We’re set to launch ICESat-2, our most superior laser instrument of its form, into orbit round Earth on Sept. 15. The Ice, Cloud and land Elevation Satellite-2 will make important observations of how ice sheets, glaciers and sea ice are altering over time, serving to us higher perceive how these modifications have an effect on individuals the place they stay. Right here’s 10 numbers to find out about this mission:
One Area Laser
There’s just one scientific instrument on ICESat-2, but it surely’s a marvel. The Advanced Topographic Laser Altimeter System, or ATLAS, measures peak by exactly timing how lengthy it takes particular person photons of sunshine from a laser to go away the satellite tv for pc, bounce off Earth, and return to ICESat-2. Lots of of individuals at our Goddard Area Flight Middle labored to construct this smart-car-sized instrument to exacting necessities in order that scientists can measure minute modifications in our planet’s ice.
Sea ice is seen in entrance of Apusiaajik Glacier in Greenland. Credit score: NASA/JPL-Caltech/Jim Spherical
Two Sorts of Ice
Not all ice is identical. Land ice, just like the ice sheets in Greenland and Antarctica, or glaciers dotting the Himalayas, builds up as snow falls over centuries and varieties compacted layers. When it melts, it could actually circulate into the ocean and lift sea degree. Sea ice, alternatively, varieties when ocean water freezes. It may possibly final for years, or a single winter. When sea ice disappears, there is no such thing as a impact on sea degree (consider a melting ice dice in your drink), however it could actually change local weather and climate patterns far past the poles.
3-Dimensional Earth
ICESat-2 will measure elevation to see how a lot glaciers, sea ice and ice sheets are rising or falling. Our fleet of satellites gather detailed pictures of our planet that present modifications to options like ice sheets and forests, and with ICESat-2’s knowledge, scientists can add the third dimension – peak – to these portraits of Earth.
4 Seasons, 4 Measurements
ICESat-2’s orbit will make 1,387 distinctive floor tracks round Earth in 91 days – after which begin the identical floor sample once more firstly. This permits the satellite tv for pc to measure the identical floor tracks 4 instances a yr and scientists to see how glaciers and different frozen options change with the seasons – together with over winter.
532 Nanometer Wavelength
The ATLAS instrument will measure ice with a laser that shines at 532 nanometers – a brilliant inexperienced on the seen spectrum. When these laser photons return to the satellite tv for pc, they cross by means of a sequence of filters that block any mild that’s not precisely at this wavelength. This helps the instrument from being swamped with all the opposite shades of daylight naturally mirrored from Earth.
Six Laser Beams
Whereas the primary ICESat satellite tv for pc (2003-2009) measured ice with a single laser beam, ICESat-2 splits its laser mild into six beams – the higher to cowl extra floor (or ice). The association of the beams into three pairs will even enable scientists to evaluate the slope of the floor they’re measuring.
Seven Kilometers Per Second
ICESat-2 will zoom above the planet at 7 km per second (4.3 miles per second), finishing an orbit round Earth in 90 minutes. The orbits have been set to converge on the 88-degree latitude strains across the poles, to focus the information protection within the area the place scientists anticipate to see probably the most change.
800-Picosecond Precision
All of these peak measurements come from timing the person laser photons on their 600-mile roundtrip between the satellite tv for pc and Earth’s floor – a journey that’s timed to inside 800 picoseconds. That’s a precision of practically a billionth of a second. Our engineers needed to customized construct a stopwatch-like system, as a result of no present timers match the strict necessities.
9 Years of Operation IceBridge
As ICESat-2 measures the poles, it provides to our document of ice heights that began with the primary ICESat and continued with Operation IceBridge, an airborne mission that has been flying over the Arctic and Antarctic for 9 years. The marketing campaign, which bridges the hole between the 2 satellite tv for pc missions, has flown since 2009, taking peak measurements and documenting the altering ice.
10,000 Pulses a Second
ICESat-2’s laser will hearth 10,000 instances in a single second. The unique ICESat fired 40 instances a second. Extra pulses imply extra peak knowledge. If ICESat-2 flew over a soccer area, it will take 130 measurements between finish zones; its predecessor, alternatively, would have taken one measurement in every finish zone.
And One Bonus Quantity: 300 Trillion
Every laser pulse ICESat-2 fires comprises about 300 trillion photons! Once more, the laser instrument is so exact that it could actually time how lengthy it takes particular person photons to return to the satellite tv for pc to inside one billionth of a second.
Be taught extra about ICESat-2: https://www.nasa.gov/icesat-2
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