Water, Pt 2

Last week we last saw our intrepid hero engaged in a search for the origin of our water…

So now that science has turned away from the population of comets resident in the Kuiper Belt (also the neighborhood in which Pluto resides… way, way out there past Neptune) as being the source for our Earthly water supply, in which direction should we turn our search?

Well, divining the answer will seem something of a shell game.  If you do not know what a shell game is, watch a W.C. Fields movie.  If you do not know who W.C. Fields is, crawl back into your mother’s womb and bake a while longer.  You can catch up with us when you have learned something.

Yes, the ol’ shell game: we have lifted one of the shells, that representing Kuiper belt icy comets, and didn’t find a pea.  Perhaps, more correctly, we found a pea that did not meet our heavy water criteria.  So now we have two shells left: water that formed or was present at the very creation of our solar system; and a newly suspected source, ice bearing asteroids from the Oort cloud. “What is the Oort cloud?” you ask. The Oort cloud is a spherically shaped collection of long-term bodies: asteroids, comets, planetesimals (like Pluto); and maybe even a dark star, twin to our energy producing Sun (I know this sets your imagination reeling, but we’ll have to wait for another blog post to address this mind bender).  While the asteroids observed that seem to have their origin in the Oort cloud have a hydrogen/deuterium ratio closer to that found in earth water than comets, there are still differences waiting to be accounted for.  There is something under the Oort cloud shell, but we’re not sure if it is a pea, or a kernel of corn. (This writing is suddenly making me hungry… Mexican for lunch?).

This leaves us with the hypothesis that our water was here all along, that it was in the material that eventually accreted into our solar system.  Substantial proof of this is present in rocks retrieved by Apollo astronauts (those are the ones that went the Moon, kiddies).  Hold on to your hand bar because if you are not familiar with the origin of the Moon, this roller coaster ride is going to blow your mind.

It is generally accepted by planetary scientists that our Moon was created in a collision between a newly forming Earth and a wandering planet (about the size of Mars) that has been named Theia.  Now I’ve warned you before about naming dogs/planets that follow you home.  Why would we name a planet that no longer exists?  It’s just going to make it that much harder when to let Theia go when some new, competing hypothesis causes us to eschew her from the textbooks.   But I digress.  The collision resulted in a debris belt bound to Earth by gravity which eventually accreted into our Moon.  For our discussion of where did water come from, it is significant that the water in rocks from the Moon are essentially identical in their Hydrogen/Deuterium isotope found in our oceans.  This is as close as were going to get today in stating definitively from whence our water came.  But at this juncture, it seems that our peas are home-grown.  Thanks, Del Monte.

And then there is the question, “Where does our water go?”  Well that is more easily addressed.  Our water goes nowhere.  It is, at the current time (that means about 4.6 billion years} a closed system.  While water may change states; frozen, liquid, gaseous; it does not leave the planet.  Rising and ebbing ocean levels over time are a function of global temperature fluctuations caused by variances in solar energy output of the Sun, not man made greenhouse gasses. As temperatures fall, water is stored in the ice caps.  When temperature rise, the ice melts and ocean levels rise.

“Then, Dale” you ask, “is it not necessary to conserve water?”  Actually, it is necessary.  From an ecological survival perspective, it is probably the most imminent of concerns.  As the human population continues to expand we use water in ways that can render it non-potable (by introducing dangerous chemicals into the supply as a result of agricultural and industrial processes).  Far more critical than global warming concerns (as we have pointed out in many previous posts), usable water must be protected.

So, yes children, turn off the water while you brush your teeth.