ICESat-2 carries a single instrument, a laser altimeter that measures height by determining how long it takes photons to travel from the spacecraft to earth and back.
NASA has launched a laser satellite to track the loss of ice sheets and glaciers across the world as the climate warms.
The mission will build on the results of an earlier, less powerful ICESat mission and a more limited NASA aircraft campaign known as IceBridge, all aimed at monitoring the planet's ice inventory over decadal time scales. "Every minute of every hour of every day for the next three years".
"The mission will gather enough data to estimate the annual elevation change in the Greenland and Antarctic ice sheets even if it's as slight as four millimetres - the width of a No. 2 pencil", NASA said in a statement.
Liftoff of the United Launch Alliance booster from Space Launch Complex-2 is planned for 5:46 a.m., the start of what officials say is a 40-minute window.
According to ULA, McDonnell Douglas created the rocket in the late 1980s to launch Global Positioning System satellites for the Air Force.
Hundreds of people, including retirees who worked for the Delta II manufacturers through the years, were invited to return to Vandenberg to see the last launch.
"I'm a little bit melancholy about this", NASA Launch Director Tim Dunn said Thursday. "Delta II holds a really special place in so many folks in the launch industry hearts".
Delta 2 rockets have launched scores of and satellite telephone relay stations, seven Mars missions - including the Pathfinder, Spirit and Opportunity rovers - Earth observation satellites, commercial payloads and trail-blazing NASA science probes, including the planet-hunting Kepler space telescope.
"The big question we always get asked is, 'Will we be able to see the launch?' Unfortunately, if you live here at Vandenberg, you know the marine layer likes to hug the coast, and we are forecasting some low clouds with patchy fog, which would reduce visibility 2 to 3 miles", said 1st Lt. Daniel Smith, launch weather officer with the 30th Space Wing at Vandenberg.