NASA is launching a new laser satellite that will study Earth’s ice sheets and changes they undergo over the next three years.
Titled the Ice, Cloud, and Land Elevation Satellite-2 (ICESat-2), the satellite will measure and track changes in ice levels across the globe from one season to another. It will be capable of detecting thickness changes as small as one-fifth of an inch.
Two previous NASA probes, the original ICESat, launched in 2003 and Operation IceBridge, begun in 2009, previously monitored changes in ice thickness worldwide.
ICESat measured ice thickness by bouncing a single laser off the surface of ice in each area it studied. Operation IceBridge, which used an airplane rather than a satellite, focused on specific regions of ice deemed crucial and was largely a stopgap mission until the current satellite was ready for launch.
Unlike the previous missions, ICESat-2 will measure the world’s ice in 3D.
“The areas that we’re talking about are vast–think the size of the continental US or larger–and the changes that are occurring over them can be very small,” explained NASA scientist Tom Wagner at an August 22 press conference. “They benefit from an instrument that can make repeat measurements in a very precise way over a large area and that’s why satellites are an ideal way to study them.”
The first ICESat mission confirmed the planet’s sea ice is becoming thinner, Wagner said. “We’ve probably lost over two-thirds of the ice that used to be there back in the ’80s.”
Capable of monitoring ice levels on both land and sea, ICESat-2 will orbit 300 miles (500 km) above Earth’s surface. Its Advanced Topographic Laser Altimeter System (ATLAS) will emit single laser beams of green light, each of which will be split into six separate beams, which will be bounced off ice surfaces in a grid-like pattern. The satellite will then measure the exact time it takes for these photons to bounce off the ice and return to ATLAS. Only a small number of the photons will return.
Mission scientists will use the amount of time the photons take to return to calculate the height of the surface from which the laser was bounced.
In order for ICESat-2 to observe the same locations during each season, “The orbit is designed so that after 91 days, which is 1,387 individual orbits of the Earth, it exactly repeats itself. This allows the mission to look at the same piece of Earth in each of the four seasons,” said ICESat-2 project manager Doug McLennan.
Launch of ICESat-2 from Vandenberg Air Force Base in California is scheduled for September 15.