ESA Document - Emits - ESA

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HMM
Assessment Study
Report: CDF-20(A)
February 2004
page 107 of 422
Long feedback loops make ground real time control impossible. System is very complex,
complete automation would be too risky and costly. High effort to make system operable for onboard
crew
Earth orbit assembly phase
Near real-time ground control is feasible. Crew presence and involvement to be minimised.
Assembly contains complex one of a kind steps. Higher level on-board autonomy is unfeasible
and unnecessary.
Critical phases operationsNominal operations to be preplanned because they contain highly
complex operations steps. Failure scenarios to be worked out with on-board automatic, crew and
on-ground decision distribution as appropriate considering the feedback loop times.
Mission planning (long term) on ground
Natural task for the ground is to set the long-term aims taking into account complex mission
parameters. Uplink of medium-term master time line.
Monitoring on ground
Highly complex (prototype) system requires detailed monitoring.
Think tank on ground to solve problem situations
Full understanding of the system is feasible only through on-ground sources.
Permanent presence of ground control
• Time for build up of critical situations shall be minimised
• Within reason smaller degradations shall be analysed to keep crew comfort at a high
level, crew may also delegate lower level tasks to ground
• Crew has to be given the feeling of being taken care of by ground
Permanent Presence shall be provided on a best effort basis. Compared to the other items above
it has a lower priority.
On-board survivability autonomy for credible failures without ground support, at least: 1 week.
Time is driven by unavoidable gaps in communications, activation times of full expert ground
support, and time to draw up recovery procedures.
(In contrast to unmanned satellites a safe mode with a deactivated satellite that buys time to
solve the problem is not feasible for Human Mission to Mars. A basic functionality has to be
always guaranteed.)
• On-board degradations management autonomy for 1 week supported by:
• Automatic redundancy management on lowest level
• Design for graceful degradations
• Crew interaction possibility on higher level to restore
• Ground control first-level support to crew available round the clock
• Ground control second-level support available on call
2.10.1.2 On-board operations
The following factors have been considered:
• Low-risk safe mode concept
• Graceful degradation of subsystems/components