And I'd guess what they're asking is how a vacuum would cool something if there's no matter providing collisions where energy transfer can happen. I.e., isn't vacuum the ultimate insulator? If I understand correctly, objects in a vacuum cool by radiating only (i.e., energy leaving as photons), and perhaps we only think of space as cold because the absence of a medium (i.e., atmosphere) means no pressure and no additional energy being provided in said medium.