Environmental Engineering Reference
In-Depth Information
reasoning, as will be discussed later), i.e., the recognition of a repetition of
clues observed previously when solving a problem in the past. The ecient
implementation of a capability of this sort lies in the domain of artificial in-
telligence. Failing at the pattern recognition level, a more lengthy general
analytical phase (the human equivalent of state modeling) typically ensues
that is manually intensive and at times very expensive.
So a spacecraft called upon to diagnose and isolate its own anomalies is
being asked not just to emulate the capabilities of human beings. In fact, it
is being asked to emulate the capabilities of the most senior and knowledge-
able individuals associated with the operations staff. Therefore, as a FSW
implementation of this function must by its nature be extremely costly, a
very careful trade must be conducted prior to migrating this function to the
spacecraft.
2.1.9 Fault Correction
Currently at GSFC, generating a plan to correct an onboard anomaly, fault,
or failure is exclusively a ground responsibility. These plans may be as simple
as specification of a mode change, or as complex as major hardware reconfigu-
ration or FSW code modification. In many cases, canned solutions are stored
onboard for execution in response to an onboard trigger or ground command,
but creation of the solution itself was done by ground system personnel, either
in immediate response to the fault, or (at times) many years prior to launch,
in anticipation of the fault. And even where the solution has been worked out
and validated years in advance, a conservative operations philosophy has of-
ten kept the initiation of the solution within the ground system. So at GSFC,
although future technical improvements in onboard computing power and ar-
tificial intelligence tools may allow broader onboard independence in fault cor-
rection, major changes in operations management paradigms will be needed
before we see more widespread migration of this functionality onboard.
2.1.10 Downlinked Data Archiving
Archiving of downlinked telemetry data (including, in some cases, distribu-
tion of data to users) is rather straightforward and highly standardized. This
ground system function will become steadily more automated via COTS tools.
2.1.11 Engineering Data Analysis/Calibration
Traditionally, nearly all spacecraft engineering analysis and calibration func-
tions (with the exception of gyro drift-bias calibration and, for the small
explorer (SMEX) missions, magnetometer calibration) have been per-
formed on the ground. These include attitude-sensor alignment and poly-
nomial calibrations, battery depth-of-discharge and state-of-charge analyzes,
