Plans for Hermes changed radically, many times over. Changes to the payload bay, crew cabin, docking tunnel, and airlock were incorporated, as was an emergency escape hatch. These changes had profound effects on the overall weight of the Hermes. Finally, after spending the equivalent of $2 billion with no space hardware to show for it, the ESA cancelled Hermes.
Nevertheless, the Ariane-5 development went on. Arianespace knew that communications satellites would increase in size, and that being the case, the Ariane-4, which was designed to launch two satellites at the same time, would become inadequate. The Ariane-5 not only had a bigger core stage, it also had two large solid rocket boosters – a configuration similar to the American Titan III and IV.