The ROSETTA mission is a European Space Agency spacecraft which will rendezvous with the comet Wirtanen. The spacecraft will deploy a Surface Science Package (SSP) to land on the comet. The spacecraft will continue to orbit the comet for the following 2 years, which will allow other experiments to be performed to study the evolution of the comet processes as a function of heliocentric distance.The spacecraft will use planetary gravity assists to gain enough energy for a rendezvous with the comet. The spacecraft will be at distances ranging from 0.9 Astronomical Units (AU) to 5.25 AU, with long periods of hibernation. The power for the mission is supplied by two Solar Arrays. This means that the available power at 5.25 AU is 3.6% of that at 1.0 AU. Thus, the heater power demand at 5.25 AU has to be low, when the spacecraft is in Deep Space Hibernation mode. Prior to the comet rendezvous, the spacecraft is woken up. With a fully operational payload, the ROSETTA spacecraft establishes an orbit around comet Wirtanen. The spacecraft follows the comet during its approach to the sun.This paper discusses the thermal design established for the ROSETTA spacecraft. The design uses louvres and high performance multi-layer insulation.