You should see the times getting longer as the soup cools. The next type of heat transfer is convection. Convection involves both the molecular energy transfer outlined above and a bulk fluid motion which carries heat away from the higher-temperature surface. Some of the water boils, and the air bubbles also help to force the hot soup upwards. So clearly, neither of these is at work in space.
Thermal radiation is energy emitted by matter at a certain temperature.
While the other two forms of heat transfer require a medium, radiation does not. In radiation, energy is given off in the form of photons. If something is hot enough, the photons emitted are in the visible spectrum, like an electric stove burner, which gets hot enough to glow bright orange. Hold your hand near the side of the pot of soup and you'll feel radiative heat transfer at work. This is, of course, how we get heat energy from the sun as well.