The Copernicus ProgrammeSentinel-2 earth observation mission developed by ESA will provide continuity to services relying on multi-spectral high-resolution optical observations over global terrestrial surfaces. Sentinel-2 will capitalize on the technology and the vast experience acquired in Europe and the US to sustain the operational supply of data for services such as forest monitoring, land cover changes detection or natural disasters management.
The Sentinel-2 mission will offer an unprecedented combination of the following capabilities:
Multi-spectral data with 13 bands in the visible, near infra-red and short wave infra-red part of the spectrum;
Systematic global coverage of land surfaces : from 56°South to 84°North, coastal waters and all Mediterranean sea;
High revisit: every 5 days at equator under the same viewing conditions;
High spatial resolution: 10m, 20m and 60m;
Wide field of view: 290 km.
Frequent revisits and high mission availability require two identical Sentinel-2 satellites operating simultaneously, which dictates a small, cost-effective and low-risk satellite. The orbit is Sun-synchronous at 786 km altitude (14+3/10 revolutions per day) with a 10:30 a.m. descending node. This local time was selected as the best compromise between minimizing cloud cover and ensuring a suitable Sun illumination. It is close to the Landsat local time and matches SPOT’s, allowing the seamless combination of Sentinel-2 data with historical images to build long-term time series. The two satellites will work on opposite sides of the orbit. The launch of the first satellite unit is expected in May 2015.
Sentinel 2 spacecraft carry a single multi-spectral instrument (MSI) with 13 spectral channels in the visible/near infrared VNIR and short wave infrared spectral range SWIR. Sentinel 2's spatial resolution varies between 10, 20, and 60 meters depending on the bands and the satellite has a swath width of 290 km.
In June 2013, the Centre National d'Etudes Spatiales released and distributed training data sets to help future sentinel-2 users develop methods and applications based on multitemporal data. From the first of February 2013 to the end of June 2013, just before its deorbitaion, SPOT4 was put on a 5 day repeat-cycle orbit, to provide time series with the same repetitivity as Sentinel-2. 45 sites (from 60*60 km² to 220*170 km²) were observed every fifth day during five months. This experiment was named SPOT4 (Take5) . Later on, beginning of 2016, the Venµs satellite will provide data sets with a repetitivity of 2 days over 100 sites (28*28 km²).