There was a whole slew of ways for the ground to keep track of a spacecraft. The faster the craft was receding from Earth, the more its radio carrier frequency was shifted, like a whistle on a speeding train. Or, to fix distance, an uplink modulation pattern — a brief digital code — could be transmitted to the spacecraft and sent straight back. The delay in receiving the copied signal would tell the specialists how far away the craft was from Earth. And on Ares another radio method was being run, an experiment involving the change in angle between Ares and a quasar, a radio source in the background sky.

But even all those techniques in combination weren’t accurate enough to position Ares; the combined accuracy was only maybe half the precision required.

The answer was to use equipment on board the spacecraft itself.

In fact Ares had its own automated optical sensors. There were two sun sensors — little cadmium sulfide photoresistors — placed on the solar cell array. And there was a star tracker, a lens with an image dissector tube. But the automatic system just wasn’t too smart. Every few days, the star tracker got fooled by bright particles, bits of junk floating along with the spacecraft in its orbit around the sun.

So — just as had sailors on Earth’s oceans for millennia — Phil Stone had to navigate his ship by the stars.

He found himself humming as he worked. He knew he was good at this. He’d practiced the techniques in planetariums on the ground, and in Moonlab; he could get a measurement true within a few thousandths of a degree, and he took a lot of satisfaction from the basic craft of it.

When he’d finished he packed away the instruments and drifted back up to his control station. He ran the numbers through the computer, to figure out the position for himself. He would feed the raw data down to Houston, of course, but it kind of satisfied him to know that he could do this independently.

Stone liked to visualize the mission trajectory, to figure out where he was.

The energy expended by the injection booster — although monumental in human terms, the result of five years’ fuel haulage to orbit — was so low on the cosmic scale that the craft’s trajectory barely diverged from Earth’s. The Ares stack, having pushed itself away from Earth, was scooting alongside the home planet in its orbit like a dog beside its master.

The first results looked good; the spacecraft was pretty much where it was supposed to be, and he figured that the TCM-2 burn would only have to be a few feet per second.

When he was done he indulged himself. He doused the wardroom’s lights and sat in the warm darkness close to the picture window, surrounded by the hum of fans.

Ares was alone in space: Earth and Moon were reduced to starlike points of light, side by side. In all the universe, only the sun showed a disk.

The sense of isolation was extraordinary: far deeper than he’d known in space before, even during his time in Moonlab. Unless you were around the back of the Moon, Earth was always in view. And in Skylab A, the Earth itself dominated every waking moment, and you took your reference from that huge quilt of light, from the continents and oceans sliding under you.

Out here, it was different. There was no “up” or “down”: there were just little islands of rock, floating around in the sky. For interplanetary flight humans would need to develop a new kind of perception, he thought, a three-dimensional awareness.

As his eyes dark-adapted, the stars came out: millions of them, far more than were visible through Earth’s murky atmosphere. He could see the galaxy, a great speckled river of stars; he made out the edge of the disk in the direction of the galactic core, in Sagittarius, with its ragged edge caused by black swirls of obscuring dust clouds and the nearby stars sparkling in the dark scars. And he could see the moons of Jupiter, four of them, in a line alongside the planet’s bright spark.

Ralph came floating out of the brightness of the wardroom area to bring him a meal, a couple of packets of warmed-up rehydrated stew. With a pencil light in his mouth Stone mashed in the water until the food was moist through. [Hr:Min:Sec] 19:37:20

After thirteen hours awake, the crew had finished up their duties for the day. York was feeling queasy again, so she took a scopolamine and went to bed. Stone wanted to spend some time alone, maybe writing letters.

But Gershon, still full of nervous energy, wanted to play darts.

The dartboard was the Mission Module’s great recreation, along with magnetic cards. The darts were tipped with Velcro, and they flew straight and level.

It was quite different from playing under gravity. To get accuracy, the best technique was rather to push the dart comparatively slowly through the air, maybe with a little spin for stability. But if the dart was too slow, currents in the air would knock it off track.

Gershon set up the dartboard in the science platform, and he and Stone threw the darts so that they arced easily the length of the workshop. [Hr:Min:Sec] 21:01:32

Gershon called him out of his sleep locker and over to the Space Ark.

Arabella’s cage hadn’t been closed properly, and the spider had gotten out. Gershon pointed out a huge, sweeping web, which spanned yards of space, crossing from side to side of the Mission Module.

Stone just hoped enough insects of some sort had survived the various sterilization checks to make it into the module to sustain Arabella. Gershon was all for shaking out the fruit fly pupae for her.

Flying to Mars, bound up in spiderweb. It was a beautiful image, Stone thought. [Hr:Min:Sec] 23:32:37

When he slept, Stone had his usual space dream.

Oddly, he was vaguely aware of the causes of the dream, even while he slept: the breeze from the wall fan, the falling sensations of microgravity, maybe a subconscious realization of the speed with which he was traveling.

All of it merged into a dream of flying.

He was surrounded by woods and rivers and blue skies, and he was flying, low like a bird of prey.

Sometimes the prospect of starting at Houston seemed attractive to York, compared to the clique-ridden, insulated world of the universities. She was moving to a place where people were doing great things: working on stuff of more substance than the next grant application, a place where achievement was measured by more than just the number of journal citations per year.

At other times, though, she couldn’t believe she was doing it.

She was offered plenty of advice against NASA, from senior staff on down. For example, she was told, the center of gravity of space science was not at Houston, but at the universities: like Cornell, where Sagan was based. Would her own work on Martian outflow channels have been improved if she’d pulled up stakes and moved to Texas?

In fact NASA seemed to be actively antiscience. In the wake of the Apollo 11 landing a shoal of scientists had abruptly quit: Bill Hess, Houston chief scientist; Elbert King, lunar samples curator; and Eugene Shoemaker, Apollo field geology principal investigator. Shoemaker talked about his concern for the direction of the space program, and what a poor system Apollo was for exploring the Moon: nothing but a rope and pulley, for instance, to haul surface samples into the LM’s cabin! And what evidence was there that things had gotten any better? Was the Mars program going to be any different?

It was depressing. If those eminent men couldn’t cut it inside NASA, what chance did she have?

Earnest friends shoved newspaper stories under her nose. The Tennessee Valley vs Hill case had just concluded, with the Supreme Court ruling that the new Tellico Dam couldn’t be built, because it would drown the only known habitat of a three-inch fish called a snail darter… People were dead against big, mindless technological stunts — hell, she was herself — and what could be bigger, more mindless, than NASA?