Non-Terrestrial Networks (NTN) require software-defined payloads to stretch the lifetime of space-components, while meeting strict real-time and power constraints. We evaluate the end-to-end 5G NTN up&downlink on a single rv64gc core. Measurements show that 273× speedup is needed to run the uplink in 1ms transmission time interval (TTI). We argue that programmable decoupled vector datapaths, implementing the RISC-V "V" extension are the key to bridge performance gaps, while preserving long term flexibility for space-grade systems.