"On Sept. 15, 2018, at precisely 6:02 a.m., a Delta II rocket lifted off in a cloud of fire and smoke from Vandenberg Air Force Base on the central California coast. The payload, a NASA observation satellite known as ICESat-2, measured roughly the size of an automobile, and weighed in at 3,338 pounds. At an altitude 310 miles above the Earth, the satellite decoupled from the rocket and moved into orbit. After that, its work began.
Traveling around the planet at 15,660 mph, ICESat-2 began aiming a six-beam, green-spectrum laser toward Earth’s surface. Its goal for the next three years — and perhaps as long as seven years, if its machinery continued working — would be to constantly measure the glaciers, ice sheets, sea ice, oceans, and tree canopies far below.
The launch wasn’t much of a news story. When the mission began, there was little talk of big breakthroughs or revolutionary ideas. Indeed, even the satellite’s name (it acts as a replacement for the first ICESat, which was launched in 2003 and burned up upon reentry in 2010) could give the impression that this might be a sequel that wasn’t as exciting as the original production. Since we already know so much about the planet, and especially how ice sheets in Greenland and Antarctica are imperiled by a warming climate, how much could it tell us that is truly new?"