On a trip to Antarctica, Thorsten Markus, head of NASA Goddard’s Cryospheric Science Lab, stood on sea ice. The broken up ice floes show the thickness -- or rather, the thinness of the sea ice he stood on... on top of 3 mile-DEEP water. These kinds of field measurements are critical for developing the upcoming ICESat-2 (Ice, Cloud, and land Elevation Satellite-2) mission. ICESat-2 will use a laser altimeter to measure changes in the thickness of sea ice, which will help scientists understand the relationship between climate, the changing sea ice cover, and sea level rise.

Interested in learning more about what Thorsten Markus does as a polar scientist? Join him for a Twitter chat on Tuesday, October 16 at 1pm ET, when he will answer all of your questions. More information about the event can be found on the event page.