“So has most of the human race since June, I would think,” Siobhan said dryly.

“Astronauts are outside the Earth’s air and magnetic field. So they aren’t shielded as they would be on the ground.”

Siobhan waved her phone around to show Perdita the cabin. Big enough to hold eight but empty save for herself, it had hefty walls whose thickness was revealed by the depth of the window sockets. “See?” She thumped the wall. “Five centimeters of aluminum and water.”

“That won’t help if a big one hits,” Perdita pointed out. “In 1972 a massive flare erupted only months after Apollo 16 returned from the Moon. If the astronauts had been caught on the lunar surface—”

“But they weren’t,” Siobhan said. “And there was no such thing as solar weather forecasting back then. If there was any risk, they wouldn’t let me fly.”

Perdita grunted. “But the sun is restless now, Mum. It’s only four months since June 9, and still nobody knows what caused it. Who’s to say if the forecasters have any idea what’s going on anymore?”

“Well,” Siobhan said a bit testily, “that’s what I’m going to the Moon to find out. And I really had better get on with some work, dear …” With expressions of love, and after sending regards to her own mother, Siobhan closed down the call. It was a mild relief to break the connection.

Of course, she suspected that Perdita’s real problem with her mission wasn’t safety at all. It was jealousy. Perdita couldn’t stand it that her mother was here, not her. With a sense of guilty triumph, Siobhan peered out of the window at the looming Moon.

Siobhan was a child of the 1990s. The first human landings on the Moon had been finished two decades before she was born. She had always looked on the relics of the Apollo missions, the grainy footage of fresh-faced astronauts with their flags and stiff pressure suits and impossibly primitive technology, as a symptom of the madness of the vanished Cold War years, up there with the UFO craze and missile silos under Kansas cornfields.

When at the opening of the century a return to the Moon had been floated on both sides of the Atlantic, Siobhan had again been distinctly unimpressed. Even as a science student it had seemed to her a jobs-for-the-boys project dominated by aviators and engineers, a bid for power and wealth by the military-industrial complex, with science goals a fig-leaf justification at best, just as manned space travel always had been.

But the rediscovery of space exploration had captured the imagination of a new generation—including her own, she admitted—and had progressed faster than anybody had dreamed.

A new fleet of Apollo—like space vehicles was flying by 2012. Though venerable Soyuz craft still toiled to and from the International Space Station, the brave, flawed space shuttles were retired. Meanwhile a flotilla of exploratory rovers and sample-return missions had been dispatched to the Moon and to Mars, as well as more ambitious unmanned missions farther afield, such as an extraordinary swords-into-plowshares venture, yet to be fulfilled, to use an antiquated weapons system called the Extirpator to map the whole solar system. Siobhan knew the science return from these missions had been good, though the solar system wasn’t her field of study—but it was galling that most people didn’t even know of the existence of the great cosmological telescopes, like the Quintessence Anisotropy Probe, whose results were fueling her own career.

While all this had gone on the American and Eurasian manned space programs had gradually merged—and in 2015, under many flags, human footsteps had been planted on the Moon once more. By 2037 humans had maintained an unbroken tenancy of the Moon for nearly twenty years, with around two hundred colonists in Clavius Base and elsewhere.

And just four years ago the first explorers aboard the spacecraft Aurora1 had reached Mars itself. The hardest cynic couldn’t help but cheer the fulfillment of that ancient dream.

Her mission was grave: at the politely worded command of the Prime Minister of Eurasia, she was tasked with finding out what was going wrong with the sun, and if Earth faced any prospect of a repeat of June 9. But the upshot was that she, Siobhan McGorran, child of Belfast, in a four-legged bug of a craft that looked like a beefed-up version of those old Apollo lunar modules, had been projected into the lunar sphere. How marvelous, she exulted. No wonder Perdita was green with envy.

A door opened at the head of the cabin. The shuttle’s Captain came swimming through and slid into an empty seat. With a soft word to Aristotle, Siobhan closed down the softscreens arrayed around her.

Mario Ponzo was an Italian. Aged about fifty, he was surprisingly tubby for a space pilot, judging by the healthy mass that strained at the stomach panels of his jumpsuit. He said, “I’m sorry we haven’t had time for more of a chat, Professor.” His accent was tinged with American, a relic of Houston, where this native Roman had trained at the NASA space center. “I hope Simon has looked after you well?”

“Perfectly, thank you.” She hesitated. “The food is rather tasteless, isn’t it?”

Mario shrugged. “An artifact of weightlessness, I’m afraid. Something to do with the body’s fluid balances. A tragedy for all Italian astronauts!”

“But I slept better here than anytime I remember since I was a child.”

“I’m glad. Actually it’s the first time we have made the run with just a single passenger—”

“I guessed that.”

“But in a way it’s oddly appropriate, for Vladimir Komarov’s last flight was also solo.”

“Komarov?—oh. For whom the shuttle is named.”

“That’s right. Komarov is a hero, and for the Russians, who have many heroes, that’s saying something. He flew the first mission of their Soyuz spacecraft. When its systems failed during reentry, he died. What makes him heroic, though, is that he got aboard that bird almost certainly knowing how bad the faults of his untested ship were likely to be.”

“So the shuttle is named for a dead cosmonaut. Isn’t that bad luck?”

He smiled. “Away from Earth, we seem to be evolving different superstitions, Professor.” He glanced at her blank screens. “You know, we’re not used to secrecy up here. It’s not encouraged. We all have to work together to keep alive. Secrecy is corrosive, Professor, bad for morale. And I’ve never known anything like the blanket of silence that has descended around you and your mission.”

“I sympathize,” she said carefully.

He rubbed a chin coated with three days of stubble; he had told her that idiosyncratically he would not shave in space, to save the inconvenience of clippings drifting around the cabin. “Not only that,” he said, “the comms links between the Moon and Earth are notoriously narrow. A bottleneck. If I wanted to prevent sensitive information leaking out onto the global nets, the Moon would be a good place to put it.”

Of course he was right; the ease of securing discussions on the Moon was a prime reason for her journey, rather than bringing lunar-based experts to Earth. She said, “But you know that I’m an envoy of the Eurasian Prime Minister herself. I’m sure you understand that the security restrictions to which I’m subjected come from much higher levels than me.” So don’t probe, she added silently. She turned back to her blank softscreens. “And if you don’t mind—”

“More studying? I think it may be a little late for that.” He glanced out the window.

Her view of the looming crescent Moon was gone, replaced by a mottling of deep black and glowing pale brown that slid past the window.

Mario said softly, “You are looking at Clavius Crater, Professor.”

She stared. Clavius, south of Tycho, was a basin so huge that its floor was convex, pushed out by the curvature of the Moon itself. As the shuttle descended she began to resolve smaller craters on that tremendous floor: craters of all sizes, craters overlapping craters down to the limits of her visibility. It was a strange, ripped-up landscape, like a Great War battlefield perhaps. But there, just emerging from the shadow of the wall, she saw a fine line, a shining thread of gold laid over the Moon’s gray floor. That must be the Sling, the new electromagnetic launch system, still incomplete but already a mighty rail more than a kilometer long. Even from here she could see that human hands had touched the face of the Moon.