The velocity changes required were well within the capabilities of Soyuz with its Block-D booster — which was, after all, capable of returning him all the way from lunar orbit and to the Earth — and it was a neat exercise in three-dimensional orbital mechanics, which Arkady conducted in conjunction with the ground, to calculate the rocket burns required.

But the manoeuvre would absorb most of the fuel reserve put aside for the return of Soyuz to the Earth, whether Arkady proceeded with the landing or not.

And so it was that when Arkady felt the gentle push of the propulsion system at his back, he knew he was, already, committed.

Arkady allowed himself a complete orbit, in his new polar orientation, before he began his descent.

As he passed over the Earth-facing hemisphere of the Moon, he spoke to Geena.

…Are you lonely up there? Do you miss me?

“Yes,” said Arkady. Yes. But I cannot tell you how much. Not when the whole world, including your ex-husband, is listening in. “I even miss Baikonur.”

Baikonur? The steppe?

“The steppe has its beauty. At this time of year the grass and flowers have burned off, and the steppe has turned grey, save for the green of the camel thorn and the pale pink of the saxifrage flowers. Sometimes after the rain, puddles form, like little lakes, in the middle of the salty desert. Swans come to breed there!…”

It sounds beautiful.

“It can be.”

Now, unexpectedly, Geena sang a song for him. Her voice was hesitant, not very tuneful, her Russian accent poor. But he recognized it immediately. It was a favourite from his childhood, On the Porch Together. Her voice was nervous and thin, reduced to a scratch by the radio loop, and it all but reduced him to tears. She had learned this song from his family, and had now brought it to the Moon for him. And she was filling his heart. Most Americans could never understand the importance of such simple human moments.

And when she was done, Geena sang one of Yuri Gagarin’s favourites — so it was said, anyhow — called I Love You, Life. All the cosmonauts knew this one, and he joined in, but his voice was weak and he feared he would lose control.

At last, without warning, he sailed around the rocky limb of the Moon, and the radio signal turned to mush, cutting short her song.

He turned off the receiver, and drifted away into the empty, ticking cabin.

In solitude once more, Arkady watched the shadows lengthen, and, for the last time, he sailed into the shadow of the Moon.

It was necessary for his craft now to perform the final burn. As so often happened with the key events of this mission, it seemed, it must be done here, in the radio shadow of the Moon, when he was alone and out of touch with the Earth.

But if it must be, it must be.