Electro emissive devices, called ESTHER, are thin sheets - similar to solar cells - whose infrared emissivity can be varied reversibely by electrical charging. Bonded to external surfaces of spacecraft radiators, they allow active control of the heat radiated to space while consuming negligible electrical energy. Applying this novel component for spacecraft thermal control, considerable cost savings in spacecraft development and operation can be achieved.Progress in the design and manufacturing process has been made since the first puplication in July '92 /1/ revealing an increased variability of emissivity and an increased duty cycle stability. The material selection process was facilitated by the exposure of material samples to the space environment during two spaceflight missions and the subsequent material analyses. For the design of the electrical interconnectors and the definition of the element-to-radiator bonding process, heritages have been made from the photovoltaic solar array technology.