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A sunshield big enough to shade a 30m by 10m space telescope would have to be darn large. Radiation pressure would certainly want to push it out of orbit. Space
by sbierwagen 5y ago
A sunshield big enough to shade a 30m by 10m space telescope would have to be darn large. Radiation pressure would certainly want to push it out of orbit. Space telescopes with big mirrors seem to be sited at L2, like LUVOIR. https://en.wikipedia.org/wiki/Large_Ultraviolet_Optical_Infrared_Surveyor https://en.wikipedia.org/wiki/Large_Ultraviolet_Optical_Infr... I assume some property of halo orbits tolerate hanging off a solar sail better.
Hubble is an unshaded warm-mirror telescope that can observe down to 1700nm, though, so I wonder why they wouldn't use that as comparison.
- max-ibel 5y agoI'm nor sure - does the big mirror have to be cooled all the way, or just a bit, and what needs to be cooled are the more compact fiddly bits in the middle ? Also, I wonder since the L2 spot is theoretically (partly) shaded by the earth, how much Watts/m^2 do you avoid ?
- sbierwagen 5y agoAn object in a halo orbit spends most of its time out of Earth's shadow: https://en.wikipedia.org/wiki/Halo_orbit#/media/File:Animation_of_Solar_and_Heliospheric_Observatory_trajectory_-_Polar_view.gif https://en.wikipedia.org/wiki/Halo_orbit#/media/File:Animati... Hubble used cooled instruments, warm mirror. If you only partially cool a mirror then thermal expansion effects will mess up the focus. In the paper they propose heating segments that are shadowed, to keep the whole mirror at the same temp.