NASA launches $1 billion ICESat-2 mission to uncover the depth of melting ice sheets

NASA has launched a satellite designed to precisely measure changes in Earth’s ice sheets, glaciers, sea ice, and vegetation.

Background:

As the name suggests, ICESat-2 is a follow-on project. The original spacecraft flew in the 2000s and pioneered the laser measurement of the height of polar glaciers and sea-ice from space. But the mission was plagued by technical problems that limited its observations to just a couple of months in every year.

About ICESat- 2 mission:

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.

Antarctica and Greenland lose billions of tonnes of ice every year – the result largely of warm water being able to melt land glaciers where they meet the ocean. This wastage is slowly but surely pushing up sea-levels worldwide.

In the Arctic, the seasonal floes have also been in retreat. Sea-ice in the far north is thought to have lost two-thirds of its volume since the 1980s. And although this has no direct impact on the height of the oceans, the reduced ice-cover is working to amplify temperature rises in the region.

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