A team led by two NASA investigators will be trekking the unexplored stretch of Antarctic ice from next week. Temperatures can drop below -20 degrees Fahrenheit with route blocks created by wind-driven ice dunes. With a motive to survey the land, they’re packing extreme cold-weather gear and scientific instruments onto sledges pulled by two tank-like snow machines called PistenBullys.
Two to three-week-long trek will start from December 20 in which they will be covering a route in arc form around the South Pole. The 470-mile expedition in one of the most barren landscapes on Earth will eventually provide the best evaluation of the precision of data gathered from space by the Ice Cloud and land Elevation Satellite-2 (ICESat-2), set to thrust in 2018.
“This traverse provides an extremely challenging and icy way to judge the accuracy of the data,” stated Kelly Brunt, ICESat-2’s calibration and validation lead at NASA’s Goddard Space Flight Centre, and an investigation expert at the University of Maryland. “ICESat-2’s datasets are going to tell us unbelievable things about how Earth’s ice is breaking, and what that indicates for things like sea level rise.”
The first few days at the South Pole station will be spent adapting to the altitude, Neumann stated, noting that the cold, dry air makes the environment even harder.
“I’ll measure the density of the snow along the way,” he stated. By shovelling out a three-foot-deep pit, he can see sheets of snow that have built up over decades, some of which can be difficult to dig past. “They’re not super dense, but they’re so old the grains of snow are bonded collectively like its cement.”
When ICESat-2 starts accumulating elevation data, the snow density determinations and the data from the ground penetrating radar will help discover how much mass is dropped when the ice sheet drops in elevation.
The 88-degree traverse is also a chance for Brunt and Neumann to play the odds. At three different positions along the route, they’ll set up a grid of nine reflector cubes, each no bigger than the top of a pinkie finger. They’ll mark the specific latitude, longitude, and elevation of each cube.
Then, once ICESat-2 is up and moving, they’ll wait. If one of the satellite’s six laser beams hits a cube, the reflected material of the cube will mirror the laser light back at a much higher than average intensity. Since they’ll know the exact location and elevation of the cube, they can check the efficiency of the spacecraft data even more accurately than with the traverse data.
“If you hit that tiny little point, you’ll know specifically where the laser hit the ground,” Brunt said. “But hitting that point is both aiming and luck. But, by putting them at 88 degrees, where you have so many orbits crossing and so much information, it’s a statistics game.”
After the traverse, the investigators will return to the United States, reconsidering their steps from the South Pole station to McMurdo Station, to New Zealand and home. With them: hard drives full of data to help explain the accuracy of ICESat-2.