The James Webb Space Telescope is the most powerful space telescope ever built, and its mirrors must be kept squeaky clean. Any debris, even tiny flecks of dust, could impact its science. Ergo, “snow cleaning:” the use of carbon dioxide snow to clean the mirrors thoroughly yet gently.
Check out the stark difference between these two satellite images, taken on March 19, 2010 and March 19, 2011. The left image shows much more ozone (in red) over the Arctic than the right image. What's happened?
You can practically see your house in this ultra-crisp image of our homeworld, newly uploaded by NASA's Goddard Space Flight Center, if you live in the Western Hemisphere. Something about the beautiful air currents and lush greenery looks terribly fragile.