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The worst obstacle and the primary roadblock to using superconductors on Earth is the ambient temperature which necessitates a coolant like LN2 or even liquid Helium (and a lot of energy for creating these).

Achieving these temperatures in space is dirt cheap, a simple sun shield keeping the superconductor in shadow is all that's needed.

As I read the mass breakdown of some ion engines, the cabling contributed quite a bit to the weight. There's a lot of other applications where using superconductors would be superior. Maybe we could get ultra-low-power superconducting electronics. What about superconductor-based bearings for all the inertia wheel needs?

So why aren't they used more commonly? What are some other obstacles?

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  • $\begingroup$ "quite a bit"? it's 3% according to the answer you linked to. Less than 1% if you include the propellant mass. $\endgroup$
    – Hobbes
    Jul 23, 2019 at 6:40

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Although space is cold, vacuum is a pretty good insulator.

That means it is difficult to get rid of waste heat. Almost any action your spacecraft performs does produces heat that must be radiated away. Radiators are very sensitive to temperatures, being victims of the Tyranny of the Stefan-Boltzmann Equation. Their efficiency depends on the fourth power of their absolute temperature, so a spacecraft operating at 140K (The current temperature limit for high-temperature superconductors) has 16 times less efficient radiators. If you must have sixteen times the area of radiators to provide the same cooling, any mass savings by using the superconductors are efficiently cancelled out.

Another concern is reliability. If the thermal system fails, your spacecraft is dead.

Using superconductors will of course reduce the heat load a bit, but you still have waste heat production from on-board electronics, actuators and reaction wheels, and of course the Sun.

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    $\begingroup$ OTOH using superconductors you will be producing far less heat... $\endgroup$
    – SF.
    Jan 29, 2016 at 23:31
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    $\begingroup$ @SF., most waste heat comes from sources other than the resistance of the wires. $\endgroup$
    – Mark
    Feb 5, 2016 at 2:53
  • $\begingroup$ It's worth noting that the JWST, despite its gargantuan sunshield, will still require active cooling to get below the 7 K threshold for one of its instruments to work. $\endgroup$
    – Michael Seifert
    Jul 22, 2020 at 21:19
  • $\begingroup$ @MichaelSeifert it also says that for the other instruments that only require a temperature of 37K, passive cooling is enough, validating the idea that you can achieve temperatures good for superconductors in space by using a sunshield. $\endgroup$
    – BlueCoder
    Jul 23, 2020 at 15:22

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