Water? In MY upper mantle?

[Michael Douglas]

There's a growing possibility that the earth holds more water than previously thought, deep, deep below the planet's crust. Also Mars. Mars might have the same large bodies of sub-surface water. Which is highly relevant.
http://www.bbc.com/news/science-environment-26553115
http://www.newscientist.com/article/dn25...5yM9yjm92t
However, if this turns out to be true, this means that terraforming just got harder - a lot of hydrogen that went into the earth's water would have come from terrestrial sources rather than in commets.

EDIT: I haven't thought about this much, but if the Earth holds around 3 quarters of its water in subterranean oceans, might habitable ocean planets be rarer than we thought, and easily terraform-able dry super-earths more common?

[stevebowers]

Three quarters of the Earth's water underground equals a total of 4x Earth's oceans; many water worlds hold tens or hundreds as much water as Earth, so these will not be affected.

Where this becomes significant is planets with similar water content to the Earth- I think it means that the mantle reservoir needs to fill up before the surface becomes waterlogged, so there might be quite a few more planets with moderate or low water cover. More dry worlds, more worlds with small oceans, more worlds with relatively shallow oceans.

This also suggests that it is quite difficult to dry a planet out completely - there might be water deep inside Venus, after all.

[Drashner1]

However, if this turns out to be true, this means that terraforming just got harder - a lot of hydrogen that went into the earth's water would have come from terrestrial sources rather than in commets.

Not necessarily - if Mars has a lot of deep water, it might be pumped to the surface to assist in terraforming. And even if a lot of Earth's water is 'local' instead of from comets - that doesn't preclude using comets to bring water in for terraforming purposes. Or mining ice moons and sending the ice to the planet to be terraformed.

It would seem to mainly mean that the possible options for terraforming might change up or even expand a bit.

Todd

[omega_tyrant]

Interesting. How might this excess water be bright to the surface for use? (I'm thinking some of this could be transferred off Earth to Space Colonies, specifically)

[Rynn]

Interesting. How might this excess water be bright to the surface for use? (I'm thinking some of this could be transferred off Earth to Space Colonies, specifically)

That is really unlikely to be a good, or viable, idea. Firstly because the gravity well of Earth means that it will take a ridiculous amount of energy to get a significant amount of water off of it. Far easier (and still a daunting tasks) to redirect water comets. Secondly I doubt that sucking out subterranean water in substantial amounts wouldn't have any effect on tectonic stability. There would likely be very undesirable side effects.

[kch49er]

Maybe some worlds will use something like the great man made river from their mantle water.

[Cray]

Wasn't the finding that the water was chemically bound or at least mixed into ringwoodite, or did I misunderstand the finding? If it's bound into minerals, that's not a pumpable water supply but rather an ore that needs mining.

[kch49er]

Wasn't the finding that the water was chemically bound or at least mixed into ringwoodite, or did I misunderstand the finding? If it's bound into minerals, that's not a pumpable water supply but rather an ore that needs mining.

I was assuming that in some terraforming operations with similar geology-(planetology?) Von Neuman or bots or ufog would be used to mine the rocks then crack it,(in the way lunar regolith might be used to get oxygen or some other process) release the water then store it in liquid form on the surface as a depoist for canals/aquaducts/rivers/lakes etc. Given y11k tech this might be used at some point in the history of the setting instead of or as well as bringing comets in and certainly a lot better than bringing water off earth

[iancampbell]

Wasn't the finding that the water was chemically bound or at least mixed into ringwoodite, or did I misunderstand the finding? If it's bound into minerals, that's not a pumpable water supply but rather an ore that needs mining.

The way I read it, it sounds as if the water is physically trapped inside microvoids rather than being chemically bound.

Incidentally, it took less than 2 days before Bible-literalist crazies started using this new (and speculative) finding as justification for the literal truth of the Bible's Flood myth. "The fountains of the great deep were broken up" or something like that.

A massive release of subsurface water is the theme of a Stephen Baxter novel, too.

[xsampa]

Could undersea seismic activity trigger seabed fragmentation leading to all the subsurface water being released over a few decades, as in Baxter's "Flood" ? Is that likely?