Sentinel-3B, the second satellite in the Sentinel-3 satellite constellation, is scheduled to be launched into space from Plesetsk Cosmodrome in Russia on 25 April 2018.

To be placed at an altitude of 814.5km in a sun-synchronous orbit, the satellite will monitor ocean, ice and land data through high-accuracy multi-spectral optical and radar instruments.

The satellite has been developed as part of Copernicus programme, which is jointly funded by the European Commission (EC) and the European Space Agency (ESA) to establish the European capacity for Earth observation.

Sentinel-3A, the first satellite in the Sentinel-3 satellite constellation, was launched in February 2016. The third and fourth satellites named respectively Sentinel-3C and Sentinel-3D are scheduled to be launched in 2021.

Eumetsat is responsible for the marine operations of the Sentinel-3 satellites, while the ESA is responsible for the land operations.

Sentinel-3B satellite design and features

The Sentinel-3B satellite’s design, assembly, construction and testing services contract was awarded to Thales Alenia Space (TAS). The satellite was developed at TAS’ cleanroom located in Cannes, France.

Designed for a life of seven years based on Prima bus platform developed by TAS, the Sentinel-3B measures 3.7m-long, 2.2m-wide, and 2.2m-high. It will have a launch mass of 1,250kg and a dry mass of 1,150kg. It includes deployable solar array and batteries, while it can generate approximately 2.3kW of power in the space.

The satellite was transported to Plesetsk Cosmodrome in Russia for pre-launch operations in March 2018.

Instruments on-board Sentinel-3B satellite

The satellite is equipped with a range of instruments to measure variables such as sea-surface topography, including ocean and land colour instrument (OLCI) with a swath width of 1,270km. It also includes a sea and land surface temperature radiometer (SLSTR) with a swath width of 1,420km.

“The data provided by the satellite will help to improve oceanographic and atmospheric forecasts.”

It also includes a synthetic aperture radar altimeter (SRAL), microwave radiometer (MWR), and doppler orbitography and radio positioning integrated by satellite (DORIS).

The spacecraft also carries a global navigation satellite system (GNSS) and a laser ranging retroreflector (LRR). The GNSS can perform precise orbit determination and track multiple satellites simultaneously, while the LRR can accurately locate the satellite in orbit.

Sentinel-3B satellite mission details

The satellite can support both maritime and land missions, including oceanography, continental hydrology, and observation of vegetation on land.

The ocean surface topography mission involves precise measurement of sea height, wave heights and wind speed over the oceans. It will also measure the temperature and colour of water in oceans, lakes and rivers.

The satellite will monitor sea and land ice topography, land-use change, forest cover mapping, fire detection and weather forecasting. As part of the land mission, it will also measure Earth’s thermal radiation for atmospheric applications.

The data provided by the satellite will help to improve oceanographic and atmospheric forecasts.

The Sentinel-3B, along with Sentinel-3A, will ensure the monitoring and understanding of large-scale global dynamics.

Launch vehicle details

The satellite launch services contract for Sentinel-3B was awarded to Eurockot Launch Services. The spacecraft will be launched on-board the Rockot launch vehicle.

The launch vehicle features a booster unit and a re-ignitable Breeze-KM upper stage. The booster unit employs the SS-19 intercontinental ballistic missile for the first and second stages, while the upper stage includes an inter-stage, a Breeze upper stage, a payload adapter and a payload fairing.

The satellite’s launch operations will be carried out from Plesetsk Cosmodrome in Northern Russia.

Contractors involved

The SRAL and SLSTR instruments for the satellite were provided by TAS. The MWR instrument was provided by EADS CASA, while the DORIS instrument was supplied by CNES.

Other suppliers involved with the satellite development are SELEX Galileo, Rutherford Appleton Laboratory (RAL), Jena-Optronik, and ABSL.