Two veterans of the US space program have marked 50 years of service with in appropriately sedate style. In 1965, a pair of gigantic crawlers were built to move the Saturn V moon rockets to the launch pad. Half a century later, they are still in service and being upgraded to handle NASA's Space Launch System (SLS) and other launch vehicles. To celebrate, the 6 million lb (2.7 million kg) Crawler-Transporter 2 (CT-2) made a rollout for a visitor and media day at less than one mph.

Once the largest land vehicles ever built and still the largest self-powered vehicles, NASA's crawler-transporters have had one of the greatest supporting roles in history, moving every Apollo, Skylab and Apollo Soyuz mission and all the Shuttle missions to Launch Pad 39 at the Kennedy Space Center in Florida.

They were built by the Marion Shovel Company in Marion, Ohio to transport the giant Saturn V boosters from the Vehicle Assembly Building (VAB) because the inclement Florida weather precluded assembling the rockets on the launch pad. Measuring 131 ft by 114 ft (40 m x 35 m), the machines supported on eight tractor treads are driven by 16 electric traction motors run by two AC generators and two DC generators powered by diesel engines.

Despite the fact that the VAB is only 4.2 mi (6.7 km) from the launch pad, NASA says that the CT-1 has gone 1,960 mi (3,154 km) and CT-2 has covered 2,207 mi (3,551 km) in their careers. Over the years, the crawlers have received several upgrades, such as a laser docking system added in 1985, and after the retirement of the Space Shuttle CT-2 was given a major overhaul increasing capacity to 18 million lb (8.1 million kg) to handle the weight of the SLS, including the installation of two 1,500 kW diesel engines and 88 traction roller bearing assemblies, which were subjected to a major test in January.

On February 18, CT-2 was rolled out to Launch Pad 39B and opened to visitors and media on February 23 to celebrate 50 years since the building of the giant machines. The space agency says that CT-1 is being strengthened to carry commercial launch vehicles and once upgrades are complete, the two crawlers will extend their service life another 20 years.

Source: NASA (Infographic)

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