Re: Can superconductors work without coolant in space?

Hi Nikos,

That's a great question. In theory, the answer is yes! Keep in mind that
space doesn't have an ambient temperature in the same way as on Earth. On
Earth, (or any planet with an atmosphere) the temperature we usually refer
to is that of air, water, ground or other medium. Space does contain some
gases and solids, but at very low densities. For this reason, it is close
to a theoretical vacuum.

So what is the temperature in space? The background radiation of
intergalactic space is around 4 Kelvins. This is easily cold enough for
most superconductors, but anything close to our solar system will be
significantly influenced by our sun and planets. The surface of the sun is
about 5700 Kelvins and Earth is 300 Kelvins or so. Satellites encounter a
range of temperatures based on radiation from the sun, Earth, and possibly
the moon. An absorbtive material (say a black plate) facing the sun can get
quite hot. Alternatively, a reflective material facing intergalactic space
can get quite cold. Satellites manage their temperature with insulating
blankets, heat sinks, and heaters to keep their internal temperature within
a reasonable
value.

On Earth, we have three methods of transferring heat: convection,
conduction, and radiation. In space, there is very little air, so there is
no convection. Radiation and conduction are dominant. Any surface that
absorbs radiation from a heat source will get hot and conduct that heat to
anything in direct contact. In order to design a very cold section, it must
be well insulated to avoid conduction with warmer areas and oriented so
that it does not absorb radiation. It's a challenge that is often solved
with the aid of thermal modeling software.

I hope that answers your question.