Environmental Engineering Reference
In-Depth Information
the failed component and the overall spacecraft state. SFDDIC concludes that
the spacecraft must remain in safemode pending consultation with ground
resources, and establishes an emergency communications link with the ground
via DSN using the procedure already discussed above.
Once a link is established, the SI data-storage and communications agent
dumps all recent data stored onboard to the ground system. The agent also
provides the results of the SFDDIC Agent's analysis as a starting point for
the ground system's more definitive trouble shooting, to be conducted by an
integrated team consisting of senior system engineers supported by the ground
system's intelligent software agents. As the ground system's work proceeds,
requests for additional data from the spacecraft may be made via more regular
and frequent DSN contacts. As new ideas are developed and need to be exper-
imented with onboard, the onboard agents may well join the ground system
team and participate in a more active fashion until the problem is resolved
and nominal function is restored.
This completes the narrative illustrating space-to-ground dialogs initi-
ated by the flight system in nominal performance of typical inflight activi-
ties. In reality, the description provided is somewhat oversimplified, as the
communication flow in the example is sparse and sequential, whereas in real-
ity, communications will probably be more frequent and there may be parallel
conversations in progress during a single contact. Also, the assumptions spec-
ify a model of far less complexity than that characteristic of a real mission.
So the example provided should be viewed as simply a token of what would
be obtained in an actual application.
B.3 Ground-to-Space Dialog Scenario
The interaction in this scenario is initiated by the ground station. Consider a
ground-space agent dialog driven by the following assumptions:
1.
The mission type is LEO Earth-pointer.
2.
The spacecraft determines its own orbit via global positioning system
(GPS). Orbit stationkeeping maneuvers are performed autonomously on-
board.
3.
The mission goal is to observe all ground-specified targets while minimizing
fuel expenditure so as to maximize mission lifetime.
(a)
The spacecraft is provided with Earth coordinates of targets desired to
be observed. Repeated observations are performed every 16 days. The
spacecraft autonomously determines when the targets may be viewed
during a 16-day cycle.
(b)
The ground maintains onboard a set of observing scenario templates.
Each target will be observed using one of those templates. The tem-
plates are populated by ground-alterable parameters controlling the
observing process.
