Arthur Clarke - Sunstorm

And she would do her duty to the last. The space agencies had always had procedures for such eventualities. If she had died in space—as had been discussed by NASA planners decades ago when the International Space Station had first been occupied—her body would have been zipped into a bag and tied to a truss until it could be returned to Earth. Here on Mars, her first duty was to the planet and its putative biosphere; she mustn’t contaminate it with her own decaying corpse. All she had to do was stand here, in fact. When her suit’s heaters failed she would quickly freeze solid, thus sealing in any rogue bugs she had brought from Earth, until her body could be retrieved. Probably the suit wouldn’t even topple over. She would be a statue, she thought, a monument to herself, and her own dumb luck.

She couldn’t bear the thought of dying beside her poor, failed rover, though. So she had decided to walk on into the Martian wilderness, just so she could see a bit more of the planet that was killing her.

Even then her luck was all bad. She had trudged across a dull plain, to this dull canyon. Here she was in the midst of the greatest catastrophe the solar system had endured since its formation, and everybody else had a better view than she had.

Something stirred at her feet. On the ground little pits were forming—craters, she thought, but none wider than her thumbnail. Could she be caught in some peculiar micrometeorite shower? But now she heard a pattering on her helmet.

She looked up. She could see the drops falling out of the sky, big fat low-gravity drops drifting slowly down all around her. When they hit, they smeared the patina of dust on her faceplate.

It was rain, the first rain on Mars in a billion years.

The sun breathed fire into the faces of all its circling children.

On Mercury the sun-side face had melted, craters as old as the planet dissolving into magma palimpsests. Venus had been stripped of much of its crushing atmosphere—the fate that might have become of Earth, if not for the shield. The ice moons of Jupiter were melted to depths of kilometers. In a strange and exquisite tragedy, the rings of Saturn, fragile bands of ice, had evaporated.

And on Mars volcanoes dormant for a hundred million years had begun to stir. The polar ice caps, thin smears of carbon dioxide and water ice, had quickly sublimed. And now rain was falling. Helena walked forward a few more steps, and watched the Martian rain falling deep into the shadows of the canyon.

One of her colleagues, excitedly, began to report on his own discoveries. “I found a ship! And what a ship; it looks like the carcass of a beached whale. And it’s covered in Mandarin lettering. But it has a hull rip the size of Mariner Valley. It came down hard …”

Helena had listened to her comrades’ communications all this long sol. She had reported in at routine intervals, but she had decided against telling them what had become of her—not just yet, anyhow. Now she stood and listened to the voice of a colleague she would never see again.

“Wait a minute. I’m climbing inside the ship, taking care to avoid all sharp edges … Oh. Oh, dear God.”

There had been more than a hundred people on the ship. They were all young men and women—all breeding age, including the pilots. Their cargo had included inflatable shelters, mechanical diggers, hydroponic seed beds. The intention was clear. This was what the Chinese had been planning for the last five years: this was what had used up all their heavy-lift capacity, instead of contributing to the shield. And this was how the Chinese had planned to ensure that something of their culture would survive the sunstorm.

“But the Chinese invasion of Mars failed … They came so close. I wonder what kind of neighbors they would have been?”

Helena suspected everybody would have got along. From here, China was very far away, just as far as Eurasia and America. Here, you were just a human—or rather, a Martian.

She looked up at the sun. Close to setting, it was smeared out in a ragged ellipse by air laden with dust and unaccustomed rain clouds. She knew the predicted schedule; the sunstorm should be abating by now—and yet something about that setting sun troubled her, as if there was still a nasty surprise to come.

The dust at her feet stirred. She looked down.

Amid the pattering raindrops, something was pushing out of the soil. No bigger than her thumb, it was like a leather-skinned cactus. It had translucent sections, windows to catch the sunlight, she thought, without losing a precious drop of moisture. And it was green: the first native green she had seen on Mars.

Her heart hammered.

The Aurora crew, during their long exile, had searched in vain for life on Mars. They had even risked a hazardous journey to the South Pole, where they had sought out the oldest, coldest, undisturbed permafrost on all of Mars, hoping to find Martian microorganisms trapped and preserved. Even there they’d found zilch. That epochal discovery would surely have made their years away from home worthwhile; it had been a crashing disappointment to find nothing.

And now here it was, just bubbling up out of the ground before her.

She felt a painful pull at her chest. She didn’t need to check her monitors to know her suit was failing. To hell with her suit; she was going to report her discovery. Hastily she turned on her helmet camera, and bent over the little plant. “ Aurora, Helena. You won’t believe this …”

Its roots were buried deep in the cold rock of Mars. It didn’t need oxygen, but fueled its glacial metabolism with hydrogen released by the slow reaction of the volcanic rocks with traces of water ice. Thus it had survived a billion years. Like a spore waiting under a desert on Earth for the brief rains of spring, this patient little plant had waited out an eon for the Martian rains to return, so it could live again.

A chain of events stretching back millennia was almost complete. The sunstorm had been wasteful of energy, of course—but not nearly so wasteful as humankind might one day have become, if allowed to infect the stars.

The sunstorm was ending. Though the sun’s relatively orderly cycles of activity would be disturbed for decades to come, the great release of energy had been cathartic, and the destabilization of the core was resolved. All this was just as Eugene Mangles’s remarkably successful mathematical models of the sun’s behavior had predicted.

But those models had not been, could never be, perfect. And before this long day was done, the sun had one more surprise for its weary children.

The sun’s tremendously strong magnetic field shapes the star’s atmosphere, in a way that has no analogies on Earth. The corona, the outer atmosphere, is full of long sheets of gas, like the petals of a flower, that can extend many radii from the sun. The elegant curves of these “streamers” are sculpted by the magnetic fields that control them. The streamers are bright—it is these plasma sheets that are visible around the blocked-out sun during a solar eclipse—but they are so hot, pumped full of energy by the magnetic field, that their spectral peak is not in visible light but in X-rays.

All this in normal times.

As the sunstorm subsided, one such streamer formed over the active region that had been the epicenter of the storm. In keeping with the giant instability that had spawned it, the streamer was an immense structure, its base spreading over thousands of kilometers, and extending so far out in space that its feathery outer edge reached the orbit of Mercury.

At the base of the streamer, flux tubes rooted in the sun’s deep interior arched to enclose a cavity. Inside the cavity, contained by the magnetic field’s arches, were trapped billions of tonnes of ferociously hot plasma: it was a cathedral of magnetism and plasma. And as the storm died, this cathedral began to collapse.