Live coverage: Delta 2 launches

A pair of European-built, NASA-backed research satellites set for launch Tuesday from California will extend 15 years of global gravity field measurements collected by the GRACE mission before it ended last year, supplying scientists with data to help track the melting of Earth’s ice sheets and chart the impacts of floods and droughts.

A United Launch Alliance Atlas 5 rocket lifted off from Cape Canaveral’s Complex 41 launch pad Sunday night with the European Space Agency’s Solar Orbiter mission, a project developed in partnership with NASA. Launch occurred right on time at the opening of a two-hour window at 11:03 p.m. EST Sunday (0403 GMT Monday).

The 32-story-tall mobile service tower is retracted from the Delta 4 rocket at Vandenberg’s Space Launch Complex 6 pad for the NROL-45 flight that will place a surveillance satellite into orbit for the U.S. National Reconnaissance Office.