Nasa fire space laser to measure ice levels
Nasa launched a laser into space yesterday to measure the condition of Earth’s ice cover. The satellite mission, called ICESat-2, should provide more precise information on how these frozen surfaces are being affected by global warming. Antarctica, Greenland and the ice floating on the Arctic Ocean have all lost volume in recent decades. ICESat-2 will track ongoing change in unprecedented detail from its vantage point 500km above the planet. The satellite was taken up by a Delta II rocket, flying out of the Vandenberg Air Force Base in California. Antarctica and Greenland lose billions of tonnes of ice every year, which is slowly but surely pushing up sea levels worldwide. Sea ice in the far north is thought to have lost twothirds of its volume since the 1980s. The laser weighs half a tonne and is one of the largest Earth-observation instruments ever built by Nasa. It uses a pioneering technique called “photon counting”. That involves firing about 10,000 pulses of light every second. Each of those shots goes down to the Earth and bounces back up. Incredibly, the whole process takes about 3.3 milliseconds.