Planetary scientists are looking to asteroids as the source of Earth’s water – not from evidence, but from desperation.

The Bible’s book of Genesis describes Earth covered with water from its creation.  Not so, say the secular evolutionists: Earth began as a hot, dry, rocky body spewing volcanoes and facing a bombardment of space debris.  Problem: why is it covered with water today?  Even though the oceans are a relatively thin veneer on the globe, making up about 1% of Earth’s mass, their prominence is one of the defining characteristics of our “water planet.”

There have been three suggestions to answer the “H2O Enigma” (see 3/26/2002): a lucky strike by a big wet planetesimal, condensation from the solar nebula, and comets.  The first two hypotheses are pretty much defunct, leaving comets.  But for the last several years, secular planetary scientists have doubted that comets brought the water (see 11/03/2009), primarily because the hydrogen-to-deuterium ratio in cometary ice differs substantially from Earth water.  (Deuterium abundance is thought to increase with distance from the sun.)  In addition, direct observation of comets by Stardust and Deep Impact have shattered theories about their origins (12/27/2007, 9/24/2008, 4/18/2011).

As reported recently, it’s unlikely scientists can retreat back to condensation from the local solar nebula.  The so-called “snow line” in planet formation theory is now thought to be even farther out than previously believed.  Earth started out dry.  Volatiles like water had to come special delivery.

Taking all the difficulties into account, NASA’s Astrobiology Magazine considered one last option: asteroids.  In ” Meteorites Most Likely Source of Earth’s Water,” NASA pointed to work by Carnegie Institute scientists who believe water-bearing carbonaceous chondrites, with their lower deuterium ratios, could have been the delivery vehicles.  Because the deuterium ratio is lower, they might have formed in the asteroid belt….

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