Sentinel-2A is the first half of the Sentinel-2 mission, which also includes the identical satellite, Sentinel-2B.
Sentinel-2 is providing high-resolution optical imagery of agriculture, forests, land-use change and land-cover change. It is mapping biophysical variables such as leaf chlorophyll content, leaf water content and leaf area index. It is also monitoring coastal and inland waters and helping with risk and disaster mapping.
The Sentinel-2 mission is providing global coverage of Earth's land surface every 5 days. The satellites' state-of-the-art Multispectral Imager (MSI) instrument offers high-resolution optical imagery.
The MSI payloads acquire, store and then download up to 1.6 TB of data per orbit. The data are transmitted to the Sentinel ground stations and via high data-rate laser links to a geostationary telecoms satellite, Alphasat, and via the European Data Relay Satellite (EDRS) system, as well as using the more usual x-band radio data downlink. The Flight Control Team uploads commands and receives satellite status and health information via ESA's Estrack ground station at Kiruna, Sweden.
Sentinel-2A and -2B will fly an initial nominal mission of seven years, with extensions possible until on-board consumables are exhausted (each carries 123 kg of fuel including that necessary for end-of-life deorbiting), to a maximum of 12 years.
In the routine phase, the Sentinel-2 Flight Control Team comprises six engineers dedicated to Sentinel 2A and 2B, and a team of spacecraft controllers shared between all the Sentinel missions. They work in a control room dedicated to Sentinels located at ESOC and in close coordination with the teams operating the other Sentinel missions.
The team are responsible for all aspects of flight control, including mission planning, maintaining attitude and orbit control, monitoring the real-time status of the satellite and its power, navigation, thermal and propulsion systems, executing orbital manoeuvres and much else. They are supported by other specialists at ESOC, including experts from flight dynamics, ground facilities, tracking stations, space debris and mission data systems. For each launch campaign and during the critical few weeks following each lift-off, the team is augmented by additional engineers and specialists.
Like many Earth missions at ESA, the ground segment for Sentinel-2 is split into two halves: the Flight Operations Segment (FOS) for flight control, based at ESOC, and the Payload Data Ground Segment (PDGS) for downloading, processing and distributing the MSI images.
At ESOC, the FOS includes the Sentinel Mission Control System (MCS), which comprises hardware and software for telecommanding, receipt and handling of telemetry, data archiving and processing all other tasks essential for controlling the mission.
It also includes the Sentinel Mission Scheduling System, the Sentinel-1, -2 and -3 satellite simulators – to support procedure validation, operator training and simulation campaigns – and the Sentinel Flight Dynamics System (FDS), which supports all activities related to attitude and orbit determination and prediction, preparation of slew and orbit manoeuvres and evaluation of satellite dynamics and navigation.
For Sentinel-2, ‘housekeeping’ telemetry from the satellites can be downlinked via the ground station, using a 2-Mb/second link, or received from the PDGS via the X-band downlinks performed every orbit.