Sentinel-3 Sets Sail

Artist's view of Sentinel-3. Image courtesy of ESA–Pierre Carril.

Artist’s view of Sentinel-3. Image courtesy of ESA–Pierre Carril.

At 17.57 GMT yesterday (16th February 2016) Sentinel-3 set sail from the Plesetsk Space Centre in Russia, heading for its 814 km sun-synchronous low Earth orbit. Like all the other Sentinel launches, we were at home watching the live feed!

This is the third Sentinel launch of the European Commission’s Copernicus Programme, following Sentinel-1 and 2. Sentinel-3, like its predecessors, will be part of a twin satellite constellation with Sentinel-3B’s launch expected to be in 2017.

Sentinel-3 carries four scientific instruments:

  • Sea and Land Surface Temperature Radiometer (SLSTR) will measure temperatures of both the sea and land, to an accuracy of better than 0.3 K. This instrument has 9 spectral bands with a spatial resolution of 500 m for visible/near-infrared wavelengths and 1 km for the thermal wavelengths; and has swath widths of 1420 km at nadir and 750 km looking backwards. It’s worth noting that two thermal infrared spectral wavebands are optimised for fire detection, providing the fire radiative power measurement.
  • Ocean and Land Colour Instrument (OLCI) has 21 spectral bands (400–1020 nm) focussed on ocean colour and vegetation measurements. All bands have a spatial resolution of 300 m with a swath width of 1270 km.
  • Synthetic Aperture Radar Altimeter (SRAL) which has dual frequency Ku and C bands. It offers 300 m spatial resolution after SAR processing, and is based on the instruments from the CryoSat and Jason missions. This will be first satellite altimeter to provide 100% coverage of the Earth’s surfaces in SAR mode.
  • Microwave Radiometer (MWR) dual frequency at 23.8 & 36.5 GHz, it is used to derive atmospheric column water vapour measurements for correcting the SRAL instrument.

The scientific instruments are supported by four positioning/navigation instruments to ensure the satellite maintains its precise orbit.

Sentinel-3 will mainly be focussing on ocean measurements and will include the measurement of sea-surface height (similar to the recently launched Jason-3); however it will also measure sea surface temperature, ocean colour, surface wind speed, sea ice thickness and ice sheets. Whereas over land the satellite will provide indices of vegetation, measuring the height of rivers and lakes and help monitor wildfires.

Sentinel-3 is a very exciting satellite for us, as the data and products it will produce are very much within the wheelhouse of the services that Pixalytics offers. Sam’s background is in ocean colour, she’s world renown for atmospheric correction research and we offer a variety of agritech services including vegetation indices. You can probably now see why we’re so excited!

The satellite is currently in its commissioning phases where ESA tests the data produced by the sensors. This is undertaken in conjunction with a group of users, and Pixalytics is one of them! This phase is expected to last five months, after which the satellite will be transferred to Eumetsat and the data should be released.

Like all the data from the Copernicus programme, it will be offered free of charge to users. This will challenge organisations, like us, to see what innovative services we can offer with this new data stream. Exciting times ahead!