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The aim of this paper is to present the Hermes Thermal Control Concept which constitutes the reference baseline for the phase 2 of the Hermes program. The technical solutions based on active and passive means, are dictated by a variety of requirements including temperature and heat flux limits, mass & power minimization, availability of space for accommodation of TCS devices. Furthermore thecomplex mission profile (including atmospheric flight and several modes of operation o002d;orbit) and the configuration of the space-vehicle, require the adoption of a particularly flexible thermal control. The ATCS (Active Thermal Control Section) is based on a dual loop concept, using both water and Freon R114 cooling loops for heat collection from the various sources, heat transportation and heat rejection through dedicated devices.

The requirements related to the thermal control of HERMES space-plane suggest the utilization of technical solutions based on active and passive techniques. The configuration of the space-vehicle with pressurized and unpressurized compartments presents a variety of different problems, which generally require dedicated solutions. The complex mission profile include atmospheric and orbital conditions, with several phases and modes of operation (free-flying and docked). The extremely wide range of environmental conditions, together with the timeline of internal power dissipations requires the adoption of a particularly flexible thermal control. The ATCS (Active Thermal Control Section) mainly relies on the capability of water and Freon 114 fluid cooling loops. They collect waste heat from the sources located inside the compartments and transport this power to the available rejection devices.

The new challenges of permanently inhabited orbital stations include the need for immediate, safe return to Earth of the station crew. In particular, in the frame of the Space Station Freedom (SSF) program, three potential emergency situations have been identified: ill/injured crew member return crew evacuation due to uninhabitability of SSF crew return due to unavailability of Space Transportation System It is recognised that station crew rescue/recovery by means of the U.S. Space Transportation System (STS) is not feasible since the time needed to setup the rescue mission would be too long for the assigned requirements. It has therefore been decided to develop an Assured Crew Return Vehicle, permanently docked to SSF and able to re-enter its crew (in total or in part) within assigned time constraints.

In the frame of the HERMES re-orientation activities, a set of studies has been started to define the most suitable scenario for a Man Transportation System (MTS). The possibility to use a non-winged vehicle to cope with different missions and requirements has been widely investigated, in a competitive study lead by Alenia Spazio as System responsible and performed in collaboration with Dassault Aviation. The study has concentrated first on the selection, from a large number of candidate shapes, of 2 promising vehicle concepts, one in the family of blunt bodies and one in the family of slender bodies. Then the design of the two selected shapes and the assessments of their expected performances have been investigated in greater detail in order to consolidate and validate the conclusions of the trade-offs performed during the first part of the study. This paper focuses on the thermal control issues of the two selected vehicle shapes.

Under the guidelines established by the European Space Agency (ESA), a specific effort was devoted to define the preliminary design concepts for a Crew Transport Vehicle (CTV) compatible with the Ariane 5 launcher. The mission objectives of this vehicle include the possibility of transporting 4 people (and a limited amount of pressurized payload) to the International Space Station Alpha (ISSA), and returning them to Earth safely. Different options were identified at system level, however a modular vehicle was commonly adopted: a Crew Module (CM) designed to withstand the typical phases of the atmospheric re-entry and provide an adequate environment for the crew during all the mission a Resource Module (RM) envisaged to provide the propulsion provisions for orbital transfer and deorbiting; in addition it carries all the necessary resources to support the mission from lift-off until separation from the CM.