ESA Document - Emits - ESA

s
Total mission time (days)
1200
1000
800
600
400
200
Conjunction class, t Short-stay, Venus return, t Opposition class, t
0
2023 2025 2027 2029 2031 2033 2035 2037 2039 2041
Earth launch date
Figure 2-19: Mission duration for the different solutions
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 51 of 422
The mass efficiency of the mission has been traded against the three types of possible mission
for the 2033 opportunity. This is considered to be a representative opportunity for all the mission
classes. The trade-off is based on the analysis of the following parameters: total ∆V, possibility
for surface permanence (time), radiation dose, and consumable mass. For the trade-off the dry
mass of the THM has not been modified.
The results of this trade-off are shown in Table 2-12:
Conjunction Opposition Venus Swing-by
Total Mission Duration (days) 963 376 579
Possible surface Duration (days) 533 30 28
∆V (m/s) 8368 15120 10230
Radiation Dose (GCR,Sv,BFO) 1.087 0.496 0.756
Consumables (tonnes) 10.2 4.2 6.4
Mass to LEO (tonnes) 1336 45938 2481
Table 2-12: Trade-off for different trajectories class
As shown in Table 2-12, for the opposition and Venus swing by class missions, the stay duration
around Mars is only 30 days, making it quite difficult to perform a landing, from an operational
point of view.
In terms of total mass to LEO, the opposition and the Venus swing-by class missions present the
highest masses.
In terms of radiation, the GCR environment was analysed. The radiation dose increases with the
mission duration, but it is still under the limits for all the missions, although the conjunction
class mission receives the higher dose.
Taking into account the mass efficiency and the surface opportunities, the conjunction class
mission was selected.
All trip opportunities from 2028 to 2043 have been analysed (the opportunities recur on a 15
year cycle basis). For the mission case one of them has to be selected. (The relevant data can be
seen in Table 2-2). The 2033 date has been taken as reference for the mission case.
Depending on the opportunity, the mission duration and its split in between trip duration and
time around Mars varies, as shown in the following examples.