Sentinel-1A and 1B are a twin pair of satellites that carry a C-band synthetic aperture radar and are operated by the European Space Agency (ESA).

Sentinel-1A was launched on the 3rd April 2014 and Sentinel-1B on the 25th April 2016 at the Guiana Space Centre in Kourou, French Guiana upon a Soyuz rocket.

The mission of Sentinel 1 is acquisition of Earth imagery using C-Band SAR data. Both satellites carry the C-band synthetic-aperture radar instrument where data can be collected day or night and in all weather conditions. These two identical satellites operate at the same altitude of 693km in a sun-synchronous orbit. They have an ability to map the entire Earth every 12 days. Within 1 hour of acquisition radar data can be delivered to Copernicus – the European Union Earth observation and monitoring programme.

Radar imagery from the Sentinel 1 mission can be used for various applications such as land surface movement monitoring via the creation of InSAR images. Data is also used for marine applications such as ocean oil spills or sea ice conditions and emergency response to name a few.