NASA is launching a laser-armed satellite next month that, in unprecedented detail, measures changes in the heights of Earth's polar ice to understand how the ice caps are rapidly melting.
In recent years, contributions from melts from the ice caps of Greenland and Antarctica alone have increased global sea level by more than a millimeter per year, accounting for about a third of the observed sea level rise, and speed is increasing.
Called the Ice, Cloud and Land Elevation Satellite-2 (ICESat-2), the mission is scheduled for launch from Vandenberg's Air Force Base in California on September 15, NASA said in a statement late on Thursday.
ICESat-2 measures the average annual height change of land ice between Greenland and Antarctica to within the width of a pencil and records 60,000 measurements every second.
"The new ICESat-2 observation technologies will enhance our knowledge of how the Greenland and Antarctic ice caps contribute to sea level rise," said Michael Freilich, director of the Earth Sciences Division at NASA's Scientific Mission Directorate.
ICESat-2 will improve after NASA's 15-year record of monitoring the change in polar ice levels.
It started in 2003 with the first ICESat mission and continued in 2009 with the operation IceBridge from NASA, a research campaign in the air that tracked the accelerating rate of change.
ICESat-2 Advanced Laser Altimeter System (ATLAS) measures the altitude by determining how long it takes individual light photons to travel from the spacecraft to Earth and back.
"ATLAS required that we develop new technologies to get the measurements scientists needed to advance research," said Doug McLennan, ICESat-2 Project Manager.
"That meant we needed to develop a satellite instrument that will not only collect incredibly accurate data, but also collect more than 250 times as many elevation measurements as its predecessor," he added.
ATLAS fires 10,000 times per second and sends hundreds of trillions of photons to the ground in six light beams.
With so many photons returning from multiple rays, ICESat-2 gets a much more detailed picture of the ice surface than its predecessor.
While it circles the earth from pile to pile, ICESat-2 measures four times a year ice height along the same path in the polar regions, allowing seasonal and annual monitoring of ice height changes.
In addition to the poles, ICESat-2 also measures the height of ocean and land surfaces, including forests.