Terraforming using celestial bodies

[Agent11]

Mars would be a great first step, it isn't too far away and we think we could give it an atmosphere, but it has some problems.

The very weak magnetic field would allow any water ice we melted to be blown away along with any atmosphere we would have worked to create, and that water would be a fairly precious commodity on Mars. The radiation would also cause mutation and sickness in any plants and animals we tried to introduce to habitate the surface.

We could always send some comets towards Mars fairly easily, giving it more water. The magnetic field issue though is a serious problem for long term feasibility.

So why don't we give mars a magnetic field? This is something I have been toying with in my head for a while.

We steal a satellite from another planet like Jupiter and send it on a trajectory such that it enters into a stable orbit with Mars.

Ideally the satellite itself would have a robust magnetic field, although one could hope that the addition of a sufficiently large enough satellite would cause enough tidal force to re awaken Mars' core and cause renewed magnetic activity, eventually.

Or we could create a satellite, collect asteroids and send them on a close enough pass to the sun to cause them to fuse and gain a molten core. This would allow us to customize the qualities of the satellite to suit our needs and would probably be easier to envision than attempting to alter the orbit of an existing large satellite. However it would involve sending a fairly large body careening around the inner solar system, which could be riskier for our planet if things go awry, although I think it could be the best option.

Now I realize this probably sounds highly unlikely, however I believe that if the human race is going to populate space successfully we will be forced to alter the orbit of satellites, and even planets in the future.

The real question is how do you alter the orbit of a moon? Even if you create a moon yourself out of asteroids how do you alter the orbit of a moon speeding freshly baked away from the sun if course corrections are needed? Satellites in strategic locations with rail guns firing high mass projectiles perhaps?

What do you think?

 

[TempName]

What I think is that you're an idiot.

Personal insults are NOT permitted in HT.
-Admin DrPizza

 

[SMOGZINN]

The real question is how do you alter the orbit of a moon? Even if you create a moon yourself out of asteroids how do you alter the orbit of a moon speeding freshly baked away from the sun if course corrections are needed? Satellites in strategic locations with rail guns firing high mass projectiles perhaps?

What do you think?

You don't. I think that in the long run it would just be easier to build custom habitats for ourselves. Massive space stations, and eventually ring worlds, and finally a dyson sphere. Mankind is going to have to give up planets altogether.

 

[Tuna-Fish]

Now I realize this probably sounds highly unlikely, however I believe that if the human race is going to populate space successfully we will be forced to alter the orbit of satellites, and even planets in the future.

Why? You are thinking about creating surfaces on which people can live. The problem with living on a planetary surface (in addition to the inherent rarity) is that being down in a gravity well *sucks*. Getting up is so very energy-expensive, that having proper interplanetary trade will probably not happen in a very long time -- it would always just make more sense to use the energy to produce locally. If you are able to move a significant population up from earth's gravity well, why would you want to put them down in another?

Instead, build on objects that have little gravity, or build completely new structures. A tube that has a radius of ~500m and a length of roughly 10km would provide living and recreational space comparative to that which can be found on major western cities today for roughly 5M people at 1G +- 5%, and a *lot* more low-gravity space closer to the centre, suitable for agriculture, engineering. (And leisure, I suppose. Pick a floor high enough and you'll be able to fly by flapping your hands.)

This would be a design that is essentially buildable with present tech (the rotational forces exert no large stresses on the structure -- in fact, they make it cheaper to keep together because it can use suspensive structure), we just lack the heavy industry in space. Such structures can be built piecemeal, without having to dedicate yourself to generational construction projects that will not create a profit within the lifetime of anyone starting the project, but most importantly, if placed in a suitable orbit, travel between other such structures is cheap and easy, meaning that they don't form isolated communities (like planets necessarily would), but an integrated society.

Also, while there is (optimistically) planetary surface in the solar system to fit ~100B people, you could fit hundreds of trillions in space habitats.

Eventually, I think it's more likely that we will tear all the convenient asteroids apart for materials rather than waste them for terraforming.

 

[SMOGZINN]

Eventually, I think it's more likely that we will tear all the convenient asteroids apart for materials rather than waste them for terraforming.

I agree with everything you said, and think that once we have used all the asteroids up we will start tearing moons, and eventually planets, apart to build more habitats.

 

[Agent11]

Well the idea is to have another world capable of sustaining a wide biodiversity. We 'could' just build habitats free floating, but I doubt we would be able to sustain the earths animal and plant life. Also a planet is much more resistant to cosmic disasters.

A gamma ray burst may wipe out all life on a large portion of a planet but life would have a chance at survival. Also most solar flares and meteor showers are easily deterred by a planet with an atmosphere and magnetic field.

If you built a large enough magnetic rail and launched a large enough projectile fast enough you could alter the orbit of mercury for example. Mercury has a large core, magnetic activity and its orbit is elliptical.

You would only have to wait for the proper alignment then give it a boost to send it to mars.

 

[Tuna-Fish]

Well the idea is to have another world capable of sustaining a wide biodiversity. We 'could' just build habitats free floating, but I doubt we would be able to sustain the earths animal and plant life.

Per amount of work necessary, space-based habitats will have much more room, not just for people, but also for all plants and animals.

Also a planet is much more resistant to cosmic disasters.

A planet is much more likely to be the target of cosmic disasters. Also, space-based habitats spread the risk out -- don't think one planet vs one space station, think one planet vs a million space stations. (Although that is probably quite generous of the cost estimate given for terraforming a planet. One planet vs billions of space stations would likely be more appropriate.)

A gamma ray burst may wipe out all life on a large portion of a planet but life would have a chance at survival.

Not in any major form above one-cellular organisms. Any GRB from sufficiently close to us to do major damage would cook the atmosphere into nitrogen oxides. Good luck with that. On the other hand, if there are a few stations in orbit around each planet, the ones that get shaded by the planets will survive completely unharmed.

Also most solar flares and meteor showers are easily deterred by a planet with an atmosphere and magnetic field.

Space stations can be trivially placed out of the reach of solar flares, and it's relatively straightforward to track everything in space, and either move it away from a station, or move the station out of the way.

If you built a large enough magnetic rail and launched a large enough projectile fast enough you could alter the orbit of mercury for example. Mercury has a large core, magnetic activity and its orbit is elliptical.

You would only have to wait for the proper alignment then give it a boost to send it to mars.

But for only very small portions of the work needed for such orbital engineering, you'd build enough space habitats for all of humanity for a few thousand times over.

Oh, and also, if you collide Mars and Mercury, the surface of Mars would be molten for a few tens of thousands of years. Good luck finding backers willing to invest in that enterprise.

 

[Agent11]

Hmm. You really think billions of space stations would be cheaper to make than a few supermassive railguns?

 

[SMOGZINN]

Hmm. You really think billions of space stations would be cheaper to make than a few supermassive railguns?

On the scale the railgun would have to be to move a planetary body? Yes.

 

[videogames101]

Mass of Mars: ~6.41693 × 10^23 kilograms

I don't think that is a number you've wrapped your head around yet.

Your railgun would use atrociously absurd amounts of power and would have to fire projectiles with sizes on the astronomic scale.

 

[Tuna-Fish]

Hmm. You really think billions of space stations would be cheaper to make than a few supermassive railguns?

Yes. I don't think you understand just how massive "supermassive" needs to be. To move things about, even with railguns, you need to use a small but significant proportion of their mass. Mercury has a mass of 3*10²³ kg. To get it in a mars-crossing path, assuming "gentle" relativistic exhaust velocities (in order of 0.1c), you'd have to lift at least 0.0001% of it, or on the order of 3*10¹⁷kg of mass. The space stations we are talking about have mass somewhere around 10⁸kg each, so a billion of them would have similar mass to the reaction mass needed by this thing. And given the energy you'd need to fling something at 0.1c, building space stations of it is going to be much cheaper.

Moreover, when thinking of cost and motivation, you always have to consider "who pays for it" and "why"?

A terraforming project that starts by crashing Mercury into Mars would be the longest project in history. After the crash, the planet would stay molten for thousands of years, during which there is little payout for the project. So the people who start moving the planet need to be perfectly willing to put the money and work down with little hope of getting paid back in their lifetime, even if you assume clinical immortality. Crashing Mars and Mercury would be a project compared to which colonizing the galaxy would look relatively short-term.

Also, who would even give the go-ahead to such a project? Don't you think quite a lot of people would want to maintain the planets as they are? This sort of engineering would require population-wide consensus, or even a majority, and unless you haven't noticed, people generally can't really agree about anything.

In comparison, once the industry and mining is in orbit, you can start building space stations piecemeal, first just making a ring that rotates around a central spoke, then extending that ring while drawing rent from the structure that already exists. Also, since the projects are of relatively small scope, they can be funded and decided of piecemeal and organically -- all you need is enough backing to do the initial investments that are on the same order as building skyscrapers or luxury liners.

So in short, terraforming is the kind of impossible megaproject that teenage sci-fi enthusiasts like to drool over, but will never happen unless a megalomaniac dictator takes over all of humanity, while building space stations is something that is going to start happening as soon as Planetary Resources (or some other asteroid mining company) gets their act together. Within our lifetimes.

 

[Tuna-Fish]

And again, that's without even considering just how crappy places to live planets are. If you are doing megaprojects, living on the surface of a tight ball of matter is right about the least efficient way you could possibly use it. And condemns the inhabitants to living in the bottom of a gravity well, which is not something you'd want to do if you want to be a part of the greater human society.

 

[Agent11]

Good points.
However wouldn't it be handy to have some supermassive railguns? It would be an efficient way of dealing with rogue planetoids and even alien armada's intent on capturing 'all our bases'.

Also they could be used to launch unmanned interstellar devices of very large scale, at high speeds... Perhaps manned devices as well, if they had some sort of sophisticated dampening system.

And yes I'm aware it would be very expensive, and very hard. But I think the idea is fascinating.

 

[SMOGZINN]

Good points.
However wouldn't it be handy to have some supermassive railguns? It would be an efficient way of dealing with rogue planetoids and even alien armada's intent on capturing 'all our bases'.

Not really. There probably is not any alien armadas, and rogue planetoids can be dealt with in other ways. Overall, it is almost certainly better to have a place for all the billions of children people insist on having to live.

 

[wirednuts]

i dont think we could give mars an atmosphere anytime soon. we just dont have the technology yet.

 

[Agent11]

The total mass of the asteroid belt is estimated to be 2.8×10^21 to 3.2×10^21 kilograms, which is just 4% of the mass of the Moon. The four largest objects, Ceres, Vesta, Pallas, and Hygiea, account for half of the belt's total mass, with almost one-third accounted for by Ceres alone

http://en.wikipedia.org/wiki/Asteroid_field

Asteroids are known to have large deposits of metals, and rare magnetic ores.

I don't think it is really all that far fetched. It would be difficult, but I don't think it would be impossible.

We could use nuclear waste as mass filler for the projectile as well. Lots of win/win aspects to this idea in my opinion.

If Mercury sailing past Venus and the Earth is too unsettling we could always do Ganymede. I doubt Jupiter would really miss it.

Ganymede's mass 1.4819 ×10^23 Mercury's mass 3.3022×10^23, quite a bit lighter too.

http://en.wikipedia.org/wiki/Ganymede_(moon)
It has lots of ice and a magnetic field as well, sounds like a good candidate to me.

And for the record, this would be orders of magnitude less expensive than attempting to build a dyson sphere, and when this sun starts to turn into a nemesis we can always use the rail guns to launch materials and vessels away from it, and you could even move the rail guns themselves to another star system as well. A dyson sphere or ring world is entirely dependent upon the star it is constructed upon and is immobile.

Man is the architect of the Earth, we have built imposing skylines, changed the coarse of rivers, irrigated desserts, bridged continental divides and annihilated forests and mountains for resources. It is only a matter of time before we shape the solar system to suite our needs, and those of other star systems as well.

 

[Tuna-Fish]

I don't think it is really all that far fetched. It would be difficult, but I don't think it would be impossible.

It would not be impossible, but it would be inefficient and stupid.

We could use nuclear waste as mass filler for the projectile as well. Lots of win/win aspects to this idea in my opinion.

The total amount of nuclear waste you could possibly produce is completely irrelevant for the mass needed for the projectiles.

Also, the scary parts of nuclear waste are actually still useful as fuel -- once we progress past "reprocessing is scary", we wouldn't want to throw them away.

If Mercury sailing past Venus and the Earth is too unsettling we could always do Ganymede. I doubt Jupiter would really miss it.

All the people who have better use for it would miss it.

And for the record, this would be orders of magnitude less expensive than attempting to build a dyson sphere

No, it wouldn't. Mostly because when you start building a dyson swarm, you don't start with the idea of covering the whole sun. You start by building solar capacity orbiting the sun, and slowly cover more and more of it.

and when this sun starts to turn into a nemesis we can always use the rail guns to launch materials and vessels away from it, and you could even move the rail guns themselves to another star system as well. A dyson sphere or ring world is entirely dependent upon the star it is constructed upon and is immobile.

You appear to have no intuition of the relative costs of building something and moving something in space. Construction is cheap, transportation is expensive. You would not want to move the rail guns, or the dyson swarm. Over the ~5B years the dyson swarm will be able to continue working, they would pay back for themselves a few billion times. Having to abandon them at that point would not really be a point against them.

Man is the architect of the Earth, we have built imposing skylines, changed the coarse of rivers, irrigated desserts, bridged continental divides and annihilated forests and mountains for resources. It is only a matter of time before we shape the solar system to suite our needs, and those of other star systems as well.

I absolutely agree with you. And like we've done on earth, we will build our habitats based on the constraints and opportunities of the time. Even though we once lived in caves, our grand cities don't look like really extensive cave complexes. Terraforming mars for the pathetic room for extra few billion at the cost it would take would be like building a modern city of millions by finding a mountain and carving it full of small holes.

You keep trying to twist this into "it wouldn't be impossible". We all agree with that. Terraforming Mars would be eminently possible given enough time and resources. It would also always be idiotic -- there would always be a better way to utilize those resources for more immediate gain.

As for "rail guns are great weapons" -- no, superweapons in general suck. Because when your weapons get sufficiently expensive, they turn from weapons into targets. By our present knowledge, we cannot really even begin to imagine just what kind of systems of destruction our descendants will build. But wisdom of tactics has survived much better than wisdom of technology, and one of it's first lessons is to disperse your power. Whatever weapons there will be in the future, they will be steadily spread out in the solar system.

As for their purpose in transportation -- rail guns are extremely destructive for the payload they fling. Something like a solar sail pushed by lasers powered by collectors in solar orbit would be a much better way to travel to the nearby star systems in the time frame that is even remotely relevant.

 

[Agent11]

A lot of the damage to rail gun projectiles is caused by the atmosphere they are fired in, in space that would not be an issue. Also a frictionless design would be possible, so that is a non issue for using it to assist interstellar travel, and I don't think a nomadic space civilization would be so wasteful as you think. The universe is a hostile place.

You know we have the technology to do this now, we would just have to start to build it. It would take a very long time, but there is no unobtainium required.

Within the some what near future I don't see us giving up planets for nomadic space life, and mars would be a lot easier to exploit for resources if it wasn't being blasted by radiation and there was a giant ball of ice orbiting it.

Worst case if it did collide with mars then it would be our gift to future generations.
Ganymedes ice would make mars a water world, a second earth right next door.

How fast do you figure a laser sail boat could accelerate? And the closer to light speed you accelerate you will require more thrust to continue accelerating. Then there is the problem of decelerating halfway there. Assuming you did not already have a dyson sphere and laser at Alpha Centauri.

 

[piasabird]

Geodesic domes?

CUT into rock and make cavern, fill with air and water and dirt. Grow plants and make compost for expansion. Use human waste as manure after composting (Done in Orient). Crush rock and make cement. We dont even really know all the possible resources that are on Mars. I think it would be neat to make some underground tunnels with those large tunneling machines. It is very hard to tell what is below the surface. Is the whole planet solid rock or is there sub-surface water etc. All we have really seen is a bunch of red rocks.

I think to do a real survey we need to drill bore holes.

Nuclear powered boring machine?

Giant laser?

 

[piasabird]

It would be nice if we could find some useful resources like coal, iron ore, or diamonds or Nuclear fissionable material. Is there nothing but red rock there?

We would need like hundreds of drones or landers to get any real work done.

 

[piasabird]

This is where we could use some kind of army of tiny little machines that can work at nanotechnology level to disassemble rock and make it into something else.

I am also thinking there may be some kind of chemical reactions that might convert materials to release oxygen, carbon, etc. Maybe look at alchemy of the air. This was a book of how to release carbon in such a way as to make fertilizer. Maybe there is material like Methane that we could collect from some other planet and take over there and use that as the basis for a chemical reaction. Even using extreme heat might help.

You cant exactly move enough water to mars. However, there may be some way to make Hydrogen and Oxygen.

 

[Tuna-Fish]

A lot of the damage to rail gun projectiles is caused by the atmosphere they are fired in, in space that would not be an issue. Also a frictionless design would be possible

Most of the damage done to the projectile in a rail gun is not because the atmosphere or friction, it's because the projectile ablates when a very high current is driven through it.

See the giant trailing explosion?

That's plasma, that used to be part of the projectile, until the driving current went trough it.

and I don't think a nomadic space civilization would be so wasteful as you think.

And this is precisely what I meant when I said "You appear to have no intuition of the relative costs of building something and moving something in space." Leaving it isn't wasteful, bringing it with you would be. This isn't making a run to the corner store to go pick up something -- to accelerate something to useful interstellar speeds pretty much always costs more than the value of that something.

You know we have the technology to do this now, we would just have to start to build it. It would take a very long time, but there is no unobtainium required.

Which no-one has claimed. It's just that it would be stupid.

Within the some what near future I don't see us giving up planets for nomadic space life

Why? What is it about planets that you like so much? Living in space is fundamentally more efficient.

How fast do you figure a laser sail boat could accelerate?

Basically, as fast as you want it to. If it's carrying organics, you'd prefer a relatively low acceleration for an extended period. 0.5G for 6 months would yield cruise speed of 1/4c.

And the closer to light speed you accelerate you will require more thrust to continue accelerating.

Well, from the point of view of the ship, it would always require constant amount of photons for 1G. Of course, from outside, the acceleration would be less. Also, the further away the ship gets, the lower the proportion of photons that actually hit the sail.

Then there is the problem of decelerating halfway there. Assuming you did not already have a dyson sphere and laser at Alpha Centauri.

This is not any larger problem than your rail gun version -- actually, the sail would be somewhat useful for decelerating, but of course it wouldn't be nearly good enough. How high of a cruise speed you want is very much a tradeoff between (perceived) travel time and how much of deceleration you are willing to do.

 

[Agent11]

Well you see we evolved in a gravity well on a planet, and it has worked out pretty well for us.


The only problem with using a rail gun to assist in interstellar travel is the g load, but with the size of the payload a railgun this big could fire it is conceivable you could work out some sort of dampening system so that passengers wouldn't be turned into paste. All that acceleration would save years and tons of fuel that can be used to continue accelerating on the way and decelerate as well.

If you are worried about ablation during firing you give the payload an ablative layer. Simple.

Quote:
And the closer to light speed you accelerate you will require more thrust to continue accelerating.

Well, from the point of view of the ship, it would always require constant amount of photons for 1G. Of course, from outside, the acceleration would be less. Also, the further away the ship gets, the lower the proportion of photons that actually hit the sail.

In other words it would be slow.

 

[greenhawk]

However wouldn't it be handy to have some supermassive railguns? It would be an efficient way of dealing with rogue planetoids and even alien armada's intent on capturing 'all our bases'.

you would be better off installing the large rail gun on a astroid sided planet and using it as an engine to push the astroid out of the system.

as to teraforming mars, be better just to start looking at ways to cool down / convert venus. Just start lobing icy rocks it's way.

 

[Tuna-Fish]

Well you see we evolved in a gravity well on a planet, and it has worked out pretty well for us.

Well yes, because we had no choice. Not living in a gravity well is just better. Between planets, you basically need space elevators to have any trade. And while there has been interesting developments with carbon recently, those are still pretty much unobtainium. But in orbit, strap on an ion engine and you can pretty much go anywhere you want, on the cheap.

but with the size of the payload a railgun this big could fire it is conceivable you could work out some sort of dampening system so that passengers wouldn't be turned into paste.

You cannot dampen something that you want to accelerate to relativistic velocity by any reasonable margin. Just can't be done. Any rail gun traveleres would essentially have to make the trip as uploads.

All that acceleration would save years and tons of fuel that can be used to continue accelerating on the way and decelerate as well

Well, and using a remotely powered sail you can get constant acceleration for the outbound leg without having to carry any fuel.

If you are worried about ablation during firing you give the payload an ablative layer. Simple.

Presently it's perfectly normal for the projectiles to lose a majority of the mass before they are out of the barrel. Just how large of an ablative layer are you thinking of here?

In other words it would be slow.

Slow? Constant half G gets you to a quarter of light speed in 6 months. Sure, it doesn't have the explosive start of a rail gun, but it'll still get there faster.