Space was for many years the domain of the Space Agency and large companies, the only ones thatcould afford the immense cost of planning, designing, building and launching satellites. But access to space has gone through a revolution in the last 10 years. The seeds of this “revolution” were originally sowed in the late 1970s and early 80s, when a handful of engineers and radio amateurs started to build cheap small satellites using Commercial Of The Shelf (COTS) electronics rather than extremely expensive space rated electronics. Originally seen as toys or curiosities, these small, low cost satellites have come of age in the past 10 years and are now taking over the roles of the traditional larger spacecraft. Their low cost allows constellations of these satellites to be built at lower prices than their single expensive predecessors, not only replacing them, but also allowing a completely new range of applications. Constellations of 10s and 100s of satellites for Earth Observation, telecommunications, meteorology, etc. are currently being developed and should be operational in the coming few years.