I walked towards that shadow in the ground, that pit, like the one I had explored in the heart of England, now transplanted into the hard Arctic tundra. Its shaft, a little more than thirty yards wide – the width of a Martian space cylinder – was lined, just as in Amersham, with an aluminium sheen. And, as I approached, cautiously like the rest, I could hear it, a great thump-thump-thump, like a beating heart, deep underground. It was the sound I had heard in England, all the time I was in the Martian Redoubt with Albert Cook, and unwelcome memories crawled.
‘They are here,’ I said. ‘Still here.’
Almost tenderly, Eric Eden took my gloved hand in his. ‘Buck up, old girl.’
I saw that a number of the tame experts were drawn away from the pit itself to inspect a broad trench, dug into the ground, perhaps three feet deep and twenty long, and oriented north-south. Those excitable scientists, mostly spectacles and beards and bald heads – senior academics were still largely men, in those days – were, with caution, using gloves, were reaching down into the trench and taking samples of what grew there: a plant of some kind, fleshy and crimson and covered in blisters, thick on the earth.
As Walter led me that way I saw that a number of other such trenches had been made, across this landscape and running down the narrow beach and into the sea. Walter reached down into one of the trenches and grabbed a handful of the stuff growing there, and gave me a share; it was dry to the touch and rubbery, but otherwise like seaweed. ‘No need to be delicate – there’s plenty of it around, and more of it every day. Growing in the ground, in a few spots on the surface – oh, and under the sea.’
‘How do we know that?’
He pointed to a machine that stood by the shore; it looked like a boiler on fat wheels, but it had a periscope like a submarine, and thick round portholes.
‘What’s that? Some kind of submersible?’
‘Yes, but not a conventional kind. It’s a Lake crawler – a design that drives along the sea bed – an old design that never really caught on, but which has its applications. Its brave crew, Russian scientists all, have taken that beast out onto the ocean floor, and far under the ice. And everywhere they went they found—’
‘This stuff?’ I held up my sample. ‘Is it red weed? I remember how quickly it grew, even the first batches the Martians brought to the earth in ’07.’
‘It seems to be a form of red weed, yes.’
‘But what purpose has it?’
For answer, he popped one of the blisters on the frond I was holding. I saw no gas emerge, smelled nothing. ‘To collect this,’ he said.
‘The gas in the blister? It is invisible—’
‘It is nitrous oxide. A compound of nitrogen and oxygen – the sample is just as reported by the first expeditions, and its purpose is as obvious now as then, to me at least.’
I remembered now Frank’s observations of the depletion of the air over fields of red weed in the Abbotsdale Cordon. ‘I don’t understand. Purpose, you say? What does it mean, Walter?’
‘The removal of the world’s air,’ he said simply.
9
AN UNRELIABLE PROPHET
That evening, back aboard the Vaterland, Walter discussed his ideas further, with myself, Eric, Joe Hopson. We spoke over a dinner of sandwiches and beer and a bowl of fruit. The restaurants were sparsely populated now; those scientists on board – the rest had stayed in the military base – had scattered to cabins become improvised laboratories, and were, no doubt, planning to spend the night in obsessive analysing, experimenting and theorising.
But Walter had already worked it all out.
‘Here is the problem,’ he said. ‘The problem for the Martians, that is. Those stranded here find themselves on a world quite unlike their own in a number of ways. The greater mass, the heavier gravity – there’s not much to be done about that. Ah, but what about our atmosphere? From a Martian’s point of view there’s far too much of it; their air is attenuated compared to ours, and a different mix: we have too much oxygen, too little argon, for example.’
Both Joe and Eric seemed to be struggling with these ideas. Eric said at length, ‘Are you saying that these Martian Crusoes might wish to change the air – to make it more like their own?’
‘Precisely. Why would they not? After all, Europeans have spread around this earth, from the Arctic to Australia, and everywhere we have gone we have cleared those lands of native life and made them suitable for our crops and stock animals. It even goes on here – did you know there are potatoes, plants from the Andes, growing above the Arctic Circle?’
‘Are there, by golly?’ Joe said. He seemed more impressed by that fact than anything else said so far.
‘Very well,’ I said heavily, thinking it through. ‘It’s just that the Martians are going one step further. But how could they do it? To change the air of a world—’
‘I have speculated,’ Walter said calmly. ‘I have studied the kinematics of meteorites, for example. We know that the Martians have learned to use the dropping of objects from space as a weapon of war. And, such is the energy released, every such fall blasts away a proportion of the earth’s air into space – not much, but some. And once gone it is lost forever. Well, I wondered, could one use similar impactors – giant cylinders stuffed with rocks, for example – to simply blow all our air away?’ He sighed. ‘Sadly, I think that’s impossible.’
Eden snorted. ‘Sadly! The man says sadly!’
‘We have studied such impacts since ’07, and the natural landings of meteorites even before that. No matter how large a rock you drop, you blast away some air, but only a kind of a skim.’ With one bony hand he took an orange from the fruit bowl on the table, and cut a flat slice off the rind, tangentially exposing a little of the flesh within. ‘Like this. The energy of the infall won’t reach around the curve of the world – you end up just nipping off a slice, tangential to your horizon. Do you see?’ He made a few more such cuts, leaving the orange’s flesh largely intact. ‘I calculate it would take thousands of rocks to get all the air away that way, and by rocks I mean not mere hundred-yard cylinders, but big hundred-mile-wide asteroids. And consider what a mess you’d make of the world if you tried it! No,’ he said. ‘I think they’ve been more subtle. I think they’ve come up with a tool, a biological mechanism—’
‘The red weed,’ I said.
‘Correct. But an adjusted variant, modified perhaps at the level of the germ plasm – we know the Martians are expert at shaping living things for their purposes. No doubt the assembled professors aboard this craft will figure it better than I can, but my guess is –’ He glanced at us. ‘What’s the atmosphere made of?’
‘Nitrogen, oxygen, and scraps,’ Joe Hopson said promptly. ‘That got beaten into us during stinks lessons at school.’
Eden winced. ‘Do shut up, Joe!’
‘Very well. I think it works like this,’ Walter said. ‘The first goal is to get rid of all that nitrogen and oxygen – yes? Because those are the bulk components. Now, we could think of ways to do that – in principle, at least. Nature has provided certain plants which “fix” the nitrogen from the air, that is, draw it down and render it into molecules suitable for take-up by other living things. That’s steady, but it’s slow if you leave it to the plants. But now we have the Haber process, which fixes nitrogen from the air to use in artificial fertiliser. And a single Haber manufacturing plant can remove as much nitrogen from the air, in a week, as all the oceans absorb in the growth of plankton, and so on, in a year. In fact we have on board Frederick Keeble of ICI, who as you may know was the first to identify nitrogen deficiency as a limit to agricultural growth, and it’s no coincidence that a man with such expertise is on this expedition.