In the frame of an In Orbit Servicing Maturation Phase (IOSMP) contract, this maturation study has been realised on the START-€ solution which is proposed to extend the lifetime of geostationary orbit (GEO) communication satellites. The START-€ servicer spacecraft will first demonstrate on a GEO communication satellite its ability to perform the critical operations related to its mission, before proceeding with several commercial life extension missions by capturing and taking the AOCS control of aged client spacecraft. For each of them, the service can be completed by a removal of the client spacecraft from GEO orbit toward an upper graveyard orbit. On the longer term, the START-€ servicer could provide other services such as refuelling, assembling and repairing.