Two leading theories for the origin of water on Earth invoke extra-planetary sources from asteroids and/or comets 4.
The question that Mojzsis’s discovery led to was where did the water come from at such an early point in the Earth’s history? "Early volcanic activity may have erupted huge amounts of steam into the atmosphere but some scientists argue that there would have been too little time for the oceans to have formed in this way. Some scientists believe that much of the Earth’s water came from outer space. According to Bill Hartmann, "We all hear about the impact 65 million years ago that wiped out the dinosaurs and you’re getting that kind of impact about once a month on the early Earth. But this rain of debris left over from the formation of the solar system continues for several million years." Comets contain dust and frozen water vapour left over from the birth of the solar system. Like giant dirty snowballs roughly half their mass is water." and 13 seconds long. One scientist has even proposed that all water came from outer space but, so far, he has failed to find evidence to support his theory. "One of Nasa’s top comet experts, Michael Mumma, believes that comets could be source of water in our oceans." It is not known how much water came from outer space. 1
Until very recently it was thought that the terrestrial planets got most of their carbon and water from comets (Delsemme 1997). Despite the fact that H2, He, H2 O, CO and N2 were the most frequent molecules in the solar nebula, their presence on Earth is not trivial, because they are highly volatile and did not get incorporated easily into planetesimals of the inner regions of the solar system. New spectroscopic observations of comet tails show that the deuterium/hydrogen ratio is a factor of two higher than in sea water, which excludes comets from a main role in the delivery of water to the terrestrial planets. Water apparently derived from the release of trapped H2O in the crystal structure of accreted silicates and as ice from those 10– 15% of accreted planetesimals with eccentric orbits that had formed near the ice-formation boundary (Rodgers and Charnley 2002). 2
Planet Earth makes its own water from scratch deep in the mantle 3
Our planet may be blue from the inside out. Earth’s huge store of water might have originated via chemical reactions in the mantle, rather than arriving from space through collisions with ice-rich comets. The simple reaction takes place at about 1400 °C and pressures 20,000 times higher than atmospheric pressure as silica, or silicon dioxide, reacts with liquid hydrogen to form liquid water and silicon hydride. The simulation showed that the water forms within quartz but then can’t escape and so the pressure builds up. Water formed in the mantle can reach the surface via multiple ways, for example, carried by magma in the form of volcanic activities. It is possible that water is still being made this way deep inside Earth today. Rather than hydrogen bonding into the quartz crystal structure, it disrupts the structure completely by bonding with oxygen and forming water-rich regions below the surface. The minerals that make up Earth’s mantle can incorporate large amounts of water, and the Earth is probably ‘wet’ in some sense all the way down to its core.
Formation and properties of water from quartz and hydrogen at high pressure and temperature 4
Reaction between silica (and silicates) and H2 in the mantle represents a source for the origin of water on Earth. At a temperature of 1700 K and pressure of 2 GPa, molecular hydrogen dissociates inside the silica, interacting with oxygen atoms, and this reaction process ends up with the formation of water molecules, as was observed experimentally by Shinozaki et al. (2014). 5 Quartz, as the most stable low-pressure polymorph of silica (SiO2), is widely abundant in Earth’s crust and mantle, exhibiting relatively high chemical stability. Silicon dioxide, known as silica, is, with its rich tapestry of various polymorphs and forms, one of the most abundant materials that can be found on Earth and other terrestrial planets. Although silica is only slightly soluble in water at ambient conditions, producing silicon-based weakly acidic compounds, water itself can be formed by dissolution of Silicon dioxide ( Silica - SiO2 ) in Hydrogen H2 fluid under high- temperature and pressure conditions. Diffusion of the H2 fluid into the quartz crystal lattice was observed upon increasing temperature and pressure, followed by interaction of dissociated, atomic hydrogen with oxygen atoms in the Silica SiO2 lattice, disrupting the lattice and leading to the formation of water. Interestingly, water is evolved in the subsurface region of the silica, and it remains confined there, isolated from the hydrogen fluid, which corresponds precisely to the ice-like spectroscopic patterns observed experimentally. The over-pressured water formed from quartz and Hydrogen H2 is a possible trigger for nucleating enigmatic deep earthquakes in the continental mantle lithosphere.
2. Intelligent life in the universe, page 44