ESA Document - Emits - ESA

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4.5 Mars Ascent Vehicle
4.5.1 Trajectories
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 363 of 422
4.5.1.1 Requirements and design drivers
The objective is to obtain an ascent trajectory which minimises the lift off mass, by means of
selecting the proper propellant masses in each stage, firing time in each stage, pitch and yaw
profile.
4.5.1.2 Baseline trajectory
4.5.1.2.1 Input data
Initial conditions
The optimal trajectory depends on both the altitude and latitude of the launch pad. The landing
site drives the latitude of the launch site, and it was agreed to be 20 degrees North as reference.
The reference altitude was assumed to be 0 Km, to be conservative. The longitude was assumed
to be equal to 0, since it has no influence in the trajectory computation.
Final conditions
The final conditions are those corresponding to a circular orbit of 500 km altitude and 32 degrees
of inclination.
Mass budget
Table 4-47 shows the mass budget used for the baseline trajectory. During the optimisation
process the mass of the tanks was considered as a variable, being equal to 3% of the propellant
mass.
Dry Mass
(except Tanks)
1st Stage 2nd Stage
Tanks Total Dry Mass Prop
Dry Mass
(except Tanks)
Tanks Total Dry Mass Prop Lift Off Mass
700 388 1088 12922 5100 81 5181 2705 21896
Table 4-47: Mass budget in Kg
Propulsion system
Table 4-48 shows the performance data of the propulsion system and the final propulsion
configuration.
Type of engine Number of engines Thrust (N) Isp(s) Nozzle Diameter (mm)
1st Stage Aestus (advance) 4 33000 330 1070
2nd Stage RD 869 4 5000 325 375
Drag coefficients and reference area
Table 4-48: Propulsion system