A few hours ago the Sentinel-3B satellite, part of the GMES / Copernicus program, was launched from the Russian Plesetsk Cosmodrome on a Rockot launch vehicle. After about an hour and a half it separated from the rocket’s last stage, called Breeze KM, it started communicating with the control center and to deploy its solar panels. Its final orbit is Sun-synchronous, which means it will pass over a certain area of ​​the Earth at the same local time, with an altitude of about 815 kilometers (about 506 miles).

The program originally called Global Monitoring for Environment and Security (GMES) and later Copernicus aims to create an autonomous territorial control system through a constellation of satellites that have different functions. The Sentinel-3A satellite, the first of its kind, was launched on February 16, 2016 and now, after some delay, its twin can get work with it.

The data collected by the Sentinel-3 satellites are first collected by the Copernicus Marine Environment Monitoring Service because they have the primary purpose of carrying out various measurements of the seas. However, they’re also used to map and monitor rivers, lakes and forests for a range of environmental monitoring goals.

The two Sentinel-3 satellites now in orbit will send data they collect within 3 hours from their detection. With the addition of Sentinel-3B, the times between a passage on an area of ​​the planet and the next will be halved. This will be particularly useful in case of emergencies such as floods but also wildfires.

However, all this will have to wait until the end of the new Sentinel-3B satellite’s test phase. To conduct it, in the first months of operations it will fly into what’s been called a tandem configuration with its twin Sentinel-3A following it at an initial distance of 223 kilometers (138 miles). The two satellites will fly together to allow a cross-calibration of their instruments and data processing.

Once that test phase is over, the Sentinel-3B satellite will be moved to its final orbit and Eumetsat will take control of it. At that point, the two Sentinel-3 satellites will be separated by 140 degrees while normally satellites pairs are separated by 180 degrees. This will allow both of them to detect certain phenomena on the ground with greater speed.