A method comprising: designing a payload stack of at least two satellites, the payload stack including at least a first satellite (210) and a second satellite (210), each of the first satellite and the second satellite including a respective payload, the first satellite and the second satellite configured to be disposed together, in a launch configuration, for launch by a single launch vehicle; wherein: said designing includes performing a quantitative optimization of design parameters of the first satellite and the second satellite, the quantitative optimization including optimizing an objective function (330, 340) of the payload stack, the objective function representing overall performance of the payload stack taking into account one or more of launch vehicle capability, launch vehicle fairing volume utilization, launch vehicle mass utilization, and orbit-raising requirements; the payload stack is configured to be deployed, following injection into a first orbit by the single launch vehicle, by separating the first satellite from the single launch vehicle while the second satellite is mechanically coupled with the first satellite; the first satellite includes a first onboard propulsion subsystem configured to execute an orbit transfer maneuver from the first orbit to a second orbit; in an on-orbit configuration, the second satellite is detached from the first satellite only after execution of the orbit transfer maneuver; the respective payload of each of the first satellite and the second satellite is configured to be operated in one or both of the second orbit, a third orbit and a fourth orbit; the first satellite has a first mass in the launch configuration, and the second satellite has a second mass in the launch configuration, the second mass being 30% to 70% of the first mass; and delivering each satellite in the payload stack, launched by a single launch vehicle, into a respective operational orbit. said designing includes performing a quantitative optimization of design parameters of the first satellite and the second satellite, the quantitative optimization including optimizing an objective function (330, 340) of the payload stack, the objective function representing overall performance of the payload stack taking into account one or more of launch vehicle capability, launch vehicle fairing volume utilization, launch vehicle mass utilization, and orbit-raising requirements; the payload stack is configured to be deployed, following injection into a first orbit by the single launch vehicle, by separating the first satellite from the single launch vehicle while the second satellite is mechanically coupled with the first satellite; the first satellite includes a first onboard propulsion subsystem configured to execute an orbit transfer maneuver from the first orbit to a second orbit; in an on-orbit configuration, the second satellite is detached from the first satellite only after execution of the orbit transfer maneuver; the respective payload of each of the first satellite and the second satellite is configured to be operated in one or both of the second orbit, a third orbit and a fourth orbit; the first satellite has a first mass in the launch configuration, and the second satellite has a second mass in the launch configuration, the second mass being 30% to 70% of the first mass; and delivering each satellite in the payload stack, launched by a single launch vehicle, into a respective operational orbit.