A satellite that will be critical to the understanding of climate change has blasted skyward from California.
Sentinel-6 "Michael Freilich" is set to become the primary means of measuring the shape of the world's oceans.Its data will track not only sea-level rise but reveal how the great mass of waters is moving around the globe.
Looking somewhat like a dog kennel, the sophisticated 1.3-tonne satellite was taken aloft from the Vandenberg base on a SpaceX Falcon-9 rocket.
The Sentinel is a joint endeavour between Europe and the US, and will continue the measurements that have been made by a succession of spacecraft, called the Jason-Topex/Poseidon series, going back to 1992.
These earlier missions have shown unequivocally that sea levels globally are rising, at a rate in excess of 3mm per year over the 28-year period. And their most recent data even suggests there is an acceleration under way, with levels recorded as going up at over 4mm per year.