> I thought telescope mirrors had to be absurdly pure. It's a radio telescope, so think more along the lines of like a giant satellite dish. At the wavelength

> I thought telescope mirrors had to be absurdly pure. It's a radio telescope, so think more along the lines of like a giant satellite dish. At the wavelength of the radio frequency signals, the tiny dust etc don't matter until they start to build up. > Why does it need to be cleaned up? The recent natural disaster(s?) in Puerto Rico damaged it massively, which given its sophistication and size likely means there's stuff strewn everywhere and facility damage. You don't generally want to leave government facilities to degrade to the extreme in disuse, so you still want to stabilize things to make it safe to traverse the area and be able to safely achieve the next goal of the facility and surrounding area.