Environmental Engineering Reference
In-Depth Information
3.
The GEOs rarely are replaced. The small LEOs are replaced fairly fre-
quently due to orbit deterioration (to reduce LEO costs, it is assumed that
onboard propulsion capacity is weak and fuel limits lifetime to 2 years).
4.
The ground stations only communicate with GEOs. The GEOs commu-
nicate among themselves, the ground stations, and the LEOs. The LEOs
only communicate with GEOs.
5.
The LEOs are fairly primitive, and can be viewed somewhat simplistically
as only possessing a FSW backbone. The GEOs possess the full range of
Remote Agent functionality discussed previously. The ground system also
is equipped with autonomous agents for lights-out operation.
6.
In support of the higher-level constellation goals, the LEOs' jobs are to pass
their SI data to the GEOs and accept commanding and changes in mis-
sion objectives from the GEOs. Otherwise, the LEOs operate in a purely
local manner, little different from the behavior of a ground-controlled sin-
gle LEO. They collect their science data, perform necessary housekeeping
functions (largely in response to external directives from the GEOs), and
conduct very simple FDC functions.
7.
The GEOs' job is to collect SI data from their equatorial orbits, communi-
cate with the ground via the ground stations with which they are in perma-
nent contact, and run the constellation. Running the constellation includes
managing the collection of science data (including all LEO commanding),
monitoring and trending all H&S data from the LEOs and GEOs, per-
forming relatively short-term continuing process improvement (CPI) type
analytical studies to increase operational eciency, and employing SFD-
DIC Agents to deal with some anomalies that cannot be handled optimally
by FDC in the FSW backbones of the LEOs and GEOs.
The ground's job is to receive and archive all science data generated by
the constellation, perform long-term analytical studies to increase operational
e
ciency, and support the GEOs in dealing with major inflight anomalies or
failures.
A typical operational scenario is now presented, where some of the agent
interactions within a single spacecraft are glossed over in favor of a cleaner
description of spacecraft-spacecraft dialogs. At the start of this scenario, the
ground has just generated calibration updates for several of the SIs and up-
dated SI observation templates for the LEO and GEO spacecraft. These data
are uplinked to the GEOs with instructions to implement the updates as soon
as possible without interfering with ongoing observations by the individual
spacecraft, while maintaining consistency (as much as possible) among ob-
servations by those spacecraft. The planning and scheduling agents of the
three GEO spacecraft caucus (by way of a “teleconference” established by
their communications agents) and examine their anticipated processor loading
(in consultation with their monitoring and trending and look-ahead model-
ing agents) over the next few hours. In this case, they determine that none
of the three GEOs on their own can easily accommodate this planning and
