Method for controlling heat transfer between two objects. In one embodiment, the method includes flowing a current through an electromagnet disposed about a container holding magnetorheological fluid to bias a first conductive element against a first end of the container and a second conductive element against a second end of the container to align particles in the magnetorheological fluid such that first conductive element is conductively coupled to the second conductive element; and reducing the current through an electromagnet such that the first conductive element is biased away from the first end of the container and the second conductive element is biased away from the second end of the container to break the alignment of the particles in the magnetorheological fluid such that the first conductive element is not conductively coupled to the second conductive element.