Big space rockets are used to transport satellites and manned spaceships into orbit, but before they can do that, somebody has to wheel them into place on the launching pad. And as you might imagine, the immense Saturn V rocket that NASA used to send astronauts to the Moon in the late 1960s to mid-1970s was quite a load to move.
The Saturn V was 363 feet (110.6 meters) tall, which made it 60 feet (18.3 meters) bigger than the Statue of Liberty, and when fully loaded with fuel for liftoff, it tipped the scale at 3,100 tons (2,812 metric tons). That's roughly the weight of 400 elephants [source: NASA]. In order to move the behemoth, NASA had to develop a truck that was nearly as big as the rocket itself, the 2,750-ton, 131-foot-long (39.9-meter) crawler-transporter, which inched along on tanklike treads on a special 3.5-mile-long (5.6-kilometer) road whose surface was coated with Tennessee river rock to reduce the friction. It was designed to be powerful enough to move the equivalent of three Saturn Vs, though nobody has ever tried such a feat.
The two crawler-transporters -- the largest tracked vehicles ever built -- cost about $14 million in the 1960s, which would translate to about $100 million in today's dollars. But they proved so adept at moving the Saturn V that NASA also used them for the Space Shuttle, and is upgrading one of the two vehicles to handle the Space Launch System, the new booster rocket that NASA is developing for future manned missions [source: Major].