Now, with the ark possibly no more than a few hours ahead, I was glad to hear him proposing talk rather than action.

Just to be sure, I rubbed in Director Rumford’s order one more time. “The colonists don’t seem to be in any great hurry for help, if they send only one message a year. A good thing, too — we have no room on Merganser for anyone else. If it comes to an all-up rescue mission, the United Space Federation will fly a whole fleet out this way.”

As I said that, I was secretly convinced that our whole journey would prove a waste of time. Before we left the Institute we had installed a loud signalling system on the Merganser, and for the past two days we had blared word of our presence and our location into the empty sky ahead of us.

Result: nothing.

The people on the Ark were deaf, or their receiving equipment was out of action; or maybe the Ark was over on the other side of the Sun, hundreds of billions of kilometers away, wandering around where Paul Fogarty had picked up the original signal.

We had reduced speed and turned off the balanced drive. At my insistence we had also switched off every possible source of electronic noise and were gliding forward through the void like a dead ship.

It was as well that we were so silent. Even with our electronic ears wide open, the Mayday signal that came in was barely above threshold. It was also well off to one side.

“That’s it!” Our receiving system automatically tuned to the direction of the source, and now McAndrew increased the gain to maximum. It didn’t help. Instead of a faint voice almost lost in white noise, we heard a loud voice equally unintelligible amid a thunderstorm of static.

“... receiving — input… signal… assistance — urgent…” And then, the first direct evidence that they had heard us. “... send… who you…”

“I have direction and distance,” I said. “Three-twenty-one million kilometers. Send a signal saying that we hear them. Tell them who we are, say we are on the way. Tell them they’ll hear nothing more from us for a while — we can’t send when the drive is on.”

“Aye.” McAndrew was peering uselessly out of the observation port, as though he might catch a glimpse of something hundreds of millions of kilometers off in the distance. “Looks like things are going worse for them, they say it’s urgent. Let’s see, three hundred and twenty-one million. Can the Merganser beat a hundred and ten gees?”

“Not with me on board it can’t. We keep it safe, Mac — we don’t want anyone having to come and rescue us.”

He scowled, but finally he said, “Fair enough.” I don’t know if he did the arithmetic in real time, or if he had stored in his head some kind of table of time against distance and acceleration, but he went on at once, “I’ll tell them we’ll be there in ten hours. That will give us twenty-five minutes for turnover before we start to decelerate. Should be ample. Set it up, Jeanie.”

I had to make one more decision before I could program the drive. What should we assume about target motion? If it was an Ark, how was it moving?

I worried for a few seconds, then decided that it didn’t matter. If the Ark were in free-fall toward the Sun, or if it were in stable orbit around it, that made little difference. The speed would be no more than about a kilometer a second. We could fine tune for that at the end, in a minute or two of accelerated flight.

As soon as McAndrew had sent our message we were on the way. We settled in for a few hours of rest and a quiet gloat. In spite of my warning that this wasn’t a rescue mission, I must admit that I was feeling cocky. We had flown out blind, far from the Sun to where no one but McAndrew had thought of looking. And against all the odds we had found a lost Ark.

A little feeling of self-satisfaction seemed to be in order.

Asteroids are the way that snowflakes are said to be, no two the same. I can’t speak for snowflakes, because I’ve only seen snow twice in my life. But I can vouch for the variability of asteroids. They come in all sizes and every imaginable shape.

That, of course, presents problems to any self-respecting engineer. Ordinary ships can be grown on an assembly line to a common template, a hundred or a thousand of them identical. Asteroids are a wilderness of single instances. Faced with the conversion of an asteroid to a space habitat, an engineer can only standardize so far.

All the Arks had begun life as asteroids roughly spherical and roughly two kilometers in diameter. Hollowing out their interiors and extracting useful metals and minerals followed a standard procedure. At that point, however, the paths for the creation of individual Arks diverged. Thickness of external walls, size and type of interior structures, on-board life forms, mineral reserves, illumination, hydroponics, computer controls, communication antennas, lifeboats, all had to be designed to order. Which was just as well, because small animals and bugs acceptable to — even required by — the Ark of Noah would be considered disgusting vermin by the Cyber Ark or the Ark of the Evangelist. On the other hand, the Cyber Ark wanted computing equipment involved in everything, while the Amish Ark would have been happy with no computers at all.

Except for the communication antennas, none of these differences showed on the outside. McAndrew and I knew that, but all the same we peered curiously at our display screens as the object ahead of the Merganser grew steadily from a tiny point of light almost lost against the background of stars, to a defined disk, and finally to a lumpy Christmas ornament adorned with the bright spikes and knobs of gantries, antennas, thrusters, exit locks, lifeboat davits, space pinnaces, and docking stations.

“This is the Merganser, at eighteen kilometers and closing.” I sent the signal, wondering why the Ark ahead had stopped broadcasting its Mayday. “Are you receiving us?”

I hardly expected an answer, so the woman’s voice that replied within seconds was a surprise.

“We are — receiving — your messages,” she said. Her speech was jerky, as though she was hard-pressed to force out each word. “We need your — assistance. Urgently. Approach — this world — and — come aboard.”

McAndrew leaned across and turned off the microphone. “Damn it, Jeanie, what are we going to do? They think we can help them, and we can’t. This ship doesn’t have the resources.”

“We knew that before we started,” I said. “Mac, the only thing we can do is find out what’s wrong, and send a message back to Director Rumford. He’ll have to take it from there.”

I turned the microphone back on. “The Merganser is a small experimental ship. We can’t do much to help. What sort of assistance do you need?”

The woman said again, just as though she had not heard me, “We need — your — urgent assistance. Approach — and come aboard. An entry port is — already — open. Proceed through to the — interior.”

We had been closing steadily as we spoke until the Ark loomed to fill the sky ahead. The blue-white glare of the Cassiopeia supernova, far brighter in this location than our own diminished Sun, threw hard shadows on the external surface of the converted asteroid. I could see the trusses of each individual gantry and the lattice work of the robot arms that handled external cargo loads. An entry lock formed a dark well next to one giant manipulator.

I stopped the Merganser two kilometers short of the Ark. “This is as far as we go.”

“Jeanie!” He was outraged. “We can’t find out what their trouble is unless they tell us, and they don’t seem able to. We have to go inside. There’s no possible danger. None of the Arks had a weapons system.”

“I know that.” I wondered why I was feeling uneasy, and relented. After all, even if I were the captain this had been his idea and it was really his expedition. “All right. We can go closer if we use suits. But the ship stays here.”