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

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

The concept of “temperature” does not make any sense of a near-vacuum. Temperature is a **characteristic of matter**. A vaccuum has no temperature. And for a near-vacuum with only a handful of hydrogen atoms bouncing around it makes absolutely no difference whether those few atoms have a temperature of -270°C or 30,000°C. There’s still next to no thermal energy in that bit of space.

>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.
>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?

Spacecraft are notoriously difficult to **cool**. You can’t dump excess heat anywhere because there is no matter around you into which you could transfer it. The only way is to use heat radiation and that requires massive radiators.