Task: Text Categorization
Input (English): Text:  Hopper was a proposed European Space Agency orbital and reusable launch vehicle. The shuttle prototype spaceplane was one of several proposals for a European reusable launch vehicle (RLV) planned to cheaply ferry satellites into orbit by 2015. The 'Phoenix' was a German-European project for a one-seventh scale model of the Hopper concept vehicle.
Output (English): 6