Definitely superconductors; that's the only viable way to generate a field that strong. Design the spacecraft properly and you may not need an active cooling system. The James Webb Space Telescope aims to keep the shaded side below 50K… while at the same time solar panels and all its solar-facing equipment will operate 250K hotter near room temperature. The trick is maintaining this temperature gradient.
Apparently the design of the JWST is sufficient to reach temperatures as low as 37K on the cold side passively — below the superconducting limit for some materials. They're additionally using a cryocooler to take the temp down to below 7K for one specific instrument.
Apparently the design of the JWST is sufficient to reach temperatures as low as 37K on the cold side passively — below the superconducting limit for some materials. They're additionally using a cryocooler to take the temp down to below 7K for one specific instrument.
https://jwst.nasa.gov/cryocooler.html