MISSION PLAN - PDS Small Bodies Node

After completion of the initial acquisition subphase, the spacecraft is essentially at a
known attitude with communications having been established. At this point the flight
team begins a characterization and calibration period of the majority of the spacecraft
subsystems. In addition, attitude control maneuvers will commence to maintain the
desired attitude. Communication during this period is near continuous.
Key subsystem performance tests will be conducted early in the checkout phase. Table
3.3-1 provides a summary of the subsystem checkout plan. Again it is noted that specific
numbers are provided for illustrative purposes only and are subject to change.
Table 3.3-1 Subsystem Checkout Plan
Subsystem Activity Time Risk / Impact Data Return
ACS Determine if Star
Camera performance can
maintain 15° deadband
L to
L+14 d
Reliance on IMU for
attitude knowledge.
Impacts power at
Star Camera images,
attitude knowledge
information
aphelion
Telecom Verify HGA
L to Less data return thru use Nominal telemetry
Navigation
Camera
(see below)
CIDA
DFMI
SRC
performance
Perform series of
calibrations, includes
Scan Mirror
Verify CIDA is
functional
Verify DFMI is
operational
Verify SRC latches are
operational
L+90 d
L+4 d to
L+18 d
of MGA.
Unable to obtain
calibrated optical
navigation data
L+5 d Unable to collect CIDA
data
L+18 d Unable to collect DFMI
data
L+90 d Minimal probability
SRC fails to open at first
ISP collection
Nav Camera images
(window
& compress)
CIDA data
DFMI data
Latch telemetry
indicating open
The first trajectory correction maneuver (TCM-1) is performed at L+15 days to correct
injection errors. At completion of this maneuver, the spacecraft will be ready for the
long cruise period that lies ahead.
Within the Activation and Checkout subphase, it is desirable to verify the performance of
the Navigation Camera, the Star Cameras, the pointing mirror, the periscope, the Attitude
Control System (ACS) and the navigation flight software algorithms of centroiding,
windowing and compression, all of which will be heavily used during encounter
operations. Table 3.3-2 provides a summary of the current imaging plans for the launch
phase.
Table 3.3-2 Launch Phase Imaging Plan
Time
L+4
days
L+18
days
Image Description
no. of
images
bits per
pixel
no. of
filters Comments
Moon Color 3 16 4 PIO-windowed, best efforts basis
depending on launch activities
Mirror pointing, alignment 20 16 1 Pattern matched, windowed
& sensitivity calibration
(nav) (10x10), nominal attitude, tight
deadband
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