In 2009, NASA started conducting the largest airborne survey of Earth's polar ice under Operation IceBridge to bridge the observational gap between the ICESat and ICESat-2 satellite missions. The campaign used research aircraft, laser altimeters, radar and imaging systems to track changes in Greenland, Antarctica, the Arctic and Alaskan glaciers. Its data helped scientists study ice thickness, glacier changes, sea ice and possible effects on sea-level rise.