Heinlein, Robert A – Expanded Universe

rather than the way Destry predicted … and God help the human race!”

Captain Harrington cleared his throat to break the silence that followed.

“Superintendent,” he said, “I would not have ventured to call had it been simply a

matter of disagreement as to interpretation of theoretical predictions-”

“You have something more to go on?”

“Yes, and no. Probably you gentlemen think of the Naval Observatory as being

exclusively preoccupied with ephemeredes and tide tables. In a way you would be

right-but we still have some time to devote to research as long as it doesn’t cut

into the appropriation. My special interest has always been lunar theory.

“I don’t mean lunar ballistics,” he continued, “I mean the much more

interesting problem of its origin and history, the problem the younger Darwin

struggled with, as well as my Illustrious predecessor, Captain T. J. J. See. I think

that it is obvious that any theory of lunar origin and history must take into

account the surface features of the moon-especially the mountains, the craters, that

mark its face so prominently.”

He paused momentarily, and Superintendent King put in, “Just a minute,

Captain-I may be stupid, or perhaps I missed something, but-is there a connection

between what we were discussing before and lunar theory?”

“Bear with me for a few moments, Doctor King,” Harrington apologized; “there

is a connection-at least, I’m afraid there is a connection-but I would rather

present my points in their proper order before making my conclusions.” They granted

him an alert silence; he went on:

“Although we are in the habit of referring to the ‘craters’ of the moon, we

know they are not volcanic craters. Superficially, they follow none of the rules of

terrestrial volcanoes in appearance or distribution, but when Rutter came out in 952

with his monograph on the dynamics of vulcanology, he proved rather conclusively

that the lunar craters could not be caused by anything that we know as volcanic

action.

“That left the bombardment theory as the simplest hypothesis. It looks good,

on the face of it, and a few minutes spent throwing pebbles in to a patch of mud

will convince anyone that the lunar craters could have been formed by falling

meteors.

“But there are difficulties. If the moon was struck so repeatedly, why not

the earth? It hardly seems necessary to mention that the earth’s atmosphere would be

no protection against masses big enough to form craters like Endymion, or Plato. And

if they fell after the moon was a dead world while the earth was still young enough

to change its face and erase the marks of bombardment, why did the meteors avoid so

nearly completely the dry basins we call the seas?

“I want to cut this short; you’ll find the data and the mathematical

investigations from the data here in my notes. There is one other major objection to

the meteor bombardment theory: the great rays that spread from

Tycho across almost the entire surface of the moon. It makes the moon look

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like a crystal ball that had been struck with a hammer, and impact from – outside

seems evident, but there are difficulties. The striking mass, our hypothetical

meteor, must have been smaller than the present crater of Tycho, but it must have

the mass and speed to crack an entire planet.”

“Work it out for yourself-you must either postulate a chunk out of the core

of a dwarf star, or speeds such as we have never observed within the system. It’s

conceivable but a far-fetched explanation”

He turned to King. “Doctor, does anything occur to you that might account

for a phenomenon like Tycho?”

The Superintendent grasped the arms of his chair, then glanced at his palms.

He fumbled for a handkerchief, and wiped them. “Go ahead,” he said, almost

inaudibly.

“Very well then-” Harrington drew out of his briefcase a large photograph of

the moon-a beautiful full-moon portrait made at Lick. “I want you to imagine the

moon as she might have been sometime in the past. The dark areas we call the ‘Seas’

are actual oceans. It has an atmosphere, perhaps a heavier gas than oxygen and

nitrogen, but an active gas, capable of supporting some conceivable form of life.