first eight months of the Space Age. However, once the gateway to space had been pushed open, there was no stopping the development of ever more complex spacecraft, which were launched with increasing frequency. The recorded number of launches, including failures, in the first four years of the Space Age was as follows: three in 1957; 23 in 1958; 25 in 1959; and 40 in 1960 ^[39].

In addition to the trail-blazers discussed above, the count included, from America, the world's first weather satellite (Tiros 1), the first passive and active communications satellites (Echo 1 and Courier 1B respectively), and the first navigation satellite (Transit 1B). The USSR's achievements, in the same period, included the launch of the first spacecraft to fly beyond the Moon (Luna 1), the first to impact the Moon (Luna 2), and the first to image the far side (Luna 3); it also launched the first prototype manned spacecraft (Sputnik 4), which in its operational version, Vostok 1, would carry Yuri Gagarin into orbit in April 1961. These and other missions are described in the context of their applications in following chapters.

Although the story of spacecraft development is, by necessity, dominated by the space race between the United States and the USSR, it is also important to note that, as with launch vehicles, other nations were interested in exploring the new frontier.