The Ice, Cloud and land Elevation Satellite, or ICESat-2, is scheduled to launch Saturday morning as part of a $1 billion mission to provide scientists with a detailed picture of Earth’s changing landscape, particularly where it comes to polar ice sheets.

Once in orbit, the satellite will be capable of estimating the thickness of the Greenland and Antarctic ice sheets to within 4 millimeters — the width of a No. 2 pencil.

“This mission and others at NASA are used to study how that change in ice affects our entire climate,” Tom Wagner, an ICESat-2 program scientist told reporters on Thursday. “There’s so much ice tied up there, and as that ice melts or flows into the ocean, it raises sea levels. And it’s raising sea levels right along our coasts right now.”

Information about how ice melt is contributing to sea level rise is badly needed. The last ICESat mission, which launched in 2003 and ended in 2009, just provided the first glimpse into this process. But global temperatures continue to rise, and 2014-2017 were the hottest years ever recorded. NASA has flown an aircraft mission, called Operation IceBridge to overlap between the original ICESat and the new mission, but “you can’t do with an aircraft what you can do with a satellite,” Wagner says. “Now with ICESat-2 set to launch, we’re gonna have measurements all over and we’re gonna have them at much higher resolution, so we can do a better job of tying the change to climate overall.”

The launch is scheduled for 5:46 a.m. local time from Vandenberg Air Force Base in Southern California. A United Launch Alliance Delta 2 rocket will launch the payload. Watch it live on

With a single, super precise instrument called the Advanced Topographic Laser Altimeter System, or ATLAS, ICESat-2 will shine a green laser beam down to Earth and measure how long it takes for the light to bounce back from the planet’s surface. The faster that photons of light come back, the higher the elevation of that location.

First, ICESat-2’s laser will go through a diffractor to be split into three pairs of beams. Then these beams will track along the surface of the planet as the spacecraft goes from pole to pole every 91 days. With the light that is reflected back, ICESat-2 will gather data on changes in heights and slopes between the beams for every season of the year.

“The brightness [of the beam] is about as bright as if you were getting a flash photo taken,” says Lori Magruder, an ICESat-2 science definition team lead at the University of Texas at Austin. And although it’s unlikely that anyone will notice the green beams unless they’re in the right place at the right time, the beams will not only inform scientists about the thickness of glaciers and sea ice, they’ll also provide information on cloud cover and forest height so researchers can incorporate those variables into climate models too. “Similar to how sunlight goes through a tree canopy and illuminates the surface below, so will the laser,” Magruder says.

Eventually, all the data gathered by ICESat-2 will also be added to the Distributed Active Archive Centers, making it available to the public. “We’d like to inspire people to think about doing more, and also to use the data themselves and understand the Earth a little bit better,” Wagner says. “This is an exciting adventure.”