DOI, AOS, LOS. More acronyms, Henry thought. Well, DOI must be descent orbit initiation. And LOS and AOS referred to loss and acquisition of signal; for, like so many of this mission’s most crucial moments, the descent burn would take place on the far side of the Moon, out of sight of Earth, and far from assistance.

The descent orbit burn would put them into a lop-sided ellipse of an orbit with a high point of sixty-nine miles, kissing Arkady’s circular orbit, and after skimming for three hundred miles around the Moon’s lighted face, they would reach a low point of nine miles: just fifty thousand feet high, close enough to touch the mountains of the Moon. And there they would burn their engine again, and fall all the way to the surface.

That was the plan.

There was no air on the Moon. Air would have made it easy, he thought. With air you wouldn’t need all this fuel. You could glide down, like the Space Shuttle returning to Earth, or even batter your way in with a heatshield and fall into the ocean under parachutes, the way the Apollo astronauts used to.

On the Moon, there was nothing to help you down. All you could do was bring along a rocket motor, and all the fuel you needed, and stand on it as it descended, all the way to the surface of the Moon. Like riding an ICBM back down into its silo, Henry thought bleakly, and about as stable. And expensive as all hell, considering the fuel load it took to bring an ounce of payload here…

Shoemaker, on my mark you’ll have twelve minutes to DOI ignition.

“Roger, Frank.”

Shoemaker, Houston, stand by for my mark. Mark. Twelve minutes.

“We copy.”

Shoemaker, Soyuz, this is Houston, three minutes to LOS. You guys look good going over the hill.

Geena said, “Shoemaker, roger.”

Arkady chimed in, “Roger from Soyuz.”

Geena called, “Arkady, have a good time while we’re gone.”

“Yes,” said Arkady. “I won’t get lonesome.”

“And don’t accept any trans-Earth injection updates.”

“Don’t you worry,” said Arkady.

And so on.

It was, Henry knew, the kind of bull pilots always exchanged when hanging out their hides. But, he had to admit, right now he could see it had its purpose. After all, here he was strapped to this table-top, on a craft that couldn’t take him back to Earth. If anything went wrong before the landing, Arkady was going to have to come down and get them, if he could. And after the landing, if the Shoemaker engine failed to restart, there was no way home.

At such a moment, what were they supposed to talk about?

The Moon was starting to reappear as his eyes opened wide: a tableau of craters, ridges and plains, worked in blue and soft grey. He could see shadows, cast by Earth itself.