“Ares, Houston, thank you. Ah, Ralph, Phil, Natalie, could we get you all in one shot for a moment, please?”

Stone looked puzzled. “Say again, Houston.”

“If we can have you all in the camera’s field of view for a couple of minutes.”

Stone drifted close to York, who stayed by the table; and Gershon floated down behind them, facing the camera.

“Ares, Houston,” Crippen said. “Just about now, ah, at five plus one plus forty-two” — one hour into the mission’s fifth day — “you are passing a significant boundary. Although you may not feel it. It’s something you might like to think about as you eat your meal today.”

“We look forward to hearing about it, Bob.”

“…Maybe one of you could tell us what you can see out of your picture window right now.”

York turned. The “picture window” was a two-foot-wide viewport set in the wall of the wardroom, big enough to have to curve to follow the concavity of the pressure hull; it was triple-paned, with the thick, tough feel about it of an airplane window.

“I see Earth and Moon,” she reported. “They’re both pretty much full, although I can see a thin slice of shadow down the right-hand limb of each of them.” Earth was so distant, its sphericity wasn’t obvious; it was reduced to a flat blue bowl of light, with its pale, shrunken companion close by its limb. “The Earthlight is still bright,” she said. “Strong enough to read a book by, I’d say. But…”

“Go ahead, Natalie.”

“Something is different.” She peered into the window to see better. “The sky is just like a clear night on Earth. And — my God — it’s full of stars. Earlier in the flight the glare of Earth was so bright it blacked out everything else. Now, I can see the stars. I can recognize the constellations again, for the first time on the trip.”

“Ares, I guess you’ve really gone up into night.”

“Yes, we have. A huge, empty, cold night at that.”

“Ares, Houston. Thank you, Natalie. Ares, here’s the significance. You’re now almost exactly five hundred and sixty-two thousand statute miles from the Earth. That’s twice as far as any human has traveled before. And you’re now passing out of the Earth’s sphere of influence.”

Sphere of influence — an imaginary bubble in space centered on Earth, an almost perfect sphere where the gravitational potential of Earth and sun were in balance. Inside the sphere of influence, Ares had essentially been in an orbit dominated by Earth; beyond that point, however, the craft had escaped from Earth and was in solar orbit, a new planet.

Stone said, “Thank you, Bob. We understand, and we’re impressed, almost humbled, with the thought…” Stone seemed dissatisfied with his own trite words. He was looking at York thoughtfully. “Natalie, you want to add anything to that?”