The crawler-transporters, formally known as the Missile Crawler Transporter Facilities, are a pair of tracked vehicles used to transport spacecraft from NASA's Vehicle Assembly Building along the Crawlerway to Launch Complex 39. They were originally used to transport the Saturn IB and Saturn V rockets during the Apollo, Skylab and Apollo–Soyuz programs. They were then used to transport Space Shuttles from 1981 to 2011. The crawler-transporters carry vehicles on the Mobile launcher platforms used by NASA, and after each launch return to the pad to take the platform back to the VAB. The two crawler-transporters were designed and built by Marion Power Shovel Company using components designed and built by Rockwell International at a cost of each. Upon its construction, the crawler-transporter became the largest self-powered land vehicle in the world. While other vehicles such as bucket-wheel excavators like Bagger 293, dragline excavators like Big Muskie and power shovels like The Captain are significantly larger, they are powered by external sources. The two crawler-transporters were added to the National Register of Historic Places on January 21, 2000.
Specifications
The crawler-transporter has a mass of and has eight tracks, two on each corner. Each track has 57 shoes, and each shoe weighs. The vehicle measures. The height from ground level to the platform is adjustable from, 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, while moving up the 5 percent grade to the launch site. A separate laser docking system provides pinpoint accuracy when the crawler-transporter and Mobile Launch Platform are positioned in the VAB or at the launch pad. A team of nearly 30 engineers, technicians and drivers operate the vehicle, centered on an internal control room, and the crawler is driven from two control cabs located at either end. Before the launch the crawler-transporter is removed. The crawlers were overhauled in 2003 with upgrades to the Motor Control Center, which houses the switchgear and electrical controls of all of major systems on board; a new engine and pump ventilation system; new diesel engine radiators; and replacement of the two driver cabs on each vehicle. As of 2003, each crawler had 16 traction motors, powered by four generators, in turn driven by two V16 ALCO 251C diesel engines. Two generators, driven by two engines, were used for jacking, steering, lighting, and ventilating. Two generators were also available to power the Mobile Launcher Platform. The crawler's tanks held of diesel fuel, and it burned. Due to its age and the need to support the heavier Space Launch System and its launch tower, in mid-2012 one of the crawlers was undergoing an upgrade involving "new engines, new exhausts, new brakes, new hydraulics, new computers", to increase its lifting capacity from. The crawlers traveled along the Crawlerways, to LC-39A and LC-39B, respectively, at a maximum speed of loaded, or unloaded. The average trip time from the VAB along the Crawlerway to Launch Complex 39 is about five hours. Each Crawlerway is deep and covered with Alabama and Tennessee river rock for its low friction properties to reduce the possibility of sparks. In 2000, NASA unearthed and restored an Apollo-era segment of the Crawlerway to provide access to High Bay 2 in the VAB in order to provide protection from a hurricane for up to three Shuttles at the same time. Kennedy Space Center has been using the same two crawlers, now nicknamed "Hans" and "Franz", since their initial delivery in 1965. In their lifetime, they have traveled more than, about the same driving distance as from Miami to Seattle.
Future use
NASA plans to use one of the crawlers to carry NASA's Space Launch System with the Orion spacecraft atop it from the Vehicle Assembly Building. Early in 2016, NASA finished upgrading crawler-transporter 2 to a "Super Crawler" for use in the Artemis program. CT-1 is now in the process of being modified to serve a variety of commercial spacecraft. In April 2016, Orbital ATK and NASA entered negotiations for the lease of CT-1 and one of the four Vehicle Assembly Building bays.
The crawler-transporters have featured in television and movies. In a season three episode of Dirty Jobs, host Mike Rowe helps workers maintain a crawler-transporter and takes the vehicle for a short drive. The crawler was also seen in the 1995 film Apollo 13, the 2011 film and the 2019 film Apollo 11. Similar vehicles also appeared in the 2013 film Pacific Rim, used for transporting and launching Jaegers. In the Fallout 3 video game add-on pack "Broken Steel", the US government survivors, The Enclave, have a mobile base built on and into a heavily modified crawler. In Sid Meier's Alpha Centauri, various units are called "crawlers" and feature chassis based on the crawler-transporters.
