ESA Document - Emits - ESA

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4.5.3 Structures
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 379 of 422
4.5.3.1 Requirements and design drivers
For the design of the Mars Ascent Vehicle the following set of general requirements were taken
into account:
• Compatibility with the vehicle launcher Energia induced mechanical loads.
• Compatibility with Energia fairing envelope.
• MAV centre of gravity must be low as possible.
All structures module shall provide the mechanical support to ensure mission success.
4.5.3.2 Assumptions and trade-off
The MAV centre of gravity is assumed to be at 1 m, with the referential at the bottom part of it.
4.5.3.3 Baseline design
Due to the short time frame for this module, no detailed analysis was performed. The analysis
performed for the THM was used as reference.
4.5.3.3.1 MAV shell
The MAV consists of a cylinder with 2.2 m of total length and 2.8 m of diameter.
For the MAV mass determination, the first analysis began with comparison with the values of
the Soyuz capsule without the heat shield. But the necessary usable volume for the MAV is
higher, so as second analysis, due to the shape similarity, it was compared with the Columbus
laboratory. For the thickness the same value was chosen as for the laboratory – 4 mm and for the
skin material the same aluminium alloy as for the Columbus laboratory – AL 2219.
As preliminary analyses the stiffeners mass was assumed to be half of the skin mass.
For strength of the MAV it was assumed to have a ring every 0.6 m. The aim of these rings is to
give the necessary rigidity to the MAV.
4.5.3.3.2 MAV propulsion module
The MAV Propulsion Module consists of two stages. Each stage has four tanks and four engines,
around a central cylinder, which accommodates a passage tunnel between MAV and SHM.
For each stage there is a plate that supports the tanks and then engines. These plates consist of
sandwich panels. All panels will be aluminium alloy for the face sheet, with 5 mm thickness and
the core 30 mm thickness. In Figure 4-114 is described the nomenclature used for the structural
parts for both stages.
Note: The MAV shape shown in Figure 4-114 shows not the last version.