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2.7 Mission Operations
Launch, Early Orbit, and Critical Event Coverage
TRACER operations will be conducted from the Mission Operations Center (MOC) co-located in
Chandra X-ray Observatory control center at the Harvard-Smithsonian Center for Astrophysics.
During launch and early orbit, the MOC will monitor spacecraft launch, and provide telemetry
and control during critical events and normal science activities. An overall operations timeline is
shown in Figure x.
Week
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Launch and Early orbit
Spacecraft/Instrument Checkout and Science Commissioning
Normal Operations
8x7
2 to 4 years
Figure x: The TRACER Launch and early operations phases follow a standard timeline.
The MOC will monitor launch event telemetry through the Pagasus Orbital Carrier Aircraft
(OCA) and standard down-range assets. Coverage switches to TDRSS once space vehicle
separation occurs after orbit insertion, ~500 sec from launch. The MOC will be responsible for
the critical event coverage and for recording and archiving the critical event data for later
analysis. These events and planned coverage are summarized in Table x.
Timeline
L+0 to 499 sec
Event
Pegasus staging through orbit insertion
L+500 to TBD sec
Spacecraft Separation
ACS automatically enabled in initial
acquisition/ safehold mode
Solar Array Deployment
Control system points spacecraft such that solar
array normal is pointed to sun (CSS, TAM,
wheels, magnetic torquers)
Ground commands switch to normal mode
Baffle door opens (TBD), and Focal Plane
Aperture is Opened
Safehold recovery
Science Operations
Coverage
Range standard
coverage
TDRSS
telemetry
TDRSS/Ground
Station
Network
Scheduled ground station, or
TDRSS if required
Commissioning. During the launch and commissioning phase, the engineering team will be
resident in the MOC. Following transfer of mission responsibility to the MOC at launch vehicle
separation, the MOC team will carry out the Commissioning Phase Plan to activate and check out
each S/C subsystem. Specifically, the pointing and star camera are calibrated, out-gassing reaches
an acceptable level, and the science instrument is calibrated and sees first-light. During this
phase, the MOM will oversee integrated flight and science operations activities. Following
commissioning, the EOT will transition to on-call operations engineering support from GSFC.
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Operations will be conducted 7x24 during the first 4 weeks and then transition to 7x8 operations
with five 8-minute passes per day. Passes out of business hours will be automated. During
commissioning, all spacecraft subsystems are checked out, the pointing and star camera are
calibrated, out-gassing reaches an acceptable level, and the science instrument is calibrated and
sees first light.
Normal Operations. Following commissioning, science operations proceed with the SOC
providing the MOC with an observing plan sufficient for two weeks of observing. The MOC team
conducts routine activities including engineering data trending, orbit determination, pass
planning, regular operations reporting, maintenance of required flight and ground procedures and
scripts, and operation of the MOC ground system. Monitoring and limit checks of real-time and
dump data are conducted automatically with pager alerts for out of limit conditions to controllers
and the MOM. Anomalies result in contact to EOT. Flight software is maintained at GFSC, with
software patches passed to the MOC for uplink. In the event of an anomaly, the MOT responds
per approved procedure, contacts the MOM who coordinates with the EOT and leads the anomaly
response team. Safehold recovery operations will execute during scheduled ground downlink
opportunities or through TDRSS coverage if they must occur within a constrained window. An
allocation of TBD min per month of TDRSS coverage is budgeted to cover contingencies if
needed.
Science Operations. The SOC receives all science telemetry, performs automated
pipeline processing to science products, archives the telemetry and products, and monitors and
trends science instrument behavior. During the early stages of the mission, emphasis will be
placed on monitoring and updating the onboard algorithms for detecting and triggering from
signals. We expect a number of parameter changes to the FPS flight software during the first 2 to
3 months of the mission, followed by periodic updates. The SOT is responsible for maintaining
the FPS software using the EU at the MOC, and for supporting instrument anomaly resolution.
The SOT maintains the calibration of the instrument and monitors the performance of the
detectors and overall system as the mission progresses. Software tools used in the processing,
analysis and archiving of science data will be available remotely via VPN providing team
members with access to a ‘virtual’ SOC.
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Other Material
2.7.2 Mission Operations Development. The MOC and Science Operations Center (SOC) will be
staffed during TRACER Instrument development and Testing (I&T) to develop the mission
operations concept, to specify system requirements for ground and flight mission operations and
data analysis, and to develop the products (procedures, scripts, displays) required for operations.
The ITOS ground system is baselined for use during spacecraft I&T and at the MOC. We reduce
risk by planning early system use with an expert staff to ensure thorough data flow checkout, gain
experience with data formats, and transfer operational products, procedures and expertise from
the development team. During I&T, the MOC team will coordinate closely with the I&T team to
ensure tight configuration management and coordination of the ITOS components, including the
command and telemetry databases, scripts, procedures, displays and support documentation used
for I&T and at the MOC. The MOC, SOC and Engineering Team will be staffed and certified to
operate the mission under the direction of the Mission Operations Manager (MOM). As has been
done with Chandra, cross-training will be used extensively to mitigate the risk of staff turnover
during the mission and to maximize expertise.