ESA Document - Emits - ESA

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4.5.5 Thermal
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 383 of 422
The MAV thermal control shall be designed to perform optimally during the Mars ascent phase
and the rendezvous and docking phases. Similar performance from the thermal control is
expected during the landed phases, as it is assumed that the ascent compartment is an integral
part of the habitable zone. During this phase, the same requirements therefore apply, with slight
difference due to its upward position.
Like the MAV, the suitability of an optimal performance during the transfer to Mars is an open
issue. Not necessarily a permanent habitable module (economy of a radiation shield), its
functions can be hold in a dormant mode, reactivated when a crew enters the module (storable
zone for example). Benefit of such scenario is a higher tolerance on the thermal control and a
lower associated budget.
4.5.5.1 Requirements and design drivers
The main requirements are the following:
• The external thermal control shall be effective in vacuum (transfer and RdV phase) and in the
Martian pressurised environment.
• The external thermal control shall cope with ascent aerodynamics thermal loads.
• The TCS functions are to maintain air temperature and humidity in the ascent vehicle zones
within preset limits, and to thermally control the on-board systems. Therefore, TCS shall be
designed to maintain:
• the habitable zones in a certain comfort zone (temperature, humidity) but respecting
also safety requirements (touch temperature, condensation avoidance). Standard
figures are a medium temperature between 18 and 27C and a relative humidity from
25 to 70%.
• a uniform environment for a crew up to three members.
• elements and/or dedicated zones within temperature requirements (electronics,
propellants, valves, …). To optimise the thermal budget, a certain rationalization of
space and grouping of elements shall be carried out. Ideally, all equipments are within
a single dedicated enclosure.
• the interfaces of the others modules (Habitation Module) within temperature
requirements.
• The candidate TCS architecture shall be also capable of:
• performing effectively under Martian gravity,
• guaranteeing adequate flexibility and reliability of the system during all phases until
the end of the docking with the TV. Lower performance can be tolerated after
docking
• guaranteeing the performance of the system for any spacecraft attitude during transfer
and RdV, as well as for any orientation after landing, this for all thermal loads
derived from the mission requirements
• to optimise the heat management system in term of efficiency versus penalties to the
system (mass, energy consumption)