A NASA satellite designed to precisely measure changes in Earth's ice sheets, glaciers, sea ice and vegetation has been launched from California. A Delta 2 rocket carrying ICESat-2 lifted off from Vandenberg Air Force Base at 6:02 am (local time) Saturday and headed over the Pacific toward polar orbit. NASA Earth Science Division director Michael Freilich says that the mission in particular will advance knowledge of how the ice sheets of Greenland and Antarctica contribute to sea level rise. ICESat-2 carries a single instrument, a laser altimeter that measures height by determining how long it takes photons to travel from the spacecraft to Earth and back. The mission is a successor to the original ICESat that operated from 2003 to 2009. Measurements continued since then with airborne instruments in NASA's Operation IceBridge.