Colin Kapp - The Unorthodox Engineers

‘Interesting!’ gasped Fritz at last, desperately trying not to throw up.

‘I hope it’s not going to do that often. I expect it when I’m drunk, but cold sober it comes as a bit of a shock to the system.’

‘I know what you mean, Jacko. On Terra “up” is up, and it’s inclined to remain that way. On Getawehi “up” not only varies in direction but also in slope according to what angle to the geocentric its gravity is pulling.’

But how in hell does that work?’

‘I don’t know, but I’ll figure an answer to it soon. Of course, even on Terra there’s a slight distortion of gravitational direction due to the pull of the moon—hence the tides. But it’s so slight it can’t normally be noticed. If Getawehi had some extremely massive satellites, that could be a possible answer.’

‘Except that Getawehi hasn’t got any satellites. With the mass they’d need to produce an effect like that it would scarcely be possible to miss them.’

‘Hmm. We’ll come back to that problem when we’ve had a chance to talk to Wooley’s crew. In the meantime, consider the potential uses of a variable-direction gravity. Given a soapbox on wheels and decent set of brakes, you have all you need in the way of low-cost transport. You wait until your destination lies downhill, release the brakes and coast towards it. When your destination shifts uphill you drop anchor and wait.’

‘You couldn’t run wheels over this stuff.’ Jacko kicked the soft ashy soil moodily.

‘I wasn’t thinking of it,’ said Van Noon. ‘That was purely by way of illustration. Something more in the nature of a sledge… to get us to the base camp.’

‘Moses!’ Jacko turned back towards the fallen ferry. It was now a stiff uphill climb, and the ferry approached from the side, looked precariously unsafe. ‘I’ve just the thing, Fritz. The plastic cabin liners. Six sections meeting to form a dome. You couldn’t have a better shape.’

As he spoke the world seemed to rear perilously upwards, ship uppermost, as some new component of Getawehian gravity roughly doubled its field and threw the gravitational angle to something approaching forty-five degrees from the geocentric vertical. Standing now on a hillside plain which fell away below them in a one-in-one slope as far as the eye could see, they stopped in horror. The huge ferry vehicle, its weight now twice that on landing, crushed the soft ash-soil at the edge of the depression it had made for itself on falling, and began to roll murderously down upon them.

Their instinctive reaction was to turn and run down the monstrous incline in front of them. With rare presence of mind Van Noon caught Jacko’s arm and forced him to run a diagonal path which took them barely clear of the rolling bulk as the rogue spacecraft rolled a deep trail in the ash-soil. The wisdom of Van Noon’s diagonal path of escape was soon apparent. The rolling ship rapidly achieved a velocity which would have fatally outstripped a running man.

Then the angle of the terrain began to flatten again and the intolerable gravity lessened. The ferry rolled to a cumbersome halt as the incline down which it was moving became insufficient to support its motion. Finally the two unorthodox engineers trudged ironically up a slight incline after their errant vessel, approaching it from tail-on in case it took it upon itself to roll again.

‘Lesson one,’ said Jacko. ‘First catch your spaceship.’

‘We seem to be luckier than Wooley’s ground crew. At least it hasn’t dissolved on us.’

‘There’s still time,’ said Jacko miserably. ‘The hatch is on the side. Dare we go in?’

Van Noon cast a wary look at the unstable skyline. ‘Not for very long. We don’t know how often Getawehi goes in for a big pull like that. It’d be fatal to be trapped inside if it rolled again. What we really need is explosives to dig a real big ditch alongside. Once we got her into that we could work inside fairly safely.’

‘There’s explosives in the tool hold.’

‘Do you know exactly where?’

‘I stowed them there myself.’

Fritz had been attempting to time the apparent rotation of the highest point of the skyline. Its movement was highly erratic, but there was a certain degree of progression. The coming angle was one soon to place the ship in a position to slip only noseward if it moved at all.

‘When I give the word, you try to get in there and out again with the explosives in about seven minutes flat. If you hit trouble, get out without the explosives. But whatever you do, keep inside seven minutes.’

Jacko nodded. When Fritz gave the signal he climbed swiftly to the hatch, fought the cover open, and disappeared inside. Van Noon spent an agonizing few minutes which lengthened into eight before a flurry of activity in the hatchway deposited a dozen packets of plastic mining explosive at his feet, followed by a box of detonators. It was ten minutes before Jacko himself got clear, having miscalculated the intricacies of manoeuvring in a space cabin with the gravitational attraction sideways on.

Van Noon was watching the shifting angle cautiously. He waved Jacko away urgently, but although the terrain began to slope in a direction which could have set the ferry rolling again, the angle did not become acute enough to bring the vessel into motion. Fritz was quick to seize the opportunity. Mentally estimating the circumference of the vessel, he paced out the distance through which the hull needed to rotate in order to leave the hatch at the top.

They placed a chain of explosives across this distance line, with a one-minute detonator at the end. Priming the detonator, they ran across-hill to a safe distance and waited. The explosion ripped a long, deep trough in the soft ash, the edge of which reached almost to the ferry’s hull. The shock of the explosion was just sufficient to overcome the forces which kept the great vessel from moving down the incline.

Ponderously it rolled into the crater and settled, almost a third of its bulk below ground level.

Now they were able to work on the ferry with the minimum of risk, although the uncertainties of exactly what was “up” were peculiarly unsettling within the confines of the fallen ship. Time and again they were disturbed by the sudden fear that the hull was beginning to roll again, as some sudden change in gravitic direction or intensity made the “floor” apparently shift under them.

It took two hours to cut the cabin liners into sections suitable for two sleds. The shapes they obtained could scarcely have been more suitable for the purpose had they been custom designed. The only brake they could devise was a crude foot-operated device like a ploughshare bolted on to angle brackets at the rear of the sections. On test the brakes proved savagely effective, but the failing light made them put away thoughts of starting their journey before morning.

Very few of the services in the ferry still worked. From the growing acridness of the atmosphere inside, it was obvious that the chemical powerplant had been damaged. For this reason Van Noon decided they would be safer sleeping in the open. They spent the remaining time before darkness removing from the ship various tools and such few items of provisions as could be carried on the sleds.

Night came with explosive suddenness. The night sky was the first tangible reminder of their peculiar extragalactic location. Part of the sky was strangely dark and lacking in stars, while the rest was aglow with the enormous spread of the Milky Way.

They scuffed shallow grooves in the ash-soil in which to settle their sleeping pods, then climbed in, anxious to get some rest to meet the demands of the coming day. Such was their trust in the ecological and atmospheric climate of Getawehi that neither thought to place their face visors over their pods to ward off precipitation or biological attack. Their only inconvenience seemed to be the shifting gravity, which imparted to the pods the feeling of movement, as if lodged in the branches of a vast and slowly-swaying tree.