Sentinel-1 is a two satellite constellation for land and ocean monitoring. C-band imaging will provide an all-weather day-and-night supply of imagery for Copernicus user services. This is the second and last satellite launched of the pair.
The 2.1a version includes conversion from analog to digital flight control system and uprated engines on the booster and the first stage with improved injection systems. The new digital flight control and telemetry systems allow the rocket to launch from a fixed rather than angled launch platform and adjust its heading in flight. A digital control system also enables the launch of larger commercial satellites with wider and longer payload fairings such as the ST-type fairing. These fairings introduce too much aerodynamic instability for the old analog system to handle. This stage continues to use the RD-0110 engine. The 2.1a/ST version is sometimes called Soyuz ST-A.
Progress Rocket Space Centre, formerly known as TsSKB-Progress, is a space science and aerospace research company which is known for manufacturing launch vehicles and satellites. Most notably, Progress Rocket Space Centre is the manufacturer of Soyuz launch vehicles.INFO WIKI
ESA officials said prospects are dimming for the recovery of a radar imaging satellite that malfunctioned nearly three months ago, but that efforts to save the spacecraft continue.