GSC Sentinel-2 PDGS STBD - emits - ESA

GSC Sentinel-2 PDGS STBDIssue 1 Revision 2 (draft) - 25.07.2010GMES-GSEG-EOPG-TN-09-0031page 34 of 603.4 PDGS Processing Resources Estimations3.4.1 OVERVIEW AND ASSUMPTIONSConsidering that the ground station network is yet unsettled, this chapter presents ananalysis of the Sentinel-2 processing budget based on two example mission operationscenarios:- The Scenario-0: This purely theoretical scenario provides a first-level analysis of theprocessing resources required based on a constant average data observation anddownlink pattern where all data acquired by the MSI at every orbit can be downlinked in asingle downlink pass at every next orbit. The data volumes associated to this averageorbit is extrapolated from the analysis provided in [RD-04];- The Scenario-1: This more realistic scenario provides a second-level analysis based onan hypothetical network of four ground stations and an observation scenario inheritedfrom the analysis provided in [RD-04] with relative apportioning of the volumesdownlinked to every station along the repeat cycle.The following inputs are taken into account:- the production timeliness constraints (recalled in chapter 3 and defined in §4.3.1.1),- the preliminary target benchmarks of each Level-1 Processing Step defined in the GPPspecifications (detailed in §4.1),- the parallelisation opportunities inherent to each Level-1 Processing Step and at systemlevel (described in §4.2),- the reference orbit data volume (estimated from the tables presented in [RD-04]) andspecified in each of the scenarios.Knowing the parallelization opportunities and the preliminary benchmarks, the analysis ofthe processing budget aims at estimating the computing resources allowing the processingwithin production timeliness constraints.The Processing Resources estimations consider the following margins:- 15% of security margin is pre-embedded in the Benchmarks figures presented in section3.2 to take into account activities necessary for the data processing and that are muchless time consuming with respect to the processing itself (e.g. data formatting);- 15 % of additional margin has been considered in the computing resources estimation totake into account the non linearity of the parallelisationNo other overhead is taken into account: the times associated to initial, intermediate andfinal data transfers, as well as all processing supervision (e.g. intermediate disk I/O, etc)shall be estimated and included in a deeper analysis to finalize system dimensioning.ESA UNCLASSIFIED – For Official Use© ESAThe copyright of this document is the property of ESA. It is supplied in confidence and shall not be reproduced, copied orcommunicated to any third party without written permission from ESA.