QinetiQ's T6 Mk4 is the GEO-communications evolution of the BepiColombo-qualified T6 Mk3. ESA documents its 3.3-5 kW operating range with 75-145 mN thrust, higher vibration and shock robustness, and faster thrust initialisation with shorter intervals between firings; ESA records functional and mechanical testing but a life test still outstanding, so current production is not asserted.