Thank you for your answers! I’m flattered, but most of my knowledge is just casual interest in space exploration and vague recollections of post-apocalyptic stories.
One of the most relevant would be
Toxic Stars, where Mars was forced to survive on its own after all civilisation on Earth and Luna was instantly destroyed by an unexpected cataclysm. Unfortunately, the thread is long dead and
the author hasn't been online since 2019; but the worldbuilding is
incredible, and I'd still recommend you to read the story in its entirety.
Florida/Ictoria in 6500 AD, a far-future medieval setting where our history and legacy have all but passed into myth, is also a good reference. And of course, the
Mars Trilogy is a respected classic for good reason. As for technical reading,
the blog of Casey Handmer (an ex-NASA JPL physicist) is one of the best layman’s resources available for Martian colonisation topics. His free e-books,
How to Get to Earth from Mars: Solving the Hard Part First and
How To Industrialize Mars: A Strategy For Self-Sufficiency are both invaluable references.
Sorry about the late reply; between office work, re-reading the entirety of
Toxic Stars, browsing two dozen articles and skimming three books about human life on Mars, it took far more time than I'd have liked to finish this brief writeup. For your consideration, here are my thoughts on fleshing out your scenario into a proper hard sci-fi setting:
1. The Last War, the Great Dying, the Long Night and the Second Dawn: your setting requires a cataclysm devastating enough to destroy an interplanetary civilisation to the point that all historical knowledge was lost, but not devastating enough to render humanity extinct or Mars and Earth uninhabitable. A solar flare or asteroid strike would not be sufficient; an interstellar civilisation of this scale would have advanced enough that hardening vital infrastructure against such known threats would likely be well within their means (not to mention that both events would only affect a single world, not the rest of the system). Nuclear war won't cut it either, since neutral states will not be targeted; all societies will suffer a collapse in technological capability and living standards, but at least a few will be able to maintain continuity of government and the electrical grid throughout the subsequent dark age, ready to rise again after a century or two (or far faster, if help from off-world survivors is available).
I would suggest a system-wide war, triggered by geopolitical tensions between the major colonial powers on Earth; this would draw in the rest of Sol into the conflagration. Extensive use of nuclear and orbital strikes, designed to deny valuable infrastructure to the enemy, leads to widespread devastation and irreversible loss of advanced technology across the entire system. As the war draws to a close, a secret bioweapons facility belonging to the losing side was unknowingly struck by kinetic kill vehicles targeting a nearby spaceport, accidentally releasing an engineered plague (artificially high transmissibility, extremely long incubation period, near-universal mortality rate - a la
Blue Death,
Simian Flu or
Captain Trips).
A last-ditch measure originally meant to be unleashed only after a domestic vaccination programme had been completed, the actual virus was a flawed prototype which swiftly mutated beyond its creators' worst fears. Carried by refugees to hitherto safe zones and neutral locations, the plague spreads like wildfire unnoticed; detection and treatment was stymied by devastated healthcare infrastructure and pervasive social instability across Sol. By the time the first deaths occur, it is already too late for any organised effort at epidemic mitigation, doomsday sheltering, or even last-ditch "fling a light into the future" knowledge preservation - the wholesale collapse of interplanetary civilisation came about within less than a single year, with mass deaths occurring so quickly that the vast majority of bodies were left unburied. As civilian authority and military command chains rapidly disintegrated, desperate field commanders attempted to create "firebreaks" against the plague by launching nuclear strikes against major refugee concentrations and infected population centres. This not only proved to be too little, too late; but combined with the war's earlier devastation, the firebreaks were enough to tip the climate scales and trigger a nuclear winter: the homeworld's number of plague survivors, already small, is now winnowed by hunger, cold and radiation to the point of near-extinction. Mars, thankfully, is spared a similar fratricide due to the lack of any ground-based ICBM installations. A few kinetic strikes, however, was still launched against Watney's Landing, the largest city (and thus, the largest infected population) on Mars; the first human footsteps on the Red Planet is scoured away in fire.
On Earth and Mars, the few who are either naturally immune or miraculously survived the plague retreated to the countryside, swiftly regressing into hunter-gatherer tribes as the exceedingly few technical specialists that remain dies of hunger, violence or old age. Physical books were the quickest storage medium to decay, with magnetic tapes following suit within a few decades and solid-state drives in a century or two; but knowledge of a precursor civilisation is still common on Earth due to the sheer extent of recognisable ruins across the homeworld.
[1] On Mars, the few extant settlements were forgotten after only a few generations: either vaporised by WMD strikes, dismantled for supplies by first-generation survivors, buried by dust storms in non-terraformed regions, or worn down by geological processes in terraformed ones.
Survivors on space stations, Lunar cities or asteroid bases are not so lucky; for those left without access to off-world transportation, starvation and suicide are their most common fates. While the orbitals and satellites will eventually reenter the atmosphere and disintegrate, any permanent structure located in stable locations with vacuum (airless moons, asteroids,
L4/L5 objects, deep-space stations) will survive more or less indefinitely; ripe for Mars to discover when the time is right.
[1] Note that this creates a potential plot hole: conditions on Earth (climate, geography, natural resources, precursor resources) are so much more favourable compared to Mars that realistically, it should be
Earthers who would first re-industrialise and take the lead in contacting Mars.
2. Terraforming and genetic engineering: completely transforming Mars into an Earthlike world is the sort of endeavour that would take a thousand years to finish, if not longer. Realistically, a civilisation that successfully terraformed Mars would almost certainly be advanced and dispersed enough that a system-wide civilisational collapse is unlikely.
For humans to survive on Mars, we would need both the right air mixture and the right atmospheric pressure. Sea level atmospheric pressure on Earth is 1,013 milibars; ideally, a 200 mbar atmosphere is enough to allow a physically fit human to breath from an oxygen mask without a pressure suit, while the Armstrong Limit of 68 mbar is the absolute lower limit. Below this level, surface bodily fluids begin to boil, and oxygen delivery can only be accomplished with a pressure suit.
By comparison, Mars' atmospheric pressure stands at a paltry 6.5 mbar. Terraforming would first involve raising the level of CO2 in the Martian atmosphere by a factor of 40, through melting the CO2 frozen into the regolith and the southern polar cap; this would not just thicken the atmosphere, but trigger a runaway greenhouse effect that would gradually warm Mars over the centuries.
As far as terraforming methods go, neither "nuking the poles" nor "crashing comets" are actually viable approaches in practice. The sum total yield of all existing warheads are only equivalent to 45 minutes of sunlight, so the nuclear option would barely shift the scales even if carefully buried beneath the ice caps. The comet option suffers from roughly the same logistical problems: the sheer quantity needed for terraforming purposes exceeds known reserves of comets, the energy and time required to redirect icy bodies from the outer solar system inward is utterly cost-prohibitive, and actually crashing so many comets into Mars would resurface the entire planet and kick up enough dust to
trigger a nuclear winter, ruining the whole "warming Mars" objective for centuries to come.
There are three viable approaches: the first to add heat, and the second and third to prevent that heat from escaping after it had arrived. They should all be simultaneously executed for maximum effect.
First,
orbital mirrors: capable of being made extremely thin (to save on material and weight) and curved (to concentrate sunlight on a particular area), a series of mirrors 100 km on a side could be constructed with as little as 40 tons of material - technically feasible for launch on a Falcon Heavy, then flown with solar wind pressure to Mars. So imagine the sheer scale of mirror arrays that could be constructed and launched by the great starships of the future, centuries from now; Martian subsurface resources could be melted down without any surface infrastructure, while carbonate and nitrate rocks can simply be vaporised to release more greenhouse gases.
Second,
dark lichen: by decreasing the Martian albedo (the amount of light reflected back into space, currently 15%), Mars could be made to absorb more heat energy from the sun. Dark-colored lichen (a symbiosis of fungi and cyanobacteria), gene-engineered to survive on the harsh surface, could be distributed across the planet; they would further grow and propagate essentially for free, saving enormous amounts of human time and effort.
Third,
greenhouse gases: CO2 is good at blocking thermal radiation across many wavelengths, but not nearly the best option out there; it does alllow some heat to escape through the atmosphere and back into space. To alleviate this, human-produced perfluorocarbons (PFCs), with thousands of times the lifespan and
Global Warming Potential of CO2, should be produced by rock-eating factories and pumped into the atmosphere as fast as possible. This can be accomplished over many decades by massive, automated, nuclear-powered digging machines, targeted at specific sites with natural resource abundance.
These processes, enacted in tandem, could likely give Mars a warm, wet atmosphere in only a few centuries. But this only means that
humans can walk round with nothing more than an oxygen mask and warm clothing; the vast majority of plants and animals are both oxygen-hungry, and unable to tolerate high CO2 levels regardless of how much O2 is available. Mars will need a higher level of oxygen on a per-area basis than Earth due to its low gravity; but converting half of the CO2 atmosphere into O2 would severely damage the greenhouse effect, cooling the planet once more.
As a result, I'd definitely argue for speeding up the timeframe to viable habitation by pairing the terraforming process with aggressive genetic engineering - not just for humans, but
all Earthen life brought to Mars. Altering the lifeform is far easier and more cost-effective than altering the planet: more efficient photosynthesis to counter the weaker Martian sunlight for plants, and CO2 and radiation tolerance gene-mods for both animals and plants (likewise for humans, but with the option of making do with a filter mask, protective gear and underground habitats).
And taking a page from
Toxic Stars, why stop there when
far more extensive augmentations could be developed, allowing human life to flourish on Mars long before the terraforming process has come to a conclusion? High cancer rates and short lifespans need not be inevitable, if Martians have already been artificially adapted before the Fall. This could also become a good narrative device, with augmented Martians effectively being a distinct subspecies compare to "baseline" Earthers; with both sides not knowing any kind of human other than their own, first contact between the two worlds would be a deep shock to both societies - their biological differences becoming a potential spark for future conflict.
Your cyanobacteria idea is actually quite workable, but instead of using comet impacts as the delivery mechanism (due to the problems I've stated above),I'd instead suggest a network of massive, automated dispersal satellites: extremely hardened against decay, and "armed" with enormous reserves of cyanobacteria reentry capsules in storage. Not targeted by any side during the Last War (everyone wanted Mars as a living prize, not a dead rock), the network survived even as human civilisation collapsed, periodically launching payloads of cyanobacteria onto the Martian surface for centuries afterwards. Some eventually succumbed to system malfunctions, debris impact, or simple decay; others were actually able to exhaust their cyanobacteria stores before going dark. By the time civilisation reemerged, the entire network had long since ceased functioning - but they had
succeeded in their task, the cyanobacteria colonies producing enough oxygen to not just sustain life in the Mariner's Valley, but gradually expanding its reach to previously barren lands. The people of Mars were unknowingly saved by ancient machines that they never knew - the satellites, their station-keeping thrusters exhausted, had long since reentered the atmosphere; while the ravages of millennia ensured that of the reentry capsules, nothing but unrecognisable scrap remains.
3. Power generation: this will be
the greatest obstacle to primitive Martians achieving their own Industrial Revolution, let alone regaining access to orbit.
The advent of industrial civilisation on Earth was made possible by the widespread availability of easy-to-access energy sources, anthracite coal being the most important; we used that energy to tap progressively harder-to-access energy sources, radically increasing the complexity of our civilisation. But should our globalised world undergoes a systemic collapse, some scholars have theorised that a second Industrial Revolution may very well be impossible - all easily-accessed energy sources have long since been exhausted, which precludes accessing higher-order sources such as deep-sea petroleum deposits and nuclear power. Without an electrical grid, the materials needed to sustain industrial civilisation (steel for machinery, potash for fertiliser, silicon for semiconductors, etc.) simply cannot be produced
en masse. And unlike past collapses, this one will be global in scale - there will be no outside capital, resources and knowledge to restart the cycle.
Now imagine restarting industrial civilisation on
Mars - a functionally energy-dead world. All of the above problems are now exacerbated a thousandfold.
- No fossil fuels, the most easily-accessed energy source for a preindustrial civilisation.
- No wood (and therefore, no charcoal) in non-terraformed regions.
- No hydropower in non-terraformed regions.
- No wind power outside regions where the atmosphere has thickened.
- Geothermal hotspots are few and far between, need considerable quantities of liquid coolant to operate, and will have major heat dissipation problems wherever the atmosphere remains thin (less atmospheric density means less heat convection; the majority of heat transfer will have to be either radiative or coolant-induced).
- Uranium ore deposits are of questionable viability: they may have mostly decayed away in naturally-occuring reactors, and in any case requires substantial industrial infrastructure to refine.
- Solar power suffers from both weaker irradiance (50-60% compared to Earth) and Martian dust storms capable of reducing power generation to zero.
- Virtually no precursor ruins, which means no preprocessed metals and alloys available to be reclaimed.
Even with a terraformed, breathable Mars, I'm struggling to see how widespread industrialisation could be triggered while strictly sticking to hard sci-fi. Without any abundant, easy-to-access energy source, a perfectly viable outcome would be Martian societies reaching a stable, low-tech equilibrium: your "medieval Mars", but lasting more or less indefinitely until Earth had advanced far enough to reestablish contact once more.
I know that "precursor ruins jumpstarting technological development" is a well-worn cliché, but perhaps this narrative option should still be given consideration. Some inspiration could be taken from "softer" sci-fi fiction: for example, combining
BattleTech's "
lostech" concept (super-hardened factories and data cores, capable of surviving centuries of neglect) with
Horizon: Zero Dawn's self-replicating machines and
Project Firebreak (an installation designed to stabilise the Yellowstone Caldera, doubling as a source of unlimited geothermal power). Note that self-replicating robots would be absolutely critical to achieving Martian autarky (
if we can make them work), so they're not at all out of place in a hard sci-fi setting.
Imagine a fully-automated, self-sustaining factory: physically hardened against decay beyond anything imaginable by 21st-century standards, maintained in pristine condition by a swarm of self-sustaining maintenance drones, and containing enough technical manuals and scientific data for even a preindustrial nation to jumpstart their sciences, if not to resume production right away. Buried miles underground to take advantage of a rare geothermal hotspot, this experimental installation was completed just after the Last War began; mothballed (but with its maintenance drones activated) before the Fall and forgotten afterwards, only to be stumbled upon millennia later by Martian explorers from a nation of your choice.
Option 1 (fully-operational factory): the exact products that the factory specialises in producing (raw materials, agricultural tools, industrial tools, consumer goods, medicine, genemods, ground vehicles, aircraft, surface-to-orbit vehicles. military weaponry, etc.) is up to you; different end products would result in radically divergent outcomes. A great power gaining control would be transformed into an unstoppable juggernaut, eventually unifying the Red Planet and landing the first Martians on Earth. A minor power would have neither the resource self-sufficiency nor the population to fully exploit their spoils and embark on global conquest; they will either willingly trade their technology and finished goods away in exchange for keeping their own sovereignty (which would lead to a broader dispersal of tech advances across Mars), or more likely be conquered by a great power (which goes back to the "juggernaut" outcome).
Option 2 (geothermal reactor and data archives only finished components, rest of factory never built): this is probably a better path narrative-wise, as Option 1 would either make the discovering nation overwhelmingly dominant, or trigger a global war for the factory's spoils. Even without any production capabilities, a functional geothermal reactor alone would be sufficient to bypass the energy source problem; the discoverers can tap into the factory's local grid for their energy needs, eventually allowing their own primitive electrical grid to be built. This would also lead to a far more "natural" pace of technological development: having an effectively infinite power source and some scientific theory is great, but all Martians will still have to build their own infrastructure from the ground up. This will take enough time that scientific advancements will be able to diffuse across national borders, resulting in a more equitable distribution of technological bounties; ultimately leading to Mars remaining divided between nations and empires, instead of being united by force. By comparison, Option 1 would have resulted in the controlling power having enormously superior technology compared to everyone else; I'm pretty sure that you don't want your setting to have railgun tanks and power-armored infantry slaughtering helpless horse cavalry, like something out of an ISOT fic.
The data archives within would be almost entirely technical in nature, allowing Martian sciences to advance by leaps and bounds after they are translated (all existing Martian tongues would be descended from the most prominent Earth languages spoken by pre-Fall colonists; the manuals would almost certainly be translatable with dedicated effort - English being the equivalent of ancient Latin or Egyptian hieroglyphs at worst, not something completely undecipherable like Linear A). The lack of any historical and cultural data is regrettable, but the mere existence of the reactor would prove beyond any reasonable doubt that there
was a precursor civilisation; gradually leading to the Earth Origin theory becoming the dominant paradigm.
I hope that my thoughts had been of some help; of course, you don't have to use any of my ideas if you think they won't be a good fit. I'm looking forward to reading the finished setting - and of course, feel free to DM me if you have any further questions.
