The shock wave from the bunker-buster punched down into the strata of ice and dust, crushing the ancient layers, and slammed into the bedrock crust beneath. A central ball was flashed to vapour, which strove to flee the explosion. Surrounding layers of dirty ice were smashed and crushed, and the cavity expanded, growing at last to a hundred yards across.

When the stellar energy of the initial explosion faded, the weight of the layers above bore down on the cavity. It caved in, and layers of rubble collapsed down into it and over each other, forming a deep rubble chimney four hundred yards tall. It was surrounded by a fracture zone, cracks racing outwards, and its base was lined with radioactive glass, the remnants of the rock dust layers.

When the chimney collapse reached the surface, volatiles — water and carbon dioxide steam — began to fount from the growing crater. It was a volcano, of water and air…

Jane had found too many symptoms to ignore, now. Changes in her bowel habits. Blood in her stools and urine; pain when she pissed. Sores in her mouth that wouldn’t heal; hoarseness and coughs and difficulty swallowing; bleeding between her normal periods. It was as if she had wished this illness on herself, and now it was coming true.

She knew she would have to face it, go find a doctor. But that would confirm what she feared. It would be like picking up the revolver to play Russian Roulette—

“I can see it,” Jack said. “I can see it. Wow.”

Jane lifted the toy telescope. The Moon leapt into detail, the craters at the terminator finely detailed by shadow, her view obscured only by the trembling of her hands and by the false-colour spectral rings of the cheap lens.

She’d almost missed the flash, the few seconds after ignition: the moment when fire touched the surface of the Moon, shining over the southern limb, brought there by human hands. Already that glow was fading. But she could see the consequences.

There was a cloud, of yellow-white vapour, which fountained up — it must have been tens of miles high to be visible from here — erupting from the limb of the Moon into the darkness of space, in slow snakes, fingers of gas.

Henry was right: there was ice at the Pole, and here was the proof of it.

The soft white glow fell back, already much brighter than the Moon’s native glow, splashing against the Moon’s grey surface, and racing over that barren ground.

For a moment she felt a stab of regret. What harm had the Moon ever done humanity? For billions of years it had patiently regulated the tides, drawing up the sap in oceans and plants and humans. It was inspiration for a million myths, maybe more bad love songs, and dreams of flight.