In 1976, CNES commenced studies into a crewed Ariane concept. Two different concepts for the vehicle were examined in detail, these being a capsule and a glider. In 1983, CNES opted to focus its attention on a space plane as the agency had concluded that such a vehicle would deliver greater convenience, comfort, and cost-effectiveness. Opting for a space plane approach was found to simplify recovery due to it possessing the necessary cross-range manoeuvrability to reach a given point on the Earth within the space of a single day, while also providing for a less challenging re-entry environment for the crew and payload, while being reusable would also serve to reduce the cost of successive missions. Critical technologies identified included thermal protection, environmental controls, life support systems, aerodynamics, and power.