Sketches of the concepts for the instrument layout, elevation wheel, and backup structure. Upper left panel: arrangements of the six science instruments inside the “rocking chair” elevation wheel. The instruments are represented by two larger and four smaller blue rectangles. The two larger science instruments are mounted on the Nasmyth platforms (pink). The isostatic four-point interface between the main reflector backup structure and the rocking chair can be seen as the magenta circles with blue + signs. Upper right panel: isometric view of the rocking chair elevation wheel. The isostatic four-point interface (magenta circles with blue + signs) between the main reflector backup structure and the rocking chair elevation wheel can be seen more clearly. Lower panel: bottom view of the backup structure showing the isostatic four-point interface to the backup structure.