ESA Document - Emits - ESA

s
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 121 of 422
of designing the backbone structure as initial assembly support structure, providing it with
manoeuvre capability and robotic arm(s).
The prolonged exposure to 0-g conditions is negative for crew health and planetary surface
operations capability. The implementation of micro gravity countermeasures for the crew is
considered necessary. A trade-off was performed, and a system was described, able to provide to
the crewmembers artificial gravity (centrifuge) during their sleeping hours. The effects of this
partial compensation are not well known yet, so they should be studied with a precursor
experiment e.g. on the ISS.
2.12.3 Model philosophy and qualification
Due to system complexity, Qualification Models (QMs) are required for the Mars Excursion
Vehicle (complete), and Earth Return Capsule (ERC) elements.
Some QM elements will be tested together on ground.
For schedule reasons the flight elements will not be tested together on the ground. Interface
reference models have to be produced for ground testing of the system elements. These models
have to be based on the design at the QM maturity stage. In principle a QM element will be used
in combination with an interfacing FM element to perform system interface tests. Later on, the
QM is kept as reference model for the whole mission.
The capability to load the cryopropellant in-orbit has to be significantly improved, to support the
required boil-off compensation before TMI. The loading system and its relevant operations have
to be qualified with a dedicated flight mission. This could be accomplished after one of the first
launches of the propulsion elements, to verify the loading on a reduced configuration of the
system.
For a program of a similar time span is the obsolescence of the components is a problem.
Considering the high rate of innovation in the field of electronic components such as processors,
memory banks and computer boards, it is guaranteed that from the time of design until the
mission exploitation, parts will rapidly evolve and new generations will replace the old. Design
of avionic subsystems and units would quickly become obsolete. It is therefore necessary to
implement some mitigating factors to this process:
• Applying open design to facilitate the implementation of more modern (space qualified)
parts along the development phase, as soon as they become available.
• Selecting components in the field of military or commercial aviation, where their usage is
planned to last decades, so the production lines are kept alive accordingly.
2.12.3.1 Qualification flight
A qualification flight is required. There is no way to assess the system’s real capability to
perform its mission and to verify its actual reliability without performing a flight test.
In the best scenario, a scaled model of the manned vehicle should be built, and launched. It
should be piloted in fully automatic mode. It should perform a complete mission sequence that
includes:
• Injection into transfer orbit to Mars
• Capture and injection into Low Mars Orbit
• Descent, landing and deployment of a Surface Element (full scale) on the same landing
site selected for the manned mission
• Launch and ascent of a Mars Ascent Vehicle (scaled)