They were tentatively beginning to talk about making a commitment for life. The only thing was that Sarah was always so tired. She barely had the energy to go to her concerts. She looked pale.
She hadn’t always been so tired. When she first started to chat to Ryan over lunchtime, over breaks at work, she had been full of energy. “She’s a real 240-volt live wire,” was how the other engineer in his office described her. Now she could barely make it from breakfast to lunch.
Ryan took her to a doctor.
The doctor ordered tests. When the tests came back, he wouldn’t talk about them, but ordered more tests, and a CAT scan. When the new tests were completed, a new doctor came to talk about them, a specialist.
It was cancer: in her liver and her pancreas, and beginning to spread. The cancer was aggressive and inoperable. The day before Easter, he brought a minister and a wedding license to the hospital, and they were married. Three days later she was dead.
Twice was enough. He went back to school for three more degrees, one in astronautical engineering and two in computer science, and decided that from then on he would stick to his studies, and would never curse another woman by becoming too close to her.
7
Butterfly
Butterfly didn’t look like anything, least of all like an airplane. It was a pile of thin, transparent foil.
The Martian atmosphere is more than a hundred times thinner than the Earth’s atmosphere. Even with the low gravity of Mars, flying in the thin air of Mars is a challenge. To fly, an airplane has to have forty times more wing area than an airplane on Earth, or else fly six times faster. Or else weigh forty times less.
Butterfly did a little of each. Its wing area was absurdly high, by the standards of Earthly airplanes, and it flew at nearly sonic speed; yet despite its high speed and large wing area, it weighed almost nothing. It was constructed out of a monomolecular membrane, a tough plastic sheet so thin as to be almost invisible. The main spars of the wings were pressurized bags, balloon-stiffness providing the rigidity. The fuselage likewise was stiffened by inflation. Ultralight foam ribs formed the wings into a high-lift airfoil.
“Do you know why they named it Butterfly?” Ryan asked.
“Because it’s so light and fragile,” Tana said. “Like a butterfly.”
Ryan smiled. “Nope. Got named when the lead engineer took one look at it, shook his head, and said, ‘Well, it butter fly.’”
The only item of any real weight was the engine.
A propeller was almost useless; the tenuous air of Mars is too thin to give a propeller much to grab. A jet engine is pointless; how can you burn carbon dioxide? Instead, Butterfly used a ram-augmented hybrid rocket engine. A feed stream of liquid oxygen was injected into a cylinder of dense rubber and ignited; the burning rubber forms a rocket engine. Rather than just shooting the exhaust product out through a conventional rocket nozzle, additional atmospheric carbon dioxide is collected—the ram part of “ram augmentation”—and mixed into the exhaust stream to augment the thrust.
The result was a high-power engine that used the thin atmosphere of Mars to increase its thrust.
This was the vehicle that Ryan Martin examined. His first task was to inflate its wing spars and fuselage with compressed gas; after that he had to fill the engine’s tanks with liquid oxygen. This second task was a tricky problem. The Butterfly had been designed to use oxygen produced from the Mars atmosphere by the same chemical plant that manufactured rocket fuel for the return vehicle. But the fuel manufacturing plant for the Agamemnon expedition was identical to the one that had failed Dulcinea.
But Butterfly was an airplane, not a rocket. It required less than a tenth of a percent as much liquid oxygen as was needed to launch the return rocket. Consultation with the experts on Earth concurred on the opinion that, for the tiny amount of liquid oxygen needed, Ryan could bypass the main atmosphere compression and Sabatier reactor and just use the electrolysis system and the Stirling liquefier. Taking precautions to avoid stressing the seals that has failed so catastrophically on Dulcinea, he should be able to fill the tanks in a few weeks of operation using only solar power. No more than a few months even under worst-case conditions.
And so, drop by drop, Ryan fueled his airplane.
8
On Ancient Shores
They were camped at the shore of what had, long ago, been an ocean. How many fossils were there in that ancient dry ocean bed, Estrela wondered? How far had life come? Had life on Mars emerged from its oceans, only to become extinct as the rivers dried and the planet froze? And what, exactly, had caused the oceans to evaporate and the atmosphere to leak away?
Estrela was beginning, slowly, to come out of the deep depression that had enveloped her over the last weeks. Eight days at the Agamemnon campsite had revived her. For the first three days she had stayed inside the habitat dome, and then she took to leaving the habitat dome for just one hour each day.
First she would walk over to the greenhouse module. She was amazed that it had survived, untended, for years on the Martian surface, and even had plants inside, some sort of tough yucca and several evergreen shrubs. She rubbed her hand over them, feeling the prickly points. You are like me, she told them silently. We are survivors.
Then she would go to walk along the deserted beach just before sunset.
The water of the ancient ocean was long gone; the sands of the beach had long ago cemented into a rocklike caliche. She could read the ebb and flow of the waves in the ripples frozen into the sandstone. She would find a shallow basin and brush away the covering dust, and find below the white layer of evaporite, salt crystals.
One time, walking a little inland, she found yet another fossil, embedded in the wall of a limestone cliff. It was exactly the same shape as the others, but this one was immense, as large as a whale, ten meters from end to end. Estrela wondered that these were the only type of fossils that they saw. Had there been only one form of life on Mars? Or perhaps only one type had fossilized.
And the sun would set, and she would return into the habitat.
Inside the dome was paradise, with plentiful liquids and warmth, with enough water to heat an entire liter of bathwater at once and let it dribble, sensuously, over her body. It felt like a decadent luxury.
Her throat no longer hurt so much. She could even speak, in a voice louder than a whisper.
She carefully plaited her now-blond hair, and barely wore clothing. Ryan was the one who would make the decision now, she knew. Two women, and he would be able to take only one home.
But Ryan barely looked at her, although she tried in a dozen subtle ways to contrive to be there, nearly naked, when he was in the habitat, and he would hardly have been able to miss her. But he never made a move.
Ryan was good-looking. Oh, not as good as João—Santa Luzia, who could possibly be as gorgeous as her beautiful João had been?—but he was fine. But he seemed to pay no attention to her.
Two women, and only one would get to go with him back home. Well, the odds were much better than they had been. She knew men, and knew that if there had been two men, somehow the men would have contrived a way to show that it was logical for the two men to go home to Earth and the women stay behind to die. It was just the way of the world.
She wondered if Tana knew how much she hated her.
9
The Canadian Astronaut