ESA Document - Emits - ESA

s
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 341 of 422
The shallowest trajectory (-4.9d) has low acceleration and heat flux (around 50kW/m 2 instead of
100kW/m 2 ). However, this trajectory is worst for the TPS sizing and IBD design in terms of heat
load (Figure 4-83). Heat load for an entry angle of -4.9d is about 7.5 MJ/m 2 whereas the
maximal heat load for the steeper trajectory is about 3.5 MJ/m 2 .
Figure 4-83: Heat load versus time
Nevertheless, for this high heat load, the shallowest entry has been selected.
Mach number requirement for the parachute is Mach 2. The corresponding altitude for the
shallowest entry is about 14 km which fulfils the requirement.
4.4.2.3.2 Mass budgets
Mass evaluation of the IBD is extrapolated from the main IBD of the Exomars mass. For a 25 m
diameter and 60 d half cone angle IBD shape, the mass is about 500 kg.
This mass takes into account only the IBD material, and the system for deployment.
4.4.3 Structures
4.4.3.1 Requirements and design drivers
For the design of the landing legs on Martian surface the following set of general requirements
were taken into account:
• Compatibility with the vehicle launcher Energia induced mechanical loads.
• Maximum of 6 m-leg footprint, due to compatibility with Energia fairing.
All module structures shall provide the mechanical support to ensure mission success.