|Detail||：||The primary mirror of the Subaru Telescope spans 8.3 m in physical diameter and requires periodic cleaning to minimize dust and other extraneous material that could interfere with observations. Standard maintenance of the telescope includes on-site cleaning of the mirror every few weeks. The structure of the telescope contains four curved wands with nozzles that are hooked up to cylinders of liquid CO2. The CO2 gas comes out from numerous small nozzles and part of it sublimates to a more solid form ("snow"), then it touches the mirror to expand 700 times in volume upon returning to its gaseous state without leaving a residue. This expansion is powerful enough to remove dust from the mirror yet soft enough for repetitive applications that will not scratch the mirror coating.
Filming: Saeko Hayashi (Subaru Telescope), June 9, 2014
How Subaru Telescope Staff Cleans an 8.3 m Mirror
June 9, 2014
Last updated: February 18, 2021