The light was changing. Benacerraf looked up from her checklist.

Mott said, “Time for the maneuver to the burn attitude. Track me, Paula.”

Benacerraf glanced at Mott. She could see Niki’s face framed inside her white helmet: calm, almost expressionless, a hint of fear about her eyes.

She reached over and, briefly, closed her glove over Mott’s. “You’ll be fine, Niki. Just like the training.”

“Sure.” Mott laughed weakly. “Just like the training.”

Neither Mott nor Benacerraf had piloted a Shuttle before, though both had worked as flight engineers. If the prelaunch plans had worked out, Bill Angel and Siobhan Libet would be sitting here now, as prime orbiter commander and pilot.

But Libet was long gone. And, after a lot of agonizing — and solitary, time-delayed conversations with the ground — Benacerraf had taken the decision that Angel couldn’t be trusted near the controls of the orbiter any more.

So, absurd as it was, Mott and Benacerraf had to pilot Discovery through its most crucial maneuver since leaving Earth orbit. All the good pilots were nearly a billion miles away, or dead, or half-crazy.

Mott reached forward. “Flight control power switch to on.”

“Copy that,” said Benacerraf. “ADI ATT switches—”

“Attitude switches to inertial, panels F6 and F8. ADI error to median. ADI rate to median…”

Mott reached for her hand controller, and pulsed the RCS jets. Benacerraf could hear the hard click of solenoids, feel the soft shudder of the little jets as they shoved at Discovery’s mass.

The light started to change.

As Discovery turned, the sun was crossing the window, right to left. It was a shrunken disc. Pale, yellowish light played directly into the cabin, the window struts casting long, sharp shadows over Benacerraf’s lap. False images sparkled in the scuffed plexiglass of her helmet visor.

Diminished since Jupiter, the sun was still more brilliant than any star or planet seen from Earth, ten thousand times brighter than a full Moon. It was a little like looking directly into an approaching headlight.

And now the limb of Saturn, a thin crescent, reached into the window frame. Precise and huge and intimidating, it reared up before the sun. It was a yellow arc, obviously flattened from the circular, blistered with turbulence. The colors were subtle, and she found she had to shield her eyes from the glaring yellow and white and green of the orbiter’s instrument lights.

Saturn was no gaudy pyrotechnic display, but an autumn-color sculpture wrought of the soft light of the remote sun. It was, Benacerraf thought with a shiver, utterly unearthly.

Mott had to turn the orbiter so it was flying tail-first. Discovery had accelerated as it had fallen into Saturn’s gravity well. Already deep within the planet’s magnetosphere the spacecraft was now plunging towards Saturn itself; it would make its closest approach over the dark side of the giant world, just a sixth of a Saturn radius above the cloud tops. And there, at the lowest point in the gravity well, the SOI burn would be initiated.

After a six year space soak, the orbiter’s OMS engines, the small orbital maneuvering system, had to burn for a hundred minutes, sucking fuel and oxidizer out of the big supplementary tanks that were strapped to the orbiter’s wings, like two fat bomb pods, slowing the craft into a looping, five-month orbit around Saturn.

The burn had to work. Otherwise, Discovery would not shed enough velocity to be captured by Saturn’s gravity. They wouldn’t make it to Titan. Not only that, the orbiter would be hurled onward in an involuntary slingshot, towards the stars.

Benacerraf had privately calculated they might make it one-tenth of the way to the orbit of Uranus, the next giant planet, before their consumables finally gave out.

And — although it hadn’t been expressed — she was sure nobody had forgotten that it was the OMS burn which had been ultimately catastrophic on Columbia’s last flight.

But whether they survived all this or not, this battered old space truck had come a hell of a lot further than had been dreamed by those old guys who had devised the Shuttle in the 1970s.

Saturn drifted out of the window frame.

“Maneuver to burn attitude complete,” Mott said.

Benacerraf forced her attention to the checklist, and to the instruments on the panels before her. She compared the attitude shown on the CRT display with that given by the eight-ball, the attitude direction indicator. They matched each other and the predictions in the checklist, to several decimal places.

“Good work, Niki,” she said. “Maneuver complete, confirm.”

“All right,” Mott said evenly. Under strain, she was visibly turning her attention to the next obstacle.

One step at a time, Benacerraf thought.

Mott said, “Let’s go for single APU start.”

“Rog. Number one APU fuel tank valve to open. Control switch to start/run, number one APU.”

“Confirm hydraulic pressure indicator one is green,” Mott said.

“Hydraulic circulation pump switches to off, one, two, three.”

“…Okay, we have single APU start.”

“Good. We’re doing fine, Niki. Now. Arm the engines.”

Mott reached forward, and over her head. “Auto pilot to auto. OMS helium pressure switches to GPC, left and right engines. OMS engine switches to arm.” She looked across at Benacerraf. “Engines armed.”

“Good girl.”

The routine, the checklists and procedures for just another OMS burn, was comforting. It allowed her to forget what they were doing here: firing rocket engines to go into orbit around Saturn, for God’s sake.

“One minute to the burn,” Rosenberg said.

Mott reached forward to the computer keyboard. She pressed the EXEC key, and the computer began its countdown to the burn.

…And suddenly, light exploded into the flight deck, for Discovery was sailing above the plane of Saturn’s rings.

To Benacerraf the rings looked like a broad sheet of colored light, as if Discovery were a mote of dust flying high above some elaborate laser display. This close, it was impossible to see their full extent; Benacerraf could see only a portion of the ring-disc framed in her window. Though the lighting was dim, the different bands within the rings were clearly visible, distinguishable by their faint, yellow-brown colorations, separated by dark gaps.

“Incredible,” Rosenberg said. Benacerraf could see the rings reflected from his visor, precise stripes of smoky, washed-out light. “It looks like an artifact, doesn’t it? Something made… But if those rings were transplanted home, they would fill up the space between Earth and Moon. Think of that. And look.” He pointed. “You can see a moon, buried in there in the structure. That’s the E ring; the moon must be Enceladus, I think. See how bright it is?”

After some searching she made out the moon, barely discernible as an icy spark, suspended in one of the dark ring gaps.

The giant shadow of Saturn, blunt and physical, lay across the rings, casting a precise terminator across their structure: perhaps the longest straight line in the Solar System. Earth itself could have rolled around that ring disc, like a ball bearing on a plate. Space here was filled by huge shapes, Benacerraf thought, like gigantic machinery.

Mott said, “Ten seconds to the burn. Five, four, three, two, one.”

The orbiter shuddered, and Benacerraf thought she could hear a remote bass roar, transmitted through the structure of the craft.

“Ignition,” Mott shouted.

“Copy OMS ignition.”

“Building up to full thrust. Point zero five G. Point zero eight. Zero nine. Stabilizing there Benacerraf felt herself sink back into her seat. It was as if the orbiter was tipping up, and she was lying on her back in her couch. The metal of her couch, folds in the fabric of her pressure suit, dug painfully into her flesh. And now there was a dark fringe to her vision, as if she was looking along a tunnel. The colors seemed to leach out of the control panel before her.