ESA Document - Emits - ESA

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HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 295 of 422
Consequently, although the final design presented in the report will maybe not be the one with
the best performances in 2015, but is one of the most reliable with the current state of art without
having a too conservative approach.
A first trade-off between the main promising candidates was performed before starting the
design itself of the subsystem.
Nuclear energy has been excluded from this study.
4.3.5.2 Requirements
4.3.5.2.1 Mission requirements
During the cruise from Earth to Mars, the power required for the MEV (thermal regulation,
check-ups…) is supplied by the power system of the TV.
The MEV needs to have an autonomous power system from the separation from the TV, during
the descent phase, during the surface operations, and during the launch from Mars until the
rendezvous with the TV.
The mission has therefore been divided into the following modes:
• Descent phase (duration estimated: 30 minutes)
• Surface operations (distinction between night and day power consumptions)
• Ascent phase (max 90 minutes)
• Parking orbit (orbit duration: 118 minutes) for several days
• Rendezvous and docking (maximum 30 minutes)
• MAV Orbital Safe Mode
The surface operations duration is 37 days long in the contingency case. The possible landing
sites to take into account are in the latitude range [20ºN, 20ºS].
During all the phases, power has to be supplied to the different subsystems.
The Figure 4-45 shows the different modes of the mission. The time durations correspond to the
reference time considered for the power design.