Two recent expeditions that took scientists 26 000 km across the Atlantic Ocean have returned critical information to make sure that the Copernicus Sentinel satellites are delivering accurate data about the state of our oceans.

Information from the Sentinels is used in a myriad of ways to make lives easier and businesses more efficient.

For example, ocean forecasting is important for maritime safety and off-shore operations, and biological productivity helps sectors such as the fishing industry.

It is therefore imperative to monitor data quality throughout a satellite's life – and this means venturing out to make in situ measurements that can be compared with measurements taken from space.