ESA Document - Emits - ESA

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HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 111 of 422
• Delta DOR
• Same Beam Interferometry
• Satellite to satellite Doppler and Ranging
• The accuracy of the above methods shall be at least the state of the art projected for 2010
(deltaDOR: 5 nrad, Doppler and Ranging as BepiColombo Radioscience (0.6*10-15
Allan variance and 10 cm ranging ground station contribution)
• Navigation on Martian surface implemented locally (i.e. not via ground)
2.10.2 Ground segment concept
The HMM is unique in several aspects:
• It has a number of technologically driving aspects, e.g. large elements rendezvous and
docking, optical communications etc. These have to be prepared by studies and precursor
missions.
• Its large size requires a special build up phase to create the pool of people with the
respective expertise. This expertise cannot be drawn from the limited number of people
involved in conventional missions.
• The staffing cannot easily be adapted to changing workloads, because there are no other
missions that large to absorb such a large workforce.
• Existing centre infrastructures cannot just be adapted. New centre facilities must be
created.
2.10.2.1 Central versus distributed control centre concept
The HMM flight operations can be subdivided into major tasks:
• Launches
• LEO assembly
• Habitation module mission
• Martian surface mission
Each respective major task should be operated centrally. It is, however, conceivable, that there
are different dedicated Control Centres for each major task.
No clear preference is given at this stage to a central or distributed approach for the overall
HMM. A control infrastructure of this size is not available and has to be built up. A central
structure makes sense if it is reused for similar endeavours. On the other hand, smaller (but still
large) control infrastructures for the individual major tasks may be easier to adapt if smaller
missions are conducted before and thereafter.
As far as the communications network is concerned there is clear preference for a centralized
approach, i.e. there should be one centre in charge of network operations.
Except for the launches, each major task is assumed to be organised hierarchically with a system
entity on top supported by entities responsible for the subsystems. The subsystem teams and
tools are shared between the major tasks as applicable.