GMES Sentinel-1 mission Ramon Torres a , Paul Snoeij a, ⁎, Dirk Geudtner a , David Bibby a , Malcolm Davidson a , Evert Attema a , Pierre Potin a , BjÖrn Rommen a , Nicolas Floury a , Mike Brown a , Ignacio Navas Traver a , Patrick Deghaye a , Berthyl Duesmann a , Betlem Rosich a , Nuno Miranda a , Claudio Bruno b , Michelangelo L'Abbate b , Renato Croci b , Andrea Pietropaolo b , Markus Huchler c , Friedhelm Rostan c a ESA/ESTEC, The Netherlands and ESA/ESRIN, Italy b Thales Alenia Space Italia, Italy c EADS Astrium GmbH, Germany abstract article info Article history: Received 20 December 2010 Received in revised form 14 April 2011 Accepted 7 May 2011 Available online 18 February 2012 Keywords: CSAR Space borne C-Band Satellite Remote Sensing GMES Constellation In the frame of the Global Monitoring for Environment and Security (GMES) Space Component programme, the European Space Agency (ESA) undertook the development of a European Radar Observatory (Sentinel-1), a polar orbiting two-satellite constellation for the continuation and improvement of SAR operational services and applications. Satellite and payload are being built to provide routine, day-and-night, all-weather medium (typically 10 m) resolution observation capability. Ground infrastructure is provided for planning, mission control, data processing, dissemination and archiving. Free and open data access is provided. Data quality of the Sentinel-1 data products is shown along with uncertainty estimation of retrieved information products confirming specified performance and indicating application growth potential. The unique data availability performance of the Sentinel-1 routine operations makes the mission particularly suitable for emergency re- sponse support, marine surveillance, ice monitoring and interferometric applications such as detection of subsidence and landslides. © 2012 Elsevier Inc. All rights reserved. 1. Introduction The short-lived but successful US SEASAT satellite provided a first glimpse of the potential of imaging radar from space in 1978. ESA's own programme to develop advanced microwave radar instruments culminated with the launches of ERS-1 (17 July 1991) and ERS-2 (20 April 1995). ERS demonstrated for the first time the feasibility of flying reliable, stable and powerful radar imaging systems in space. The dependability and all- weather capability of the instruments also provided a foundation for developing and exploiting radar images for a wide variety of applications. While the initial objectives for ERS-1 at launch were predominantly oceanographic, other applications were con- sidered during the project's preparation. The ESA Remote Sensing Advisory Group in 1974, for example, emphasised commercial ap- plications such as agriculture, land-use mapping, water resources, overseas aid and mapping of mineral resources in its advice on ERS objectives. The rigorous design of the ERS SAR hardware – emphasising instrument stability in combination with accurate and well-calibrated data products – created new opportunities for scientific discovery, revolutionised many Earth science disci- plines and laid the foundations for commercial applications. For example, ‘SAR interferometry’, which can track land shifts of only a few millimetres, was developed mainly using ERS data and is now commonly used in Earth sciences and commercial applications. The potential of space radars viewing the same scene only a short time apart was demonstrated in 1995 and 1996 during the ERS ‘tan- dem mission’, when the orbits of ERS-1 and ERS-2 were carefully matched but with a 1-day gap. An important milestone was the launch of the Advanced SAR (ASAR) on Envisat on 28 February 2002. This ensured the contin- uation of C-band data and added enhanced capabilities such as wide swaths and dual polarisation, features that have since rapid- ly been integrated into and exploited by many applications. The archive of radar data since 1991 is extremely valuable for science and applications, providing a consistent set of data spanning 16 years. The ESA Sentinels constitute the first series of operational satel- lites responding to the Earth Observation needs of the European Union (EU) — ESA Global Monitoring for Environment and Security initiative. The GMES Space Component (GSC) programme relies strongly on new complementary developments by ESA in addition to existing and planned space assets from different agencies. As part of the GSC, ESA is currently undertaking the development of 3 Remote Sensing of Environment 120 (2012) 9–24 ⁎ Corresponding author. E-mail address: paul.snoeij@esa.int (P. Snoeij). 0034-4257/$ – see front matter © 2012 Elsevier Inc. All rights reserved. doi:10.1016/j.rse.2011.05.028 Contents lists available at SciVerse ScienceDirect Remote Sensing of Environment journal homepage: www.elsevier.com/locate/rse