GSC Sentinel-2 PDGS OCD - Emits - ESA

GSC Sentinel-2 PDGS OCD
Issue 1 Revision 2 (draft) - 25.07.2010
GMES-GSEG-EOPG-TN-09-0008
page 82 of 350
Before uplink-time, the FOS requires the PDGS to provide the mission planning input in
advance of actual operations with typically 3 working-days margin to allow for contingency
handling on the mission-planning loop if needed. This margin may be reduced down to one
working day in case of required spontaneous re-planning as for instance during the
commissioning phases.
4.3.7.2 MSI Parameter Tables Uplink
Some MSI parameter tables (cf. section 3.5.2.4) driving the instrument performance will be
managed under controlled configuration in the PDGS. In counterpart, the FOS will be in
charge of the uplink and activation operations whenever a change on the MSI configuration is
needed e.g. after PDGS Cal/Val activities.
For table uplink, the FOS will apply the mechanisms reflected in [AD-03]. Depending on the
table, uplink operations will be carried out either via specific telecommanding, or through the
generic patch functionality of the OBC (PUS service 6). In all cases, uplink will be performed
through the S-Band 64kbps TC channel (cf. 3.5.6) using the appropriate PUS services and at
the specific S-Band contact opportunities dedicated to Sentinel-2 as presented in the previous
paragraph.
While most parameter tables are expected to be of relatively limited size and be associated
with very seldom required updates, the NUC table will weight about 2 Mbytes and is expected
to need recurrent fine-tuning at a frequency ranging from two weeks to several months to
maintain the quality of the measurements over time. Due to the size of the table, a specific
uplink scenario is defined in [RD-28] which will require delta-uplink functionalities provided
through the PUS service 6, as well as an accurate coordinated planning between PDGS and
FOS embedding automation to the maximum feasible extent.
4.3.7.3 HKTM Delivery Constraints
As introduced in paragraph 3.5.4.3 and detailed in SOCD [AD-03], the HKTM data is
systematically recorded on-board and can be downlinked independently from MSI data trough
one of the 280Mbps X-Band channels to PDGS-managed ground-stations.
To allow for spacecraft operation and safety monitoring during the complete orbit, the FOS
requires that this data be systematically supplied by the PDGS. It further requires that HKTM
data increments be provided with an update frequency of no less than once per orbit and
delivered at a defined FOS interface within maximum one hour from data-reception at the
PDGS.
4.3.8 SPACECRAFT OPERATION CONSTRAINTS
The Sentinel-2 PDGS operations concept is highly driven by the satellite capabilities and
constraints described in [AD-03]. This section reviews the one having a direct impact on the
PDGS operation concepts. Details on each of the introduced factors are provided in specific
sections making emphasis on the impact on PDGS operations, mostly at mission-planning
level.
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