Measuring the height of Earth from space

Laser Technology brings scientists closer to answers

Using Earth’s ice, either in the form of land ice sheets like glaciers and icebergs, or sea ice, NASA scientists are beaming lasers down from space to measure displacement to receive accurate elevation readings and melting statistics.

“We are measuring the elevation of the entire Earth,” said Thorsten Markus, ICESat-2 project scientist at NASA Goddard Space Flight Center (GSFC) in Maryland, USA, in an educational video. “We are measuring the third dimension of our globe.”

As polar caps melt, there is less and less ice to reflect the sun’s rays. As more and more of that heat is absorbed, the world’s oceans steadily rise in temperature. This not only impacts global climate but can also cause detrimental effects to the millions of species of animals and plants that make these waters their homes. Scientists study this effect on the environment to better understand why it’s happening and how to find solutions to prevent and correct the situation.

“Both the ice and oceans in the polar regions drive global climate,” said Charles Webb of the ICESat-2 Project Science Office in the video. “When the oceans heat up, that raises temperatures in the Arctic, in turn causing more melting of the ice.”

The Ice, Cloud and land Elevation Satellite-2, better known as ICESat-2, will carry into space the Advanced Topographic Laser Altimeter System (ATLAS), an instrument that will transmit six precise laser beams to Earth and detect the photons that are reflected back to take accurate measurements. ATLAS determines Earth’s elevation by measuring the time it takes light to travel to the surface of the ice and back. Displacement of the ice is calculated by taking the measurement of ice’s thickness over time. ICESat-2 measures this thickness by recording the height of the sea ice surface and the height of the water beside it and taking that difference.

“As you measure the distance from the satellite down to the surface of the ice, we’re able to tell how thick the ice is over time,” said Aprille Ericsson, ICESat-2 project instrument manager, in the video. “We’ll pass back over that path and we know if the ice has grown or if it has melted.”

Explore next chapter: Replicating geospatial data from space

Story: Measuring the height of Earth from space
Chapter 1: Introduction
Chapter 2: Laser technology brings scientists closer to answers
Chapter 3: Replicating geospatial data from space
Chapter 4: Moving into the next frontier of measurement