Mission Specialist Andrew Thomas look closely at the shoes of one of the tracks used on a Crawler-Transporter.

STS-114 Mission Specialist Andrew Thomas (center) and Pilot James Kelly (right), along with NASA Systems Engineer Robert Rokobauer (left), look closely at the shoes of one of the tracks used on a Crawler-Transporter. The 10-foot-high track on a crawler contains 278 “shoes,” weighing 2,200 pounds each. The crawlers are guided by four trucks, one on each corner. The crawlers had recent modifications to the cab and muffler system. The STS-114 mission is Logistics Flight 1, which is scheduled to deliver supplies and equipment plus the external stowage platform to the International Space Station.