I've heard that the moon is moving away from Earth. If we add mass by building a base on the moon, will it speed up that process
Photo by NASA
Scientists have determined that the moon creeps 1.5 inches farther away from the Earth every year, mostly as a consequence of the tides gradually slowing the Earth's rotation. But could adding mass to the moon's surface alter its orbit even more, just as a glob of mud affects a baseball's spin?
NASA's plan to build its first lunar base by 2024 is ambitious, but it won't move the moon. The moon's mass is about 80 billion billion tons, which easily dwarfs the few dozen tons of construction that NASA has proposed. To put this in perspective, imagine a flea sitting on the Great Pyramid and somehow shifting the giant tomb a few inches to the left.
Unlikely as it is, though, adding mass to the moon could theoretically change its orbit. Scott A. Hughes, an assistant professor of astrophysics at the Massachusetts Institute of Technology, calculates that we would need to send more than 540 trillion tons to the moon to push it an additional 1.5 inches away. That, however, would require well over a billion flights of NASA's proposed moon transporter, Orion. There's a greater chance of an asteroid hitting the moon and altering its orbit.
The Earth-moon separation will ultimately lengthen our days and severely diminish the magnitude of high and low tides, says Jim Bell, an associate professor of astronomy at Cornell University. But this won't happen for a few billion years. And by then, the sun will be burning away the Earth's atmosphere and oceans, so we'll have more pressing things to worry about.
—Katherine Ryder