The invention relates to an artificial satellite which includes: a mounting structure supporting equipment-bearing walls; a launcher-adapter rigidly connected to the mounting structure; a first radiator (26); and at least one first system (42) for transporting heat by a fluid, including at least one duct (44) having a first heat-exchange section (50) and a second heat-exchange section (52), said second heat-exchange section (52) being capable of being in thermal contact with said first radiator (26), characterised in that said first heat-exchange section (50) is in thermal contact with at least one portion of the launcher-adapter (16). The invention also relates to a method for filling a tank of propellent gas of said artificial satellite.