The Lyappa (or Ljappa) arm, officially Automatic system of re-docking (Russian: Автоматическая система перестыковки (АСПр), romanized: Avtomaticheskaya sistema perestykovki (ASPr)), was a robotic arm used during the assembly of the Soviet/Russian space station Mir. Each of the Kvant-2, Kristall, Spektr and Priroda modules was equipped with one of these arms, which, after the module had docked to the core module's forward (or axial) port, grappled one of two fixtures positioned on the core module's hub module. The module's main docking probe was then retracted, and the arm raised the module so that it could be pivoted 90 degrees for docking to one of the four radial docking ports.
A fundamentally new element in this operation is the re-docking manipulator. Sometimes we just called it “paw”, which was clearer. This electromechanical arm, short and powerful, really resembled the paw of a Siberian bear, hence its name.
This means the two future science modules, Wentian (“Quest for the heavens”) and Mengtian (“Dreaming of the heavens”), cannot dock directly to their planned radial port locations. [...] To account for this, each module will carry a Russian Lyappa robotic arm — like the ones used on Mir for the same purpose — to move the module from the forward port to its respective permanent location on a radial port of Tianhe’s docking hub.
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