California’s catalog of historic artifacts includes two pairs of boots, an American flag, empty food bags, a pair of tongs and more than a hundred other items left behind at a place called Tranquillity Base.

The history registry for New Mexico lists the same items.

That might be surprising, since Tranquillity Base is not in New Mexico or California but a quarter of a million miles away, in the spot where Neil A. Armstrong and Buzz Aldrin stepped onto the moon in 1969.

But for archaeologists and historians worried that the next generation of people visiting the moon might carelessly obliterate the site of one of humanity’s greatest accomplishments, these designations were important first steps toward raising awareness of the need to protect off-world artifacts.

“I think it’s humanity’s heritage,” said Beth L. O’Leary, a professor of anthropology at New Mexico State University. “It’s just an incredible realm that archaeologists haven’t begun to look at until now.”

Dr. O’Leary herself had not given much thought to historic preservation on the Moon until a student asked her in 1999 whether federal preservation laws applied to the Apollo landing sites.

“That started the ball rolling,” she said....