# Could we terraform Mars by crashing a comet into it?



## matt-browne-sfw

This idea really exists: (M. Savage)


  Evaporate the dry ice caps (they are made of carbon dioxide) and thus raise the temperature. Send a comet (perhaps multiple comets) crashing in to Mars to bring in some water and to liberate some carbon dioxide and water from the soil. Use algae to turn carbon dioxide into oxygen.

Any thoughts?


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## The Ace

It would be fun finding out.   Just don't put the US military in charge of the scheme, for some reason a few people seem to be rather fond of this planet.


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## Nik

*Terraforming-- THE Book...*

Terraforming: Engineering Planetary Environments, by Martyn J

One comet won't do, a couple of dozen might but, IIRC, you'd have to be careful not to strip existing atmosphere on subsequent impacts....

You need the tour-de-force by Martyn Fogg.

Sorry, my copy's packed away else I could have quoted solid numbers...


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## Delvo

It would take a lot more than dozens to create enough atmosphere for the whole planet; it would have to be well into the thousands, probably millions. One proposal to get enough of them was to send a self-replicating robot into the Oort Cloud to land on an object, mine for resources, build more of itself which then launch to seek out other objects, and then somehow steer the object in toward Mars. Only with the robots manufacturing more of themselves could a large enough number of objects be brought in in a reasonable amount of time, and even that was still centuries. Think of it this way: how many miles wide are these comets? And how many miles long and wide is a planet's surface, and how many miles tall would its atmosphere be? The former number is so tiny compared to the following ones that it wouldn't really be noticed. That's why things like Mars and the moon have many craters but little or no atmosphere already: because those impacts just don't donate much gas.

But even if we could fix the atmosphere on mars, that wouldn't be enough. Its "soil" is physically and chemically not much like anything that plants can grow in, and even if it could be suitably organified, that would still leave two other big problems.

One is its gravity. It's not only unhealthy for Earth life forms and impossible to move in in the way that Earth life forms are designed to move, but also really weak for holding on to whatever atmosphere we give it, so even if we modified the DNA of every species we took with us to handle the gravity and gave the planet an atmosphere, the atmosphere would be short-lived. Planets' gravity can only be increased by an increase in mass, and the project of increasing Mars's mass enough to make a difference would be millions of times bigger. For example, consider one of the most massive objects that ever hit planets: the kind of asteroid/comet that is thought to be behind several of Earth's mass extinctions or maybe all of them. They're a few miles wide. A million of those would add up to a volume just a few hundred miles long, wide, and tall. Compared to Mars, that's like a small grape or marble compared to slightly larger than average apple or orange... in volume. But they're not as dense, so the actual fraction of the planet's mass that those million objects would add up to is an even lower fraction than that, so making an appreciable percentage of increase in mass would require multiple millions. And the goal would need to be an increase of something like 200%; most of what was there when we were done wouldn't even be from Mars. Even crashing our moon into it, even if all of that matter stayed in one piece instead of getting knocked off into space, would still leave the combined moon-Mars object with less than half of Earth's gravity. And adding that amount of mass, even if possible, also introduces complications in the planet's rotational and orbital movements because when the mass is transferred, momentum is too. And the impacts would create huge amounts of heat which would take hundreds of millions of years to cool off at least. (Earth's had billions and still hasn't finished cooling off yet.)

The other remaining problem is worse. Mars’s greatest and least distances from the sun in its year are 1.38 and 1.67 times as far as Earth’s average distance from the sun. That means that Mars receives from 35.9% to 52.5% as much sunlight as Earth’s average overall... barely over half at best, and just as often barely over a third. And not only does that keep the planet cold, but plants can't photosynthesize with light that just isn't there, so finding a way to warm it up wouldn't help with that. And look at that range alone. That’s the fluctuation due to the distance from the sun flopping up and down in an elliptical orbit. Earth’s orbit is more circular; the greatest distance is 4.3% greater than the least. For Mars, the equivalent figure is 20.6%. Earth’s relatively circular orbit allows the seasons to be controlled ultimately by the tilt of its axis, which makes fairly little difference and keeps things here mostly constant in the big picture, even though the seasonal changes can seem drastic to us. On Mars, the incoming light varies so much that it creates huge swings in temperature that overwhelm the effects of its axial tilt, AND its tilt is about a degree and a half more drastic than ours anyway, so the annual weather fluctuations (and stormy periods) would be several times greater than anything we've ever seen. If you terraformed it to the right temperature for half of the year, it would still be too hot or cold for the other half, and that's still saying nothing about water vaporization and humidity levels and storm wind speeds. Tinker with the atmosphere all you want, and you'll still be thwarted by its size and orbit.


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## mosaix

Should we?


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## chrispenycate

How many comets it would take relies on the size of the comet, and the percentage of the mass which is volatiles. It probably wouldn't be millions; a few megatons of gas go a long way.
As regard the "Short lived" for the atmosphere, sure, a few molecules would achieve escape velocity and leave the planet for ever. More would fall back though, and this temporary atmosphere could easily hang around for a few hundred thousand years, short in terms of planetary age or evolving lifeforms, but considerable in terms of human history (it doesn't just hiss off into space like a punctured balloon)
As regards the effects of gravity on living beings, we just don't know. Not enough experience. But fish and certain very small insects are effectively living independent of gravity so life can adapt- and I have great faith in life's ability to adapt to any conditions.
Obviously, the atmosphere generates by vaporising a comet would not be anything breathable, and even anaerobics would probably complain, so oases of terrestriod conditions would be needed, from which life – tough life, adaptable life - could invade the surface. Centuries, at least probably millenia before an unprotected mammal like me could walk outside; but I consider the comet strike (or, even better, spiralling in graze, to throw less of the newly acquired matter back out into space) a good start at warming the place up, while adding a blanket that might, in the fullness of time, be converted into air.
I hope they arrange the impacts when Earth is in conjunction; imagine the lines of fire spreading over the face of the red planet as the comet fragments and boils, sonic booms causing marsquakes, fireworks across a hemisphere… 
Well, I won't be around to see it.


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## Nik

I've a 'short' from my Convention arc about comet-impact Terraforming of Nova!, just posting it in Critique section.

Last time I edited it was a decade ago, original dates back thrice that, but still fun...


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## RVM45

.....Have any of y'all ever heard of "Paraterraforming"?

.....According to one theory; there will never be enough gases to terraform Mars properly. However, at Martion gravity; it should be quite possible to build enough one mile high towers to cover Mars with a giant cleart canopy; and pump in a mile high blanket of Earth-pressure atmoshere.

.....What's really neat, is that theoretically you could Paraterraform the moon- though I have no idea what kind of climate would result from 14 days of sun; folowed by 14 days of night. Perhaps, given the smallness of the world; and designing it judiciously; you could get enough atmospheric mixing to avoid the worst extremes of temperature.

Matthew Johnson's Terraforming Method - Article - Red Colony

.....Check out this article/site.

.....RVM45


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## woodsman

mosaix said:


> Should we?


 
I think this is a key question, personally. 

I'd love to see the moon colonised in a small way, but then I wonder if we have the right to start trashing other areas of the solar system?

Wouldn't it be better to create a false atmosphere inside giant revolving cylinders, with the plants growing on the inside of the outer walls and transparent panels allowing sunlight in? these would limit destruction of other systems/planets whilst providing small areas for self-sufficient communities to live in. 

Would we even need to terraform Mars? Couldn't plants be grown underground - hydroponically - with the correct resources. Supporting a mining/holiday based colony?


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## Ice fyre

Err I wouldnt be recomending a Holiday on Mars, I mean quite apart from the rebels and mutants living there the place quite literally has no atmosphere!

Or was that just me going into the Edinburgh branch of recall? 

Seriously though I believe that they are speculating about water under the polar caps, who knows what bacteria could be still living there. If any ever evolved in the first place. If it did I supect there may be surviors still in the ice. we have seen how well some species can survive in the most hostile enviroments on earth, some even can survive the vacum of space.

My point is wont that ease the nescessary load of comets required. Also how many do they think are hanging around our solar system? Would we have enough?


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## robertinventor

Actually there are plenty of comets available in the Kuiper belt or in the Oort cloud. So long as you are in no particular hurry they could be moved to the inner solar system via the "interplanetary transport network" of trajectories using gravity assist and requiring minimal delta v to transport anything from almost anywhere to almost anywhere else in the solar system.

The original idea as I've seen it described by Zubrin is to use methane rich comets. So the idea is to use it as a greenhouse gas. It could warm up the planet quite quickly and seems reasonably achievable. Quite a large project but not exactly quite "mega-engineering".

Yes lots of volatiles on Mars but no-one knows quite how much. Might be that much of the early atmosphere and oceans are still there on Mars in frozen form. If so, the main problem is how to get them back into the atmosphere - and will they stay there.


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## robertinventor

woodsman said:


> I think this is a key question, personally.
> 
> I'd love to see the moon colonised in a small way, but then I wonder if we have the right to start trashing other areas of the solar system?
> 
> Wouldn't it be better to create a false atmosphere inside giant revolving cylinders, with the plants growing on the inside of the outer walls and transparent panels allowing sunlight in? these would limit destruction of other systems/planets whilst providing small areas for self-sufficient communities to live in.
> 
> Would we even need to terraform Mars? Couldn't plants be grown underground - hydroponically - with the correct resources. Supporting a mining/holiday based colony?



Absolutely no need to terraform Mars. There is enough material in the asteroid belt to make habitats for trillions of colonists. I worked out that Ceres alone can supply material for 700 times the land area of the Earth with a 4 meter thickness enough to shield from solar radiation twice over.

So free flying and orbital colonies can support thousands times as many colonists as the surface of rocky bodies in our solar system.


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## jastius

I agree with you, Robert. Should we start destroying the planets beyond our own with our overweening ambitions, we just export the same set of problems we already have. only this time  we are also eliminating any native flora or fauna even if it only exists in fossilized or microbial forms. what exists is important to preserve. we seem to forget this in the grand march to progress. 

much safer really to colonize orbitals that can be rearranged later ..

What is needed it a near earth type planet.. so why not share the elliptical with another? spin a new satellite into path at the far end of our elliptic plane. terraform all the dragged comets into a near earth.


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## Gordian Knot

One fatal flaw to terraforming Mars I haven't seen listed yet. If it has, my bad for repeating. The single greatest problem that would prevent us from terraforming Mars is the same thing that destroyed the planet's original atmosphere in the first place. Mars does not have the magnetosphere that we do which protects our atmosphere. Any climate we could potentially create on Mars would just be sheared off by the solar winds all over again.


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## robertinventor

woodsman said:


> I think this is a key question, personally.
> 
> I'd love to see the moon colonised in a small way, but then I wonder if we have the right to start trashing other areas of the solar system?
> 
> Wouldn't it be better to create a false atmosphere inside giant revolving cylinders, with the plants growing on the inside of the outer walls and transparent panels allowing sunlight in? these would limit destruction of other systems/planets whilst providing small areas for self-sufficient communities to live in.
> 
> Would we even need to terraform Mars? Couldn't plants be grown underground - hydroponically - with the correct resources. Supporting a mining/holiday based colony?



I'd argue that we absolutely need to have experience of an artificial atmosphere inside habitats before we think about terraforming Mars. Don't need to be on the surface, actually easier in space. Because it costs much less to get materials from Earth to Mars orbit (much less delta v) and there is a very good chance you can get everything you need from the Martian moons (which are thought to probably have ice in their interior though this is not known for sure yet). Either that or supplied from NEOs - very low delta v to get from them to Mars orbit.

Because in a habitat if you make a mistake, if worst comes to worst you can just remove all the soil and atmosphere and start again. If there is a build up of noxious gases in the atmosphere you can scrub it, and so on.

With a planet, if you make a mistake, not going to be easy to reverse it. If the mistake involves introducing the wrong life forms to the planet, or introducing e.g. aerobes too early so they consume the oxygen as fast as it is created - then there is almost zero chance of doing anything about it.

Landing humans on Mars I see as one thing that could be a mistake making it impossible to terraform it. Because we are like a big zoo and botanical garden all combined in one at the micro-organism level. Just our skin has a trillion micro-organisms in 1000 species in 19 genera (genera is a classification level one higher than animals with backbones).  Then there is our food, water, the air we breath, and the micro-organisms in our guts. 

I see no way at all you could confine that to one small section of Mars. Especially since there may be habitats on Mars that micro-organisms can colonize (the morning and evening dew on the surface already shown to support lichens enough to photosynthesize, and possibly thin films of cold salty brine near the surface warmed up by the midday sun enough for life to reproduce).

Some say that it doesn't matter because none of our micro-organisms will survive on Mars, but some micro-organisms are "polyextremophiles" able to survive just fine in a very wide range of habitats. Dump so many on Mars and probably at least one or two will survive. Especially since the habitats will include areas like the airlocks where micro-organisms will be able to acclimatize to the Mars conditions and gradually harden through micro-evolution.

I wish I was a good sci. fl. writer. What I'd like to do is to write a story about first of all the great race to Mars. Could include a company like Mars one. Follow the tribulations and successes - and then when they get there - after all the euphoria of getting there first - gradually it dawns on them that they have contaminated Mars irreversibly. 

This could happen surprisingly quickly, by exponential growth. Even averaging just one division a month, micro-organisms could colonize all suitable habitats on Mars within a few years by exponential growth. So you might even see the tide of life contamination visibly spread across the planet from space - maybe turning it a muddy reddish-green or a greyish-black.

So gradually they realise this. Meanwhile they also can be afflicted by e.g. allergies to the Mars dust and to any existing Martian lifeforms. This could (if you want to make it really dystopian) be a fatal allergy like peanut allergies, so some or all of them die.

They also realize that from then on their expedition to Mars will be remembered as the expedition that contaminated the planet and made it impossible to terraform it successfully. Can do it so that the life introduces some noxious gas to the atmosphere such as NO2 or Ammonnia, which is then very hard to do anything about, and could also reduce the amount of CO2 as well making a situation that is very hard to reverse.

Also then they find tantalizing signs of an early life form on Mars that followed a different pathway from DNA, and either it actually survived until just before their expedition - or else - that there were biologically perfect remains of it that got "eaten" by the introduced microbes. Maybe just in one small niche on Mars (probably make a better story) - as the early Mars had bodies of water separated from each other, and no continental drift this could well happen. And the scientists are fascinated by it but the evidence is so totally trashed by the influence of the introduced life that they can only speculate about how exactly it lived. Perhaps they try to recreate it but are unable to make anything able to reproduce in their experiments.

So would be a distopian short story. You could also do it with humour, though that would require a deft touch to do well.

Possibly as an alternate history type thing. Have some small event in the past of one of the characters, and it going one way leads to this future, and it going the other way leads to a future with the Mars surface left pristine and explored from orbit via telepresence.

I'd like to write this because I think people are often more influenced by sci fi (also sci fi. movies) than by science. And I think partly why so many feel it must be okay to send humans to Mars is because there have been story after story about Mars colonization happening successfully and even terraforming of Mars - and hardly any stories where it went wrong, especially ones where the human beings by landing on the planet contaminated it irreversibly. I can only think of one short story that handles that theme.

The trouble is though I've tried my hand at short sci fi stories myself, I am not very good at it. Am okay at the science of course, and pretty good at descriptions of landscapes and not too bad with the technology. Where I fall down is in characterization. Getting a bit better but feel I'm not good at even the most basic believable characters yet. Just don't seem to have a great insight into how people "tick" and what motivates them in a way that is useful for writing fiction.

Maybe some of you here though may be interested in some of these ideas?


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## chrispenycate

Much of this is about energy sum, and time taken. If you could get an atmosphere on Mars at a relatively trivial price – oh, trillions, (of dollars, huan, Euros, Afros, almost whatever; order of magnitude stuff) but only sort of planetary military budget figures, with some hope of, at some future time, making it breathable) you can start installing colonists immediately. Moving a comet, if you've got time, requires little more than a hydrogen bomb up its tail. Assuming a near unlimited energy you can live underground (equivalent of asteroid) and the gravity well needn't be too disturbing, and there an atmosphere is not essential (but if you're going to get it by comet impact, start early; settlers are not going to approve of the 'serious turbulence' of anything that size hitting an atmosphere, let alone a habitation).

Now, I'm not against asteroid colonisation – see my latest in critiques – but, convenient as lacking an appreciable gravity well might be, we don't know if humans can survive the lack of gravity long term. Which, with present day physics, means spinning up an asteroid to get a decent fraction of a gee inside, which is more energy than you might think, and will take longer. Building a habitat out of prefabricated parts robot mined and shaped; if you've got enough mass for decent shielding, it's nearly as much of a problem as your tunnelled asteroid, though you don't have to worry about wobble, or bits flying off.

Who was the author who proposed drilling into a nickel iron asteroid, putting a big lump of comet ice (or maybe it was Saturn ring ice) into the heart of it and welding in the plug, then turning slowly in front of a really big solar focusing mirror,until the metal begins to melt and the steam blows it up like a balloon. Then you drill symmetrical near tangental holes round the rim (with a laser, not a Black and Decker) and the steam spins the whole caboodle up to your predetermined rotation speed and cools it at the same time..?

Better weld that plug in real tight, podner.


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## jastius

robert, haven't you ever read ray bradbury's the martian chronicles? 

i  could write you stories in a heartbeat if that is what you wish, but i would rather not trod upon the feet of the master to do it, if i can help it.. 

and i have no idea whether anything i can come up with would be appreciably different.. 

but if you want a story, i love writing them.

and couldn't we rectify the magnetosphere problem by the injection of a molten iron core crashed into the center of mars that is positively and negatively charged?
heat it up with a giant solar laser into plasma  and achieve a magnetic field array.?


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## robertinventor

Oh, I haven't read the Martian Chronicles. I've heard the name many times before, not sure how I missed out on them. Have checked the summary on Wikipedia and I have definitely not ready those stories.

The story I remember was a short whimsical one about an astronaut who traveled to Venus - that dates it because Venus was a planet you could explore on foot in a spacesuit in the story, I think with a spacesuit but there was no known life on the planet.

The astronaut encounters an alien lifeform on the planet, kind of plant like but more mobile than a plant. He takes photos of it with great excitement. Then he departs but leaves his human wastes sealed in a bag. Little does he know that hte photos he took were the only ones ever to be taken of this life form which was attracted to the human waste, rich in (might be phosphorus, I'm not sure) and tried to eat it but it was too rich for it and it died.

Now I might have mis-remembered some of those details and made up stuff to fill the gaps, is hard to know after so long as I read it years ago. Recently did a google search and found it again but forget the details and can't find it now. Can't remember the author. Could be Arthur C. Clarke just possibly. Anyone know it?

BTW this is my attempt at the sort of story, as a kind of flash fiction, maybe the only thing I could possibly do. I was going to do different versions each for a different colour of Mars. So Red for the pristine, blue green could be a fully terraformed successfully with lakes, seas and vegetation just like Earth, green could be a world mainly of vegetation and so on. 

Could also have e.g. sky blue for a Mars-formed Mars - the idea that if there is indigenous life on Mars maybe different basis from Earth life then you could try to foster the native life rather than Earth life, so "mars form it" and maybe you have a sky blue coloured lichen that spreads over the rocks (or something, some distinctive colour). 

And also another possibility is a Mars where life never evolved at all but you have evidence of the early stages just before life formed. Then you could warm it up and then see how it develops - though could be tricky because of modern life easily contaminating it. Anyway that one could be blue and red (because no life on land at that early stage) so maybe a magenta colour.

"
Black Mars

The sands of Mars are black. The sands of mars were red, they now are black. Why are they black? Why are there no humans on Mars?

You get news casts from Ganymede, the ice poles of Mercury, even Venus now that it's terraformed, but Mars is in quarantine, no-one is permitted to land there except for robots.

It started in the early twenty first century. Was great to start with, they started a human colony, with regular supplies from Earth. The search for Mars life was a failure though. Fossils were found, only a thousand years old. But all the living things were related to Earth life. They were traced back to the first human spaceships to Mars.

Humans had made the Martian life extinct.

Then one particular type of black mould adapted to the Mars surface. From Earth you could see the black stain spread out from the habitats, first slowly, just a small patch around the settlement. Then with exponential growth it spread faster and faster until within a few years the entire surface was covered.

Humans were severely allergic to the black mould. It was a polyextremophile also able to survive in human occupied habs. Many died before the planet finally was evacuated and quarantined. 
"

Work in progress obviously, and needs a punchier ending. (Or does it? I'm too close to it, does it work as is? I feel it needs a little something to give it extra impact.) 

But you get the idea .

I can sort of do stuff like that, at least not too bad at describing things, but when you get humans involved I just don't have the knack, have tried. Also not too good at a story line either. I suppose it is the sort of thing you can work at and learn the craft and main thing may be just that I haven't given it enough time.

Anyway if anyone else wants to play with the idea and run with it, I think you could do stuff like this in lots of ways either flash fiction or longer stories. Could be humorous or sad, or tragic.

It would be up to date and topical with the Martians as micro-organisms or non existent - so don't think you would need to worry too much about stepping on Ray Bradbury's toes .

I don't know about your magnetic Mars idea, maybe there is something in it? Maybe collide Mercury with Mars, as it has a significant magnetic field already, if you could do it somehow without disturbing the rest of the solar system.

You can do long term changes of the orbits of planets in the solar system by not too hard to believe mega-engineering if in a very stable civilization. What you need are small asteroids that continually go back and forth between the bodies, making course corrections as they approach one or the other deep in the gravity well. So could for instance in that way speed up the orbital motion of Mars at its aphelion and slow it at its perihelion and so circularize it. Then could also slightly slow down Jupiter to make no significant difference to it, and transfer all that angular momentum to Mercury. 

So here is an idea of how it might work - just a guess, you would need someone to test it with a proper gravity simulation. Would probably take many millenia, even geological time periods so needs an advanced civilization with a lot of patience.

The aim would be to get a close flyby of Venus by Mercury which would then send it careering through the solar system and eventually to a circum-solar orbit close to that of Mars (through repeated encounters with Mars and the other asteroid) and then finally arrange the gentlest possible impact with Mars so that hardly any material is lost, and the dense core of Mercury just sinks into the centre of Mars.

I don't know for sure if that would work but it might be worth a try if one can find someone to do the sums properly. . Just an idea.


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## chrispenycate

I don't think Mercury's a good idea.

Firstly because, even if it's a small planet it's still a planet, in a stable orbit, and would require an unreasonable amount of energy to move it before the sun  gets round to swallowing it (which is a long time hence).

Secondly, because it is a very small planet, relative to Venus, and thus is going to have relatively little influence

And thirdly, because it is inside Venus' orbit the total vector sum of the movements is going to fend to pull Venus closer to the sun, not push it out.

If you want to play Velikovski billiards, start with something well out; I suggest Uranus. This is a gas giant (actually an ice giant, but the same elements) , so no shortage of fuel (and we're not going to need it later; I had a project for someone building a Dyson swarm in a thousand years, and most of the matter I mined from Mercury; nice high energy gradient). By fusing a fair amount of the hydrogen in Uranus' atmosphere and directing it as a jet we make the orbit steadily more elliptical until, after a few centuries (you weren't in a hurry, were you?) the perigee reaches the orbit of Venus then, careful calculation, trim it in, and use its gravitational field to drag Venus further out. If you're really careful you can do a Mars flyby, and pull that further in. Since you have your powered tow truck, keep bringing it close to each to recircularise the orbits; a few more centuries, who's counting, and you drag excess atmosphere off Venus with every correction (Getting it back from Uranus and farting it into Mars might be a little more problematic).  Venus' atmosphere is still drastically poisonous, but a whole lot thinner. If we want to pound some comets into Mars, Uranus' apogee is out in the Oort cloud, and you can probably pick up a couple while passing through.

Like Halley's comet your (steadily diminishing but still more massive than Earth) keeps flying through the inner solar system every century or so, which is dangerous and disruptive, so we either recircularise its orbit a little further in than it used to be, or extend the ellipse until it achieves solar escape velocity (and put your starships in orbit round it, for convenient refueling).


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## robertinventor

Okay Mercury was just a thought. Suggested it mainly because of its magnetic field and because it is quite small so maybe easier to move round without doing too much to the other planets. Plus some simulations gave a small chance that it would exit the solar system anyway through chaotic interactions of its orbit with the other planets.

But it is obviously a pretty way out idea with issues for stability of solar system, and taking ages to do it.

But if you can use the atmosphere of a gas giant to propel it around the solar system you have a lot of traction, though also opportunity to do serious damage to the solar system, maybe that can be avoided by careful choice of orbits so only the target planet is affected??? Plus many flybys of Jupiter at just the right time to correct its orbit?

Anyway, I'll leave you to work out the details of your idea . Sort of thing you can do in sci. fi. anyway and maybe some unimaginable for us technology of a few centuries or millennia from now.


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## chrispenycate

Oh, if I want to do it I've got my graviotronic drive; shifts the gravity field from omnidirectional to slightly directional, the amount of power required depending on how directional you want it, and the magnitude of the local gravity field. You just organise that every time Mars and Venus are in conjunction you intensify the attraction between them by a few percent. Much less dangerous than the stream of high-speed alpha particles jetting out of Uranus (and faster, too) pulling Mars in and Venus out.

Now I just need to invent it (I need it for my WIP anyway).


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## jastius

what about a vectored virtual gyroscope that  works by sub neutrino pulse in a patterned form. a virtual cern reaction. minimal equipment and only the diddly bits start diddling.. 
two actual poles and a simulated network of signal condensers that work upon the surface of said planet. ( instead of being an actual physically attached network)

this network would outline the form of the planetary electromagnetic spectrum. it would serve as both a map and as a energy redistribution and amplification system. each guidepost would act in conjunction with its alternates both around it and on the other side of the planet.

 the idea being that you are holding the planet on a rotational axis at each of these points, but are not piercing the planet all the way through.

 instead you have a virtual axis of rotation induced through the energy pulse of the counteracting beams. by firing these axis' in a certain order, you would re-allign the spin and create wobble and secure an atmosphere to the planetary body.


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## BetaWolf

I agree that there's really no need to terraform Mars. The lack of geological activity is a big problem in itself. Spinning orbital habitats at the proper Lagrangian points would be a better idea. 

As for private enterprise, I don't see what Mars has that any capitalist would want. The asteroid belt is a good prize; Venus's atmosphere is full of interesting gases and holds more allure personally. Mars is just dead, low-grav, etc. I've got some story ideas that I don't want to share yet, but I think that Mars is a low priority target, this half-century's equivalent of the moon landing: Wow, we got there. Plant the flag and go home.


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## Vertigo

If you do want to see some ideas on terraforming Mars you might like to the Kim Stanley Robinson's books Red Mars, Green Mars and Blue Mars. I've only read the first book and whilst the story was painfully slow, the ideas presented were fascinating. However he does rather depend on finding vast aquifers below the Mars' surface which is ultimately (and rather optimistically) pure speculation.

One of the biggest problems you would have (other than the major radiation one already mentioned, which I think is probably the biggest stopper) is heating the planet and its atmosphere, and that has to be done before you can have liquid water.


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## Mirannan

Gordian Knot said:


> One fatal flaw to terraforming Mars I haven't seen listed yet. If it has, my bad for repeating. The single greatest problem that would prevent us from terraforming Mars is the same thing that destroyed the planet's original atmosphere in the first place. Mars does not have the magnetosphere that we do which protects our atmosphere. Any climate we could potentially create on Mars would just be sheared off by the solar winds all over again.



You are quite right. The low gravity of Mars would cause similar problems. However, the timescale is the key here; the introduced atmosphere would last probably millions of years - and there is no reason whatsoever why, having done it once, more comets couldn't be diverted for a refill.

As for the exotic and highly corrosive chemicals in Martian soil - again, quite right. However, most of them are unstable in the presence of significant amounts of water.

IMHO the main problems would be the climate (nothing to be done about low insolation, and an eccentric orbit wouldn't help), the low gravity (potentially) and one problem that hasn't been mentioned yet; Mars is highly asymmetrical between north and south, so just about all the water would end up in the Martian arctic and subarctic. The elevation difference is a couple of kilometres, IIRC. High radiation levels due to the lack of a magnetosphere might also be a problem.

Mars, even if marginally terraformed, will probably always be for the most part a cold, dry desert with extreme seasons. As someone else has already said, IMHO orbital habitats would give much more, and more pleasant, bang for the buck.


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## chrispenycate

Ah, but rotating habitats have to be built, constructions bigger than anything mankind has so far attempted in an environment we haven't mastered with raw materials – not exactly lacking, but not convenient for delivery, and no convenient construction shacks (if you think I'm going to trust pre-programmed robots to do the work unsupervised, you've never worked with Windows) living off the ships that brought us there. Pushes the delivery date a long way down the line, probably a century from starting; and where are the finances going to come from during that period?

Asteroids are better. At least you start with a physical structure, and you can start exporting minerals practically straight away (although how long they will take to deliver is another question). You're an awfully long way from home in case of having forgotten to bring the tin opener, but you've got line of sight communications and can go on receiving Coronation Street, which is more than the covered wagon pioneers crossing the prairies could say. Still, they did have large reserves of breathable air, frequently drinkable water, and didn't have to carry vitamin supplements.

Suppose that you did manage to get enough volatiles onto Mars, perhaps, as the thread title suggests, by crashing a series of small comets into it, or preferably bringing them in low angle to burn up in the atmosphere. This would, at the same time, bring up the temperature and, if you're clever enough, circularise the orbit a bit. (unfortunately moving the orbit closer to the sun requires rather more mv that we're considering). So the atmosphere would drift off, some perhaps carried by solar wind, but much because, with the lower gravitational pull, the molecules would achieve escape velocity at livable temperatures, much as practically all the helium in Earth's atmosphere is there from radioactive decay (alpha particles = helium nuclei). What matter? If it only hangs around for a hundred thousand years (a mere heartbeat of planetary time) it's enough time for humanity to move on to the next stage, whatever that may be.


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