Resumen de Viewed from above
Efforts to keep tabs on Earth from above began with NASA's Landsat programme, which started in 1973. It currently has two satellites in orbit imaging the whole of Earth's surface every 16 days. The resolution is high enough to capture major roads, but not individual houses. More recent satellites supply far greater detail--and more often. Thanks to private firms like SpaceX, the cost of launching a commercial satellite is also a lot less than it used to be. Here, Hodson talks about cheap satellites.
