1st Lt. Daniel Smith, launch weather officer, 30th Space Wing, Vandenberg Air Force Base, speaks to members of the news media and social media participants during a prelaunch mission briefing for NASA's Ice, Cloud and land Elevation Satellite-2 (ICESat-2), a mission to measure the changing height of Earth's ice, on Sept. 13, 2018 at Vandenberg Air Force Base (VAFB) in California. ICESat-2 will launch aboard a United Launch Alliance Delta II, the rocket’s final mission, from Space Launch Complex 2 at VAFB. Launch is scheduled for 8:46 a.m. EDT (5:46 a.m. PDT).

Social media participant sketches NASA and industry leaders speaking to members of the news media and social media participants during a prelaunch mission briefing for NASA's Ice, Cloud and land Elevation Satellite-2 (ICESat-2) on Sept. 13, 2018, at Vandenberg Air Force Base (VAFB) in California. ICESat-2 will launch aboard a United Launch Alliance Delta II, the rocket’s final mission, from Space Launch Complex 2 at VAFB. Launch is scheduled for 8:46 a.m. EDT (5:46 a.m. PDT). The satellite will measure the height of our changing Earth, one laser pulse at a time, 10,000 laser pulses per second. ICESat-2 will provide scientists with height measurements that create a global portrait of Earth's third dimension, gathering date that can precisely track changes of terrain, including glaciers, sea ice and forests.

Helen Fricker, Scripps Institution of Oceanography, La Jolla, California, ICESat-2 science definition team member, speaks to members of the news media and social media participants during a prelaunch mission briefing for NASA's Ice, Cloud and land Elevation Satellite-2 (ICESat-2), a mission to measure the changing height of Earth's ice, on Sept. 13, 2018 at Vandenberg Air Force Base (VAFB) in California. ICESat-2 will launch aboard a United Launch Alliance Delta II, the rocket’s final mission, from Space Launch Complex 2 at VAFB. Launch is scheduled for 8:46 a.m. EDT (5:46 a.m. PDT).

A photon demonstration was conducted in front of news media and social media participants during a prelaunch mission briefing for NASA's Ice, Cloud and land Elevation Satellite-2 (ICESat-2), a mission to measure the changing height of Earth's ice, on Sept. 13, 2018 at Vandenberg Air Force Base (VAFB) in California. ICESat-2 will launch aboard a United Launch Alliance Delta II, the rocket’s final mission, from Space Launch Complex 2 at VAFB. Launch is scheduled for 8:46 a.m. EDT (5:46 a.m. PDT). The satellite will measure the height of our changing Earth, one laser pulse at a time, 10,000 laser pulses per second. ICESat-2 will provide scientists with height measurements that create a global portrait of Earth's third dimension, gathering date that can precisely track changes of terrain, including glaciers, sea ice and forests.

Tim Dunn, launch director, NASA's Kennedy Space Center in Florida, speaks to members of the news media and social media participants during a prelaunch mission briefing for NASA's Ice, Cloud and land Elevation Satellite-2 (ICESat-2), a mission to measure the changing height of Earth's ice, on Sept. 13, 2018 at Vandenberg Air Force Base (VAFB) in California. ICESat-2 will launch aboard a United Launch Alliance Delta II, the rocket’s final mission, from Space Launch Complex 2 at VAFB. Launch is scheduled for 8:46 a.m. EDT (5:46 a.m. PDT).

Tim Dunn, launch director, NASA's Kennedy Space Center in Florida, speaks to members of the news media and social media participants during a prelaunch mission briefing for NASA's Ice, Cloud and land Elevation Satellite-2 (ICESat-2), a mission to measure the changing height of Earth's ice, on Sept. 13, 2018 at Vandenberg Air Force Base (VAFB) in California. ICESat-2 will launch aboard a United Launch Alliance Delta II, the rocket’s final mission, from Space Launch Complex 2 at VAFB. Launch is scheduled for 8:46 a.m. EDT (5:46 a.m. PDT).

NASA and industry leaders speak to members of the news media and social media participants during a prelaunch mission briefing for NASA's Ice, Cloud and land Elevation Satellite-2 (ICESat-2) on Sept. 13, 2018, at Vandenberg Air Force Base (VAFB) in California. ICESat-2 will launch aboard a United Launch Alliance Delta II, the rocket’s final mission, from Space Launch Complex 2 at VAFB. Launch is scheduled for 8:46 a.m. EDT (5:46 a.m. PDT). The satellite will measure the height of our changing Earth, one laser pulse at a time, 10,000 laser pulses per second. ICESat-2 will provide scientists with height measurements that create a global portrait of Earth's third dimension, gathering date that can precisely track changes of terrain, including glaciers, sea ice and forests.

Cathy Richardson, Deputy Program Manager, Earth Science Projects Division, NASA Goddard Space Flight Center, speaks to members of the news media and social media participants during a prelaunch mission briefing for NASA's Ice, Cloud and land Elevation Satellite-2 (ICESat-2), a mission to measure the changing height of Earth's ice, on Sept. 13, 2018 at Vandenberg Air Force Base (VAFB) in California. ICESat-2 will launch aboard a United Launch Alliance Delta II, the rocket’s final mission, from Space Launch Complex 2 at VAFB. Launch is scheduled for 8:46 a.m. EDT (5:46 a.m. PDT).

Lori Magruder, University of Texas at Austin, ICESat-2 science definition team lead, speaks to members of the news media and social media participants during a prelaunch mission briefing for NASA's Ice, Cloud and land Elevation Satellite-2 (ICESat-2), a mission to measure the changing height of Earth's ice, on Sept. 13, 2018 at Vandenberg Air Force Base (VAFB) in California. ICESat-2 will launch aboard a United Launch Alliance Delta II, the rocket’s final mission, from Space Launch Complex 2 at VAFB. Launch is scheduled for 8:46 a.m. EDT (5:46 a.m. PDT).

Tom Neumann, ICESat-2 deputy project scientist, NASA's Goddard Space Flight Center, speaks to members of the news media and social media participants during a prelaunch mission briefing for NASA's Ice, Cloud and land Elevation Satellite-2 (ICESat-2), a mission to measure the changing height of Earth's ice, on Sept. 13, 2018 at Vandenberg Air Force Base (VAFB) in California. ICESat-2 will launch aboard a United Launch Alliance Delta II, the rocket’s final mission, from Space Launch Complex 2 at VAFB. Launch is scheduled for 8:46 a.m. EDT (5:46 a.m. PDT).

Michelle Thaller, NASA Communications (left), and Tom Wagner, ICESat-2 program scientist, NASA Headquarters (right) speaks to members of the news media and social media participants during a prelaunch mission briefing for NASA's Ice, Cloud and land Elevation Satellite-2 (ICESat-2), a mission to measure the changing height of Earth's ice, on Sept. 13, 2018 at Vandenberg Air Force Base (VAFB) in California. ICESat-2 will launch aboard a United Launch Alliance Delta II, the rocket’s final mission, from Space Launch Complex 2 at VAFB. Launch is scheduled for 8:46 a.m. EDT (5:46 a.m. PDT).

Tom Neumann, ICESat-2 deputy project scientist, NASA's Goddard Space Flight Center, speaks to members of the news media and social media participants during a prelaunch mission briefing for NASA's Ice, Cloud and land Elevation Satellite-2 (ICESat-2), a mission to measure the changing height of Earth's ice, on Sept. 13, 2018 at Vandenberg Air Force Base (VAFB) in California. ICESat-2 will launch aboard a United Launch Alliance Delta II, the rocket’s final mission, from Space Launch Complex 2 at VAFB. Launch is scheduled for 8:46 a.m. EDT (5:46 a.m. PDT).

Scott Messer, program manager, NASA Programs, United Launch Alliance, speaks to members of the news media and social media participants during a prelaunch mission briefing for NASA's Ice, Cloud and land Elevation Satellite-2 (ICESat-2), a mission to measure the changing height of Earth's ice, on Sept. 13, 2018 at Vandenberg Air Force Base (VAFB) in California. ICESat-2 will launch aboard a United Launch Alliance Delta II, the rocket’s final mission, from Space Launch Complex 2 at VAFB. Launch is scheduled for 8:46 a.m. EDT (5:46 a.m. PDT).

Doug McLennan, ICESat-2 project manager, NASA’s Goddard Space Flight Center, speaks to members of the news media and social media participants during a prelaunch mission briefing for NASA's Ice, Cloud and land Elevation Satellite-2 (ICESat-2), a mission to measure the changing height of Earth's ice, on Sept. 13, 2018 at Vandenberg Air Force Base (VAFB) in California. ICESat-2 will launch aboard a United Launch Alliance Delta II, the rocket’s final mission, from Space Launch Complex 2 at VAFB. Launch is scheduled for 8:46 a.m. EDT (5:46 a.m. PDT).

Bill Barnhart, ICESat-2 program manager, Northrop Grumman, speaks to members of the news media and social media participants during a prelaunch mission briefing for NASA's Ice, Cloud and land Elevation Satellite-2 (ICESat-2), a mission to measure the changing height of Earth's ice, on Sept. 13, 2018 at Vandenberg Air Force Base (VAFB) in California. ICESat-2 will launch aboard a United Launch Alliance Delta II, the rocket’s final mission, from Space Launch Complex 2 at VAFB. Launch is scheduled for 8:46 a.m. EDT (5:46 a.m. PDT).