Environmental Engineering Reference
In-Depth Information
4.
Targets are acquired autonomously by the spacecraft.
(a)
The spacecraft utilizes “quick-look” realtime image data to verify tar-
get acquisition and to determine whether targets are obscured by cloud
cover such that data collection is useless during this pass.
(b)
The spacecraft uses the results of its analysis of quick-look data to
transition SI configuration autonomously to nominal high data rate
mode if target conditions are suitable for the science observation to
commence.
(c)
Pattern recognition is performed onboard, as necessary, to support the
observation.
5.
The spacecraft autonomously generates H&S commanding where necessary
(e.g., SI re-configuration at SAA entrance/exit).
Each day for each ground station pass, the ground initiates contact with
the spacecraft for the purpose of receiving science and engineering/diagnostic
data. During ground-selected passes, the ground system uplinks to the space-
craft an updated target list, as well as changes to parameters controlling the
science observations.
At each orbit, the planning and scheduling agent uses data supplied by the
orbit determination agent to identify which ground targets can be observed
and when. At a database-specified lead-time prior to encountering the target,
planning and scheduling notifies the SI commanding-and-configuration agent
of the need to configure the SI for use according to the state specified by the
template. SI commanding and configuration then generates the appropriate SI
commanding and forwards its requests to the executive agent, which relays the
package to the FSW backbone, which (following its own command validation)
ships the commands to the SI.
When a target is encountered, the SI data processing agent examines the
initial quick-look data to verify that the observation can be performed. The
agent passes its assessment to SI commanding and configuration and, if the
conditions are suitable, commanding and configuration issues the necessary
directives to initiate generation of high volume data. The directives are then
relayed as before to the backbone so that the required adjustments can be
made. Similarly, if special fine SI adjustments are needed to home-in on a
specific landmark or feature, SI data processing performs the necessary pat-
tern recognition function and informs SI commanding and configuration of
its results. As science data are output from the SI, an observation file is con-
structed by the SI data-storage and communication agent for downlink when
requested by the ground system.
While these observations are performed, parallel onboard processing (con-
trolled by the data-monitoring and trending agent in conjunction with SFD-
DIC) determines when the orbit requires correction and informs the planning
and scheduling agent, which in turn schedules an orbit stationkeeping maneu-
ver (commanding for which is generated by the orbit-maneuvering agent at
the request of planning and scheduling) so as not to conflict with upcoming
