"Goodness! Matthew, I wish you wouldn't talk about an atom bomb being over Des Moines, even in fun."
"In fun?" Matt had been puzzled. "As a matter of fact ... let me think; we're about forty-two north and ninety-four west-" He glanced at his watch finger and studied for a few moments. "Jay-three ought to be along in about seven minutes-yes, it will be almost exactly overhead by the time you finish your coffee." Long weeks in the Nobel, plotting, calculating,, and staring in radarscopes had gotten Matt so that he knew the orbits of circum-Terra prowler rockets a bit better than a fanner's wife knows her own chickens; Jay- three was an individual to him, one with fixed habits.
His mother was looking horrified. She spoke directly to her husband as if she expected him to do something about it. "John. ... I don't like this. I don't like it, do you hear me? What if it should fall?"
"Nonsense, Catherine-it can't fall."
Mart's younger brother chortled. "Mom doesn't even know what holds the Moon up!"
Matt turned to his brother. "Who pushed your button squirt? Do you know what holds the Moon up?"
"Sure-gravity."
"Not exactly. Suppose you give me a quick tell, with diagrams."
The boy tried; his effort was hardly successful. Matt shut him off. "You know somewhat less about astronomy than the ancient Egyptians. Don't make fun of your elders. Now, look, Mother-don't get upset. Jay-three can't fall on us. It's in a free orbit that does not intersect the Earth-like smarty-pants here says, it can't fall down any more than the Moon can fall. Anyhow, if the Patrol was to bomb Des Moines tonight, at this time, it wouldn't use Jay-three for the very reason that it is overhead. To bomb a city you start with a rocket heading for your target and a couple of thousand miles away, because you have to signal its robot to start the jet and seek the target. You have to slow it down and bend it down. So it wouldn't be Jay-three; it would be-" He thought again. "-Eye-two, or maybe Ache-one." He smiled wryly. "I got bawled out over Eye-two."
"Why?" demanded his brother.