WEBVTT FILE 1 00:00:00.050 --> 00:00:04.050 The Ice, Cloud and land Elevation-2 (ICESat-2) will add the third dimension to our study of Earth. 2 00:00:04.070 --> 00:00:08.100 3 00:00:08.120 --> 00:00:12.140 ICESat-2 will measure the height of ice sheets, glaciers and sea ice with an unprecedented level of precision and detail. 4 00:00:12.160 --> 00:00:16.190 5 00:00:16.210 --> 00:00:20.220 To do this, ICESat-2 will fly the most advanced laser altimeter NASA has ever launched. 6 00:00:20.240 --> 00:00:24.250 The laser fires 10,000 pulses of light a second. 7 00:00:24.270 --> 00:00:28.290 The instrument measures the time of flight of individual photons, down to Earth and back, within a billionth of a second. 8 00:00:28.310 --> 00:00:32.320 9 00:00:32.340 --> 00:00:36.340 With this new technology, ICESat-2 will track annual ice sheet change to a fraction of a centimeter. 10 00:00:36.360 --> 00:00:40.380 11 00:00:40.400 --> 00:00:44.410 Measuring the height of our polar regions will reveal ice mass changes 12 00:00:44.430 --> 00:00:48.470 and help us forecast how these changes will impact sea level and climate beyond the poles. 13 00:00:48.490 --> 00:00:52.490 14 00:00:52.510 --> 00:00:55.767