This paper studies the sustainability of an Earth observation mission that utilizes a multiple-payload fractionated system consisting of twelve eight-unit CubeSats, with respect to the CubeSat failures. It proposes practical approaches to the CubeSat replacement, deorbiting and orbit insertion maneuvering, as well as task reallocation. The performance and failure analyses, using Monte-Carlo simulations, suggest that by having a maximum of four reserved CubeSats in orbit the impact of CubeSat failures on the mission can be notably lessoned. It can also lower the total number of required launches for the entire mission lifetime. A maneuvering sequence that can set a new CubeSat on a precise trajectory to reach its designated orbital position is formulated, and it is shown that the total Delta V required for correcting the initial orbit deviation can be significantly reduced by taking benefit from the J2 perturbation. A deorbiting analysis proves that each failed CubeSat can be safely removed from the orbit if equipped with a stand-alone drag sail unit. A dynamic approach is proposed toward the reallocation of the tasks of the failed CubeSats to the operational ones, using a combinatorial auction-based real-time algorithm, and its performance is studied, in terms of success rate, optimal utilization and CPU time, under different circumstances with respect to the use of reserved CubeSats, partial or complete reallocation, and task redundancy.
