The experiment, which investigates how heat is transferred in space, was originally part of the Dutch Soyuz DELTA Mission to the ISS with ESA astronaut André Kuipers in April 2004. The results of HEAT are relevant for thermal control in satellites.
During the DELTA Mission difficulties were encountered with the HEAT experiment. The problems were thought most likely to be due to a loose connection with the heating plate. Although the solution was fairly straightforward, there was no time to repeat the experiment during Kuipers' mission (19-30 April). Consequently ESA requested that Kuipers' NASA colleague Mike Fincke repeat the experiment. Kuipers and Fincke flew to ISS together with Russian cosmonaut Gennadi Padalka in April.
The HEAT experiment performed flawlessly. "It really was perfect", explains Marc Heppener, ESA's head of ISS scientific research.