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Earth Explorer Missions Payload Data Segments: GOCE

Daniela Bencivenni(1), Roberto Medri(1), M. Pastori(1), V.D. Spaventa(1), Paolo Spera(1) and Antonio Vollono(1)

(1) ACS, Via della Bufalotta, 378, 00139 Roma, Italy

Abstract

In the frame of two European tender competitions, Advanced Computer Systems SpA has been awarded by ESA of the contracts for the design and development of the Payload Data Segment (PDS) and of the Instrument Processing Facility (IPF) of the first two Earth Explorer Missions, CRYOSAT and GOCE.

Following the design and development activities, the GOCE Operational PDS/IPF system has been successfully deployed in Frascati (ITALY) during June 2006 and it is now ready to support the mission operations in view of the satellite launch planned for the next coming year.

The PDS/IPF System is characterised by several innovative and powerful features. The main one is the infrastructure design and the overall architecture of the Processing subsystem. The Core of the PDS is the Storage Archive, represented by an integrated collaboration of a DBMS and a Hierarchical Storage Management system (HSM) completely designed and developed by ACS. The HSM, designed originally for the management of very large multimedia archives (500 TBytes of the RAI digital audio archive), has been for the EO systems usage completely wrapped by a DBMS-based facility, designed to support and allow a Data Driven access to EO data, both for ingesting and processing systems.

Although it can be seen as an hybrid solution between an Event Driven and a Data Driven System, for its natural way of activating, carrying on parallel actions, distributing the intelligence rather than centralising it, it is surely not belonging to a classical Event Driven system and is to be regarded instead much closer to a Data Driven System. In brief it allows:

• Distributed architecture against centralised decisions

• No Time-programmed actions have to be designed. Scheduling policy based on tasks allocation made by each available node, rather than on predefined assignment of nodes to a predefined task

• Shortened latency (i.e. sub-elements wake up immediately in the moment new input data is available)

• Easy to be integrated as interfaces are simple and often ASCII based (XML)

• Easy to expand to heterogeneous elements (e.g. other processing chains have to be integrated with minimum effort)

• Light control on each facility but deep and effective monitoring

• Priority processing to manage systematic and on demand production orders in the various modalities foreseen

Aim of this paper is to provide an overview of the design and of the developed infrastructure of the PDS for these two Missions. The Data driven approach will be discussed against the Event Driven one, showing its advantages, demonstrating the high level of optimisation reachable by systems based upon its data management philosophy. Moreover the PDS modern and innovative design will be detailed, being it an “hybrid” solution between Data Driven and Event Driven, taking benefits by both approaches advantages and mitigating their weak points.

 

Workshop poster

Keywords: ESA European Space Agency - Agence spatiale europeenne, observation de la terre, earth observation, satellite remote sensing, teledetection, geophysique, altimetrie, radar, chimique atmospherique, geophysics, altimetry, radar, atmospheric chemistry