Science: Tunnel on the Moon

As a leading authority on the Arizona meteorite crater, Dr. Harvey H. Nininger is naturally interested in the moon, whose face has apparently been pocked by thousands of flying meteorites. In the current Sky and Telescope, Nininger speculates that one large meteorite may have blasted a tunnel through one of the moon’s ridges.

Most experts believe, says Nininger, that the moon is covered with a thick blanket of meteoritic material, chips knocked off lunar rocks and other loose stuff. There is no water to help cement the fragments together, and the moon’s gravitation is feeble. Pulverized lunar rock, he says, would weigh on the moon less than pine sawdust weighs on earth. He thinks there may be a considerable depth of this light debris on some parts of the moon.

Then Nininger points out a peculiar pair of lunar pockmarks named Messier and W. H. Pickering. They lie on either side of a ridge running across the moon’s Mare Foecunditatis. Both were formed, he thinks, when a large meteorite hit the ridge at a very small angle. Its speed carried it through the loose material and down to the solid rock below the peak of the ridge. Then it bounced up like a ball and tore into the open, leaving a tunnel. The inside of the tunnel may be lined with a casing of glassy once-molten rock which solidified quickly enough to keep the moon’s gravitation from collapsing the tunnel.

If rocket-borne explorers from the earth ever land on the moon, Nininger suggests, they may be grateful for his tunnel. It will give them valuable shelter from small meteorites and other annoying hazards of the moon’s airless surface.