Operation IceBridge

Operation IceBridge is a 2009–2018 NASA mission that aims to monitor changes in polar ice from a fixed-wing aircraft. It is a temporary replacement for the ICESat satellite until the ICESat-2 launch in 2018.

Since 2003 NASA has used a satellite, ICESat (Ice, Cloud, and land Elevation Satellite), for observing polar ice. ICESat was retired in 2009 due to a technical malfunction, leaving NASA without a satellite dedicated to ice observance. A new satellite is not expected to be launched until 2018. NASA therefore introduced the IceBridge program which utilizes an aircraft to make similar measurements.

IceBridge flights began in October 2009 using a DC-8. Beginning in 2010, the DC-8 was joined by a P-3 Orion and other aircraft such as a King Air B-200, Gulfstream V and Guardian Falcon.

There are tradeoffs to using an aircraft instead of a satellite. One drawback is that a satellite can observe a far wider area. Also, satellites take measurements full-time, while IceBridge aircraft measurements are limited to annual campaigns that are several weeks long. Aircraft, however, have the advantages of being able to carry more instruments and target and focus on scientifically interesting areas instead of just flying a fixed path. Also, certain instruments such as ice-penetrating radar only work from the lower altitudes afforded by aircraft like the P-3 Orion and DC-8.

IceBridge aircraft carry a suite of specialized science instruments. Among these is the Airborne Topographic Mapper, a laser that measures the surface elevation of the ice. Also on board is a Gravimeter, an instrument capable of measuring the shape of cavities in the ice. There are numerous other pieces of equipment on board, including the Land, Vegetation and Ice Sensor, the Multichannel Coherent Radar Depth Sounder, a Snow Radar, a Ku-Band Radar Altimeter, a magnetometer and the Digital Mapping System.

Airborne Topographic Mapper (ATM) – The Airborne Topographic Mapper (ATM) is a laser altimeter that bounces laser light off ice surface and measures how long it takes for the light to return. By combining this timing data with information about the aircraft's position and attitude, researchers can calculate ice elevation. By flying over the same areas of ice year after year, they can build a time series of changes in elevation. This instrument works similarly to the lidar instrument used in ICESat and is helping maintain a record of elevation changes until ICESat-2 becomes operational.

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