How It Works

Docking with the ISS

Docking with the ISS can potentially be catastrophic. Suffice to say, precision manoeuvring a manned shuttle onto a space station docking ring while orbiting the Earth is just a little more complicated than parking your car in the garage. Fortunately, the world’s space agencies tend to recruit very talented pilots into their ranks, whose skills and flight experience make this task a lot less hazardous.

Whenever a shuttle delivering equipment, supplies or new crew needs to dock at the ISS, there’s a strict procedure to which the pilot must adhere. First, the orbital manoeuvring and reaction control systems are used to thrust the shuttle into an orbit approximately 110 metres (360 feet) below the station, before the reaction control system finishes the approach. Firing rockets located in the nose and tail sections to alter the pitch, yaw and roll, the shuttle is stopped 50 metres (164 feet) from the station. Then it awaits clearance from mission control to continue.

Once it has clearance, the pilot moves the shuttle at a much slower rate of five centimetres (two inches) per second until it’s ten metres (33 feet) from the ISS. Here, the pilot will stop for a few minutes to fine-tune the final approach: the station’s docking target is lined up in the viewer with a cross mounted 30 centimetres (11.8 inches) above the target, called the stand-off cross. When aligned, the shuttle is manoeuvred the remaining distance onto the docking ring, where a series of hooks fixes it in place. The passage takes two hours to pressurise, after which the crew can open the hatch to pass between space station and shuttle.