SPESAR targets satellite-based multilateration (LMAT) and CNS-as-a service, raising TRL6 for surveillance capabilities to increase ATM system robustness (IR-3-09) and resilient integrated surveillance as a service (IR-3-01), as outlined in the European ATM Master Plan. Building on ESA EURIALO, SPESAR aims to deliver a global, space-based MLAT service resilient to GNSS jamming and spoofing, optimise surveillance infrastructure, and support EU sovereign ATC surveillance. Objectives include consolidating operational needs, developing a SESAR solution for integrated space and  ground surveillance, validating services in multiple operational environments, and preparing certification and business frameworks.