Environmental Engineering Reference
In-Depth Information
2.1.2 Command Loading
By contrast to the P&S function, command loading is quite straightforward.
It consists of translating the directives output from planning and scheduling
(plus any realtime directives, table loads, etc., generated at and output from
the control center) into language/formats understandable by the flight com-
puter and compatible with the communications medium. As communications
protocols and the input interfaces to flight computers become more standard-
ized, this ground system function will become steadily more automated via
commercial off-the-shelf (COTS) tools.
2.1.3 Science Schedule Execution
Science schedule execution refers to all onboard activities that directly relate
to performing the science mission. They include target acquisition, science in-
strument (SI) configuration, and SI operation on target (for example, exposure
time management).
2.1.4 Science Support Activity Execution
Science support activities are those that are specifically performed to ensure
the success of the science observation, but are not science observations them-
selves, nor are they routine housekeeping activities pertaining to maintenance
of a viable observing platform. They are highly mission/SI specific activities
and may include functionality such as optical telescope assembly (OTA) cal-
ibration and management and SI direction of spacecraft operation (such as
pointing adjustment directives). These activities may be performed in imme-
diate association with ongoing science, or may be performed as background
tasks disjoint from a current observation. Although executed onboard, much
(if not all) of the supporting calculations may be done on the ground and the
results uplinked to the flight computer in the form of tables or commands.
2.1.5 Onboard Engineering Support Activities
Onboard engineering support activities are routine housekeeping activities
pertaining to maintenance of a viable observing platform. The exact form of
their execution will vary from spacecraft to spacecraft, but general categories
are common within a mission type (e.g., geosynchronous earth orbit (GEO)
earth-pointer, LEO celestial-pointer, etc.). Engineering support activities in-
clude angular momentum dumping, data storage and management, antenna
pointing, attitude and orbit determination and/or prediction, attitude control,
and orbit stationkeeping. These activities may be performed in immediate as-
sociation with ongoing science, or may be performed as background tasks
disjoint from a current observation. Again, although executed onboard, some
of the supporting calculations may be done on the ground and the results
uplinked to the flight computer in the form of tables or commands.
