“How, Mac?”

“In a free-fall trajectory. We’re in a fifty gee gravity field because we’re in a stationary position relative to HC-183. But if you were to let yourself fall in a free orbit, you’d be able to swing in right past us, and away again, and never feel anything but free fall. Agreed?”

“Right. We’d feel tidal effects, but they’d be small.” Wenig was calling out displays as he talked, fingers a blur over the computer console. “We can fly right past you, but we’d be there and away in a split second. What could we do in so short a time?”

“Why, what we need.” McAndrew sounded surprised by the question. “Just give us a good bang on the side as you go by.”

It sounded easy, as McAndrew so glibly and casually suggested it. When we went into details, there were three problem areas. If we went too close, we’d be fried in the Merganser’s drive. Too far off, and we’d never get a strong enough interaction. If all that was worked out correctly, we still had one big obstacle. For the capsule to be freed as Dotterel applied sideways pressure, the drive on the other ship would have to cut off completely. Only for a split second, but during that time McAndrew and Nina would feel a full fifty gee on them.

That’s not quite as bad as it sounds — people have survived instantaneous accelerations of more than a hundred gee in short pulses. But it’s not a picnic, either. Mac continued to sound cheerful and casual, mainly for Nina Velez’s benefit. But when he listed the preparations that he was taking inside Merganser, I knew he was dealing with a touch-and-go situation.

After all the calculations (performed independently on the two ships, cross-checked and double-checked) we had started our free-fall orbit. It was designed to take us skimming past the Merganser, with a closest separation of less than two hundred meters. We daren’t go nearer without risking crippling effects from their drive. We would be flying right through its region of turbulence.

Four hours of discussion between McAndrew and Wenig — with interruptions from Nina and me — had fixed the sequence for the vital half-second when we would be passing the Merganser. The ships would exert gravitational forces on each other, but that was useless for providing the lateral thrust on the life capsule system that McAndrew thought was needed. We had to give a more direct and harder push some other way.

Timing was crucial, and very tricky.

Whatever we threw at the other ship would have to pass through the drive exhaust region before it could impact the life-capsule column. If the drive were on, nothing could get through it — at those temperatures any material we had would be vaporized on the way, even if it were there for only a fraction of a second. The sequence had to be: launch mass from Dotterel; just before it got there, kill drive on Merganser; hold drive off just long enough for the Dotterel to clear the area and for the mass to impact the Merganser support column; and back on with their drive, at once, because when the drive was off the Merganser’s passengers would be feeling the full fifty gees of the mass plate’s gravity.

McAndrew and Wenig cut the time of approach of the two ships into millisecond pieces. They decided exactly how long each phase should last. Then they let the two on-board computers of the ships talk to each other, to make sure that everything was synchronized between them — at the rate things would be happening, there was no way that humans could control them. Not even Wenig, with his super-fast reflexes. We’d all be spectators, while the two computers did the real work and I nursed the abort switch.

There was one argument. McAndrew wanted to use a storage tank as the missile that we would eject from our ship to impact theirs. It would provide high momentum transfer for a very brief period. Wenig argued that we should trade off time against intensity, and use a liquid mass instead of a solid one. Endless discussion and calculations, until Mac was convinced too. We would use all our spare water supply, about a ton and a half of it. That left enough for drinking water on a twenty gee return to the Inner System, but nothing spare for other uses. It would be a scratchy and smelly trip home for Dotterel’s passengers.

Drive off, we felt only the one-gee pull of our mass plate as we dropped in to close approach. On Merganser, McAndrew and Nina Velez were lying in water bunks, cushioned with everything soft on the ship. We were on an impact course with them, one that would change to a near-miss after we ejected the water ballast. It looked like a suicide mission, running straight into the blue furnace of their drive.

The sequence took place so fast it was anti-climactic. I saw the drive cut off ahead of us and felt the vibration along the support column as our mass driver threw the ballast hard towards Merganser. The brief pulse from our drive that took us clear of them was too quick for me to feel.

We cleared the drive region. Then there seemed to be a wait that lasted for hours. McAndrew and Nina were now in a ship with drive off, dropping towards HC-183. They were exposed to the full fifty gees of their mass plate. Under that force, I knew what happened to the human body. It had not been designed to operate when it suddenly weighed more than four tons. Membranes ruptured, valves burst, veins collapsed. The heart had never evolved to pump blood weighing hundreds of pounds up a gravity hill of fifty gees. The only thing that Mac and Nina had going for them was the natural inertia of matter. If the period of high gee were short enough, the huge accelerations would not have time to produce those shattering physical effects.

Wenig and I watched on our screens for a long, long moment, until the computer on Merganser counted off the last microsecond and switched on the drive again. If the life-capsule was free to move along its column, the computer would now begin the slow climb out of HC-183’s gravity well. No action was needed from the passengers. When we completed our own orbit we hoped we would see the other ship out at a safe distance, ready for the long trip home.

And on board the ship? I wasn’t sure. If the encounter had lasted too long, we might find no more than two limp and broken sacks of blood, tissue and bone.

It was another long day, waiting until we had been carried around in our orbit and could try to rendezvous the two ships. As soon as we were within radar range, Nina Velez appeared on the com screen. The drive was cut back, so we could get good visual signals. My heart sank when I saw the expression on her face.

“Can you get over to this ship — quickly?” she said.

I could see why all the professors at the Institute had lost their senses. She was small and slight, with a childlike look of trust and sad blue eyes. All a sham, according to everything I’d been told, but there was no way of seeing the strong personality behind the soft looks. I took a deep breath.

“What’s happening there?” I said.

“We’re back under low gee drive, and that’s fine. But I haven’t been able to wake him. He’s breathing, but there’s blood on his lips. He needs a doctor.”

“I’m the nearest thing to that in thirty billion miles.” I was pulling a suit towards me, sick with a sudden fear. “I’ve had some medical training as part of the Master’s License. And I think I know what’s wrong with McAndrew. He lost part of a lung lobe a couple of years ago. If anything’s likely to be hemorrhaging, that’s it. Dr. Wenig, can you arrange a rendezvous with the mass plates at maximum separation and the drives off?”