Environmental Engineering Reference
In-Depth Information
At this point, the fault-detection agent could rule that all targets that
previously were validated as acceptable and that required a solar array ori-
entation other than the safemode position should now be considered invalid,
thereby requiring that the scheduling agent delete those targets and at least
compress the schedule, or possibly even generate a new one reflecting the
currently degraded hardware state.
6.4.7 Adaptable Scheduling Goals and Procedures
A previous subsection discussed the cooperation of onboard Remote Agents to
satisfy a ground-specified goal. In this subsection, we examine how the goals
themselves might be modified/specified by the flight system based on inflight
experience. Also, ground-specified procedures used for achieving those goals
(either science observation or calibration goals) could similarly be modified.
The input data for the goal modification process might be obtained from
either of two sources, described now in the following paragraphs.
First, one could envision an onboard validation process that applies
ground-supplied metrics to the execution of science observations, or for that
matter, engineering support activities. Sticking to the science application for
simplicity, a monitoring and trending agent could calculate an overall ob-
serving eciency, as well as individual eciencies associated with the various
different types of science (a function of SI, mode, target type, etc.). The fault
detection agent might then look for relatively poor eciency outliers, so the
fault diagnosis, isolation, and correction agent could determine which onboard
goals or canned scripts/procedures might require enhancement.
Second, to define what changes might be made to those scripts/goals
deemed inecient, an onboard simulation function (under the control of the
monitoring and trending agent) could be dedicated to running simulations
on other approaches, either canned options provided by the ground or new
options independently derived by the spacecraft (via ground-supplied algo-
rithms) by running “what if” simulations in the background on a nonimpact
basis.
Although this capability would be primarily useful for missions where the
spacecraft can expect to be out of contact with the ground altogether for entire
phases of the mission (or during nonscience cruise phases where most of the
onboard computing power is idle), it might also prove useful for spacecraft
constellations where several spacecraft themselves are cooperating to achieve
overall constellation goals (see Chap.
9
).
6.4.8 Science Instrument Direction of Spacecraft Operation
This section examines how a smart SI can influence the behavior of spacecraft
platform subsystems. It is not unusual to allow SIs to command the ACS
to adjust the attitude of the spacecraft to facilitate a target acquisition, or
to shift the target from one SI aperture to another. For example, HST used
