The National Aeronautics and Space Administration (NASA) announced on March 27, 2018 that it would be launching two new satellite missions and conduct an array of field research in 2018 to enhance the understanding of Earth's ice sheets, glaciers, sea ice, snow cover and permafrost.


These missions come at a time when decades of observations from the ground, air and space have revealed signs of change in the frozen regions of Earth, called the ‘cryosphere’.
Significance
The changes in the cryosphere, which often occur in the remote regions, have shown impact on people all around the world like sea level rise affects coastlines globally and melting of snowpack affects billions of people who rely on the water.
Besides this, the diminishing sea ice that covers the Arctic Ocean plays a significant role in Earth's climate and weather patterns.
Key Highlights
• The mission called the Gravity Recovery and Climate Experiment Follow-On (GRACE-FO) mission would be launched by NASA along with the German Research Centre for Geosciences.
• Under it, twin satellites will be launched to continue the original GRACE mission's legacy of tracking fluctuations in Earth's gravity field in order to detect changes in mass, including the mass of ice sheets and aquifers.
• Following this, NASA would be launching the Ice, Cloud, and land Elevation Satellite-2 (ICESat-2), which will use a highly advanced laser instrument to measure the changing elevation of ice around the world, providing a view of the height of Earth's ice with greater detail than previously possible.
• Together, the two missions will make critical, complementary measurements of Earth's glaciers and ice sheets.
• The missions will also make other key observations such as, the GRACE-FO will measure groundwater reserves and deep ocean currents and ICESat-2 will measure sea ice thickness and vegetation height.

According to NASA Research, the permafrost, which is the permanently frozen ground in the Arctic that contains heat-trapping gases such as methane and carbon dioxide, is melting at faster rates now than before.
About the original GRACE mission
• The Gravity Recovery and Climate Experiment (GRACE) was a joint mission of NASA and the German Aerospace Center.
• The two GRACE satellites -GRACE-1 and GRACE-2 - were launched aboard a launch vehicle from Plesetsk Cosmodrome, Russia on March 17, 2002.
• Since their launch, the twin satellites took detailed measurements of Earth’s gravity field anomalies and their data transformed scientists’ view of how water moved and was stored around the planet.
• By measuring gravity anomalies, GRACE showed how mass is distributed around the planet and how it varies over time.
• The data gathered from the satellites proved to be an important tool for studying Earth's ocean, geology, and climate.
• The mission exceeded its initial 5-year target, operating for fifteen years until the decommissioning of GRACE-2 on October 27, 2017.