The U.S. is exploring a railroad for the moon. It has a good reason.

The first U.S. transcontinental railroad, completed with a spike hammered into the track in 1869, transformed the nation. Perhaps the same will happen on the moon.The Defense Advanced Research Projects Agency, or DARPA — an ambitious federal innovations division — has begun collaborating with over a dozen companies on potential future lunar technologies, including a moon railroad. It's called the 10-Year Lunar Architecture Capability Study, or LunA-10, and its mission is to find tech