ESA Document - Emits - ESA

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2.7.15.4 Influence of the mass of the MEV
Mass to LEO (Tonnes)
1500
1400
1300
1200
1100
Influence of MEV
1000
20 25 30 35 40 45 50 55 60
MEV mass (Tonnes)
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 89 of 422
Figure 2-45: Influence of the MEV mass
As shown in Figure 2-45, the influence of the MEV mass on overall mass is lower than that of
the THM, as it is discarded during Martian orbit.
2.8 In orbit assembly
2.8.1 Assumptions and trade-offs
Note that when considering the mission architecture:
• A chemical mission results in a high mass into LEO and a configuration with several
elements
• The parameter to assess the feasibility of a mission architecture is the time-toassemble
such elements in LEO (or the selected orbit)
• A long assembly time would result in:
o Aging of elements even before the mission starts (potentially, unacceptable
aging).
o Unacceptable boil-off losses for the case of cryogenic-propulsion.
o Delay of the following mission within a chosen exploration strategy.
Several orbits are candidates for the assembly operations:
• LEO
• Nuclear safe orbit
• MEO
• GEO
• HEO
Note that when choosing the orbit for the assembly operations:
• All the elements have to be inserted into the assembly orbit and perform a
rendezvous & berthing or docking with the already existing composite.
• Human interaction may be required to complete any given addition to the composite.
• Nuclear safe orbits will only be considered if nuclear devices are present in the
composite, currently none are baselined.
• Elliptical orbits are discarded due to the complexity of the RVD manoeuvre.
• GEO and HEO are discarded due to the loss of performance of the launchers and the
(potentially) more hostile environment.