Don't mess with the moon, NASA tells future visitors

NASA is seriously nervous that a hike in lunar traffic could put the moon's historic relics at risk and is asking future moon visitors to steer clear of swaths of the barren terrain. The agency has even drawn virtual "do not cross" perimeters around such treasures as the Apollo landing sites. Why the sudden rush? In addition to several countries' anticipated unmanned lunar probes, 26 companies hope to send robots to the lunar surface to snap high-def images of ancient NASA trappings to win the $20 million Lunar X Prize. Just one gravity-free collision or spray of highly abrasive moon dust could decimate a piece of momentous human history -- not to mention any existing scientific experiments.