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The first Sentinel-2 satellites, which constitute the next generation of operational Earth observation satellites for optical
land monitoring from space, are undergoing completion in the facilities at Astrium ready for launch end 2014. Sentinel-2
will feature a major breakthrough in the area of optical land observation since it will for the first time enable continuous
and systematic acquisition of all land surfaces world-wide with the Multi-Spectral Instrument (MSI), thus providing the
basis for a truly operational service. Flying in the same orbital plane and spaced at 180°, the constellation of two
satellites, designed for an in-orbit nominal operational lifetime of 7 years each, will acquire all land surfaces in only 5
days at the equator. In order to support emergency operations, the satellites can further be operated in an extended
observation mode allowing to image any point on Earth even on a daily basis. MSI acquires images in 13 spectral
channels from Visible-to-Near Infrared (VNIR) to Short Wave Infrared (SWIR) with a swath of almost 300 km on
ground and a spatial resolution up to 10 m. The data ensure continuity to the existing data sets produced by the series of
Landsat and SPOT satellites, and will further provide detailed spectral information to enable derivation of biophysical or
geophysical products. Excellent geometric image quality performances are achieved with geolocation better than 16 m,
thanks to an innovative instrument design in conjunction with a high-performance satellite AOCS subsystem centered
around a 2-band GPS receiver, high-performance star trackers and a fiberoptic gyro. To cope with the high data volume
on-board, data are compressed using a state-of-the-art wavelet compression scheme. Thanks to a powerful mission data
handling system built around a newly developed very large solid-state mass memory based on flash technology, on-board
compression losses will be kept to a minimum. The Sentinel-2 satellite design features a highly flexible operational
concept, allowing downlink of all mission data to a nominal X-band core ground stations network. In addition, users
could receive mission data sets at selected X-band local user ground stations or through an Optical Communication
Payload (OCP) via an inter-orbit optical link to a geostationary EDRS relay satellite at Ka-band user ground stations.
Different priority schemes can be selected in flight to allow transmission of critical image data with the shortest possible
latency. The system is designed for high system autonomy allowing for pre-programming of the operational schedule for
15 days in advance without interference from ground. Apart from the nominal and extended imaging modes, the satellites
also feature a calibration mode to support regular in-orbit radiometric calibration of the instrument. Overall, the Sentinel-
2 satellites are designed to provide in-orbit availability for the instrument data greater than 97%, which fulfills the
requirements of a fully operational system for multispectral Earth observation.
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