At NASA's Kennedy Space Center moves up the gravel crawler way at Launch Pad 39A.

At NASA's Kennedy Space Center in Florida, crawler-transporter No. 2 moves up the gravel crawler way at Launch Pad 39A. The crawler-transporter is undergoing testing to check out recently completed modifications to ensure its ability to carry launch vehicles such as the space agency's Space Launch System heavy-lift rocket to the pad.

NASA's Ground Systems Development and Operations Program is leading the 20-year life-extension project for the crawler. A pair of behemoth machines called crawler-transporters has carried the load of taking rockets and spacecraft to the launch pad for more than 40 years at NASA’s Kennedy Space Center in Florida. Each weighing six and a half million pounds and larger in size than a professional baseball infield, the crawler-transporters are powered by locomotive and large electrical power generator engines. The crawler-transporters will stand ready to keep up the work for the next generation of launch vehicles to lift astronauts into space. For more information, visit http://www.nasa.gov/exploration/systems/ground/index.html Photo credit: NASA/ Jim Grossmann