ICESat-2
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| ICESat-2 | |
|---|---|
| Name | ICESat-2 |
| Manufacturer | Ball Aerospace |
| Launch date | 2018-09-15 |
| Launch vehicle | Delta II |
| Launch site | Vandenberg Space Force Base |
| Orbit type | Low Earth orbit |
| Instruments | ATLAS (instrument) |
| Program | ICESat program |
ICESat-2 ICESat-2 is a NASA satellite mission focused on precision altimetry of Earth's cryosphere, oceans, and vegetation canopies. Developed by NASA Goddard Space Flight Center, built by Ball Aerospace, and launched from Vandenberg Space Force Base, the mission continues the legacy of the ICESat program and complements observations from ICESat predecessors, CryoSat-2, and SMAP. Its primary payload, the Advanced Topographic Laser Altimeter System (ATLAS), uses photon-counting lidar to measure surface elevation with global coverage and near-monthly repeat cycles.
Overview
ICESat-2 was conceived to address questions raised by the Intergovernmental Panel on Climate Change assessments and to support campaigns coordinated with Operation IceBridge, Arctic Monitoring and Assessment Programme, and international partners such as the European Space Agency and Canadian Space Agency. Designed to succeed the original ICESat mission, the satellite provides centimeter-to-decimeter accuracy over ice sheets like those in Greenland and Antarctica and supplies dense elevation profiles across continental United States and boreal regions in collaboration with programs such as US Geological Survey initiatives. The mission’s data underpins models used by agencies including NOAA, National Snow and Ice Data Center, and research groups at institutions like University of Colorado Boulder and Columbia University.
Mission Design and Instruments
The centerpiece ATLAS instrument aboard the spacecraft implements a 532 nm photon-counting laser system developed in partnership with teams at NASA Goddard Space Flight Center, Lockheed Martin, and Photonetics, Inc. ATLAS emits a 10 kHz pulse train organized into six beams via a beam-splitting optical bench, producing three pairs of spots to derive surface slope and track cross-track topography. Payload subsystems integrate with spacecraft bus components supplied by Ball Aerospace and flight software maintained by NASA Jet Propulsion Laboratory collaborators. Precision pointing uses a star tracker from Honeywell and reaction wheels comparable to systems used on Landsat 8 and Terra. Orbit parameters were chosen to align with reference ground tracks similar to ICESat and to enable synergy with missions such as Sentinel-3, ICESat-1, and CALIPSO.
Launch and Operations
Launched aboard a Delta II rocket from Vandenberg Space Force Base, the spacecraft entered a near-circular, 500 km altitude, 92° inclination orbit enabling repeat ground tracks and pole-crossing patterns used by teams from NASA Goddard Space Flight Center, NOAA, and United States Geological Survey. Mission operations are coordinated through flight dynamics and mission planning groups with heritage from Landsat and Terra operations; on-orbit commissioning involved cross-calibration with GRACE Follow-On and ICESat datasets. Routine operations include instrument mode adjustments, telemetry downlink scheduling through the Near Earth Network, and campaign coordination with field programs like NASA Operation IceBridge and Antarctic research stations such as McMurdo Station.
Science Objectives and Results
Primary science objectives target mass balance of polar ice sheets, sea ice freeboard and thickness estimation in Arctic and Antarctic regions, and vegetation canopy structure across boreal and temperate biomes. Results have quantified elevation change trends across Greenland Ice Sheet outlet glaciers, detected ice shelf thinning near the Pine Island Glacier, and provided sea-ice freeboard maps consistent with independent measurements from CryoSat-2 and airborne lidar campaigns. ICESat-2 data underpin studies published by researchers at University of Washington, Scripps Institution of Oceanography, University of Cambridge, and ETH Zurich—contributing to assessments by the IPCC and informing International Arctic Science Committee reports. The mission has also measured canopy height and biomass over forests monitored by US Forest Service and ecological studies at sites like Harvard Forest.
Data Processing and Products
Level-1 raw photon event streams are processed by science teams at NASA Goddard Space Flight Center into geolocated photon lists, then into Level-2 geophysical products including land ice height, sea ice freeboard, inland water elevation, and vegetation canopy height. Processing pipelines leverage algorithms developed in collaboration with National Snow and Ice Data Center, Jet Propulsion Laboratory, and research groups at University of Maryland and Massachusetts Institute of Technology. Data products are distributed through archives such as the NSIDC and the NASA Earthdata system, and are compatible with formats used by European Space Agency data systems. Calibration and validation campaigns involve field sites at Summit Camp (Greenland), Svalbard, and the Alaskan Arctic with airborne counterparts like ICESat-2 Airborne Simulator and airborne lidar from NASA Armstrong Flight Research Center.
Applications and Impact
ICESat-2 data support applications across cryospheric science, sea level rise projections used by IPCC working groups, coastal planning by agencies like Federal Emergency Management Agency, and navigation and operations in polar regions by United States Coast Guard. Forestry and carbon accounting efforts by Food and Agriculture Organization and research at Woods Hole Research Center use canopy height estimates for biomass and carbon stock assessments. Hydrology applications include inland water level monitoring for basins studied by World Meteorological Organization partners and reservoir management used by national agencies. The mission’s precise topography also aids geodetic reference frame improvements pursued by International Earth Rotation and Reference Systems Service and contributes to interdisciplinary programs coordinated through institutions such as National Academies of Sciences, Engineering, and Medicine.
Challenges and Future Developments
Operational challenges include photon noise in low-reflectance surfaces, surface slope-induced geolocation errors, and degradation risks similar to those encountered on missions like ICESat and CryoSat-2. Ongoing enhancements include algorithm refinements from teams at University of Colorado Boulder, improved cross-calibration with GRACE Follow-On and Sentinel-6 Michael Freilich, and plans for synergy with future missions proposed by NASA and international partners including JAXA and CSA. Research groups at Caltech and Princeton University are investigating machine learning approaches to photon classification, while institutions such as Imperial College London explore assimilation of ICESat-2 products into cryosphere and ecosystem models. Continued international collaboration through bodies like Committee on Earth Observation Satellites will guide next-generation spaceborne laser altimetry capabilities.