Orbital construction trades a floor and gravity-driven leverage for free-flying robotics, choreographed spacewalks, and a mass budget set by launch cost. This scene shows a simplified assembly yard: a Canadarm-style manipulator berths and bolts prefabricated truss segments onto a growing station core while an astronaut assists on a tether, and reaction-control thrusters (RCS) fight the station's tendency to tumble whenever an off-center mass is added.
The International Space Station was assembled from over 40 major flights across more than a decade, and every truss segment or module handled by Canadarm2 had to be captured and berthed with millimetre precision — with zero friction to slow a mistake down.
A robotic arm bolts truss segments and solar-array panels onto a growing space station core while an astronaut works alongside on a tether — switch off RCS station-keeping to watch the unbalanced structure tumble under conserved angular momentum.
Every mass bolted on off-center shifts a station's inertia tensor; without active reaction-control thrusters, that produces uncontrolled tumbling and precession, which is why real assemblies rely on RCS and momentum management during EVA construction.
Drag the assembly progress slider to build the truss and unfurl solar arrays step by step, pose the robotic arm's reach, and toggle RCS station-keeping and the EVA astronaut to see how construction and attitude control interact.
The ISS was assembled over more than a decade from 40+ flights, with Canadarm2 and spacewalking astronauts berthing multi-tonne modules to millimetre precision — with no floor, no friction, and no room for error.