Sentinel-1 Payload Data Ground Segment Operations Concept. B. Rosich, Sentinel-1 PDGS Project Manager N. Miranda, G. Sabella, C. Putignano, P.

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1 Sentinel-1 Payload Ground Segment Operations Concept B. Rosich, Sentinel-1 PDGS Project Manager N. Miranda, G. Sabella, C. Putignano, P. Potin Outlook Overall context Key role Main operations concepts Challenges and status

2 Sentinel-1 PDGS Overall Context The GSC Operations Concept will rely on a GSC Ground Segment consisting of: a GSC Core Ground Segment, with GSC-funded functions and operations, providing: the primary access to all Sentinel Missions core products as well as the coordinating access functions to Contributing Missions and Sentinels data, a GSC Collaborative Ground Segment, with non GSC-funded operations, providing through dedicated operational interfaces: a supplementary access to Sentinel Missions data, i.e. either through specific acquisition services (e.g. with shorter timeliness), or specific products, the frame for international cooperation GMES Space Component EO Sentinel-1 Users Sentinel-1A Collabora tive Centre G A M C Collaborati ve GCentre A S Collaborati ve Centre A Collaborati ve Centre A GMES Collaborati Collaborativ ve Centre A e Ground Segment Collaborati ve Centre A ISPs Sentinel-1B TM/TC Acquisition Stations TT&C Stations FOS Sentinel-1 GSC PDGS S-1 Core Ground Segment GC GS M GC GS M GC GS M GC GS M GC GS M GC GS M GMES Contributing Missions (ESA, EUMETSAT, National member-states missions, etc) EO Users GSC Coordinated Access System Services Users GSC Request GSC Provision GMES GMES Service Entities EO Users Sentinel-1 PDGS Key Role Reception and Ingestion Archiving X band raw data Sentinel 1 PDGS Mission Planning Mission Performance Precise Orbit Determination The Sentinel-1 PDGS as a component of the overall GMES Space Component (GSC) Ground Segment, in charge of the following key activities: Implementing the Sentinel-1 mission observation scenario X-Band data reception Generating the operational core ground segment products Reacting to emergency orders with rush instrument tasking and processing Circulation and Dissemination Configuration, Monitoring and Control Mission Access User Interface Products Providing access to Sentinel-1 data Ensuring the long term mission data archiving Monitoring the instrument and mission performance Ensuring Sentinel-1 core operational user products meet the expected quality, with necessary calibration and validation activities

3 Sentinel-1 PDGS main operations concepts Predefined instrument planning timeliness PDGS Layout Core GS operational user products Predefined instrument planning timeliness PDGS Layout Core GS operational user products

4 Sentinel-1 Core PDGS Operational User Products (1) The Sentinel-1 PDGS provides a set of Core operational SAR user products. These user products are made available in an harmonised format based on XFDU, wrapping a set of annotation files in XML and image file/s in binary (L0), geotiff (L1), NetCDF (L2) Other products (supported products) are generated by the Sentinel-1 Core PDGS for internal purposes or to fulfil specific GMES requirements (e.g. stack products for emergency). Additionally: - Hosted processing will be supported within available resources, allowing the generation of other user- defined & implemented products as part of the systematic processing flow. - Other products/services may be provided by the collaborative GS Sentinel-1 Core PDGS Operational User Products (2) LEVEL-0 PRODUCTS Level 0 products contain the compressed, unprocessed instrument source packets, with additional annotations and auxiliary information to support the processing. Only SAR Level-0 products for SAR SM, IW and EW modes are made available to the S-1 users. LEVEL-1 PRODUCTS Level-1 Slant-Range Single-Look Complex Products (SLC): SLC products provide focused data in slant-range geometry, single look, containing phase and amplitude information. Level-1 Ground Range Detected Geo-referenced Products (GRD): Focused data is projected to ground range, detected (phase information is lost) and multi-looked. is projected to ground range using an Earth ellipsoid model, maintaining the original satellite path direction and including complete geo-reference information. LEVEL-2 PRODUCTS Level-2 Ocean (Wind, Wave and Currents) products Ocean wind field, swell wave spectra and surface currents information as derived from SAR data. L2 ocean products are available for all modes (although information content may slightly vary per mode)

5 Predefined instrument planning timeliness PDGS Layout Core GS operational user products Sentinel-1 PDGS Layout The Sentinel-1 PDGS is a distributed system, with elements deployed in various core PDGS centres Core Ground Stations reception NRT processing and dissemination Reference Platform Centre Reference facility for AIV activities CGS CGS CGS CGS RPF PDMC MPC PAC PAC PAC PAC Payload Management Centre LTA Mission Planning and management MMUS and Archiving Centres Fast-24h processing and dissemination POD Medium term archiving Mission Performance Centre Instrument performance, calibration and quality control In addition the Sentinel-1 PDGS includes the following services: Long Term Archiving Service (LTA) Precise Orbit Determination Service (POD) Multi-Mission User Services (MMUS)

6 Predefined instrument planning timeliness PDGS Layout Core GS operational user products Sentinel-1 PDGS Timeliness access to systematically generated products is provided according to the following timeliness: Standard timeliness: within 24h from sensing for all systematic products NRT timeliness: < 3h from sensing (within 1h from downlink) < 1h from sensing for data acquired in direct downlink over specific areas (e.g. European waters). <24h S1-A < 3h 10 min / 1 h time Inst. sensing S1 NRT data S1 NRT data S1 24h data X-Band downlink CGS PAC X-Band downlink Inst. sensing CGS

7 Predefined instrument planning timeliness PDGS Layout Core GS operational user products Predefined instrument planning Based on the Sentinel-1 mission observation requirements from GMES Services, National Users, continuity needs, a pre-defined Long Term Plan is built up by the Sentinel-1 PDGS and used as baseline for instrument tasking. This Long Term Plan: -defines the instrument sensing and downlink activities during the LTP period, solving any observation conflicts and ensuring compliance with spacecraft constraints -is defined in line the available downlink resources & affordable instrument sensing activity (up to 25 min of HBR mode dual polarisation per orbit) -is expected to be interrupted only to satisfy emergency/crisis requests whenever they can be fulfilled by the Sentinel-1 mission -is updated regularly in time to follow the evolution of the user observation needs and the availability of GS resources. -is available for consultation through the Sentinel-1 access interface (ngeo) (*) The Sentinel-1 Core Ground Stations network is currently being selected through open ITT.

8 Predefined instrument planning for TOPS interferometry TOPS burst synchronization is essential to exploit TOPS data for interferometry Full synchronisation Synchronization is achieved by defining a set of tie points around the orbit (separated by the TOPS cycle time) and ensuring the TOPS acquisitions start in one of these tie points. Partial synchronisation Mission planning is performed by the PDGS based on position, rather than absolute time. Tie points position remains fixed during the mission and selected start position is converted in time onthe-fly by the spacecraft using the on-board GNSS. IW1 IW1 IW3 IW2 TOPS cycle time 2.7 sec IW acquisition #N IW acquisition #N+1 Predefined instrument planning timeliness PDGS Layout Core GS operational user products

9 (1) Based on a baseline observation scenario, after resolving potential conflicting observation needs, Sentinel-1 data is acquired in a pre-defined mode/polarisation and frequency around the world. From the same data acquired according to this plan, multiple processing requirements can be fulfilled in terms of regional areas and product type. Accordingly, the Sentinel-1 data processing scenario is based on a pre-defined set of products systematically generated over well defined areas and timeliness in a data driven mode, constituting the Sentinel-1 data sets or collections, e.g.: Collection 1: IW SLC products generated for all IW data acquired over Saint Andreas Fault and made available within 24h from sensing Collection 2: IW SLC products generated for all IW data acquired over the Etna and made available within 24h from sensing Collection 3: IW GRD products generated for all IW data over Italy and made available within 24h from sensing Collection 3: IW GRD products generated for all IW data acquired over Artic sea-ice areas and made available within 3h from sensing. (2) Concept Global Instrument mode SM, IW, EW Product Type Timeliness (availability after sensing) Comment SAR L0 SAR L1 GRD <24h All acquired data WV SAR L2 OCN <3h All acquired WV mode data (oceans areas) SAR L2 OCN <3h For regional maritime surveillance areas in HBR mode defined through HLOP Regional SM,IW,EW SAR L0 SAR L1 GRD SAR L1 SLC <3h available in 3h from sensing from the core PDGS for regional areas defined through HLOP SAR L1 SLC <24h available in 24h from sensing from the core PDGS for regional areas defined through HLOP Local SM,IW,EW SAR L0 SAR L1 GRD <10 min Only for data acquired in direct downlink over the S-1 Core Ground Stations when not addressed by collaborative stations Archive SM,IW,EW, WV SAR L0 SAR L1 GRD SAR L1 SLC SAR L2 OCN Offline All systematically generated data is available on-line on a Non Time Critical basis (e.g. nominally 24h) Products non systematically generated (e.g. SLC outside the systematic regional areas) can be requested from L0 Global: Applies to all acquired data Regional: Applies to data acquired over well defined geographical areas, including areas required in NRT, (cf. HLOP) Local: Applies to well defined geographical areas fulfilling specific constraints (e.g. within the stations coverage area) (cf. HLOP)

10 processing strategy (1) Sentinel 1 instrument operations: High Bit Rate (HBR) modes (SM/IW/EW) are operated for max 25 min / orbit WV mode is operated continuously over ocean Sentinel 1 systematic observation scenario results in large acquisition segments (data takes of few minutes) 6 min IW 15 min IW 2 min IW processing strategy (2) For Sentinel-1 access to long product stripes (e.g. similar to ASAR MR WSM or IMM products today systematically disseminated) would result in an unmanageable product size for Sentinel- 1 L1 HBR modes. As a matter of example: L0 products L1 products Sentinel 1 Level 0 and Level 1 products will be segmented and made available in slices of defined length along track, optimised per instrument mode. Several minutes IW data take L0 slice#1 L0 slice#2 L0 slice#3 L0 slice#4 L0 slice#5 L0 slice#6 ` L1 slice#1 L1 slice#2 L1 slice#3 L1 slice#4 L1 slice#5 L1 slice#6

11 processing strategy (3) Slices are referred to the start of each acquisition segment. Sliced GRD L1 products Slices cover a sub-set of the data take in along-track direction and the complete data take area in the across track direction. Slices are standard independent products. Slices can be seamlessly concatenated by the user into a continuous product or stripe covering up to the complete data take. Predefined instrument planning timeliness PDGS Layout Core GS operational user products

12 On-line Access Main concepts In line with the Sentinels Policy, the Sentinel-1 products will be made available on-line to registered users. access is mainly based on a concept of subscription to a set or sub-set of products systematically generated (podcast concept). Additionally, data discovery and download of any product systematically generated is possible through the user data access interface (ngeo) In case the selected product to be downloaded is not available in the GS (i.e. in case it was not part of the systematic processing scenario), the product is generated onthe-fly from the source L0 product, transparently to the user. However, limited GS resources may be available to support this scenario. On-line Access Main mechanisms The next generation user services for Earth Observation (ngeo) will be the main user data access interface for Sentinel users. It will provide: - A web based interface for: - discovery - Interactive data selection and download - Definition of personal subscription (identifying an area of interest and a mode/product type) - A download manager application, which the user installs and runs as a daemon in its own premises, which is in charge of downloading any new product matching the user defined order - The possibility to download only a set of product components (e.g. only one polarisation for dual polarisation products, or only one sub-swath for TOPS SLC products) - Information on interferometric baseline and burst synchronisation

13 On-line Access Main scenarios GMES Services requiring regular access to a pre-defined collection of systematically generated S1 products: -The user will be able to subscribe to the desired collection/data set through the CDS -the user will have transparent on-line download capability for any new product associated to the subscribed data sets through a transparent data access client Users requiring access to regular access to S1 products systematically generated but over a limited user-specific area: -The user will be able to define his personal data set (e.g. any IW SLC over a user defined area) through ngeo -Any new product systematically generated matching the user request definition will be automatically downloaded by the ngeo download manager. Users requiring occasional access to S1 products: -The user will be able to discover Sentinel-1 acquired data through the ngeo front-end and select a past acquisition and product type to be downloaded -If the selected product type - is available in the GS archives, it is made available on line to be downloaded by the user - is not available in the GS archives, it is generated on-the-fly from the source L0 product transparently to the user (within available resources) Main challenges and Status

14 Sentinel-1 PDGS challenges Challenging requirements in terms of data volume (~ 1 TB/day of data downlinked, > 1 TB/day of new products generated) and data policy implementation For Real time (~1h from downlink) : The Sentinel-1 represents a volume increase of a factor 30 compared to the most demanding ESA EO SAR Scientific mission (under a minimum systematic S-1 product generation scenario) NRT S1-A => GS Operational requirements never achieved worldwide for SAR missions (volume, availability, reliability, ) GB ENVISAT ASAR NRT(Average S-1 Scenario) [GB/day] Largely distributed system, with core ground segment centres being selected New capabilities to be exploited in terms of collaborative interfaces Operational products with traceable and maintained quality through the mission Extremely demanding data access needs for an open and free access to all systematically generated data. but also new challenges for Sentinel-1 users to be ready to make the best use of it!!!! Sentinel-1 PDGS Status System Requirements Review: April 2009 Preliminary Design Review: Nov 2010 Core Ground Stations and PACs selection Critical Design Review: Dec 2011 v1 Factory Acceptance: Dec 2011 reference platform v2 Acceptance Review: Jun 2011 first partial deployed system v3 Acceptance Review: Oct system deployed for CP operations Satellite Launch & Commissioning v4 Acceptance review: Launch + 3 months

15 Thank you