The European Space Agency (ESA) is currently cooperating with NASA on a Mars Sample Return (MSR) campaign aimed to retrieve and bring back to Earth physical samples of Martian soil for scientific investigation. The Earth Return Orbiter (ERO) is one of the European contributions to MSR. The ERO spacecraft consists of three modules: the Return Module (RM), the Orbit Insertion Module (OIM) and the Capture, Containment and Return System (CCRS). It is based on a hybrid propulsion architecture, with both a high-power Electric Propulsion (EP) system and a 1 kN-class Chemical Propulsion (CP) system. The EP system is fully solar electric and will be capable of generating up to 1N thrust from around 35 kW near Earth and about half at Mars. The basic mission design foresees an Earth-Mars outbound transfer using EP, an initial Mars Orbit Insertion using Chemical Propulsion (CP), spiral down/up phases using EP, and Mars-Earth inbound transfer using EP. The ERO Thermal Control System (TCS) is being developed to provide all equipment and structures with the thermal environment (temperatures, gradients, stability, heat fluxes) required to ensure the full performance of the system in all mission phases. The ERO TCS shall cope with classical design drivers for Mars missions (e.g. variable thermal environment with solar distance ranging from 0.91 to 1.76 AU), but also with challenges specific to the ERO mission, such as the high power dissipation to be rejected during EP operations, variable spacecraft configurations depending on the mission phase, long eclipse duration in spiral up and down phases and simultaneous firing of two main engines to perform the Mars insertion maneuver. This paper describes the overall thermal architecture and the design solutions implemented in the ERO spacecraft with a focus on the Return Module. Key thermal analysis results are provided as well.
Laneve et al. (Sun,) studied this question.