1. Sentinel Convoy: Synergetic Observation by Missions Flying in Formation with European Operational Missions Workshop to engage a wider science community Dates: 31 October - 1 November 2011 Venue: ESA ESTEC, Noordwijk, The Netherlands E-mail (Dr Neil Humpage): nh58@le.ac.uk Website: www.le.ac.uk/sentinel-convoy-land

2. Background ESA are undertaking three studies investigating possible synergistic satellite missions flying in formation with the operational GMES and METOP satellites These three studies are focussed on:- a) sea and ice b) land c) atmosphere SSTL, the University of Leicester and Astrium Ltd are undertaking the second of these studies: Sentinel Convoy: Synergetic Observation by Missions Flying in Formation with European Operational Missions, Focusing on the Land Theme.

3. Overall Study Objectives Sentinel Convoy: Synergetic observation by missions Flying in Formation with European Operational Missions. To identify and develop, (through thorough systematic analysis), potential innovative Earth science objectives and novel applications and services that could be made possible by flying additional satellites, (possibly of small- class type), in constellation of formation with one or more already deployed or firmly planned European operational missions, with an emphasis on the GMES Sentinels, but without excluding other possibilities. In the long-term, the project aims at stimulating the development of novel, (smaller), mission concepts in Europe that may exploit new and existing European operational capacity in order to address in a cost effective manner new scientific objectives and applications

4. Overall Study Logic Step -1 Identification of science gaps that might be addressed by a “convoy” mission flying with the Sentinel satellites Step-2 Identification of candidate mission concepts that may address the identified gaps Step-3 Down-selection of most promising concepts from list of candidates Step-4 Detailed technical study of selected concepts Step-5 Cost and schedule analysis of selected concepts

5. Aims of the Workshop Step -1 Identification of science gaps that might be addressed by a “convoy” mission flying with the Sentinel satellites Step-2 Identification of candidate mission concepts that may address the identified gaps FOCUS OF THE WORKSHOP PRELIMINARY DISCUSSION

6. Preparation Material - Contents List To facilitate the discussions during the workshop, the following slides provide:- Workshop Part 1 1.1 Information on the priority science areas which are likely to be discussed 1.2 Definition of potential “gaps” 1.3Parameters relating to the information products which might be generated from the convoy system Workshop Part 2 2.1Examples of some existing and proposed synergistic missions 2.2Data on the Sentinel satellites with which the convoy missions will fly 2.3 Performance parameters which will be relevant to the mission concepts 2.4 Operational constraints relating to collaboration with the Sentinel missions 2.5 Definitions of Formation Flying and Constellation as we shall use the terms in this study

7. The following science areas will be highlighted during the workshop:- The water cycle The carbon cycle Terrestrial ecosystems Biodiversity Land use and land use cover Human population dynamics 1.1 Priority Science Areas

8. 1.2 Gaps The focus of this workshop is to engage a wider scientific community regarding the identification science gaps and user needs. Gaps in capability could include:- The need for data with higher spatial/spectral/radiometric resolution The need for more synoptic data collected over a greater percentage of the Earth’s surface in a given time period The need for more frequent observation opportunities over given regions, or longer time-histories of particular target locations The need for observations at novel wavelengths to collect new signatures

9. 1.3 Information Products Workshop participants are invited to consider the nature of the information products that would be required to satisfy the identified science gaps Parameters that will be relevant to the definition and level of the information products include: The frequency with which the final product will need to be generated The frequency or time period over which the individual data sets will be needed The land area over which the data will need to be collected The spatial resolution of the data that will be required The spectral resolution of the data that will be required The radiometric quality and calibration of the data that will be required

10. NASA A-train –Combining data sets from instruments gives better understanding of parameters affecting climate change PREMIER (infrared limb sounder & mm- wave limb sounder) –Earth Explorer 7 Candidate mission will fly ahead of nadir viewing MetOp satellite. Synergy of atmospheric observations down to Earths surface (without cloud) Sentinel-5 Precursor (S5p) – Will fly with NPP/JPSS Atmospheric chemistry, with cloud data provided by NPP/JPSS Earth Explorer 8 candidates –FLorescence Explorer (FLEX) and CarbonSat flying with Sentinel-3 2.1 Examples of Synergistic Missions

11. 2013 / 2015 Sentinel 1 – SAR imaging All weather, day/night applications, interferometry x 2 satellites, 693 km, Dawn dusk orbit 2013 / 2016 Sentinel 2 – Multi-spectral imaging Land applications: urban, forest, agriculture,.. Continuity of Landsat, SPOT x 2 satellites, 786 km, LTDN 10:30 am 2013 / 2017 Sentinel 3 – Ocean and global land monitoring Wide-swath ocean color, vegetation, sea/land surface temperature, altimetry x 2 satellites, 814 km, LTDN 10:00 am 2019 Sentinel 4 – Geostationary atmospheric Atmospheric composition monitoring, trans- boundary pollution 2020+ Sentinel 5 – Low-orbit atmospheric Atmospheric composition monitoring (S5 Precursor launch in 2014) 2.2 Sentinel Mission Summary

12. The second element of the study will involve the translation of the science requirements into a satellite mission concept The endpoint of our mission concept work will include specifications for parameters such as:- Mass Volume Power Duty cycle Data storage requirements Data downlink requirements Satellite/sensor orientation during operations Required pointing accuracy and stability Thermal control Radiation shielding Environmental limits (e.g. Vibration, RF interference, etc.) Meta-data requirements (e.g. time inputs from GPS) To get to this point we will need to answer questions relating to system capacity and operations, as well as defining information products 2.3 Mission Concept Performance Parameters

13. Potential areas for discussion include:- –Mission/experiment lifetime Duration of overlap with Sentinel mission –Orbit type and orbit maintenance Relative position with respect to Sentinel mission Relative ground trace with respect to Sentinel mission Relative time of coverage with respect to Sentinel mission –Satellite/experiment orientation during operations Pointing relative to Sentinel mission –Duty cycle relative to Sentinel mission Proportion of time spent in “cooperative” modes –Information required to permit effective convoy operations Sentinel orbit data accuracy Sentinel mode of operation Sentinel station-keeping cycle Etc. 2.4 Operational Issues

14. 2.5 Definitions of Constellation and Formation Flying Constellation example: RapidEye Formation flying example: Tandem-X