Constella is a novel very quick response satellite platform that can be used in any Low Earth Orbit, It can be used as a single unit or as part of a constellation of spacecraft. It can be pre-manufactured to a large extent, and a selection of subsystems can be ready to select from, to provide last-minute configuration options for both the payload and platform. This satellite contains a number of innovations that have not been used in space before, and they will allow very quick response missions to take place. Only a very short time is required to decide on the mission and plan the satellite design, then assemble the final parts, and test and launch the satellite into orbit. The total time can be down to weeks or even days. Unlike most quick-response missions, where anything under one year is included, and where the satellite typically has to be completely ready and tested, waiting for quick call-up, the Constella can be tailored with interchangeable attitude sensors, propulsion units, communications equipment, payloads and more, just before launch, even right at the launch site if required. The platform produces almost the same amount electrical power, irrespective of orbital inclination or ascending node time, removing the need for solar panel design changes at the configuration stage.