My God, she thought. I’m greying out.

She was experiencing acceleration, for the first time since the CELSS farm had been transferred to the centrifuge, more than three years ago.

The checklist fell from her lap against her chest, landing with a thud that knocked the air out of her. Her arms were across her chest, and she could feel where they lay, like concrete beams compressing her lungs, her gloved hands huge and massive. And her internal organs, her heart and guts and lungs, were settling out, moving to some new equilibrium inside her. She couldn’t have moved, reached up to a control, to save her life. And this is only a tenth of a G. We’ll be incapacitated on the surface of Titan. Even if we survive the reentry.

“Holy shit,” Mott said. Her voice was remote, weak.

Benacerraf tried to turn her head to see Mott, but her skull felt as heavy as a ball of concrete. “Take it easy, kid,” she said. “Discovery can fly itself; we don’t have to do a damn thing.” The burn went on and on.

Discovery sailed into the shadow of Saturn. The darkness seemed cool, immense, deepening their isolation. It was the first time in six years that the orbiter had not been bathed in sunlight.

And now, with the instruments in the payload bay gaping at the planet, Discovery fell through the plane of the ring system. The rings were less than a mile thick, and at Discovery’s interplanetary velocity, the plane was crossed in a fraction of a second.

Benacerraf, staring back along the path of Discovery, could see the shadowed rings above her. They were a huge roof of darkness, occluding the patchy stars. Here and there she thought she could see a gap in the ring system, a fine circular arc, full of stars. The bulk of the planet was to her right, a flat-infinite wall of shadowed cloud, just a sixth of Saturn’s radius away.

Discovery was a fly circling the flank of an elephant. And now, as her eyes continued to dark-adapt, she saw that there was a patch of light tracking over the shadowed ceiling of the ring system: a diffuse circle, like the image of the sun seen through fog. It seemed to be matching the movements of Discovery.

It was the light of Discovery’s engines — the burning of monomethyl hydrazine and nitrogen tet, hauled out here all the way from Earth, reflecting from the icy rings of Saturn.

Then, as Discovery fell beneath Saturn’s equatorial plane, the diffuse glow faded out. There was a bang, sharp, muffled by the thickness of her helmet.

It was gone so quickly she wasn’t sure if it had been real.

“Niki. Did you hear that?”

“No.” Mott hesitated. “But I felt something. A shudder.”

A bang, a shudder. Put it together, Paula.

Benacerraf felt fear gather like a sharp knot in her stomach. But she was helpless, trapped in her seat by this minuscule gravity.

The sounds of the cabin, the whir of the pumps and fans — already subdued by the helmet around her head — died away.

“We’re losing pressure,” Mott said, her radio-transmitted voice full of wonder.

Rosenberg started yelling. “Bill, close your eyes! Bill, if you can hear me, close your eyes!”

…Light seeped into the cabin. Above Benacerraf, the ring-plane terminator was sliding into view, a geometrically straight line that could have stretched from Earth to Moon. The subdued gold-brown light of the rings soaked over her face.

Rosenberg, with no reply from Angel, quit yelling.

“What the hell happened, Rosenberg?”

His voice was fragile. “We got hit by a ring fragment.”

“But we’d already passed through the plane of the damn rings. And besides, we aimed for a gap.”

“But the rings we see are patterns imposed on a complex, chaotic cloud of particles or dust and ice. This is a crowded part of space, Paula. We only came this deep because we needed the benefit of a low periapsis. We gambled we wouldn’t hit anything on the way through.”

“Lucked out,” Nicola Mott said.

Rosenberg pointed out, “Bill isn’t answering.”

“How long until the burn’s done, Niki?”

“Eight more minutes, Paula.”

Rosenberg said, “Look, we have to go down and help Bill. Vacuum exposure will kill him.”

Mott said, “Sit still.”

“She’s right,” Benacerraf said wearily. “If you try to get out of your couch you’ll just fall the length of the cabin. Rosenberg, we have to wait.”

“If we wait, we’ll find him dead,” Rosenberg said. “Damn it, Paula. If Bill is dead I hope you can live with yourself.”

Benacerraf felt herself smile, tiredly. And there’s my function on this flight, she thought. Blame Paula: not that asshole Angel for endangering his own life by his madness and stupidity, not the confluence of forces which delivered us to this perilous point in space and time in such a fragile craft, not the malevolent God who put that fragment of primordial ice right in our path in the middle of the one and only traverse, by humans from Earth, of the rings of Saturn…

At last the burn died.

“Good burn,” Mott whispered. “Residuals were less than three tenths, on all axes.”

“Welcome to Saturn,” Rosenberg said drily.

The mid deck, like the flight deck, was in vacuum.

The chunk of ring material had entered the mid deck at about waist height in the middle of the left hand wall, close to the galley. They found a neat round hole in the panel there, almost big enough for Benacerraf to push her finger into. And there was a matching hole in the floor, a few feet away, as if the particle had slanted down like a sniper’s rifle shot through the cabin.

In fact, they had been lucky, she realized. It was a clean impact. A grain the size and speed that hit them could have done a lot more damage than just puncturing the pressure hull so cleanly.

Ring material. At least, thought Benacerraf, it was more glamorous than the particle of flaked-off paint or frozen cosmonaut urine that had zapped them during their Earth flyby.

It was simple to slap patches over the damage; soon the air pressure in the mid deck was restored.

They found Angel sitting strapped into his fold-up seat. He had his pressure suit helmet on, with the visor closed; but the helmet wasn’t locked correctly at the neck. He was unconscious. Benacerraf could see his eyes were closed, his face contorted. And there was some kind of fluid, smeared over the inside of his visor, making it difficult to see inside.

Rosenberg peered into Angel’s helmet, and shrugged. “He must have been exposed to vacuum for a few seconds, low pressure for a while longer. We got to get him out of here.”

They manhandled Angel through the airlock at the rear of the mid deck, and into the hab module. Then the three of them went into the resuscitation routines they had rehearsed on Earth.

With Benacerraf and Mott holding Angel’s limbs, Rosenberg checked for breathing, then braced himself against a wall and pumped four mouth-to-mouth breaths into Angel’s lungs. There was no response, so Rosenberg had the women move Angel around so that he could push his arms around Angel’s thorax and under his arms. He grabbed Angel’s elbows and worked them like a bellows, up and down, four times.

“All right,” he said, breathless. “Now we got oxygenated air in his lungs,” He looked exhausted, his glasses sweat-streaked, as if he might pass out himself. “Now, the heart.” He felt for Angel’s carotid pulse. “Nothing. Niki, you’re stronger than me. Come around here.”

Mott pulled herself behind Angel. She placed her left hand fist in Angel’s sternum and grabbed the fist with her other hand. She pulled Angel’s back against her chest, then compressed his sternum, hauling him hard towards her, counting. “One. Two. Three…—” The idea was to squeeze the heart between the sternum and the thoracic vertebrae, and so push oxygenated blood through Angel’s body.