A few sleepless hours later she was joined by Sax, Vlad, Nadia, and Ann. Her companions belted in, and they ran through the check-out together. Toggles were flipped, there was a countdown; and their rockets fired. The lander drifted away from the Ares. Its rockets fired again. They fell toward the planet. They hit the top of the atmosphere, and their single trapezoidal window became a blaze of Mars-colored air. Maya, vibrating with the craft, stared up at it. She felt tense and unhappy, focused backward rather than forward, thinking of everyone still on the Ares; and it seemed to her that they had failed, that the five of them in the lander were leaving behind a group in disarray. Their best chance for creating some kind of concord had passed, and they had not succeeded; the momentary flash of happiness she had felt while brushing her teeth had been just that, a flash. She had failed, then. They were going their separate ways, splintered by their beliefs, and even after two separate years of enforced togetherness they were, like any other human group, no more than a collection of strangers. The die was cast.

Part Three

The Crucible

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It formed with the rest of the solar system, around five billion years ago. That's fifteen million human generations. Rocks banging together in space, and then coming back and holding together, all because of the mysterious force we call gravity. That same mysterious warp in the weft of things caused the pile of rocks, when it was big enough, to crush in on its center, until the heat of the pressure melted the rock. Mars is small but heavy, with a nickel-iron core. It is small enough that the interior has cooled faster than Earth's; the core no longer spins inside the crust at a different speed, and so Mars has practically no magnetic field. No dynamo left. But the one of the last internal flows of the molten core and mantle was in the form of a huge anomalous lumping outward on one side, a shove against the crust wall that formed a continent-sized bulge, a bulge eleven kilometers high, three times as high as the Tibetan plateau is above its surroundings. This bulge caused many other features to appear: a system of radial fractures covering an entire hemisphere, including the largest cracks of all, the Valles Marineris, a lace of canyons that would cover the United States coast to coast. The bulge also caused a number of volcanoes, including three straddling its spine, Ascraeus Mons, Pavonis Mons, and Arsia Mons; and off on its northwest edge, Olympus Mons, the tallest mountain in the solar system, three times the height of Everest, one hundred times the mass of Mauna Loa, the Earth's largest volcano.

So the Tharsis Bulge was the most important factor in shaping the surface of Mars. The other major factor was meteor fall. In the Noachian Age, three to four billion years ago, meteors were falling on Mars at a tremendous rate, millions of them, and thousands of them planetesimals, rocks as big as Vega or Phobos. One of the impacts left behind Hellas Basin, 1600 kilometers in diameter, the largest obvious crater in the solar systems; although Daedalia Planum appears to be the remains of an impact basin 4500 kilometers across. Those are big; but then there are areologists who believe that the entire northern hemisphere of Mars is an ancient impact basin.