Great question. It depends on the size of the satellite! We’re building a CubeSat, and this will take us 3 years from design to launch. It will orbit for 1-2 years. But larger satellites will be many years in the making. Decades even! The usual process involves designing, building prototypes, testing the prototypes, building the real thing and then launching. It doesn’t end there – then you have to operate the satellite in space!