Of course the relationship between the little red people and the introduced Terran organisms was already complex. To understand it fully you have to remember the little red people’s even smaller cousins, the old ones. These were the Archaea, that third order of life along with bacteria and eucarya – and in this case, also citizens of the panspermic cloud which four billion years before fell on Mars from space, having flown many light-years from their point of spontaneous generation around an early second-generation star. Mostly Thermoproteus and Methanospirillum, it seems, with a few Haloferax thrown in as well. They were hyperthermophiles, so the early Mars of the heavy bombardment suited them just fine. But then some few of these travellers were blasted off the surface of Mars by a meteor strike, and crash-landed later on Earth, fructifying the third planet and sparking the long wild course of Terran evolution. Thus all Earthly life is Martian, in this limited sense, though in truth it is also far more ancient than that.
Then later Paul Bunyan, the distant descendant of these panspermic Archaea, came back to Mars to find it cold and ostensibly empty, though some of the old ones still persisted, golluming around in various submartian volcanic percolations. Paul and his big blue ox Babe were bested by Big Man, as you know, and inserted by him through the planetary interior; crust, mantle and core. From there Paul’s inner bacterial family spread through all the regolith on the planet, and began the so-called cryptoendolithic great leap forward, that first submartian terraforming, which produced at the end of its evolution the little red people as we know them.
So the Martians had come home again, almost as small as the first time around – about two magnitudes bigger than the old ones left behind, that’s right. But the relationship between the little red people and the Archaea was clearly not a simple one. Second cousins thrice removed? Something like that.
Despite this blood tie, the little red people discovered early on in their civilization that their ancestors, the Archaea, could be grown and harvested for food, also for building material, cloth and the like. Inventing this form of agriculture, or husbandry, or industry, allowed for a tremendous population explosion, as the little red people had just taken a step up the food chain, by exploiting the level of life just below theirs. Fine for them, and because they have helped us so much in their subtle way, fine for the humans on Mars as well; but the Archaea considered it barbarous. The little red people interpreted their sullen bovine glares as subservience only, but all the while the Archaea were looking at them thinking, You cannibals, we are going to get you some day.
And so they hatched a plot. They could see that the terraforming was just more of the aerobic same old same old; that the little red people would adapt to it, and become part of the new larger system, and move up onto the surface and take their little red place in the growing biosphere; and meanwhile the old ones would remain trapped in pitch darkness, living off heat and water, and the chemical reactions between hydrogen and carbon dioxide. It isn’t fair, the Archaea said to each other. It won’t do. It was our planet to begin with. We should take it back.
But how? some said. There’s oxygen everywhere you go now, except down here. And they’re making it worse every day.
We’ll find a way, some of the others replied. We are Thermoproteus, we’ll think of something. We’ll infiltrate somehow. They’ve poisoned us; we’ll poison them back. Just bide your time and keep in touch. The anaerobic revolt will have its day.
FOUR THE WAY THE LAND SPOKE TO US
You know that the origin of the big dichotomy between the northern lowlands and the southern cratered highlands is still a matter of dispute among areologists. It might be the result of the biggest impact of the early heavy bombardment, and the north therefore the biggest impact basin. Or it may be that tectonic forces were still roiling the early crust, and an early proto-continental craton, like Pangaea on Earth, had risen in the southern hemisphere and then hardened into place, as the smaller planet cooled faster than Earth, without any subsequent tectonic plate break-up and drift. You would think these would be interpretations so diverse that areology would quickly devise questions that would make one or the other explanation either certain or impossible, but so far this is not the case; both explanations have attracted advocates making fully elaborated cases backing their views, and so the matter has shaped itself into one of the primary debates in areology. I myself have no opinion.
The question has ramifications for many other issues in areology, but it’s worth remembering just what the big dichotomy means for people walking across the face of Mars. Hiking across Echus Chasma to its eastern cliffs gives one perhaps the most dramatic approach to the so-called Great Escarpment.
The floor of Echus Chasma is chaos at its most chaotic, and for someone on foot, this means endless divagations and extravagances to make one’s way forward. Nowadays one can follow the trail, and minimize the ups and down, end-runs, dead-ends, and backtracking necessary to make one’s way in any direction; and the Maze Trail is the very model of route-finding efficiency through such torn terrain; nevertheless, if one wanted to get a sense of what it was like in the early days, it is perhaps better to leave the trail, and strike out to forge a new and unrepeatable cross-country ramble through the waste.
If you do that, you will quickly find that your view of your surroundings is inadequate to plan a forward course very far. Often you can see across the land for only a kilometre or less. Big blocks of chunky eroded basalt and andesite are the entirety of the landscape; it’s as if one were crossing a talus whose particulates were two or three magnitudes larger than the talus one usually crushes underfoot. So that one threads through the terrain as an ant must make its way through talus. Small but unclimbable cliffs confront one everywhere one looks. The only way to make progress is to keep to ridgelines, skirting great hole after great hole, while hoping the ridgelines will connect to each other in ways that can be clambered over. It’s like negotiating a hedge maze by staying on the hedge tops.
Chaotic terrain: the name is quite accurate. Here the surface of the world once lost its support, when the aquifer below it drained rapidly away, downhill and over the horizon in a great outflow flood – in this case, down Echus Chasma, round the big bend of Kasei Vallis, down Kasei’s gorge canyon and out onto Chryse Planitia, some two thousand kilometres away. And when that happened the land came crashing down.
So you walk, or climb, or crawl, for day after day, across the tilted surfaces and broken edges of the great blocks of the fallen crust. You can see just what happened: the land dropped; it shattered; there was more of it than there was room for, and so it came to rest all atilt and acrackle. The violence of this ancient collapse has been scarcely masked by the three billion subsequent years of wind erosion and dustfall. It is an irony that such an unstable-looking landscape should actually be so ancient and unchanged.
Then at the peak of one long roofbeam of a ridge, you find yourself high enough that off to the east, a great distance away, just poking over the crackle, lie the tops of a mountain range, pale orange in the late afternoon light. If you camp on this prominence, in the alpenglow the distant range looks like the side of a different world, rolling slowly up into the sky.
But the next morning you descend back into the maze of potholes and passlets, ridgelines and occasional flat block plateaux, like low rooftops in Manhattan. Crossing these terrains commands all your attention, and so you almost forget the sight of the distant mountain range, the problems are so great (it was in this region we found a providential crack in a thirty-metre cliff, which allowed us to climb down safely, lowering our packs on ropes) until at the next prominence in your path through the chaos, it heaves back into view, closer now and seemingly taller, as one can see farther down its side. Not a mountain range, one now sees, but