The European Union has launched its latest Sentinel Earth Observation Satellite.
Sentinel-3b is a multi-purpose satellite, but will focus much of its work on the oceans and monitor their behavior and health.
The space probe was launched from the Russian spaceport Plesetsk with a modified intercontinental missile.
There will be an identical platform, Sentinel-3a, which was sent into orbit two years ago.
This is the seventh satellite launched by the EU in its ambitious Copernicus program, which aims to bring the largest volume of Earth observation data into the hands of politicians, scientists, businesses and the public.
All the Sentinels are watching is open information that anyone in the world can access with a computer and an Internet connection.
Missions 3a and 3b have been designed for a variety of tasks, from measuring Arctic sea ice thickness and monitoring forest fires to assisting in hurricane prediction to identifying marine pollution.
As with all Sentinels, the procurement and early operations of 3b are assigned to the European Space Agency (ESA), the EU's technical agency for Copernicus. But for this new mission, Esa has decided to do something different.
The Russian Rokot thrower injects 3b directly in front of 3a so that the performance of the two instruments can be directly compared when flying over the same piece of earth.
"3b will fly 21
This should eventually see two perfectly cross-calibrated spaceships making neatly nested observations of the planet. The production of the Sentinel 3 series is industrially operated by Thales Alenia Space of France, but benefits from the contributions of about 100 companies throughout Europe, including the United Kingdom.
Britain had the core task of testing the sea and land surface temperature radiometer (SLSTR) on each spacecraft.
The UK's involvement in the EU's flagship programs after Brexit is currently subject to many uncertainties and future cooperation in the Galileo satellite navigation system is becoming increasingly unlikely. But there is hope that Galileo's suffering will not be mirrored by Copernicus.
Britain reaffirmed its desire to stay in the Earth Observation Program on Wednesday. To underscore this intention, the UK Space Agency has devised new ESA feasibility studies for the planning of future Sentinels in the 2020s – several years after the nation officially withdrew from the EU.
Sam Gyimah, Minister of Science, said: "The British space sector is a success story and our capabilities in Earth Observation Satellite technology are second to none, and these recent contracts confirm Copernicus's crucial role in UK research, innovation and industry."
"It was clear to us that we want our companies and universities to continue to participate in the major space programs of the EU as long as they can participate fairly and openly, and our leading role in the European Space Agency will not change if we leave the EU, and this government will ensure that Britain thrives on our modern industrial strategy in the era of commercial space. "
The Europe-funded Sentinel series
- Sentinel -1: Radar satellite that can see the Earth's surface in any weather
- Sentinel-2 : Multi-wavelength Investigators for Investigating Land Changes
- Sentinel-3: Similar to S2, but set to observe ocean characteristics and behavior
- Sentinel-4: High-orbit sensor for measuring atmospheric gases
- Sentinel-5: Low noise airborne sound sensor Air quality monitoring station
- Sentinel -6: Future version of Jason's long-running sea range
What is the Copernicus program?
- EU project procured with the help of the European Space Agency ESA
- Monitoring of space and ground data  Will use a number of spaceships – some already there, others still to fly
- For Invaluable scientists studying climate change
- Important for response to disasters – earthquakes, floods, fires, etc.
- Data will also help in the design and enforcement of EU policies: catch quotas, etc.