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 161 of 350
○ Support problem investigations during OSV, Phase-E1 and Phase-E2 of the
spacecrafts as required by the corrective-maintenance activity;
○ Support the qualification phase of all PDGS system upgrades before deployment as
required by maintenance or evolution activities;
○ Support the PDGS deployment phases of the initial and upgraded versions in
configuring and assembling the deployed-configuration elements to be deployed.
As holding a true functional role including during the entire PDGS operational phase, the
PDGS RP is intended as a specific functional item of the PDGS with a dedicated associated
operations concept.
4.6.2 SYSTEM STATES AND CONFIGURATIONS
Throughout its lifetime, the PDGS will evolve between several configurations and states as
required by its development and maintenance activities and by the gradual phase-in of the
Sentinel-2 constellation spacecrafts it will serve.
As regarding the successive phase-in of the Sentinel-2 units with their respective mission
phases, and while it is assumed that a single and unique PDGS system will be shared to
serve the constellation, a distinction has to be made between the PDGS instance and the
specific state in which it is operating.
The instance of the PDGS refers to its specific existence as an integrated system. As such,
there will be a single physically deployed PDGS instance. In complement, a localised (in a
single location) reference instance of the PDGS called the Reference-Platform (RP) will be
used for testing, simulation and long-term maintenance purposes (cf. previous section).
In counterpart, the state of the PDGS refers to its capability in serving a specific spacecraft
mission. Hence, it is assumed that a single PDGS instance can operate in 2 distinct states
simultaneously, one per Sentinel-2 unit. E.g. the PDGS may operate operationally for
Sentinel-2A at the time Sentinel-2B is launched for which it operates in pre-operational state
until the end of its commissioning phase.
Finally the configuration of the PDGS applies to a particular PDGS instance and is configured
to operate on one or both missions each one in their respective states.
The following paragraphs describe those concepts in more details.
4.6.2.1 System States
As driven by the successive phases of the Sentinel-2A and Sentinel-2B missions described in
section 1.3 leading to a fully operational system supporting the Sentinel-2 constellation, as
well as beyond this point, the following states of the PDGS are identified:
○ Development state: In this state, the PDGS is being built and pre-assembled as a
system on the RP for testing purposes. It is assumed it embeds at this point some but
not necessarily all of its intended functionality and as such may support only partial
services limited to testing activities in a reduced configuration e.g. external interfaces
compatibility testing, etc;
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