ESA Document - Emits - ESA

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4.5.2.2 Constraints
HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 368 of 422
Figure 4-104 shows a pictorial representation of the balance between all the constraints
mentioned and in particular the contradictory one of safety, ∆V consumption and time used for
the rendezvous.
Unfeasible
Un-Safety
Risky
RvD ∆V
Costly
Ideal
Risky
Ideal
Costly
Ideal
Unfeasible
Desired
Desired
Unfeasible
Figure 4-104: R & D constraints
RvD time
To be able to elaborate a rendezvous strategy for the HMM, the past experience was reviewed.
In general, there are similarities and differences of the lunar rendezvous with Mars rendezvous:
they have the same purpose and target and they have the same physics and principles.
However, they take place in different planetary scenarios and they use different sensors and
actuators.
The main conclusion drawn here is that the lunar rendezvous experience is not directly
applicable to our problem. In particular, there is a very long distance component in all maneuvers
established that leads to a time lag between Ground Segment and Astronauts that need to be
properly addressed and accounted for.
4.5.2.3 Assumptions and trade-offs
The two mission arcs of ascent and rendezvous are “apparently” independent. However, for
humans missions the ascent arc is much connected to the rendezvous one; In fact, the ascent and
rendezvous arcs are in some strategies and trade-offs the “same” arc.