eli5: if space is virtually empty, does a space shuttle stay hot from when it exits the atmosphere because there’s less particles to absorb the heat? Or does it do the opposite and cool rapidly?

Question

I’m just curious as to the process and behavior of the surface temp of a shuttle once there’s virtually no particles in contact with the craft.

I’m aware space is cold due to the absence of matter,

But does a space shuttle take a much longer time frame to cool down with less matter available to transfer the heat of the craft to, or does the lack of matter cause the shuttle to cool rapidly?

In: 141

Answer 1

The space shuttles didn’t get all that hot when they exited the atmosphere because they weren’t going all that fast. Rocket launches first go up to get out of the atmosphere, then go fast to get up to orbit speeds. When shuttles or capsules come back in, they use the atmosphere for braking rather than burning rocket fuel to slow down.

But yes, cooling things off in space is harder. With no air, you have to radiate away the heat rather than convection. Not so much the shuttles or anything with a heat-shield. More like, anything that has computers or takes energy to do work. All our deep probes use RTG nuclear batteries which have a lot of fins for cooling. (And all that works against them when in direct sunlight).

Convection is when atoms rub each other and exchange heat, the velocity of the electrons, and then leave taking away the heat. Air-conditioning.

Radiation is slower. Everything emits radiation. The infrared wavelengths are heat, but any energy leaving the system cools it down. Usually, when it’s around other stuff that’s also radiating, it’s a net zero effect and this doesn’t do much. But in the void of space, that radiation leaves and the stars don’t heat you up much.