How NASA will use a space laser to measure the Earth’s thinning ice sheets

An artistic view of the ICESat-2 satellite to study the Earth’s polar ice caps.


This weekend, NASA is planning to launch a spacecraft that will make use of a half-dozen bright-green laser beams to measure seasonal and annual changes on Earth’s icy poles.

The mission, called the Ice, Cloud and land Elevation Satellite-2 (ICESat-2), will be incredibly precise measurements of ice sheet depth, allowing scientists to add the third dimension, they lose when we look at the aerial or space-based images of the distribution of the ice.

That is crucial information, for example, when it comes to building an accurate picture of the changes of the ice in the time, because the thinner ice is the same way as shrinking ice. But simply because it is an important type of data does not mean that it is easy to collect, that is where NASA’s affection for the space-based lasers in the game. [How Satellites Watched Birth of a Giant Iceberg in the Antarctic (Photos)]

ICESat-2 will perform on only one instrument, the Advanced Topographic Laser Altimeter System (ATLAS). ATLAS produces six tuned laser beams of light-green light, which it beams down to bounce off earth’s surface. (Don’t be afraid, the laser is not strong enough to melt the ice.)

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  • ICESat-2

Many of those photons are lost, scattering out in all directions. But a little bounce back perfectly to meet the satellite. Scientists can then translate the spacecraft incredibly accurate measurement of the travel time of each photon — accurate to a billionth of a second, but in the distance it traveled, in essence, is the measure of the height of the surface at that point.

For sea ice, the top of the ice is compared to the surface of the ocean around. Then scientists can calculate how much extra ice must be hidden in the water. For the land-ice, the process is a little more complicated, but works on similar principles.

The spacecraft produces 10,000 pulses of photons every second, and for each signal, the same process plays. ICESat-2 will orbit from pole to pole, taking measurements along the way, but the offer of the closest height maps in the vicinity of the poles.

Every three months the spacecraft will have a total of 1,387 orbital paths, then begin to return to his work, which he revisits the same swath of ice in the 91-day steps. And because the instrument creates six individual laser beams in three pairs, scientists can modify the data if the satellite ends up wandering a bit of the planned road.

That’s a big improvement from the original ICESat mission, which was active from 2003 to 2010, but only produced data with the help of a single laser beam. Nevertheless, it is possible that the mission provided crucial evidence that the Greenland ice sheet was thinning.

The ICESat-2 mission will cost a little more than $1 billion, and the spacecraft is about the size of a Smart car. The first mission is scheduled for the last three years, with the timeline beginning about two months after the launch to the team for the calibration of the instruments. That said, the spacecraft have enough fuel for 10 years, so the mission could be extended.

The spacecraft is scheduled to take off from the Vandenberg Air Force Base in California on Saturday, Sept. 15 during a launch window that opens at 5:46 a.m. local time (8:46 pm EDT, 1246 GMT) and the last 2 hours and 34 minutes. You can watch the launch live beginning at 8:10 a.m. EDT (1210 GMT) on with thanks to NASA TV. The launch will be the last trip of the Delta II rocket has been flying for 29 years.

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