Environmental Engineering Reference
In-Depth Information
Flight Autonomy Enablers of Command Execution:
Request Orchestration
To this point, discussion of commanding has focused largely on the execu-
tion of stored ground requests, primarily relating directly to carrying out
the science observing program. However, the FSW must deal not only with
this class of commands, but also with realtime ground requests and with com-
mands dealing with engineering and/or housekeeping activities, in many cases
originating autonomously from within the FSW itself. In the past, although
the FSW was provided with sucient “intelligence” to keep commands from
these various sources from “bumping into” each other, much of this complex-
ity could be managed by the ground. This was especially true for missions
where the spacecraft primarily executed absolute-timed stored commands, or
for missions like the International Ultraviolet Explorer (IUE) where continu-
ous ground contact (enabled by a Geostationary orbit) allowed the ground to
conduct observations via block scheduling and realtime commanding.
However, as more spacecraft take advantage of the benign space environ-
ment of earth-sun Lagrange points (e.g., the James Webb Space Telescope
(JWST) now in development), the opportunities presented by event-driven
commanding orchestrated by a more autonomous onboard scheduling system
likely will be increasingly exploited. This, in turn, will place a greater re-
sponsibility on the flight system to manage and prioritize commands from
these various sources to optimize science data gathering capabilities without
jeopardizing spacecraft health and safety.
Flight Autonomy Enablers of Ecient Resource Management
When the ground system generates the spacecraft's science observation sched-
ule, it implicitly makes a series of assumptions regarding the spacecraft state,
e.g., that su cient power is available to operate the hardware required for the
observations, that sucient angular momentum capacity is present to enable
the spacecraft to be oriented properly to observe the targets, that enough
science data have been downlinked from onboard storage to permit the stor-
age of newly captured science data, etc. These considerations have already
been discussed in some detail in Sect. 3.1.1 ; however, it is worth repeating
here simply from the standpoint that some elements of resource management
(e.g., computing power and internal data transfer) are so intimately associ-
ated with the running of the FSW that they have effectively become part of
the spacecraft infrastructure. So, for these resources, one tends to view the
job of resource management not as an independent application running on
the FSW, but instead as an element of the FSW facilitating the running of
applications.
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