<P> The station in its complete form has several smaller external components, such as the six robotic arms, the three External Stowage Platforms (ESPs) and four ExPRESS Logistics Carriers (ELCs). While these platforms allow experiments (including MISSE, the STP - H3 and the Robotic Refueling Mission) to be deployed and conducted in the vacuum of space by providing electricity and processing experimental data locally, their primary function is to store spare Orbital Replacement Units (ORUs). ORUs are parts that can be replaced when they fail or pass their design life . Examples of ORUs include pumps, storage tanks, antennas and battery units . Such units are replaced either by astronauts during EVA or by robotic arms . Spare parts were routinely transported to and from the station via Space Shuttle resupply missions, with a heavy emphasis on ORU transport once the NASA Shuttle approached retirement . Several shuttle missions were dedicated to the delivery of ORUs, including STS - 129, STS - 133 and STS - 134 . As of January 2011, only one other mode of transportation of ORUs had been utilised--the Japanese cargo vessel HTV - 2--which delivered an FHRC and CTC - 2 via its Exposed Pallet (EP). </P> <P> There are also smaller exposure facilities mounted directly to laboratory modules; the Kibō Exposed Facility serves as an external' porch' for the Kibō complex, and a facility on the European Columbus laboratory provides power and data connections for experiments such as the European Technology Exposure Facility and the Atomic Clock Ensemble in Space . A remote sensing instrument, SAGE III - ISS, was delivered to the station in 2014 aboard a Dragon capsule, and the NICER experiment is scheduled to be delivered in 2016 . The largest such scientific payload externally mounted to the ISS is the Alpha Magnetic Spectrometer (AMS), a particle physics experiment launched on STS - 134 in May 2011, and mounted externally on the ITS . The AMS measures cosmic rays to look for evidence of dark matter and antimatter . </P> <P> The Integrated Truss Structure serves as a base for the station's primary remote manipulator system, called the Mobile Servicing System (MSS), which is composed of three main components . Canadarm2, the largest robotic arm on the ISS, has a mass of 1,800 kilograms (4,000 lb) and is used to dock and manipulate spacecraft and modules on the USOS, hold crew members and equipment in place during EVAs and move Dextre around to perform tasks . Dextre is a 1,560 kg (3,440 lb) robotic manipulator with two arms, a rotating torso and has power tools, lights and video for replacing orbital replacement units (ORUs) and performing other tasks requiring fine control . The Mobile Base System (MBS) is a platform which rides on rails along the length of the station's main truss . It serves as a mobile base for Canadarm2 and Dextre, allowing the robotic arms to reach all parts of the USOS . To gain access to the Russian Segment a grapple fixture was added to Zarya on STS - 134, so that Canadarm2 can inchworm itself onto the ROS . Also installed during STS - 134 was the 15 m (50 ft) Orbiter Boom Sensor System (OBSS), which had been used to inspect heat shield tiles on Space Shuttle missions and can be used on station to increase the reach of the MSS . Staff on Earth or the station can operate the MSS components via remote control, performing work outside the station without space walks . </P> <P> Japan's Remote Manipulator System, which services the Kibō Exposed Facility, was launched on STS - 124 and is attached to the Kibō Pressurised Module . The arm is similar to the Space Shuttle arm as it is permanently attached at one end and has a latching end effector for standard grapple fixtures at the other . </P>

Where did the international space station launch from