NASA is launching a laser-armed satellite next month that will measure — in unprecedented detail — changes in the heights of Earth’s polar ice to understand what is causing ice sheets to melt fast. In recent years, contributions of melt from the ice sheets of Greenland and Antarctica alone have raised global sea level by more than a millimeter a year, accounting for approximately one-third of observed sea level rise, and the rate is increasing.
ICESat-2 will measure the average annual elevation change of land ice covering Greenland and Antarctica to within the width of a pencil, capturing 60,000 measurements every second.
ICESat-2’s Advanced Topographic Laser Altimeter System (ATLAS) measures height by timing how long it takes individual light photons to travel from the spacecraft to Earth and back.
The satellite mission has four science objectives:
- Measure melting ice sheets and investigate how this effects sea level rise.
- Measure and investigate changes in the mass of ice sheets and glaciers.
- Estimate and study sea ice thickness.
- Measure the height of vegetation in forests and other ecosystems worldwide.
ATLAS will fire 10,000 times each second, sending hundreds of trillions of photons to the ground in six beams of green light. With so many photons returning from multiple beams, ICESat-2 will get a much more detailed view of the ice surface than its predecessor. As it circles Earth from pole to pole, ICESat-2 will measure ice heights along the same path in the polar regions four times a year, providing seasonal and annual monitoring of ice elevation changes. Beyond the poles, ICESat-2 will also measure the height of ocean and land surfaces, including forests.
ICESat-2 will improve upon NASA’s 15-year record of monitoring the change in polar ice heights. It started in 2003 with the first ICESat mission and continued in 2009 with NASA’s Operation IceBridge, an airborne research campaign that kept track of the accelerating rate of change.
The new observational technologies of ICESat-2 will advance the knowledge of how the ice sheets of Greenland and Antarctica contribute to sea level rise.