"Mission lifetime" refers to the duration that a specific task or project is intended to be active or in operation. It defines the period from the beginning of the mission until its expected completion or termination. Full definition
«It would allow CubeSats to enter higher orbits or achieve multiple orbital planes in a single mission, and extend mission lifetimes. (sciencedaily.com)
Elliptical primary mirror: 1.1 x 0.7 metres Mission lifetime: 4 years Payload mass: ~ 300 kg Dry mass: ~ 950 kg Launch mass: ~ 1200 kg Destination: L2 Cost: Launch vehicle: Ariane 6 - 2 (ariel-spacemission.eu)
Engineers constructed TESS to last well beyond its original mission lifetime, as long as funding persists. (seeker.com)