[LaurieAG]

Originally Posted by Thunderbird

Terraforming Mars

NASA has on occasion suggested that the human race could one day colonize Mars, and also initiate life to take hold on the surface. I understand that there have been nigh Sayers in the past about the limits of science, and I hate to be one, but I do not believe this at all feasible. It is a dead planet, and always will be, period.... What do you think ? Does NASA know something about Geophysics that I do not?

Hello Thunderbird,

If you could drop a couple of large icy Kuiper belt objects on its surface you may just have a chance of making Mars habitable. Getting this same large amount of water from Mars itself would be a huge problem.

Maybe astrophysics not geophysics, or a combination of both.

[Thunderbird]

Originally Posted by LaurieAG

Hello Thunderbird,

If you could drop a couple of large icy Kuiper belt objects on its surface you may just have a chance of making Mars habitable. Getting this same large amount of water from Mars itself would be a huge problem.

Maybe astrophysics not geophysics, or a combination of both.

It would need to start with some astrophysical engineering. But even if you could somehow move these objects; Billions of tons across 100s of millions of miles, it would still take Billions of years for the planet to reform itself.
It would be for more pactical to improve our way of living by reengineering how we live on this planet.

[CraigD]

Originally Posted by LaurieAG

If you could drop a couple of large icy Kuiper belt objects on its surface you may just have a chance of making Mars habitable. Getting this same large amount of water from Mars itself would be a huge problem.

Originally Posted by Thunderbird

But even if you could somehow move these objects; Billions of tons across 100s of millions of miles, it would still take Billions of years for the planet to reform itself.

I don’t think this is true.

The various “watering/atmosphere-thickening” plans involving colliding KBOs (comets) with Mars don’t involve impacts that would damage Mars so much that it would need to “reform”, nor do they propose to duplicate the natural evolution of a biosphere. They simply propose to – quickly, within decades and centuries, not thousands and millions of years - add water and gas to create more human-friendly surface conditions.

Unlike the planet-moving examples in previous posts of this thread, the orbital mechanics of colliding large numbers of large KBOs with a planet, while obviously beyond humankind’s current engineering capabilities, are not energetically prohibitive for a fairly reasonable extrapolation of our near-future. KBOs regularly perform the trick on their own, with no artificial intervention, resulting in the appearance of new comets. Best speculation (we lack, by just a little, the instruments to actually observe these events) is that low-probability, effectively random gravitational encounters between large and small, or nearly equal mass KBOs transfer them from somewhat circular into very eccentric orbits, sometimes permitting stronger gravitational encounters with Neptune or other giant planets, that haphazardly transfer them to even more eccentric orbits. Though unlikely, there are a lot of KBOs, so these random events occur with enough frequency that new comets appear often.

Engineering comet strikes on a planet would be, I think, largely and observation and planning project, locating suitable KBOs that could be nudged into a series of gravitational passes with others, then one or more precisely guided passes with the giants, and some terminal guidance into target Mars.

Time-wise, comet orbits, which have semi-major axes from about 15 to 25 AUs, have orbital periods of 60 to 125 years, so these collisions could be engineered to begin happening about 30 years into a modest-energy program’s implementation.

Originally Posted by Thunderbird

It would be for more pactical to improve our way of living by reengineering how we live on this planet.

True. However, terrestrial reengineering is bound to occur regardless of any space engineering plans. IMHO, the promise of dramatic increases in available per-human power offered by space engineering - not precisely the same, but related to projects like comet-steering – makes it worth the high initial cost – and an inescapable necessity if our civilization is to climb the Kardashev scale.

Kim Stanley Robinson wrote a critically, popularly, and by-me lauded hard scifi trilogy on the subject of terraforming Mars, “the Mars trilogy”. Though one should be careful not to confuse scifi with real engineering, I recommend these books, not only for their engineering speculation, but for their cultural and sociological.

[Thunderbird]

Originally Posted by CraigD

I don’t think this is true.

The various “watering/atmosphere-thickening” plans involving colliding KBOs (comets) with Mars don’t involve impacts that would damage Mars so much that it would need to “reform”, nor do they propose to duplicate the natural evolution of a biosphere. They simply propose to – quickly, within decades and centuries, not thousands and millions of years - add water and gas to create more human-friendly surface conditions.

I don't think this will ever be enough, You cannot just add water and gas and expect to initiate the dynamics of a cyclical ecosphere upon a static undersize dead rock.
You would need to add enough mass initiate a cataclysmic planetary melt down, and reboot the entire system, and start from scratch.

[LaurieAG]

Originally Posted by Thunderbird

I don't think this will ever be enough, You cannot just add water and gas and expect to initiate the dynamics of a cyclical ecosphere upon a static undersize dead rock.
You would need to add enough mass initiate a cataclysmic planetary melt down, and reboot the entire system, and start from scratch.

Hi Thunderbird,

By adding a moon you could possibly drag Mars, kicking and screaming, back to life (or at least try to regenerate its dynamo in a 'soft' reboot).

[CraigD]

Originally Posted by LaurieAG

If you could drop a couple of large icy Kuiper belt objects on its surface you may just have a chance of making Mars habitable. Getting this same large amount of water from Mars itself would be a huge problem.

Originally Posted by Thunderbird

It would need to start with some astrophysical engineering. But even if you could somehow move these objects; Billions of tons across 100s of millions of miles, it would still take Billions of years for the planet to reform itself.

Originally Posted by CraigD

I don’t think this is true.

The various “watering/atmosphere-thickening” plans involving colliding KBOs (comets) with Mars don’t involve impacts that would damage Mars so much that it would need to “reform”, nor do they propose to duplicate the natural evolution of a biosphere. They simply propose to – quickly, within decades and centuries, not thousands and millions of years - add water and gas to create more human-friendly surface conditions.

Originally Posted by Thunderbird

I don't think this will ever be enough, You cannot just add water and gas and expect to initiate the dynamics of a cyclical ecosphere upon a static undersize dead rock.
You would need to add enough mass initiate a cataclysmic planetary melt down, and reboot the entire system, and start from scratch.

“Making Mars habitable” and having “the dynamics of a cyclical ecosphere” are different requirements.

Conventionally, terraforming refers to making a moon or planet similar enough to Earth that it’s habitable by humans, not recreating an ecosystem of similar power and complexity to Earth’s.

Originally Posted by LaurieAG

By adding a moon you could possibly drag Mars, kicking and screaming, back to life (or at least try to regenerate its dynamo in a 'soft' reboot).

Given that an ionosphere, which Mars currently has, even with its thin (about 0.01 Earth’s pressure) atmosphere, provides most of the habitability benefits that a magnetic field contributes to, why would you want to spend effort to give it a magnetic field?

In short, I remain of the opinion that, while with much greater space engineering capabilities than are currently available to humankind, terraforming Mars is technically possible, I doubt it will be economically or esthetically attractive at any time in the next 100 years.

[Thunderbird]

From Wikipedia, the free encyclopedia

Liquid water cannot exist on the surface of Mars with its present low atmospheric pressure, except at the lowest elevations for short periods


Mars lost its magnetosphere 4 billion years ago, so the solar wind interacts directly with the Martian ionosphere, keeping the atmosphere thinner than it would otherwise be by stripping away atoms from the outer layer. Both Mars Global Surveyor and Mars Express have detected these ionised atmospheric particles trailing off into space behind Mars.

It would be like pouring water into a leaky bucket.

[CraigD]

Originally Posted by Thunderbird

It would be like pouring water into a leaky bucket.

Yes, but a planet-size, slowly leaking bucket. Best current data and theory suggest that in its distant past (the Noachian era, 3.8 to 3.5 billion years ago), Mars had significant amounts of liquid water, for on the order of 100 million years.

Again, the conventional goal of terraforming is not making an Earth-like world that will last long enough to recreate billions of years of terrestrial biological evolution, but to make other planets and moons human habitable for periods of time long by human standards – thousands, not hundreds of millions of years.

[LaurieAG]

Originally Posted by CraigD

Given that an ionosphere, which Mars currently has, even with its thin (about 0.01 Earth’s pressure) atmosphere, provides most of the habitability benefits that a magnetic field contributes to, why would you want to spend effort to give it a magnetic field?

Hi CraigD,

If you used a non ice object (your new moon) to gather and lead all the KBO's to Mars you could save multiple trips and get the moon/staging post for free.

Originally Posted by CraigD

In short, I remain of the opinion that, while with much greater space engineering capabilities than are currently available to humankind, terraforming Mars is technically possible, I doubt it will be economically or esthetically attractive at any time in the next 100 years.

Lets hope our societies can last that long.

[modest]

Originally Posted by Thunderbird

It would be like pouring water into a leaky bucket.

You may be wrong about that - and I think you are - Craig makes an excellent point.

Nevertheless, I think I may agree that it is slightly futile to bombard mars with comets in hopes of habitation. I fail to see how putting ice on an iceberg will help you grow an apple tree. Mars is frozen. It will remain so until it has an atmosphere and quite a substantial atmosphere at that. There's probably a clever way to overcome that problem, I just can't think of it.

-modest