The mission was proposed in 2001 to reuse the design of the "Mars Express" mission. However, some mission characteristics led to design changes: primarily in the areas of thermal control, communications and electrical power. For example, since Mars is approximately twice as far from the Sun as Venus, the radiant heating of the spacecraft is four times greater for "Venus Express" than "Mars Express". Also, the ionizing radiation environment is harsher. On the other hand, the more intense illumination of the solar panels results in more generated photovoltaic power. The "Venus Express" mission also uses some spare instruments developed for the "Rosetta" spacecraft. The mission was proposed by a consortium led by D. Titov (Germany), E. Lellouch (France) and F. Taylor (United Kingdom).