Soyuz was freefalling towards the Moon. The gravity field of that rocky world would make the craft fall around the Moon’s far side. But, without intervention from its strapped-on rockets, Soyuz would skim through the Moon’s shadow, pass through a zone of occlusion from Earth’s radio signals, and then whip around to the sunlit side — and back towards Earth. To enter lunar orbit, the craft would have to burn its Block-D booster to shed some velocity, slow down sufficiently to be captured by the Moon’s feather-light gravity field.

…Soyuz, Houston. You’re go for LOI. You’re riding the best bird we can find. Godspeed, Soyuz… Soyuz, this is Korolyov. Do not rush to hell ahead of your fathers…

LOI: lunar orbit insertion, the burn of two of their three remaining booster packs to put them into lunar orbit. Maybe the most crucial moment of the mission so far. The irony was, it would happen the first time they were out of contact with Earth, on the far side of the Moon.

And since, with characteristic caution, Arkady had already turned the stack to the precise orientation for the burn — that is, ass-backwards — none of them could see where they were heading.

Henry said, “You know, we’ve come a quarter of a million miles across space, and we’re aiming at a world two thousand miles across, and we’re going to go into orbit sixty-nine miles above the surface. Not much room for error. And we can’t even see where we’re going.”

Geena grimaced. “Every pilot hates not to be able to eyeball the target. That’s why LOS is so important.”

“LOS?”

“Loss of signal. When we go around the corner of the Moon, and into radio shadow.”

Arkady found a place on his checklist. “They can calculate our trajectory to the second, in advance. And if LOS comes when the list says it should, at sixty-five hours, fifty-four minutes, five seconds, we’ll know we’re on course.” He grinned at Henry. “Trust me.”

…And, as the craft turned in response to Arkady’s touches, the Moon came into Henry’s view: only eight thousand miles away now, less than four diameters, it was a gigantic crescent bathed in sunlight, pocked with craters, wrinkled by hills.

And it was growing in his view, even as he watched.

“My God,” murmured Geena. “It’s like a dive-bombing run.”

But they were approaching the Moon’s dark side, and as the Moon neared that sunlit crescent narrowed, even as it spread across space.

Henry leaned into the window and craned his neck to see the sweep of the Moon, from horn to narrowing horn.

Jenny Calder packed her two kids off on the train with her sister. She watched as it pulled out of Glasgow Central Station, at the start of their long journey to their aunt’s home on the south coast of England.

It broke her heart to do it.