EDSN Flight Units, Flight Spares, and Engineering Units

The 8 EDSN flight units, flight spares and engineering units. The EDSN flight units are the satellites that operate on orbit during the missions. Flight spares and engineering units were built throughout the project to develop software, verify the design, perform environmental qualification testing and serve as backup satellites if any issues are observed in the flight units prior to launch.

Image Credit: NASA Ames Research Center