ICESat-2 carries a single instrument called the Advanced Topographic Laser Altimeter System (ATLAS), equipped with a multiple-beam laser, which sends 10,000 pulses of light to the ground each second. A small fraction of the light photons bounce off Earth’s surface and return to the instrument, where a photon-counting detector times their flight. Knowing this time, and the satellite’s position and orientation in space, scientists can calculate Earth’s elevation below.
ICESat-2 continues key elevation observations begun by the original ICESat satellite (2003 to 2009) and Operation IceBridge (2009 through present), to provide a portrait of change in the beginning of the 21st century. ICESat-2 is slated for launch on a Delta-II rocket in 2017.