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Earth Science and Applications from Space 19 ICESat-II Ice, Cloud, and Land Elevation Satellite II Launch: 2010â2013 Mission size: Medium Orbit: LEO, non-SSO Agency: NASA Estimated cost: $300 million Areas of interest: Climate, Ecosystems, Water Instruments: Laser altimeter Benefits: Data on changes in ice sheet volume due to climate change to improve forecasts of sea-level rise Data on land carbon storage to understand responses of vegetation to changing climate and land use Laser altimetry is a proven method for measuring the height and inferring the volume of glaciers, ice sheets, and sea ice. The topo- graphic data obtained by the ICESat mission since 2003 have led to the first basin-wide estimates of sea ice thickness, a critical measure for the Arctic Ocean in a warming climate. Although sea ice extent has been monitored by satellite since the 1970s, no comparable record exists for ice thickness. Laser altimetry is also the preferred tech- nique for measuring ice volume over large areas and long time periods. It has also proven useful for measuring the depth of forest canopies, an indicator of biomass. ICESat-II will extend the unique record of ICESat into the next decade to provide data that, together with the data provided by GRACE-II (see page 17), will enable scientists to monitor both the mass and the thickness of the Greenland and Antarctic ice sheets and clarify their contributions to sea-level rise. ICESat-II will also complement the ice data from DESDynI (see page 13) and contribute to studies of vegetation. The payload will include a single- channel lidar with GPS navigation and pointing capability to allow for repeated high-accuracy sampling of ice elevation. Limitations to the lidar technology now being used in ICESat will be corrected in ICESat-II.