The Galileo in-orbit verification engineering model satellite platform, showing the power subsystem undergoing testing at Thales Alenia Space, Rome. Credits: ESA / Thales Alenia Space Italia
These tests are an important step in the process of building and launching the first four Galileo satellites. Integration testing is carried out to verify the correctness of the interfaces between the unit or subsystem under test and the larger system into which it has been integrated. The scope of functional testing is to demonstrate that the integrated units or subsystems are compliant with their design specification.
The purpose of the engineering model of the Galileo In-Orbit Verification (IOV) satellites is to mitigate the design risks associated with the proto-flight model and the three flight model satellites, by performing an early verification of the electrical functionality and interfaces of the spacecraft and the performance of the payload before the test campaign for the proto-flight model starts. The engineering model is also used to debug the functional test environment and the test procedures that will be used for the flight models. Using an engineering model also has the advantages of verifying the electrical ground support equipment interfaces and functionality as well as the satellite’s compatibility with the Galileo ground segment.
The engineering model is representative of the flight models in form, fit and function, but does not possess the complete redundancy of its flight counterparts. As the individual units of the engineering model do not have to undergo the lengthy and expensive environmental test campaigns needed for the flight models, it can be built far in advance of them, at a fraction of the cost.