Earth Observation Data Handling Processes
As a requirement for all earth observation payload ground segments the German Satellite Data Archive (D-SDA) is driven by the following basic group of processes:
- Systematic, product-data-driven processes
- Event-based, request-driven processes
- Operations support processes.
The systematic processes are driven by sensor data which are continuously acquired, ingested and processed. This is typical for global, systematic missions continuously scanning the earth such as those with low and medium resolution optical sensors and atmospheric spectrometers.
The Data Information Management System DIMS supports systematic processes through its distributed service components. The Processing System Management (PSM) component supports these data-driven processing workflows up to ingestion into the Product Library (PL), a digital library for the long-term archiving of earth observation data products. In addition, newly available products are automatically disseminated to subscribed users and uploaded into online catalogs (EOWEB®) and data access systems.
Request-driven processes are usually triggered by orders submitted from online catalogs containing metadata on existing and potential future products. This is typical for individually-tasked missions producing a large amount of raw data such as those employing SAR and high resolution optical sensors.
Incoming orders are processed by Ordering Control (OC), which is responsible for checking the data policy, initiating acquisition (Mission Planning Interface MPI, Receiving Station Interface RSI), retrieval from the Product Library, postprocessing, and finally data dissemination and delivery either online or through storage media and shipment. Thereby other DIMS components come into action such as Production Control (PC) and Offline/online Product Generation and Delivery (OPG).
Operation support processes are very important for keeping these continuously active services with their high availability requirements up and running. Monitoring and control of the German Satellite Data Archive are supported by the unified DIMS Operating Tool (OT), a single, highly configurable graphical operator interface allowing interaction with every running service to control system activities. This is complemented by the Monitoring and Alarm (MA) component supporting automatic supervision of all services and all kinds of underlying resources, creating alarm messages to operators if critical situations are detected.
