My experience is that ESA lets the industry (and maybe universities) do most of the SW/HW development and ESA does stuff like requirements and high level management. But I have never followed a project from start to finish, only been in the aforementioned industry :)
You are right, ESA usually oversees the projects and hosts the main data archive. Esa also takes care of the launch vehicle and interfaces with Arianespace for example.
The hard- and software development for the payload is usually done in numerous science institutes, part of them also universities. They usually have subproject-leads, while they again subcontract to external companies, as needed.
A complex structure that has to do mainly with the way how European projects are funded.
What did you do for Esa? What is your view on these projects? We always had the impression, the companies are under a lot of budget pressure during the missions.
My experience is that ESA lets the industry (and maybe universities) do most of the SW/HW development and ESA does stuff like requirements and high level management. But I have never followed a project from start to finish, only been in the aforementioned industry :)