Complex sentence: Subsequent satellites in the series are provisionally planned for launch at 5 year intervals to match the 5-year design life and provide continuity of services, however in case of extended mission lifetime a period of dual operations is expected.
Split into simpler sentences: Subsequent satellites in the series are provisionally planned for launch at 5 year intervals to match the 5-year design life and provide continuity of services. However, in case of extended mission lifetime, a period of dual operations is expected.