GSC Sentinel-2 PDGS OCD - Emits - ESA

ESA UNCLASSIFIED – For Official Use
GSC Sentinel-2 PDGS OCD
Issue 1 Revision 2 (draft) - 25.07.2010
GMES-GSEG-EOPG-TN-09-0008
page 105 of 350
o The seldom mission configuration change operations (e.g. new spacecraft or EDRS
phase-in periods) requiring specific care and coordination;
o The shipment and reception of data via media within PDGS centres as a trade-off
solution whenever such operations cannot be automated via digital networks due to
the excessive volumes to be transported;
o The resolution of contingencies occurring in the automated processes.
The above operations will nevertheless be designed so as to strictly bridge the computerised
processes and embed procedural steps such that:
o Cal/Val and product QC operations requiring expertise or decision making are
triggered according to well-defined procedures clearly isolated within the automatic
workflow;
o Mission reference configuration is centrally performed allowing the dispatch of
coordinated updates by computer means to the whole PDGS and external interfaces
as needed;
o Media loading, release and shipment procedures to circulate data between centres are
mechanical and generally modelling an automated transportation network;
o Operator alerts are centralised within an operational centre allowing for maximised
efficiency.
The system integration, verification and validation processes required by the corrective
maintenance or system evolutions and which cannot generally be efficiently automated will be
supported by wide-ranging tools covering the specific needs of this activity.
4.5.1.4 Centre Operation Autonomy and Federative Data-Access Concept
The PDGS operations, scattered in stations and centres, will be based on a federative model
with a maximised independence at centre-level converging at PDGS-level into a unique entity
as seen from the data-access viewpoint. This model is depicted on Figure 4-13.
As applied to the Sentinel-2 mission, this model has the following advantages:
o It is well adapted to the high data volumes generated by the Sentinel-2 mission as per
the inherent issues related to data transportation.
In this model, the data is transported from place to place within the PDGS centre
network with the sole aim of bringing the Sentinel-2 data closer to the consumers or to
provide for redundancy. Likewise, real-time data-access can be provided right at the
station whilst it is circulated to other centres with relaxed timeliness constraints to
improve accessibility and access performance in the longer term;
o It matches adequately with the mostly regional and continental expected usage of the
mission data. In this model, local access can be optimised by operating community
centres (e.g. national) fed with regional data and mirroring it globally with maximised
performance when accessed from within their geographical perimeter.
o It well matches the required operability in a distributed setting whereby each
operational centre has a maximised independence to ensure alone that it fulfils its
dedicated role allocated within the global operation picture.
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