The Red Mars trilogy, by Kim Stanley Robinson, has a fairly realistic depiction of how Martian terraforming could be accomplished.
The biggest obstacle to terra-forming Mars is its lack of a strong magnetic field. Any atmosphere we were to somehow generate would eventually blow away in the solar wind. Short of dropping Ceres and possibly Vesta on Mars, I don’t know how you would be able to get an iron core big enough to have a spinning liquid component.
if only you had total recall.
Quaid, start the reactor!
Sharon Stone must have something to do with it.
You paid for a vacation and woke up and went back to your life and wife.
However, let’s not get into this old debate again. 
You’d need an environmental impact statement from God.
Yes, but that process takes a LONG time.
If mars is close enough to a tipping point, like a large comet strike could kick start transforming then it is possible to the same degree that we may be able to prevent earth from being struck with a large comet. This is also very dependent on having the comet in the right place and time.
Another reasonable approach would be to find or bio-engineer a microbe that could thrive in the environment on mars and start to alter it’s climate, by perhaps releasing greenhouse gases.
Along the lines of the above, creating self replicating nanobots to do the above.
Other macro level methods I don’t feel have a chance unless we can get to a gas releasing stage like we have on earth with the burning f fossil fuels.
Or, even more plausibly…
Jupiter’s almost big enough to become a star, right? So we just find some hydrogen – I think Saturn can spare some – and poof! Suddenly mars is in a habitable zone. At least some of the time.
I think the best bet would be to create some sort of gravity field (i.e. wiggly science fiction) that would hold the atmosphere close to the generator, large enough for a community and some farming. Maybe you could link several together.
To Io, Ganymede, and Callisto it did, you mean. The lack of a drop of sweat on my brow proves I’m telling the truth!
What bacteria is this?
The title of the thread implies “possible” in the context of reality not invoking special conceits of science fiction. If we could control gravity to the extent of being able to create Earth-normal field on Mars and contain an atmosphere, we’d be far beyond needing to terraform worlds; you could build Escher-like structures with variable gravity, protected by repelling any potentially hazardous objects with the same capability.
Stranger
What about not terra-forming Mars? I like the idea of inflatable habitats. Once established, would it be possible to make such things as concrete and glass from the Martian environment? If so, it should be possible to build more permanent structures. What about subterranean – er, ‘submartian’ – structures? Excavate caves (or find them in a suitable place), seal them, pressurise them, and have a colony that way.
No, it was in that excellent report, Edgar Rice Burroughs’ A Princess of Mars, serialized in 1909 and published in book form in 1912.
If anybody else did anything like that, I’d say they owed a debt to old ERB.
But you’d still most likely be having people living on Mars, if for nothing else than the mineral resources.
There are plenty of mineral resources available in interplanetary space, in the form of small and easily extracted small asteroids. By the time you have the technology to move any substantial amount of population to another planet, you also have the technology for long term habitation in space. At that point, there isn’t much reason to build settlements on planets, which are dangerous to descent to and difficult to ascend from.
Stranger
If we can terraform a planet, we can certainly hand out ponies while we’re at it. We can even make them robot ponies with lasers as a bonus!
People may well decide that they like planets better; we evolved on one after all. And it’s my understanding that Mars is small enough that a space elevator could be built even with nothing better than modern materials, so getting up and down isn’t likely to be a problem for a permanent future population that wants to got to the trouble.
We also evolved to wander nomadically around the savannahs of Africa scavenging and opportunistically hunting, which doesn’t prevent the vast majority of us from preferring the benefits of urbanization, industrialization, and modern agriculture. Similarly, it is easier to create idealized Earth-like environments in a controlled and enclosed habitat than to attempt to terraform an entire planet; the former is plausible with practicable extension of existing technology; the latter requires technology and timescales that are beyond the foreseeable future.
That isn’t true, and even if material strength were not at issue, the actual construction and maintenance of such a device is still well beyond existing technology.
Stranger
You greatly underestimate “the foreseeable future”.
Since when isn’t it true?