The Excelsis was a big ship. To make as sure of her as possible we were going to attach every parachute we carried and that meant a lot of work. Nevertheless we had more than three-quarters of the bolts in place before we began to decelerate. That meant we'd plenty of time, for our rate of deceleration was the same as our acceleration and would therefore take longer. We had to lose, you see, not only the speed we had worked up, but also the speed the wreck was travelling when we found her, in order to ease her close to Earth at as slow a rate as possible. It meant several weeks of slowing up.
It's no good my being too technical, but I must give you some idea of the ticklish job it is to land a wreck successfully. There are a hundred things which can go wrong. Dozens of calculations to make, and a slip in any of them is likely to mean failure.
The first stage is to attain a state of equilibrium between the Earth and the Moon where one is stationary—again I speak relatively as one must do in space, actually one is moving round the Earth, but at a constant distance from it. There the final preparations for descent are made.
The salvage ship again refills her fuel tanks and any surplus fuel from the derelict is jettisoned for safety. Much wreckage has already been cut away in the first clearing up, now the empty fuel tanks are cut out and set adrift with an impulse in the direction of the Moon. The hulk is made as light as possible for it is intended to drop her in the sea and it is hoped that she may float. We had little hope of the Excelsis floating, seeing the weight of gold and ganywood she carried, but on general principles we saw to it that she was as light as she could be.
Then the ship is sealed up, the main coupling hawsers which have bound the two together are cast off leaving only the magnets and their hawsers as links, and the parachutes are made fast to the ring-bolts. The practical work for the crew is finished; the rest depends upon the captain's calculations and his consequent manoeuvres. He and the first officer get down to figuring and checking one another's results.
This is no light work. The captain knows the approximate spot where he intends to drop the derelict and he has got to get her into such a position that she will fall there or thereabouts. He knows the load his magnets will hold and that, with his estimated weight of his salvage, tells him how much pull and steerage effect he will be able to exert. He must work out the balancing of forces—the pull of the Moon, of the Sun, of the Earth, and the rotation of the spot he aims at, relatively to the Moon. Everything which can be used to slow or shorten the final descent must be employed. Finally, he must find out by radio as much as he can about weather conditions on Earth and make allowance for them at the last possible moment.
In general, we were feeling that we were near the end of a profitable and not too onerous piece of work. From the salvagers' point of view the Excelsis was as straightforward a job as one could hope for, except for the heavy cargo. It simplifies tasks a great deal when the air has been held; you don't have to build new pieces of double wall or fit automatically-closing valves to take in air as she drops.
Seeing that the Plume Line yards were in North Ireland, Captain Belford aimed to drop her a bit out in the Atlantic and make it a short tow by sea. He informed the Salvage Register Office that he was aiming at the neighbourhood of 51° North by 12° West and received their approval. He and the First Officer verified the chronometer's reading and went ahead with the calculations. They checked and re-checked one another's figures with care before they announced to us the exact minute of action.
With some eight hours to go before that time came we all turned in for a while.
Chapter Four
FALL OF THE EXCELSIS
Half an hour before we were due to start, Captain Belford had already fastened himself into his chair and was firing short bursts on the side tubes to obtain the right inclination. We all strapped on our safety-belts and waited, watching the minute-hand on the chronometer.
On the correct second the Dido began to throb gently as her tubes fired. We felt a slight tug a moment later as the hawsers on the magnets took up. We moved gradually Earthward. Behind us came the Excelsis, started on her long last fall.
The First Officer and I were making continuous observations, reporting our angles and distances to the Captain. He verified them on a table he had drawn up and pinned on a board in front of him, correcting the slightest deviation from his planned time-course by a short burst on one or another of the bunches of rocket tubes.
This manoeuvre, known technically as a 'linked fall,' would go on for a long time yet. It should last, in fact, until we were within four or five thousand miles of the Earth's surface when we would cast off and look to our landing while the Excelsis fell free.
But all the first part was a time of constant watch and correction. We were falling together, but the Dido's was no dead fall. All the time she was moving laterally, now this way and now that, tugging and altering the course of the larger vessel, trimming her to hit a calculated spot on the surface of Earth which grew all the time larger and nearer. As delicate a job as any there is. for the disabled ship must be urged to one side or another with the utmost nicety and precision; there must be no jerks or sudden bursts of power which might detach the magnets from her hull. Their hold was the limiting factor of our power over her, but used by an expert it was enough.
The radio operator looked up quickly and reported.
'North-westerly wind rising rapidly to gale force, west of Ireland, sir,' he said.
Captain Belford, hunched in front of his chart, grunted.
'Tell them I'll try to compensate.' He altered the position of some of his controls, muttering more to himself than us: 'Gale, and they gave it as twenty-four hours fair prospect. I suppose they'll learn something about weather, one day.'
He steered the Dido round to the other side of the Excelsis and in that moment the thing, which was to spoil the rest of his life, happened.
He fired on his tail rockets and I say it now, again, as I said it in evidence before, no man could have handled them with better judgment. There was no jerk. I was looking out of the window directly facing the Excelsis and I saw the magnet float away from her side. To this day I cannot say why—it may be that the cable kinked and broke, that there was a short somewhere; I can't tell, but I know that that magnet was loose before our cable to the other magnet drew taut.
Instinctively and instantaneously I shouted a warning, but it came too late. Captain Belford's judgment had been based on the hold of two magnets. Before he had time to reach the controls the second magnet had pulled off and came skimming towards us as though the wire rope which held it had been elastic.
I had never known the Captain to lose his head, and he kept it now. A burst on the side tubes jumped us out of the way, so that the heavy magnet just missed us and went past with its 200 yards of cable looping behind it.
'Cast off,' he ordered.
A man leaned over and pulled a switch. An automatic jaw severed the cable and the magnet sped away into space with the rope curling like a slowly moving snake behind it.
It was a nasty half-minute. That second magnet had sprung back at us with a force which might have holed us if it had hit: at best, we should have got some nasty dents. With that danger past we looked again at the Excelsis.