Arthur Clarke - Sunstorm

“Yes,” Mikhail said. “But we have placed satellites at such positions before. You can actually orbit the Lagrangian point, use a small amount of fuel to station-keep. It’s well within the envelope of experience: astronautically, not a problem.”

Toby had held his hand up to the ceiling light, experimentally shadowing his face. “Forgive a stupid question,” he said. “But how big would this shield have to be?”

Mikhail sighed. “For simplicity, assume the sun’s rays are parallel as they reach Earth. Then you can see you need a screen as large as the object you’re trying to shield.”

Toby said, “So the shield has to be a disk with at least the diameter of the Earth. Which is—”

“About thirteen thousand kilometers.”

Toby’s jaw had dropped. But he pressed on doggedly. “So we’re talking about a shield thirteen thousand kilometers across. To be built in space. Where the largest structure we’ve put up so far is—”

“I suppose the International Space Station,” Mikhail said. “Much less than a kilometer.”

Toby said, “No wonder I didn’t find this before. When I ran my own search for solutions, I screened out the obviously implausible. And this is obviously implausible.” He glanced at Siobhan. “Isn’t it?”

Of course it was. But the three of them had hammered at their softscreens to figure out more.

Toby said, “There have been studies of this sort of thing before. Hermann Oberth seems to have been the first to come up with the idea.”

“You’d use ultrathin materials, of course,” Mikhail said.

Siobhan said, “Everyday plastic wrap comes in at ten micrometers thick.”

“And you can get aluminum foil the same thickness,” Mikhail said. “But surely we can do better.”

Toby said, “So with an area density of less than a gram per square meter, say, and even adding an element for structural components, your weight could be as little as a few million tonnes.” He looked up. “Did I really just say as little as ?”

Siobhan said, “We don’t have the heavy-lift capacity to get that amount of material off the Earth, even given years.”

“But we don’t need to lift it off Earth,” Mikhail said. “Why don’t we build it on the Moon?”

Toby stared at him. “Now that really is crazy.”

“Why so? On the Moon we already manufacture glass, process metals. And we have our low gravity, remember: it’s twenty-two times easier to launch a payload into space from the Moon as from Earth. And we’re already building a mass driver! There’s no reason the Sling project couldn’t be accelerated. Its launch capacity will be huge.”

They factored an estimate of the Sling’s launch capacity into their back-of-the-envelope calculations. It was immediately clear that if they could launch the bulk of the shield’s mass from the Moon, the energy savings would indeed be prodigious.

And there was still no obvious showstopper. Siobhan had felt frightened to breathe, as if she might break the spell, and they had worked on.

But now, sitting in her flat with her mother and daughter, listening to Alvarez announce this preposterous idea to the whole world, different emotions surged in her. Suddenly restless, she walked to the window.

It was nearly Christmas, 2037. Outside, kids were playing soccer. They were wearing T-shirts. While Santa Claus still bundled up on the Christmas cards, snow and frost were nostalgic dreams of Siobhan’s childhood; in England it was more than ten years since the temperature had dipped below freezing anywhere south of a line from the Severn to the Trent. She remembered her last Christmas with her father before his death, when he had railed about having to cut his lawn on Boxing Day. The world had changed hugely in her own lifetime, shaped by forces far beyond human control. How could she be so arrogant as to suppose she could manage an even greater change, in just a few years?

“I’m afraid,” she blurted.

Perdita glanced at her, troubled.

“Of the storm?” Maria asked.

“Yes, of course. But I had to work hard to get the politicians to accept the idea of the shield.”

“And now—”

“Now Alvarez is calling my bluff, in front of the whole world. Suddenly I’ve got to deliver on my promises. And that’s what frightens me. That I might fail.”

Maria and Perdita walked over to her. Maria hugged her, and Perdita rested her head on her mother’s shoulder. “You won’t fail, Mum,” Perdita said. “Anyhow you have us, remember.”

Siobhan touched her daughter’s head.

On the softwall, the President continued to speak.

“I offer you hope, but not false hope,” Alvarez said. “Even the shield alone cannot save us. But it will turn an event that would be nonsurvivable for any of us into a disaster survivable for some. That’s why we must build it—and that’s why we must build on the chance it gives us.

“It goes without saying that this will be by far the most challenging space project ever undertaken, even dwarfing our colonization of the Moon and our first footsteps on Mars. Such a mighty project cannot be managed by one nation alone—not even America.

“So we have asked all the nations and federations of the world to come together, to pool their resources and energies, and to cooperate in this most vital of space projects. I am delighted to say that we have had a virtually unanimous response.”

“ ‘Virtually unanimous’ my arse,” Miriam Grec grumbled. Here in her Euro-needle office she sipped her whiskey and settled a little deeper into the sofa. “How can you call it ‘unanimous’ when the Chinese have refused to take part?”

Nicolaus replied, “The Chinese play a long game, Miriam. We’ve always known that. No doubt they see this problem with the sun as just another geopolitical opportunity.”

“Maybe. But God alone knows what they are up to with all those taikonauts and Long March boosters …”

“Surely they will come around, in the end.”

She studied him. Even as he spoke, Nicolaus Korombel had one eye on the softscreen bearing Alvarez’s image, the other on monitors that showed in a variety of ways the world’s response to Alvarez’s unfolding message. Miriam had never met anybody with Nicolaus’s ability to parallel-process. It was just one of the reasons she valued him so much.

Although it was an odd thing, she thought, that his very hard-nosed, almost cynically robust thinking, which made him so valuable to her, also made him very opaque. She really knew very little about what he thought and believed, deep inside. Sometimes a faint worry about that gnawed at the edge of her awareness. She must get him to open up, she thought, get to know him better. But there was never any time. And in the meantime he was just too useful.

“So how’s the reaction?”

“Markets down seventeen percent,” Nicolaus said. “As a snap reaction goes, that’s not as bad as we feared. Space and high-tech stocks are booming, needless to say.”

Miriam marveled at such a response. She supposed the impulse to get rich was natural enough—indeed, the global economy wouldn’t work without it. But she did wonder what those eager investors imagined they might achieve if their financial feeding frenzy hindered the ability of the aerospace companies and others to actually get the job done.

Still, it could be worse, she told herself. At least the President’s speech was being made. Even getting the project this far had been a close-run thing.

In the world’s grandest councils, there had been a lot of heated discussion about the wisdom of the solution Miriam had pushed. The shield project would absorb the economic energies of the participating countries for years—and for what? Even the energy the shield was bound to leak through would still add up to a devastating disaster.