ESA Document - Emits - ESA

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4.3.2 Propulsion
Figure 4-21: Plan of top level
4.3.2.1 Requirements and design drivers
The MEV mass prior to the landing is 42 tonne.
The gravitational acceleration is assumed 3.7 m/s 2
The engines for the descent are fired from a height of 2000 m from the Martian surface.
4.3.2.2 Assumptions and trade-offs
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 268 of 422
The starting descent velocity assumed feasible from the parachute design is 107 m/s and the
maximum allowed impact velocity on the Martian surface is 2 m/s.
The choice of the thrust is obtained excluding the contribution of the Martian atmosphere,
therefore the drag is not considered and the thrust level is slightly oversized.
The descent manoeuvre can be obtained with a thrust level of 280 kN with a short firing time of
around 37 seconds. Due to the exceeding thrust a new design of the engine with high ability to
perform full throttle (30-40 %) is required.
Only storable bi-propellant has been considered.
No attitude and steering manoeuvres have been considered.