Copernicus, also known as Global Monitoring for Environment and Security (GMES) is program established in 1998 by the European Commission to provide independent global Earth observation system. It utilizes ground stations, air stations and research satellites to provide most accurate information about Earth condition. Program is mainly focused on gathering information on land, ocean, atmosphere and climate change. Also it is helpful in emergency response and security monitoring. Space part of the program could be divided into two groups. First consists satellites developed especially for Copernicus and in second group includes satellites utilized for Copernicus purposes but realizing other missions. Second group included inter alia: European Remote Sensing Satellite ERS-1, Envisat Earth observation satellite, Cosmo-Skymed imaging satellites, various meteorological satellites like MetOp or MSG or JASON-2 ocean topography research satellite.
Spacecrafts developed under Copernicus program are generally divided into six types which stand after “Sentinel” name. Following satellites from each type are signed with letters in the end. First type, Sentinel-1, is radar imaging satellite providing imaging of land and seas in all weather conditions, also in night. First Sentinel-1 (Sentinel-1A) was launched on 2014. Next group is Sentinel-2 – optical imaging satellite providing high resolution pictures for utilizing during emergency situations, with first satellite launched on 23 June 2015. Sentinel-3 is scheduled for 2016 (You can read more here) and will provide global monitoring services. Further type of Sentinel, called Sentinel-4, scheduled for 2012, will be gathering data on atmospheric composition. Sentinel-5 is planned as replacement of ENVISAT satellite lost in 2012; Sentinel-6 is developed to replace JASON-2 in future.
Sentinel-1 satellites are based on Prima bus which was developed by Italian Space Agency (ASI) and Alenia Aerospazio as main contractor on 2001. Bus was designed as universal, modular solution possible to utilize in various types of satellites. Using this bus by Thales Alenia Space was natural solution due the fact that Alenia Aerospazio is part of Thales Alenia Space and its easy adopting for different purposes. Prima also showed its advantages as bus for imaging satellites being utilized in four Cosmo-Skymed satellites utilized for Copernicus program. Sentinel-1 satellites are equipped with C band synthetic aperture radar (SAR) for radar imaging with ground resolution from 5 to 25 meters. Onboard instruments are powered by deployable solar arrays and batteries. Sentinel-1 weighs 2280 kg and has operational life at 7 years.