Solar power satellite. Artwork of a future solar power satellite in Earth orbit. Large arrays of solar panels (brown) are converting the energy in sunlight into laser or microwave beams. One beam (purple) is transferring energy to south-western USA. Other beams could be used to power orbiting spacecraft or satellites. Such future technology would require advances in wireless transmission of energy, solar cell technology and assembly robots. The control centre of the solar power satellite is being serviced by a spacecraft (lower right). Such systems are under consideration by NASA, the American space agency.