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# How to save the day

Or lets blow up the moon
 (+3, -6) [vote for, against]

Jim has been pondering the far future of mankind --- and sees a bleak outcome that can be prevented. Discounting mans ability to save the sun Jim reckons that it will not be too difficult to save the day.

Jim requires some nukes and a rocket bound for the moon. When said rocket intersects the moons orbit the nukes will detonate destroying or at least liberating the moon from its current deadly dance with the earth.

To be clear... the moon is gaining momentum from the earths rotation so the days are getting longer. At best guess the day will become 55 (present) days long when the earths rotation matches the period of the moons orbit around the earth. At this point the earths rotation cannot impart more to the moon.

Anyway to stop this happening we need to liberate the two planetary bodies.

Jim takes charge...

// sees a bleak outcome that can be prevented//
Jim invents the apostrophe?
 — coprocephalous, Feb 11 2009

Well not really Jim has never really been successful at apos...

Any calculations on gigatonnage required for this project?
 — coprocephalous, Feb 11 2009

Space: 1999?
 — phoenix, Feb 11 2009

 //Discounting mans ability to save the sun// how expensive was it before?

Anyway, once we build a space elevator we can just keep extending it and then prod the moon away.
 — marklar, Feb 11 2009

 //Any calculations//

When the task is this urgent, who has time to make the calculations? [+]
 — pertinax, Feb 11 2009

The moons period will be 55 days at 6 x 10^5 km and this is the point at which the earths rotation exactly matches the moon. Pretty soon (relatively speaking) the day will be twice as long and people will start to waste away overnight. When the day is as long as a week everyone will go to sleep one night and not wake again...

Could we start slowly creating a counter moon with a different orbit that will unscrew us? This new astral body could be made of junk or could be a death star-esque spacestation. Eventually we could gently dock the 2 celestials giving a little punt into a stable orbit. Calculations abound obviously, but we can make more accurate guesses in the millenia it takes to accumulate the thing. Also, every launch can push the Earth a little, which will add up if the total mass launched is going to be big enough for a moon shunt.
 — marklar, Feb 11 2009

 I quite like the moon, rather than destroying it (btw didn't there used to be an idea here called "Destroy the Moon"?), if we mounted rockets to speed up its rotation around earth, we might be able to halt the slowing, or even speed up the length of the day - and still have something to write songs about.

 I'm not sure the moon *gaining* momentum is the problem. There's a few different things going on here - 1st, the moon has been slowing down the earth due to tidal friction for billions of years (which hasn't been a bad thing when you consider that it was probably a primary factor in the formation and development of early life) Not only does this tidal friction slow the rotation of the earth, but it also has an equal and opposite effect on the rotation of the orbiting moon, and so a month today is longer than it might have been a billion or so years ago. Since it's the sloshing effect of the water that causes this slowing, an alternative to destroying the moon would be to evaporate, drink or otherwise get rid of all the water in the oceans - or alternately to block-off all the water in the oceans to stop it swirling about so much*. Anyway, back to the point, the moon isn't so much gaining momentum as losing it due to it spending it on slowing the earth via tidal swirling.

 - 2nd - the moon is slowly getting further away, meaning that its tidal powers are already waning - so I'm not sure if the slowing of the earth's rotation can be extrapolated in a linear fashion - it may be that there's a point at which it's just too far away to have any further effect - whether that happens before our 'day' is 55x24 hours long or not is unknown - did Jim factor that into his calculations?

 - 3rd - blowing up the moon wont be enough on its own, you will have to shift all the bits out of orbit, which might be tricky if they are whizzing about the place after a catastrophic explosion.

* another alternative would be to employ big pumps in the ocean to make the water travel round in such a way as to spin the earth faster against the pull of the moon - this should also have the effect of speeding up a month.
 — zen_tom, Feb 11 2009

How about using hydraulic stilts, powered by the rising tide, to raise up the level of the land?

Or you could put a big net around the moon to catch all the bits when it gets blown up.
 — DrBob, Feb 11 2009

 Ok regarding calculations...

 The effect of the moon on the tides is equal to the difference between the period of the earths rotation and the period of the moons cycle. When these periods match the moon no longer affects the tides (and any transfer of momentum will stop).

 Of the options open disentangling the moon and earth orbits is viable. Personally I could live without the moon and the tides but I could not stand a month long day (and night)...

 Of the other options proposed all seem to have a greater negative effect on the environment than the loss of the moon (which is going to happen anyway).

 The best other option (not yet proposed) is to dig a great cause way for the oceans to course through. The highest mark will always point towards the moon. This will reduce the frictional effect of the oceans on the earths rotation and it will remove any gravitational effect the oceans have on the moon.

 I am not sure of the orientation of the cause way though because the earths tilt is also affected by the moon (and jupiter).

Go figure...

Fill the ocean with cornstarch. That'll slow down the moon's meddling.
 — vincevincevince, Feb 11 2009

 An anti moon that spirals the other dirrection, hmmm. We could do that with a moon below geosync going the same way as the earth that finally crashes in. and the moon or a counterspin moon as proposed, no not so much. I understand that the moon supposedly affects seasonal changes and tilt in the long term climate too. It is good to note that what we are talking about is geosync's orbit will be merging with the moon's orbit. so what I am talking about can be farther out than current geosync. we can wait until perhaps day = 1.25 present days and insert a moon at 1.24999 and thus perterb every geosync satilite out of orbit. so, the idea with a more massive moon spinning in the opposite dirrection would simply slow down the earth as well until either the earth is spinning in the opposite dirrection and tidally locked either in orbit or in one planet.

 I think we have just enough time to do this as proposed in a controled manner. I still think our first large scale orbital adjusment should be Mercury. I think it is easiest since we can smack it with a jupiter rock and stop it's rotation then use that to power everything else.

Excellent idea naming and I happen to be partial to the subject matter.
 — MercuryNotMars, Feb 11 2009

 //The effect of the moon on the tides is equal to the difference between the period of the earths rotation and the period of the moons cycle. When these periods match the moon no longer affects the tides (and any transfer of momentum will stop).//

 A gross oversimplification, Jim needs to consider the mathematics - the effect of the moon/tides combination is going to be at an inverse-square proportion to the moon-earth distance - so if it is moving away, while the effect will indeed remain, it will be massively reduced to the point of insignificance - depending on the speed of the moon's recession and the rate at which the tidal forces are slowing the earth - we may yet get away with it.

Plus, I'm not convinced that there would only be a stable state at 1:1 r:m (where r=earth's rotation and m=moon's orbital period) - there ought to be some harmonic points at which the forces start balancing out. Perhaps 1/2r:m? 1/4r:m? 1/8r:m? I'd have thought that the viscosity of the fluid might play a role as well - anything other than an ideally non-viscous ocean would generate a delay which would shift the harmonics out of phase - even at 1:1 - so, even if we don't have to solidify the oceans with cornflour/custard powder - we might be able to tweak their viscosity for some fine adjustments.
 — zen_tom, Feb 11 2009

 Couldn't you just do a two-fer and blow up the Moon and use the debris to create a ring for the Earth.

 The ring would block a lot of light and prevent global warming.

This might be necessary because the loss of tidal action will shut down the Jet streams and cause a lot of localized heat buildup. Surfing will suck but I think there would be a net lowering of major disasters. I do worry that the loss of Typhoons may make certain places arid.
 — MisterQED, Feb 11 2009

 To be honest --- the month long day is due to occur at just about the time the sun explodes so there is not a deperate need to re-model the solar system. The moral of the story is to get out while the getting is still good.

Jim just goes...