  Among the mitigation measures introduced to cope with the space debris issue
there is the de-orbiting of decommissioned satellites. Guidelines for
re-entering objects call for a ground casualty risk no higher than 0.0001. To
comply with this requirement, satellites can be designed through a
design-for-demise philosophy. Still, a spacecraft designed to demise has to
survive the debris-populated space environment for many years. The demisability
and the survivability of a satellite can both be influenced by a set of common
design choices such as the material selection, the geometry definition, and the
position of the components. Within this context, two models have been developed
to analyse the demise and the survivability of satellites. Given the competing
nature of the demisability and the survivability, a multi-objective
optimisation framework was developed, with the aim to identify trade-off
solutions for the preliminary design of satellites. As the problem is nonlinear
and involves the combination of continuous and discrete variables, classical
derivative based approaches are unsuited and a genetic algorithm was selected
instead. The genetic algorithm uses the developed demisability and
survivability criteria as the fitness functions of the multi-objective
algorithm. The paper presents a test case, which considers the preliminary
optimisation of tanks in terms of material, geometry, location, and number of
tanks for a representative Earth observation mission. The configuration of the
external structure of the spacecraft is fixed. Tanks were selected because they
are sensitive to both design requirements: they represent critical components
in the demise process and impact damage can cause the loss of the mission
because of leaking and ruptures. The results present the possible trade off
solutions, constituting the Pareto front obtained from the multi-objective
optimisation.
