During activity in the Spaceport’s S3B clean room facility this week, Sentinel-1B was “topped off” with its propellant load, marking another step in preparations for liftoff on April 22.

Sentinel-1B carries a C-SAR (C-band synthetic aperture radar) instrument for all-weather, day/night images, and will join Sentinal-1A – lofted two years ago by Arianespace on another Soyuz mission.

Built by prime contractor Thales Alenia Space, the satellite will have a liftoff mass of approximately 2,300 kg. and is to operate in low Earth orbit at an altitude of 694 kilometers. It is based on a Prima spacecraft platform developed by Thales Alenia Space on behalf of the Italian space agency, ASI.

Sentinel-1B and the identical Sentinel-1A are part of Europe’s Copernicus Earth observation program, managed by the European Space Agency (ESA) program in partnership with the European Commission. Copernicus has the goal of ensuring European independence in the acquisition and management of environmental data concerning the planet, as well as to support local authorities and policy-makers.

The April 22 mission is designated Flight VS14 in Arianespace’s launcher family numbering system, and will be the company’s third of 12 targeted missions in 2016 with its medium-lift Soyuz, heavy-lift Ariane 5 and lightweight Vega vehicles.