Don't drop it! In this picture you can see a team at NASA Goddard Space Flight Center's Calibration, Integration and Alignment Facility moving the James Webb Space Telescope's mirror. Slipping isn't an option.
The mirrors built for the telescope — which will be the most powerful space telescope ever built — are rather special. Over their entire surface, they're accurate to 0.1 microns. That's about 1/400th the thickness of a human hair. No pressure, guys.
Image by NASA