The ISO Ground Segment at Villafranca: Its Integration and End- to-End Validation

ESA's Infrared Space Observatory (ISO) was successfully launched from the Guiana Space Centre in Kourou on 17 November 1995. Its requirements in terms of ground-segment preparation were particularly demanding due to the limited mission lifetime, which calls for highly efficient operations, the very fast pace of the ISO observations, some lasting just a few minutes, the severe pointing requirements which demand sophisticated planning, and the real-time commanding of the highly sophisticated payload of four instruments with multiple operating modes from a computer-generated, automatically executing file. It was recognised that, given these demanding constraints, a well thought out approach to overall ground-segment integration, testing and validation would be required to ensure success. The approach that was chosen, based on the concept of end-to-end testing supported by sophisticated instrument simulators, proved highly effective. As a result, the ISO ground segment was ready to support all of the mission's operational phases in time for the spacecraft's launch.