Today, the study of Arctic is important because scientists need to learn more about how climate and weather are changing. Scientist go to Arctic to investigate how Arctic climate and weather interact with the rest of the world, and they are also working to understand how climate change will affect the region. Scientist sometimes study the Arctic by travelling to the field to conduct experiments or make observations. They study the properties of snow and sea ice, digging snow pits to examine the properties of snow, or measuring the thickness of sea ice by hand to determine how the ice cover is changing. Scientists also study the frozen ground and permafrost that covers much of the Arctic lands. And biologists research the unique plants and animals that live in the Arctic. The Arctic is a huge region, and scientists cannot conceivably measure every bit of it in person, so researchers also use other tools to study the Arctic from afar. They make observations using remote sensing, a variety of tools that allow them to measure factors that they cannot see directly, or which are too big to observe in person. Instead, they mount sensors on airplanes or satellites to record data. For example, satellite data provides estimates of the sea ice cover on the Arctic Ocean as well as weather patterns over the Arctic. And scientists from NASA recently flew a series of missions over the Arctic during the Ice Bridge project, to study details of Arctic sea ice thickness as well as changing glaciers in Greenland.