The Unorthodox Engineers

The Black Hole of Negrav

‘The basic philosophy behind the Unorthodox Engineers is simple,’ said Fritz Van Noon. ‘As our penetration of deep space continues, so communications and supply lines grow longer, finally impossibly long.

And the transport costs of even simple items become disproportionately high.

‘For instance, the price-penalties of space-freight are such that a simple spanner required on Aldebaran-seven costs sixteen times its weight of platinum on Terra. Assuming you can afford it, delivery time by hyper-ship can be anything up to three years.’

He waited until the buzz of conversation in the audience had died again. Then he continued. At his side, he was aware of Colonel Belling’s dark scowl of disapproval, but decided to ignore it.

‘If we’re to take advantage of the new space-territories the hyper-ships are opening up to us, if we’re to build out on the Rim something men can use as the foundations of a colony, we need engineering—and we need plenty of it.

‘So who should we send? Mechanics who can’t obtain any steel? Engineers whose nearest machine shop is fifty light years away? Or should we send the men who can make a plough out of a stick, a stone, and a length of creeper? The answer’s obvious. You can send a few tools, but the thing that counts most at the edge of the galaxy is man’s own unparalleled ingenuity—the ability to use anything available to your own peculiar advantage.

‘And that, Gentlemen, is the function of unorthodox engineering. It’s the habit of breaking with the traditional disciplines and learning how to construct the nucleus of a functional civilization out of bits of string and matchsticks, if necessary. To hell with what it says in the book. It may not even look like engineering—but if it works, it’s justified.’

Shortly the chairman brought the assembly back to order.

‘Well, now we’ve heard both sides of the argument—orthodoxy versus unorthodoxy in space engineering. I’m sure we’ve all been greatly enlightened, not to mention amused by Lieutenant Van Noon’s account of railways built over small volcanoes, and the use of harps as electrical power generators. While Van Noon’s approach may not seem as elegant as some of the precise and mathematical approaches we’ve heard his afternoon, it’s brought some very practical solutions to some very intractable problems. I therefore suggest we conclude this session with an opportunity for questions from the floor. Of particular interest would be a problem which orthodoxy has failed to solve.’

At his side on the speakers’ platform Van Noon felt Colonel Belling stiffen with anticipation, and knew that his worst fears were about to be confirmed. Belling’s consummate hatred of unorthodoxy was almost a legend, and a public showdown before such an influential audience was too good a chance for the Colonel to have missed.

The next question would be a loaded impossibility. Regardless of who delivered it, Belling would have had a hand in the draft.

A young officer in the uniform of the Space Territories Administration rose to his feet. He was obviously one of the new breed of academic officers not long from space college. He began with his own introduction.

‘Captain-Administrator Wilson, Rim Territories Survey. I’ve been fascinated by Van Noon’s treatise on the uses of unorthodoxy. It so happens that out on the Rim we have a good example of one of these intractable problems. We’ve known for some time that the star Springer 218G has a complex binary-planet system. But closer inspection revealed that the two bodies were of disparate size and we couldn’t understand how this orbit could be stable. That’s because the smaller one is really just a large asteroid we’ve called Negrav.’

Van Noon stole a sly look at Colonel Belling, whose expression of smug innocence confirmed his worst suspicions. This problem had been hand-picked by a master.

‘Perhaps I should explain,’ continued Wilson, ‘that the companion planet in the binary, it’s been named Leda, is a body of considerable interest to us because of its mineral resources. However, because of the rather odd complications of this system, we want to put an observation platform on the asteroid to let us study the situation before we commit expensive resources to the planet.’

Fritz Van Noon listened to this with a patient frown. So far nothing unusual had emerged. Therefore, whatever the problem was, it had to be a honey.

Wilson was deliberately avoiding looking at Belling. ‘I said the asteroid was called Negrav. The reason for the name is that the centrifugal force of its rotation at the equator exceeds the gravitational attraction of its mass. Thus except at the poles it has a negative gravity averaging about point seven Terrestrial. Unfortunately, because of its spin alignment, it’s a point on the equator we need for a base.’

‘If I understand you rightly,’ said Van Noon, ‘yours is a simple problem of securing buildings on to a surface which exhibits an effective negative gravity. This is slightly more difficult than free-fall work, but not much. Any good adhesive can get you started, and once you’ve obtained a reasonable foothold, you can anchor into the surface by any of a great number of standard methods?’

Wilson took the point sedately, but caught Colonel Belling’s eye and was hard-put to restrain the amusement which welled suddenly inside him.

‘It’s not quite as easy as that,’ he said, striving to retain his academic pose. ‘I said that Leda was one of an odd binary pair. It’s always been a puzzle how this could be stable—but now we know for sure that Negrav is not large enough to substantially affect the gravitational balance. Rather, it functions as a satellite to the real companion of Leda—which is a small black hole.’

‘A what?’ said Van Noon, sitting down weakly.

‘A black hole,’ said Wilson happily, under the approving eyes of his triumphant mentor. ‘The second component of the binary is a small black hole of roughly Terran mass, which has an event horizon of about one centimetre.’

‘And Negrav is in orbit about this?’

‘A very close elliptical orbit.’

‘How close?’ asked Fritz suspiciously.

‘It actually shaves the surface on its closest approach. Our problem on Negrav isn’t getting an observatory to adhere, it’s how to stop it being eaten by the black hole in grazing orbit—no pun intended. Orthodoxy doesn’t have any good answers. I’d be interested in hearing the unorthodox approach.’

Colonel Belling was still laughing the next morning. When Van Noon received a summons to report to his superior’s office at the Engineering Reserve he sensed it was only so that salt could be rubbed into an already smarting wound. It made a change, however, to find his commanding officer in a congenial mood so early in the morning. This was a situation Van Noon had plans to rectify.

‘Ah, Fritz! Sit down! I’ve to congratulate you. Your reputation for unorthodoxy is unimpaired. Nobody ever gave such an unorthodox reply to a question at a Space Engineering Symposium. I was particularly intrigued by what you told him to do with his black hole.’

‘It was deliberate provocation,’ said Van Noon. ‘A put-up job designed to discredit unorthodox engineering.’

‘Which it did beautifully,’ said Belling happily. ‘I always said I’d show you crackpots up for what you are.’

‘Then you haven’t heard yet?’ asked Fritz carefully.

‘Heard what?’ Belling’s suspicion was palpable.

‘General Nash was in the assembly representing Space Engineering Command.’

‘Of course. What of it?’

‘Well, the Unorthodox Engineers have pulled him out of several holes in the past. I think he saw the chance to return the favour.’

‘What chance?’

‘That building an observatory on Negrav wasn’t entirely a leg-pull. With respects, Colonel, you were so busy looking at the absurdity of it, that you overlooked the possibility there might be a genuine need. It so happens there is a need. The Negrav-Leda complex promises to provide easily-won mineral resources for a large sector of the Rim, avoiding the long hauls from Terra.’

‘Go on!’ said Belling grimly.

‘Well, General Nash got together with the Director of the Space Territories Administration and offered to build the Negrav observatory for him. The Director was delighted, and an inter-Service contract was drawn up on the spot.’

‘And?’ asked Belling. He had the look of a man who knew what the answer must be, but hoped against hope that the truth could not be as bad as he imagined.

‘The contract makes this Engineering Reserve responsible for building the observatory,’ said Fritz, with an evil smile. ‘That means it’ll be your pigeon.’

‘I’ll never forgive you for this, Fritz.’

‘But I did nothing. It was you who had the matter raised.’

‘I still shan’t forgive you. It has all the hallmarks of your devious organization.’

‘And it raises a good question, Colonel. Who’re you going to send to Negrav? An orthodox engineering team —or a bunch of unorthodox crackpots?’

‘I still think it was a heck of a tough way of proving your point,’ said Sergeant Jacko Hine.

Van Noon scowled at his second in command. ‘Not even Colonel Belling believes me, but I had nothing to do with us being sent to Negrav. The construction orders came down from General Nash, and Belling had to recant on his orthodox approach because there wasn’t an orthodox way to do it.’

‘My understanding is that everybody else refused point-blank to go! I suppose it never occurred to you that there might not be an unorthodox way to do it, either?’

‘The thought did strike me, but I dismissed it as unlikely. Just how the heck we’re going to do it, I don’t have a clue at the moment. But at least it puts us marginally up on Belling’s approach.’

‘How do you figure that?’ asked Jacko dubiously.

‘Belling’s certain it can’t be done. I’m certain that it can. So all we have to figure out is how. That simplifies the problem no end.’

‘Ri-i-ight,’ said Jacko Hine slowly. ‘You’d better clue me up on black holes. If we’re to tangle with one, I’d like to know something of the enemy.’

‘The classical theory’s that of the collapse of a burned-out star. Once a star’s used up its nuclear fuel the radiation pressures holding it up fall right away. It begins to contract under its own gravity. The size of the star controls how far the collapse can go—the larger the star, the smaller it will become. If the start is large enough then nothing can prevent it continuing indefinitely. The whole thing collapses down to an infinitely small point called a singularity. Around the singularity is a region of space where the gravitational field is so strong that not even light can escape from it—this is what’s known as the “event horizon”.’

‘Since nothing that happens beyond that can ever be seen.’

‘Sure. Light—or anything else for that matter—can be drawn into a black hole by the intense gravity, but nothing, nothing at all, can ever get out again. It’s a one-way hole in space.’

‘What happens to the things it swallows?’ asked Jacko uneasily.

Ripped apart to atoms, and then those are ripped apart until all that’s left is randomised radiation. As to what lies on the far side—there are plenty of theories, but nobody actually knows.’

‘So how big is it?’

‘We can never know the radius of the singularity, but the size of the event horizon is determined by the mass of the black hole. Sol is too small to make a black hole, but if it could, the event horizon would be about three kilometres.’

‘But Wilson was speaking of one about a centimetre in size.’

‘There’s another possible way by which black holes could have been formed. In the big bang which kicked off the expansion of the universe. Theory has it that baby black holes of a mass around ten to the minus five grammes and ten to the minus thirty-three centimetres in diameter could have been formed then and would have been wandering space ever since, consuming whatever mass they chanced to find in their travels. It’s entirely possible for one of these mini black holes to be able to eat an entire planet and still not finish up much larger than a marble. It’s likely that’s what we’re dealing with at Negrav.’

‘It gives me a very curious feeling,’ said Jacko, to think of a little black hole which could eat a planet. The more I hear of this expedition, the less I begin to like it. As I said just now, I think you’ve chosen a heck of a tough way to prove your point.’

The great hyper-ship of the STA had carried them out to Chronos, on the Rim. From there another Navy vessel had taken them on to the STA base on New Australia. Here, a smaller vessel took them on the three week sub-light trip to Springer 218G, with its curious binary satellites and the asteroid Negrav. Two days from arrival, Van Noon called a conference of his five-man team.

‘Now you’ve all read the preliminary STA survey report on Negrav. When we get within telescope range, we’ll be able to supplement what we know with our own observations. I hope to be able to discover a few items which the STA observers haven’t mentioned because they weren’t looking specifically for them. It’s highly unlikely that Negrav is totally composed of nickel-iron alloy, or that its entire surface is as smooth and unbroken as the STA report suggests. Initially we’ll need to establish a foothold, and this’ll have to be well below the orbital path of the black hole, so what we want particularly is a deep fissure or crack which we can hook into and work safely below the black hole’s grazing orbit.’

‘Check!’ said Jim Fanning, the UE geologist. ‘But if the STA photographs are to be believed, you’d stand more chance of hatching ball-bearings than you do of finding fissures in the surface of Negrav.’

‘I’m aware of that,’ said Fritz. ‘The theory’s that Negrav was once a full-sized planet, and all we see now is a remnant of the core. The rest of it’s been eaten by that darned black hole. But I’m hoping at least for a blowhole or some form of depression. The frequency with which the black hole sweeps the surface gives us less than thirty-six hours between touching the surface and getting safely tucked down underground out of its way.’

‘If I judge you right,’ said Jacko, ‘you’re thinking of building the observatory beneath the surface?’

‘We obviously can’t build on the surface, because anything there gets eaten by the black hole. Besides which, it makes sense in other ways. Below the surface you don’t have to bring in construction materials. You simply carve out the shape of cavity you want. Also you can make use of the negative gravity, because the centrifugal force’ll drift you towards the roof of the cavity, thus producing a semblance of positive gravity. Once the observers get used to making their observations by peering down through windows below their feet, it should be a fairly effective working situation.’

‘All of which sounds very nice,’ said Fanning. ‘But I foresee a couple of practical snags. Like how do we get in deep enough quick enough to avoid being eaten by the black hole? And having got into the surface, how do we carve an observatory-sized cavity in what promises to be a very strong nickel-iron alloy?’

‘I admit it may be tough,’ said Van Noon.

‘Tough!’ Fanning was aghast. ‘Blasting won’t do much more than deform the surface, and oxy-acetylene cutting would take a lifetime—assuming you could get the supplies. So you’re largely back to processes like laser drills and the occasional hand file. At a rough guess, Colonel Belling was damned right when he said it couldn’t be done.’

‘I’ve told you all before,’ said Van Noon sternly. ‘Physical limitations aren’t absolutes. They’re a state of mind. They said iron ships wouldn’t float. They reached that conclusion because they hadn’t taken all the facts into account. From this distance I can’t see the answer to the Negrav problem either. But I’m sure as hell there is one: All we have to do is find it.’

Once they were orbit around Negrav subsequent observations did nothing to support Van Noon’s optimism. Negrav was a ball of solid nickel iron, and its surface was flawless and honed to a micro-finish which would have done credit to a precision ball-bearing. Because of its small size, the black hole remained invisible. Its relentless orbit around Negrav—or rather the orbit of the asteroid around it, which came to the same thing relatively speaking—had for some millions of years ceased to take more than microns of further material from the surface.

Now the black hole’s path hovered millimetres above the surface of Negrav and pursued a progressive rotation which effectively swept the entire sphere over a period of thirty-six hours. The position of the black hole was known with mathematical certainty at any time, but libration and other effects of the binary on the orbit of Negrav introduced an uncertainty factor. The black hole’s progress across the surface had to be described in terms of statistical paths rather than positional lines. In practice this meant that thirty-six hours was the longest period any point on the surface of Negrav could be guaranteed safe from the marauding black hole.

‘Which isn’t long enough,’ said Jacko Hine. ‘Working under space conditions and negative gravity, we wouldn’t have time to cut far enough into the surface to be any significant use. We’ve not only got to get into the hole, but around some considerable corner to prevent being drawn out by the black hole’s gravity.’

‘How far d’you estimate we could penetrate in thirty-six hours?’ asked Van Noon.

‘Judging by spectro-analysis of the surface material, we’d be hard-put to remove more than a cubic metre with the tools available. And once we get deeper, the work would slow considerably because we could only keep one man at the face.’

‘That’s not good enough,’ said Van Noon. ‘I’m going down to Negrav myself to study the problem from the surface.’

‘If it’s not a rude question, how do you intend to hold to the unbroken surface against negative gravity? Chewing gum?’

‘No, permanent magnets. Nickel iron of that structure ought to be highly magnetic. If the negative gravity’s only point seven I should get all the attraction I need from a fairly small magnet pack.’

‘It’ll be a right game if you end up orbiting the black hole as well!’

If he was being strictly honest, even Van Noon would have admitted his confidence had fled as the little scudder dropped him towards Negrav’s implacable surface. The nearer they approached, the more smooth and polished the asteroid’s surface appeared, until from twenty metres up he could see the perfect reflection of the scudder mirrored in the giant metal ball.

The first problem was to secure a contact with the surface. Whilst the power manoeuvrings of the scudder could keep station over a particular point on the asteroid, the problem of trying to attach an assembled magnet package to the surface was akin to trying to throw it twenty metres vertically above his head. It was not until he had experienced the situation that he began to appreciate the reasonings behind Jacko’s pessimism. What he had failed to accept subconsciously was that any work in negative gravity was akin to working on the ceiling, and that any drilling would have to take place in a “hands down, feet out” position, which was both unnerving and extremely tiring.

Jacko’s estimate of a cubic metre of material removed in thirty-six hours began to look wildly optimistic.

After a series of hair-raising manoeuvres by the scudder, the pilot managed to bring Van Noon within striking distance of the nickel-iron “ceiling”. After a few breathless moments, the magnet package stuck and the long cable trailed outwards with Fritz swinging uncertainly on the end of it. Thereafter he had to climb up the cable to reach his destination, which was no mean feat despite the lightweight flexibility of his spacesuit. This did not accord at all with his ideas on how a conquering hero, even an unorthodox one, should reach the planetary body of his choice.

Having secured himself on the cable, he then began to probe the surface above him. A small drill bit cleanly but slowly into the metal surface, though he was afraid to exert too much pressure lest he should lever away the magnets which held him there. He dutifully collected samples of the swarf which came away, tapped the hole, and screwed in a prepared eyebolt to which he attached a second line. More secure now, he brought up a large drill and drilled a hole sufficiently large for a second eyebolt to be inserted completely recessed below the surface.

This was the first permanent foothold secured on Negrav.

‘Getting any ideas, Fritz?’ Jacko’s voice came over the headphones.

‘It strikes me that with the small size of the black hole, the chances of any particular attachment to the surface being eaten in any one orbit are negligible. If we were to suspend a stand-off platform from the surface and attach it by more than an adequate number of cables, we could give ourselves a relatively safe work stage. Furthermore, it would be more comfortable than this fly on the ceiling approach.’

‘Do you want me to organize a platform?’ asked Jacko.

‘Not yet, because the chances of cutting our way in seem quite as remote as Jim Fanning predicted. There has to be an easier method. Before I leave, I want to see what the explosive charge will do. But I don’t really have much hopes unless the stuff is a lot more friable than it seems.’

‘Right. When you get those swarf samples back we’ll have some idea of the answers anyway.’

Van Noon attached his explosive package to his first eyebolt, carefully levered free his precious magnet pack, then dropped down the cable from the second eyebolt to make the precarious rendezvous with the scudder. When it had stood off to a safe distance, he fired the explosive charge remotely.

The flash was impressive because of the highly reflective surface, but the destructive effect was negligible. A further close pass in the scudder revealed only the barest depression in the solid metal surface. A slight element of plastic flow had taken place, producing an extremely shallow crater, but there was no evidence that any material had actually been removed.

Van Noon returned thoughtfully to the ship. On the face of it his exploratory trip to the surface of Negrav had been a failure. They had learnt nothing they did not already know, and the few straws at which he had clutched had disappeared like vapour in a vacuum. The problem of building an observatory on Negrav appeared as intractable as ever. As the hours wore on, however, he developed the curious quizzical look at the corners of his eyes which signalled he was far from being beaten.

He spent hours viewing the surface of Negrav with the ship’s video facilities, imagining he could see the small black hole as it sped hungrily across the surface. The optical detection of such a small object from this distance was an impossibility, and his patient perusal of the scene began to worry Jacko Hine.

What’s the score, Fritz?’

‘One up to Negrav. Our turn to play.’

‘Are we still in the game?’

‘Very much so. Negrav’s going to have its observatory, and we’re going to build it.’

‘Crazy like a fox!’ said Jacko.

‘Am I? You remember my theme at the symposium. The ability of the unorthodox engineer is to do the job with anything he can lay his hands on. Well, Negrav’s a classic set-piece—the problem and the answer bound together in a single cosmological package.’

‘You need to be joking!’

‘Think about it. Ours is a problem of method. Cutting’s too slow, and blasting’s ineffective. But suppose I gave you a tool that’ll not only cut nickel iron without effort, but will also consume the detritus? Suppose this tool needs no external power supply, and the tool wear is so low that it even finishes up marginally larger than it started. And all for no transport costs. Couldn’t you do the job with that?’

‘Yes—but—,’ spluttered Jacko, and then realization dawned. ‘You’ve lost your mind!’

‘Our cutting tool’s right down there, Jacko. And for a bonus we get an eternally spinning workpiece to go with it. No lathe required. All we need to arrange is the traverse mechanism. With the black hole we can cut a toroidal cavity right around Negrav’s equator, and they can build a hundred observatories inside there if they like.’

‘Fritz,’ said Jacko, ‘this time you’ve surpassed even your own idiot genius. But there’s one tiny point you’ve overlooked. You can’t pick up a black hole and use it as a tool. You can’t hold it. You can’t even approach it. It’ll utterly absorb anything you can fling at it.’

‘All that’s accepted,’ said Van Noon. ‘But when you’ve a job to do and there’s no conceivable way to do it, there’s only one approach left open to you. You have to exercise some good old human ingenuity.’

The work-vessel took them back to the STA base on New Australia. This was the nearest point on the Rim where Fritz could find anything like the computer capacity he needed. He would have preferred to have gone back to Chronos, but was unwilling to waste the time whilst his enthusiasm was still at fever pitch. Once they had become convinced that Van Noon was intent on going through with the scheme, his team, too, had become infected with his eagerness, and their deliberations had considerably refined and improved Fritz’s initial ideas.

The STA technicians on New Australia listened to Van Noon’s proposals with critical alarm, and sent a message by subspace radio to Terra for confirmation that the project could proceed. In the meantime, Fritz got on with his computations.

The message which came back from Terra read :

’If van Noon wants to stick out his fool neck on a scheme like that, don’t stop him. We might get lucky!

Belling, Commanding engineering reserve.’

Van Noon could almost picture the gleam in the colonel’s eye as he penned the message. Nevertheless, he received all the help he needed from the STA staff on New Australia. With his precious calculations complete, and sufficient supplies for the job, he returned with his team to the keep-station around Negrav to begin the careful observations on which the success of the operation would depend. It was fairly obvious that the rest of the ship’s crew regarded the project as insane. There were moments when Van Noon was not too sure himself. Nevertheless, the future of unorthodox engineering was riding on his back, and having declared his intention, he was unable to retract.

Above all else, timing was critical. The accurate gauging of Negrav’s rotation was aided considerably by a huge dyespot which Jacko managed to produce on the surface. This was achieved in the course of a hair-raising approach to the asteroid in a scudder which was carefully manoeuvred while the dye was sprayed from pressurized canisters. With the spot in place, the rotational speed of Negrav was determined with an accuracy previously unobtainable, and Van Noon’s calculations were complete.

By far the hardest part of the operation was to give the order to proceed. Not only were the dangers considerable, but the timing needed to be immaculate and the positional accuracies held within very small limits. Additionally, there were still a few unknowns which added not only to the hazards but also to the virtual certainty of unorthodox engineering becoming a standard joke throughout the Service if things went wrong.

Having rehearsed and re-rehearsed his team, Van Noon finally reached the critical point, and gave the fateful order. Once the first scudder had left the ship and headed towards the surface, there was no turning back. It was only when he had passed this point that he began to appreciate the immensity of the forces with which he played.

Once started, there was no leisure for further thought. Jacko Hine went down with the first scudder and attached his package as specified. The second scudder was on its way before he returned. The third and most critical package, Van Noon took down himself.

There being no natural features on the surface of Negrav, he could only judge his position from the radioed instructions from observers on the ship and the relative movement of Jacko’s dye marker. This made easy sense during the long space descent but when the orb of the asteroid began to dominate the sky he lost orientation. In sudden panic he had the scudder halted until he could recalculate his bearings. It was this hesitation that probably saved his life.

As he directed the scudder to continue the descent, a sudden warning was issued by the observers on the work vessel. ‘Look out below! You’re off course and running right into the path of the black hole.’

The pilot reacted before Fritz had time to formulate his instruction. Veering crazily away in a tight arc, the little spacecraft struggled to escape from the gravitational well of the black hole which was overtaking it from the rear. Unless they could build up to escape velocity they were liable to be dragged irrevocably down into this hole to end all holes.

For a short time it looked as though they might escape completely. Then the full power of the scudder’s tiny motors became insufficient to move them any farther against the intense gravitational attraction which now arrested and began to drag them back towards the surface. There was nothing the occupants could do except sit helpless as they were seized as if by a giant hand and thrown back on to the asteroid.

The touchdown, when it came, was unexpectedly mild. Fortunately their descent had been delayed by the scudder’s motors just long enough for the black hole to have sped on its uncaring way. The friction of the craft against the asteroid’s surface was sufficient to prevent them being drawn in the black hole’s wake. Almost immediately the gravitational spasm was over, and Negrav’s own negative gravity spun them crazily back into space.

Dazed and shaken, Van Noon checked his equipment, whilst the scudder pilot tested his craft. Miraculously there had been very little damage. The scudder, though dented, was still spaceworthy even though much of its instrumentation had failed. Van Noon’s precious package, which had been the reason for the descent, likewise appeared to have suffered no permanent harm.

His timing, however, had been completely destroyed. This was a factor beyond recovery. Because of the orbiting black hole, the packages which had already been placed on Negrav had only a limited life expectancy. If his own package was not now put in place, the existing ones would all be destroyed before any new calculations could be made.

Van Noon shrugged his shoulders and took a chance. He placed the package with its magnet pack on the nearest part of the surface, knowing that its position was far from being where he had originally intended. The results would be in the lap of the gods, but it was either this or make the long haul back to New Australia for a fresh set of supplies. Then tired and disconcerted, he ordered the scudder back to the ship.

Compared to this first trip, the rest of the journeys to Negrav seemed uneventful. No less than seven other trips followed some achieving the desired accuracy, others varying. There was no time left, however, to make any corrections. Fritz had to suffer the errors and hope against hope that some overseeing deity would bring the project through. Otherwise he shuddered to think of the final results.

Then came the final phase. One after another in controlled sequence great explosions flared upon the surface of Negrav; appearing as little more than pinpoints of light to the distant observers, yet in reality being ample charges of super-high explosive. The timing was accurate according to the original schedule, but because of misplacement of several of the charges, the net effect would be anything but optimum. There followed a long period of waiting, after which the remaining charges were fired.

As Van Noon read the final collation of results, his heart sank like a stone. He had arranged to check the orbital velocity of Negrav so that it fell into a lower orbit around the black hole. In effect this meant that for a number of rotations the black hole would actually orbit inside the surface of Negrav. Then he had planned to correct Negrav’s velocity so that the black hole would return to the surface leaving a toroidal cavity inside the asteroid’s equator. Probably due to misplacement of the charges, the scheme had gone disastrously wrong. The black hole had remained inside Negrav…

Stupefied, he read the figures, but they no longer registered in his brain. Instead he saw the asteroid of Negrav being progressively eaten from inside by a small black hole so voracious that it could consume its entire host without particularly noticing the meal. Worse, if it remained inside Negrav, the asteroid would disappear entirely. Van Noon did not much fancy being known for the rest of his career as the man who lost a whole asteroid.

In an agony of indecision, he called for the orbit of the asteroid to be monitored continuously, while he searched through the ship’s stocks hoping to find sufficient explosive to kick the asteroid’s velocity up and bring the black hole again to the outside. A trip to New Australia for fresh supplies was out of the question because of the time involved. By the time they returned, Negrav would have been swallowed whole.

He was unlucky. The explosives he had brought from New Australia had been carefully calculated for the job, and the entire stock had been used. Nor did the ship carry any stocks of its own. He briefly thought of trying to nudge the asteroid with the ship itself, but concluded that the vessel was unlikely to survive the ordeal.

Disconsolate, he sat down again to check the results of the orbital monitoring. As he did so, he began to brighten considerably. When Jacko found him, he was chuckling uncontrollably, and tears of laughter were streaming down his face.

‘You’re the first person I ever saw get a belly-laugh out of a computer printout,’ said Jacko warily. ‘We don’t have a strait-jacket, so I’d better give you a shot of tranquillizer. I’d advise you not to struggle.’

‘Knock it off, Jacko! I’ve just received proof of the theorem that the deserving don’t always get what they deserve. Alternatively, the unorthodox looks after its own.’

‘Crazy like two foxes!’

‘Look at these orbital figures, Jacko. And tell me what it was about the original problem we forgot.’

Jacko took the sheets of printout and looked through them wonderingly. Then he, too, began to smile.

‘Negrav’s speeding up. If it continues to do that, the black hole’ll come outside again of its own accord— and soon.’

‘Right! We forgot about conservation of momentum. As the black hole removes some of Negrav’s mass, the asteroid gets lighter but its initial momentum remains. Therefore it has to go faster, and climb into a higher orbit. It’s a self-stabilizing system because whenever the black hole removes some mass from the asteroid, Negrav itself automatically retreats from the attack.’

‘So what’re we left with? The same problem only with a slightly smaller Negrav?’

‘No. Unless my figures are wrong, the black hole’s been in there long enough to give us a concentric ball and shell effect—like a marble in a table-tennis ball. The increase in Negrav’s speed is running up an exponential curve, so that when the black hole does come out it should do so at some considerable angle. With luck it’ll only puncture the shell as it comes, not eat it away. And do you realize the implications of that, my boy?’

‘We were lucky?’ asked Jacko uncertainly.

‘Yes, but not only that. It means that Negrav will be safer from attack by the black hole than ever before. And if that cavity’s the size I think it is, they’ll be able to build a major base in there, not just an observatory. They can mine Leda at their leisure, and use Negrav as an on the spot refinery and transfer station from which they can load hyper ships direct. It’ll be the most valuable space facility on the Rim.’

As the figures had predicted, the black hole did come out of Negrav. It reappeared some thirty-two hours later and finally stabilized with an orbital separation of eleven kilometres. This new orbital distance was a measure of the amount of mass which had been removed from Negrav.

The next part of the exercise was to explore the cavity itself. This was aided by the fact that they could now anchor a structure permanently on to the surface to give them safe working conditions without fear of being eaten by the black hole. With this new facility, the work progressed rapidly. Twenty metres in, they broke into free space inside the asteroid. Van Noon was first through, followed by Jacko and an assemblage of powerful lamps. Once inside, they gazed into the vastness with amazement.

Fritz’s ball and shell concept was substantially true, but random deviations in the rotation of Negrav had not produced a completely clean cavity, but rather one populated here and there with crazy spires and towers and bridges, and many vast columns which rose up to support the central core nearly a kilometre above the inner surface. Every line was curved in representation of some complex mathematical equation, as though designed by a mammoth computer programmed to seek out the ultimate in form and shape; and everything was cleanly cut and polished in flawless nickel iron alloy.

They made a tour of inspection which lasted nearly twelve hours, and came out so impressed with the wonder of it all that it was difficult to believe that these fantasies had been the results of interference with their own hands. As an STA base, the situation was, and would be always, without parallel. Had it not been situated on the Rim, it would have been a tourist attraction with no conceivable opposition. They had juggled precariously with Nature, and been rewarded with a marvellous demonstration of natural design that made them feel humbled and just a little bit afraid.

They found the points by which the black hole had entered and left the cavity, and had these sealed. Over their original entry point they built a docking hatch and an airlock. They then radioed New Australia for the STA to come and take possession of the prize. Captain-Administrator Wilson was the first STA man to arrive. He went in with a disbelieving sneer, and came out so passionately impressed that he couldn’t speak.

From then on, the more orthodox engineers took charge, ferrying gases to provide a breathable atmosphere in the cavity, bringing in power plants and treatment plants and all the paraphernalia necessary to support existence in the far reaches of space. Their task done, the unorthodox engineers returned in triumph back to Terra.

‘You don’t have to rub it in, Fritz,’ said Colonel Belling, when next they met. ‘I admit I was wrong and you were right. Unorthodoxy does have a use in unorthodox situations.’

‘Actually we’re only arguing about definitions,’ said Van Noon. ‘Orthodoxy for us is the tools and techniques which have been evolved for dealing with our local Terran situation. We can’t expect these to be the optimum for a completely altered set of conditions. What’s orthodox in one part of the galaxy may be unorthodox in another. All that I’m saying is that the most useful thing we can take to any problem is an open mind.’

‘Well you’ve certainly proved your point. The STA are so delighted with their acquisition that they’ve asked permission to call their Negrav installation Base Van Noon. I thought it only fair to let you make your own refusal.’

‘Refusal?’

‘That’s what I said, Fritz. While you’ve been journeying back, I’ve been analysing your figures. As I read it, this was a battle you actually lost, but were saved by a most fantastic stroke of luck. D’you really mean to claim it as a victory?’

‘In the circumstances, I take your point. But I claim the right to nominate my own alternative.’

‘Which is?’ asked Belling ominously.

‘How about Serendipity?’

The Colonel’s face broke into a smile. ‘I’ll go along with that, Fritz. I’ll even buy you a drink on it. And while you’re here, there’s another matter I want to discuss. It concerns the tunnelling problem on Eggar III. Now I’ve been thinking that if you can find another black hole…’