The Canadarm 2, built by the Canadian Space Agency measures 17.5 m 57.7 ft in length and weighs 1641 kg 3618 lbs. It was attached to the International Space Station on 22 April 2001 during a 7-hour spacewalk by US astronaut Scott Parazynski and Canadian astronaut Chris Hadfield - the first Canadian ever to walk in space. This new arm is based on the technology of the original Canadarm, which is used on the space shuttle. Canadarm 2, which will remain permanently in space, can handle and manipulate masses up to 116,000 kg 255,736 lbs - almost 4 times the maximum capacity of the shuttle's robotic arm. Also, the Canadarm 2 can detach from the station at either end and 'inchworm' its way around the station's hull in order to handle construction and cargo on any part of the station. Other high-tech features include automatic collision avoidance and sensors which provide a sense of touch to the arm. It can be controlled autonomously or by astronauts, utilising 4 colour video cameras located on the arm.