WEBVTT FILE

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NASA is about to launch the most advanced laser instrument of its kind,

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the Ice, Cloud and land Elevation Satellite-2, or ICESat-2,

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will measure changes in glaciers, ice sheets and sea ice. So to prepare

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for launch, we're counting down ten quick facts about ICESat-2.

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Ten thousand. That's how many times the ICESat-2 laser will fire

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each second. More pulses mean more height data. The fast-firing

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laser will allow us to measure the average annual change in the vast ice sheets

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down to the width of a pencil. Nine years of data from Operation

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IceBridge will be added to ICESat-2's new data. The airborne mission

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bridged the gap between the original ICESat and ICEsat-2 with

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flights over the Arctic and Antarctica. Eight hundred picoseconds,

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less than one-billionth of a second. That's the precision at which individual

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laser photons will be timed as they complete their roundtrip journey from

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the satellite to the Earth and back. Seven kilometers per second is

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how fast ICESat-2 will zoom above the planet. It'll complete an orbit

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around Earth in 90 minutes. The orbits will converge around the poles, focusing the data

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in the regions with the most expected change. Six laser beams

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split from one on board ICESat-2. That's six times the beams

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of the original ICESat. More beams will cover more ground--or ice--and allow

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scientists to assess the slope of the surface they're measuring.

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Five hundred and thirty-two nanometers, the wavelength of the bright green laser.

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When these laser photons return to the satellite, filters block any light that's not exactly

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at this wavelength, keeping the amount of data noise down.

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Four times a year, every 91 days, ICESat-2 will measure the same ground

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tracks, allowing scientists to see how glaciers and other frozen features change

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with the seasons, including over winter. A 3-D look at Earth.

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Now with more height. ICESat-2 will measure elevation to see how much

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glaciers, sea ice and ice sheets are rising or falling and give us a more

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complete picture of our planet. There are two types of ice that ICESat-2 is after:

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land ice and sea ice. Land ice builds up year after year

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from snowfall, but sea ice forms when the ocean water freezes. It can last

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for years or just one winter. Only one instrument,

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but it's a really good one. The Advanced Topographic Laser Altimeter System,

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or ATLAS, was built by hundreds of people at NASA's Goddard Space Flight Center

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to exacting requirements so that scientists, very soon, can measure

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minute changes in our planet's ice.

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