WEBVTT FILE 1 00:00:00.000 --> 00:00:04.000 Narrator: Operation IceBridge, you may know it from the 2 00:00:04.000 --> 00:00:08.000 the beautiful photos that pop up in your feed. 3 00:00:08.000 --> 00:00:12.000 But did you know that IceBridge is the largest polar airborne survey of its kind? 4 00:00:12.000 --> 00:00:19.000 IceBridge was designed to study annual changes in thickness of sea ice, glaciers, and ice sheets. As well as bridge the 5 00:00:19.000 --> 00:00:23.000 gap between the ICESat and ICESat-2 polar observing satellites. 6 00:00:23.000 --> 00:00:27.000 Between 2009 and 2019, IceBridge flew over a thousand 7 00:00:27.000 --> 00:00:31.000 missions, gathering data that has redefined 8 00:00:31.000 --> 00:00:35.000 our understanding of the cryosphere. 9 00:00:35.000 --> 00:00:39.000 So, let’s take a look back at some of the mission milestones from over the years. 10 00:00:39.000 --> 00:00:43.000 One of the first steps to measure sea ice thickness is to get a handle on the amount of 11 00:00:43.000 --> 00:00:47.000 snow that accumulates on top of it. 12 00:00:47.000 --> 00:00:51.000 The IceBridge team pioneered the use of a snow radar instrument to gather the first 13 00:00:51.000 --> 00:00:55.000 widespread dataset of snow thickness on top of both Arctic and Antarctic sea ice. 14 00:00:55.000 --> 00:00:59.000 Closer to land, 15 00:00:59.000 --> 00:01:03.000 the point at which a glacier begins to float is called a grounding line, 16 00:01:03.000 --> 00:01:07.000 and it’s a very challenging place to measure ice thickness. 17 00:01:07.000 --> 00:01:11.000 Using two instruments, a radar sounder and a gravimeter, 18 00:01:11.000 --> 00:01:15.000 the IceBridge team was able to survey hundreds of these complex transition zones, 19 00:01:15.000 --> 00:01:19.000 enhancing scientists’ understanding of the rapid changes in glacier behavior. 20 00:01:19.000 --> 00:01:23.400 In 2011, NASA scientists discovered 21 00:01:23.400 --> 00:01:27.000 a 19-mile long crack across the Pine Island Glacier, 22 00:01:27.000 --> 00:01:31.000 one of the fastest retreating glaciers in Antarctica. 23 00:01:31.000 --> 00:01:35.000 The crack measured 260 feet wide and 195 feet deep 24 00:01:35.000 --> 00:01:39.000 when it was observed. 25 00:01:39.000 --> 00:01:43.000 Throughout the mission, IceBridge was able to map rifts in ice shelves prior to major 26 00:01:43.000 --> 00:01:47.000 calving events. And while these events are part of a natural cycle, 27 00:01:47.000 --> 00:01:51.000 IceBridge’s observations helped scientists better record the changes in calving 28 00:01:51.000 --> 00:01:55.000 frequency and model how they may be related to a thinning ice shelf. 29 00:01:55.000 --> 00:01:59.000 The motion of the Antarctic Ice Sheet, 30 00:01:59.000 --> 00:02:03.000 the largest ice sheet in the world, is heavily influenced by 31 00:02:03.000 --> 00:02:07.000 the topography of the bedrock underneath. 32 00:02:07.000 --> 00:02:11.000 In 2013, the British Antarctic Survey used over 25 million measurements 33 00:02:11.000 --> 00:02:15.000 collected by IceBridge and other projects 34 00:02:15.000 --> 00:02:19.000 to develop a 3D map of Antarctica’s bedrock topography. 35 00:02:19.000 --> 00:02:23.000 Called Bedmap-2, it provided unprecedented 36 00:02:23.000 --> 00:02:27.400 detail of how the continents bedrock shaped the flow of the ice sheet. 37 00:02:27.400 --> 00:02:31.000 Data collected by IceBridge enabled 38 00:02:31.000 --> 00:02:35.000 many discoveries in the Arctic as well. 39 00:02:35.000 --> 00:02:39.000 A team from the University of Bristol used IceBridge’s radar data, 40 00:02:39.000 --> 00:02:43.000 along with other datasets, to uncover a 400-mile long canyon buried 41 00:02:43.000 --> 00:02:47.000 under nearly two miles of ice. 42 00:02:47.000 --> 00:02:51.000 This hidden canyon is longer than any other known on earth, provides a critical clue to modeling how melting ice 43 00:02:51.000 --> 00:02:55.000 is funneled into the Arctic Ocean. 44 00:02:55.000 --> 00:02:59.000 Using ice-penetrating radar data collected by IceBridge, 45 00:02:59.000 --> 00:03:03.000 scientists were able to build the first-ever age map of the layers 46 00:03:03.000 --> 00:03:07.000 deep inside the Greenland Ice Sheet. 47 00:03:07.000 --> 00:03:11.000 For the first time, scientists could navigate the history of Greenland’s ice layers, 48 00:03:11.000 --> 00:03:15.000 extending previously collected ice cores to better understand 49 00:03:15.000 --> 00:03:19.000 the ice sheet’s history and help build models of its future. 50 00:03:19.000 --> 00:03:23.000 An international team of scientists 51 00:03:23.000 --> 00:03:27.000 used decades of NASA data to uncover a massive impact crater 52 00:03:27.000 --> 00:03:31.000 hiding beneath the Hiawatha Glacier in northwest Greenland. 53 00:03:31.000 --> 00:03:35.000 At roughly a thousand feet deep and more than 19 miles wide, 54 00:03:35.000 --> 00:03:39.400 it is potentially one of the youngest large impact craters on Earth. 55 00:03:39.400 --> 00:03:43.000 56 00:03:43.000 --> 00:03:47.000 Cockpit: "It’s going to happen..5..4..3 57 00:03:47.000 --> 00:03:47.400 ..2..Mark on the overpass 043435 Zulu" 58 00:03:47.400 --> 00:03:51.400 Narrator: Ice was bridged on April 8, 2019, 59 00:03:51.400 --> 00:03:55.000 60 00:03:55.000 --> 00:03:59.000 with the direct underflight of the ICESat-2 61 00:03:59.000 --> 00:04:03.000 satellite over Arctic sea ice. 62 00:04:03.000 --> 00:04:07.000 For the first time, both ICESat-2 and IceBridge would be taking the same 63 00:04:07.000 --> 00:04:11.000 elevation measurements of the same ice. 64 00:04:11.000 --> 00:04:15.000 These mirrored measurements were critical in validating the satellites instruments 65 00:04:15.000 --> 00:04:19.400 and continue the legacy of IceBridge after the mission was completed. 66 00:04:19.400 --> 00:04:23.000 67 00:04:23.000 --> 00:04:27.000 Over the course of its 11-year mission, IceBridge 68 00:04:27.000 --> 00:04:31.000 completed 1056 scientific flights and provided a wellspring of data 69 00:04:31.000 --> 00:04:35.000 that fueled the publication of more than 660 papers 70 00:04:35.000 --> 00:04:39.000 and counting. 71 00:04:39.000 --> 00:04:43.400 The mission provided new insight into the processes driving the changes in the cryosphere, 72 00:04:43.400 --> 00:04:57.707 helping scientists better understand what we can expect in the future.