Artist's impression of ATV 3, ‘Edoardo Amaldi’, approaching the Zvezda module on the International Space Station (ISS). The cargo carrier was assisted by a wireless link to the Russian module, referred to as the 'proxy link', and relative GPS measurements. For these, the satellite-based global navigation system position data obtained from the ISS and ATV on-board computers is evaluated and compared; the results are used for making fine adjustments to the position of ATV-3. The Russian KURS radar supports navigation from a distance of about 3.5 kilometres. Over the last 250 metres, an optical sensing system sent laser pulses to four reflectors on the Zvezda module and calculated distance, relative position and approach speed on the basis of the reflected signals. For the final 50 meters, ATV-3 navigated using a video system. The docking manoeuvre took a total of three and a half hours.