ESA Document - Emits - ESA

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2.7.6 Trade-offs
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 50 of 422
2.7.6.1 Trajectories
The general problem is to find a trajectory to go to Mars and back. Only a few solutions are
possible for this problem, and that establishes a direct link between the mission duration and the
energy required (∆V):
• short mission – high ∆V
• long mission – lower ∆V
The ∆V required for the mission has a exponential impact in the amount of propellant required
for the mission. On the other hand, the mission duration has a linear impact on the wet mass of
the THM. The THM mass can vary depending on the following factors:
• THM structures remain the same as the required volume is constant for missions over
100 days
• Life support equipment for the level of closure selected will remain the same (slight
modification due to the storage facilities for the consumables)
• Consumables vary linearly with time
• Radiation shielding for the GCR, no impact for missions below 1000 days, as the
required protection is already provided by the structure and internal equipment
• Storm shelter could be slightly reduced if the duration is shortened, but still required for
single events
The existing solutions to the trajectories problem for the period 2028 – 2043 have been provided
by Mission Analysis, 2.4.
Low-thrust trajectories have not been studied, since the mission case shall be simple.
The typical solutions are the opposition class trajectory (long duration, low ∆V), the conjunction
class mission (short duration, high ∆V) and missions including swing-bys at Venus (medium
duration, medium ∆V).
Total DV (km/s)
25
20
15
10
5
Conjunction class, ∆V Short-stay, Venus return, ∆V Opposition class, ∆V
0
2023 2025 2027 2029 2031 2033 2035 2037 2039 2041
Earth launch date
Figure 2-18: ∆V required for the different solutions