I need assistance with a question regarding Terraforming...

[retrowire]

What would be the most efficient way to cool down a planet? WITHOUT the idea of putting giant discs in space to block out the sun.

[Maedhros]

1. Spread kilotons of fine particulate matter in the upper atmosphere.

This happens with massive explosive eruptions, as with Krakatoa.

[retrowire]

3. hmmm...

Anyway to do it without blocking out the sky?

[Maedhros]

7. There are limited options.

One is to increase the planet's albedo (the amount of sunlight reflected away from, and not absorbed by, the planet's surface), which is what the tropospheric particulate matter is for. I suppose one could coat the surface of the planet with a reflective material (e.g. snow).

Another would be to chemically remove greenhouse gases from the atmosphere (if that is the source of the warming). This would require a very long time frame, but could be achieved under certain circumstances - such as adding calcium to the oceans, promoting the absorption of carbon dioxide into precipitated calcium carbonate (i.e. limestone).

[retrowire]

8. What about a means

of pushing the planet into a new orbit that is further from it's star and moreso in the goldilocks section of orbit? Would that be feasible?

[Maedhros]

11. Given enough energy, it could be done.

Check out Larry Niven's "A World Out of Time."

In this novel, in the far future mankind needs to move Earth away from the sun as it expands into a red giant. They build a truly gargantuan rocket motor on Uranus or Neptune (can't recall which) that uses the planet's atmosphere as fuel. They fly the gas giant close enough to Earth to capture it in the giant's gravity well, then drag it out and plant it in the orbit of Jupiter.

[retrowire]

12. Wow! Thanks so much!

I looked all over the web for creative ways about doing this, and saw nothing about this. That's great inspiration.

I'm working on a novel regarding this and that's why I'm asking. In my novel, humanity seeks to colonize a planet because of it's unique elements and ores, but it's too hot for habitation, so they have to cool the planet. I wanted to move the planet by the means that I mentioned, but this methodology you mentioned is another great way to execute that. Thanks!

[Maedhros]

18. Don't thank me - thank Niven.

He comes up with some weird shit

[muriel_volestrangler]

20. I don't think 'gargantuan' begins to cover it

How did he connect the rocket to the planet? If it's inside the atmosphere, then your rocket exhaust has to fight its way through the atmosphere, which would transfer most (all?) of its momentum back to the planet/atmosphere, and make it fall back down again. If it's outside, you have to transport the fuel up to it, and then (assuming the rocket is in front of the direction you want to force it in) fire the rockets sideways enough for their exhaust to again miss the atmosphere (so that, relative to the planet, it looks like it's hovering, but it's really pushing the exhaust somewhat backwards), or you've again just transferred the momentum back to the planet. Or if you want to put the rocket behind the planet, you need a rigid connection capable of taking the compression between the rocket and the planet.

And then you have to work out the force needed to make any kind of dent in the forces on the planet, compared with the others it encounters (how did he get Uranus/Neptune past Jupiter on the way in? This presumably took thousands or millions of years, so did he move it out of the plane of the solar system? Can you do that and keep it far enough away from Jupiter at all times that it would get thrown off course by Jupiter's gravity?)

[Maedhros]

21. Here's what I remember:

How did he connect the rocket to the planet?

The rocket engine was huge. One end comprised a fuel intake, which was pressed against the planet's atmosphere. The intake sucked up atmospheric hydrogen, fused it, and expelled it as propellant. The exhaust was pointing away from the planet and was outside the atmosphere. The more thrust generated, the greater the pressure of the intake against the atmosphere.

how did he get Uranus/Neptune past Jupiter on the way in?

In the novel, this was done in the far past from the perspective of the protagonist. Details were not provided.

[muriel_volestrangler]

22. 'pressed against' meaning 'floating in it', really

The atmospheric pressure under the rocket would have to be enough to take the entire weight of a tube that reaches up out of the atmosphere (and is rigid enough to have a vacuum inside against this huge pressure keeping it floating), plus the thrust of the rocket. I'm not convince it would stand up to any calculation. And then the rocket rotates with the planet, which means it's only pointing in a reasonably useful direction for some of the time, and you have to keep it stable sideways, and ...

[Fumesucker]

28. That can be done by using an asteroid to transfer momentum from a gas giant to your world

But it's an extremely long term process, tens of thousands of years or more. I suspect anything that would do it in less than thousands of years would probably disturb the planetary crust so much it would trigger overwhelming volcanism.

https://www.newscientist.com/article/dn14983-moving-the-earth-a-planetary-survival-guide/

In the Niven book discussed downthread the Earth moving process got screwed up and the Earth ended up orbiting too close to an overly heated Jupiter (probably after a small planet or large moon got dropped in it) and became largely uninhabitably hot except at Antarctica.

[RufusTFirefly]

2. Sulfuric acid has been suggested

Injecting sulfuric acid into the atmosphere could theoretically mimic the effect of historic volcanic eruptions that have reflected back some of the sun's rays and cooled the Earth as a result.

Apparently it wouldn't take much:

According to {Harvard professor of applied physics David} Keith’s calculations, if operations were begun in 2020, it would take 25,000 metric tons of sulfuric acid to cut global warming in half after one year.

Of course, it wouldn't get to the root cause of the problem, nor is it clear what sort of detrimental effects would result from messing with Mother Nature in this fashion.

http://www.technologyreview.com/featuredstory/511016/a-cheap-and-easy-plan-to-stop-global-warming/

[retrowire]

4. Anyway to do it without blocking out the sky? n/t

[Hydra]

5. Not really

We either have to cut down the carbon and methane(even more greenhousey) in the atmosphere or reduce the amount of solar energy we're getting. Jet trails are actually cutting down some of the warming, for instance.

I don't favor the sulfuric acid method because then we'll just burn more fossil fuels instead of moving off toxic sources of energy.

[retrowire]

6. Damn, well

that paints a different picture of my sci-fi novel then. D:

I'm writing a novel about a sect of humanity that goes to colonize a planet for it's ores but in order to make it habitable they go about cooling down the planet.

So I was looking for logical ways to go about doing so.

Tell me if this seems illogical. They create some sort of thing that is capable of pushing the planet further out of it's orbit, into an orbit that is further from the star it orbits. Does that make sense?

[Hydra]

9. Ya, but unintended consequences

Which could make for a good story anyway. When you move a body that is big enough to have it's own noticeable gravity to a new location, the other bodies nearby react to that new set of balance points...sometimes it's good, sometimes it's bad, but it's always "interesting."

[retrowire]

13. Hmm, I didn't consider the "every reaction has an equal and opposite reaction" clause...

Would the other bodies nearby have their gravity affected and vice versa or would gravity remain unchanged?

My laymans understanding of gravity is that it's based entirely on the mass and volume of the mass (planet) in space. Does proximity to other bodies affect gravity? Or does it affect something else?

[Hydra]

15. I'm not an expert either

But regardless of the actual mechanism, gravity is like a set of invisible strings or rubber bands that affects nearby objects in a relative matter to their mass/gravity in curvy ways. Planets around suns, moons around planets, asteroids and comets flowing by along the curve trails.

It's all very elegant and mathematical...Einstein was sure he was observing the hand of God in looking a the laws that governed all of it...but I only know enough to get in trouble :p

[retrowire]

16. Well I thank you anyways!

It sends me into the direction of more research.

[Silent3]

10. It's not like we're talking about the sky turning black

The sky would look pretty much the same as it does now, just very subtly dimmer and/or cloudy more often. It wouldn't take much reduction of the incoming sunlight to have a significant effect.

[retrowire]

14. Huh. Okay, that's true....

Thanks for pointing that out.

[Thor_MN]

17. Not an expert by any means, I doubt I could do the math...

But I'm thinking one could push some convenient large asteroids into a planet grazing orbit that they are accelerated out of the system, thereby gradually moving the planet further from the star. That could also steal some of the atmosphere that is surely causing the planet to retain heat.

[DetlefK]

19. Okay. Very, very outlandish. "Thermoelectric effect."

You need two wires made from different metals, tied together at one end. You connect the other two ends to the poles of your electricity-consuming device.
At the knot, the different densities-of-state of the metals will shift upon contact until a voltage has built up that balances the different amounts of available elctric charges. But apart from this tiny, tiny current, nothing will happen.
But, if your device and the point where the metals touch have different temperatures, the densities-of-state shift again. Again, a voltage builds up and a current flows to cancel this imbalance out. The temperature-difference leads to a voltage.


My idea:
1. You put the knot into something really, REALLY cold. Arctic temperatures and lower. (Liquid nitrogen is cheap...)
2. The other end, the device, is thermically conductive connected to the planet's ocean.
3. Now we have to get rid of the voltage. The electric energy is dispersed by shooting a powerful beam into space, at a frequency which is badly absorbed by the atmosphere.

Result: You suck the warmth out of the ocean and shoot it into space.
It sounds outlandish at first, but if you use two alloys that have been specifically designed to have radically different electric densities-of-state and if the temperature-difference is really big and if you use not just wires but cables at least a foot thick...
And if you set up hundreds of stations like this on the planet...



EDIT: After a hundred years, the oceans will have cooled by 1 K or so (more like 0.1 K), but this means a lot in terms of global climate and leads to a growth of the polar ice-caps and glaciers. While the difference in temperature is insignificant for the thermoelectric effect, the new ice-sheets would reflect sunlight, accelerating the process.

[NeoGreen]

23. This might help...

...
http://www.amazon.com/How-Build-Habitable-Planet-Humankind/dp/0691140065/ref=sr_1_1?s=books&ie=UTF8&qid=1440017532&sr=1-1&keywords=how+to+build+a+habitable+planet



Mandatory reading in my Environmental Science 101 class way back in 1989.
(but maybe not this edition)

[SoLeftIAmRight]

24. Here is some info on terraforming

We need a complete conversion of the agricultural systems.
It will not be fast, easy, or cheap.
The issue is too important to let corporations control make the decisions.


This is only the beginning – hope to spend the time to expand

Sustainable production – less input – co2 sequestration – no gmo's


Start with

Allan Savory – Ted Talk

http://www.ted.com/talks/allan_savory_how_to_green_the_world_s_deserts_and_reverse_climate_change

Then
Gabe Brown
Soil health

This talk is directed to farmers that have a anti-environmental bend – so less emphasis on environmental issues – when speaking to a more enlightened group his talk is less country twang and more science based

http://www.bing.com/videos/search?q=gabe+brown+soil+health&FORM=HDRSC3#view=detail&mid=4145088DB3EF49DFB8CF4145088DB3EF49DFB8CF


Mike Hands – this is only a little info on this subject – see the full documentary

http://www.bing.com/videos/search?q=mike%20hands%20inga%20frontline&qs=n&form=QBVR&pq=mike%20hands%20inga%20frontline&sc=0-0&sp=-1&sk=#view=detail&mid=46F489526F819D99DF6E46F489526F819D99DF6E

[Bonobo]

33. Great information.

Thanks.

[DhhD]

25. Could be: The expansion of the planet while it cools, would move particles (of matter and force)

from a volume of greater concentration and more pressure to a greater volume with less pressure.


May find this information interesting.
https://search.yahoo.com/search?p=Chemistry-Brown+effect&fr=dss_yset_chr


Seems like today's most stable atmospheric gases are diatomic until they reach the Thermosphere.

Seems like there is a play between particles of force and matter, even without a Big Bang.

[Agnosticsherbet]

26. Carbon nanofibres made from CO2 in the air

[link:Carbon nanofibres made from CO2 in the air|Carbon nanofibres made from CO2 in the air]

[DetlefK]

31. Bad idea.

You suck the CO2 out of the air with plants, then burn them under very specific circumstances to create carbon-nanotubes by pyrolysis.

Problem: Nanoparticles don't stay where they are supposed to stay. You breathe them in, you eat them... And ingesting CNTs is very dangerous because they are rigid and pointy and puncture cell-walls.

[MillennialDem]

27. Increase the albedo to reflect more ligh back into space. On Earth if we could spread the ice sheets

thinner over a larger area...

[DetlefK]

30. How???

How are going to cut glaciers into slices and spread them out?
How would you do this without them melting away?

[MillennialDem]

32. I didn't say it was easily doable :p I imagine massive bulldozer operations could push them to

the south (or north in the southern hemisphere) into areas where it is below freezing but not covered by glaciers currently. I suppose another option would to place them on large anchored barges in parts of the ocean where it is very cold.

Aside from the massive undertaking, it would be quite tricky because yes the area would have to stay cold enough for the glaciers to not melt (though you could keep moving them). Maybe it would be better to just build large flat panels with white reflective paint.

[Fumesucker]

29. "The most efficient way would be to dim the star" said Tom darkly