Watch NASA's Crawler Transporter as it carried the mobile launcher during a return trip from Launch Pad 39B at Kennedy Space Center in Florida following two weeks of structural and other testing in late 2013. The 355-foot-tall structure is to be used by the Space Launch System during its launch on Exploration Mission 1 in November 2018. The crawler-transporter has a mass of 6,000,000 lbs and has eight tracks, two on each corner. Each track has 57 shoes, and each shoe weighs 900 kg (1,984 lb). The vehicle measures 40 by 35 meters (131 by 114 ft). The height from ground level to the platform is adjustable from 6.1 to 7.9 m (20 to 26 ft), and each side can be raised and lowered independently of the other. The crawler uses a laser guidance system and a leveling system to keep the Mobile Launcher Platform level within 10 minutes of arc (about 30 cm (1 ft) at the top of the Saturn V), while moving up the 5% grade to the launch site. A separate laser docking system provides pinpoint accuracy...