The Great Water Conundrum 2
Did Earth's Water come from Asteroids? (Jan 2011)
The discovery of water ice on asteroids has opened up new possibilities for astronomers keen to explain the source of Earth's abundant water.
It is now clear that the water signature of cometary ice is different to that of the water on Earth. As such, the long-held belief among scientists that much of the Earth's water was deposited by impacting comets has been severely challenged. I wouldn't say that this theory is now entirely rejected among astronomers, because at the same time a large grey area has emerged between the nature and composition of comets versus asteroids. In astronomical parlance, the 'snow-line' has shifted. Nevertheless, it is clear that if water was deposited here early on, it did not come from the edges of the solar system. Rather, the water here is consistent with that found in the asteroid belt.
Because of this finding, scientists are now speculating that water was deposited upon a desiccated Earth by asteroids (1). While most asteroids sit quite happily in the main asteroid belt safely located between Mars and Jupiter, there are asteroids which have more eccentric orbits, and there are many 'near Earth objects'. The problem for scientists is that the speculation revolves around the water surprisingly featured on main belt asteroids such as 24 Themis and 65 Cybele. They don't come anywhere Earth, and never have. If one believes the currently accepted models of planetary formation in the solar system, then the Earth has always been where it currently is, and the main belt asteroids where they are. The two do not mix socially - so how did the water actually get to Earth if it was supposedly located on distant asteroids in the first place?
Zecharia Sitchin's vision of the early solar system offers a solution to this question - the asteroids and Earth come from the same source. According to his readings of ancient texts, he argued that Earth was once a much larger, watery world. Vitally important to the issue of the origin of Earth's water, the Earth was initially located where the asteroid belt is now. That argument holds great promise here, because if the early Earth was once located up to four times further away from the Sun, then its early water need not have been driven off by the Sun early on. This would also explain why there's water on the Moon.
There's a lot of evidence for massive collisions upon the Earth early in its history. The leading scientific theory about the formation of the Moon holds that the Earth was struck by a planet the size of Mars. Furthermore, the Earth (along with other worlds) was pummelled by massive asteroids/comets/planetoids 3.9 billion years ago, during the late heavy bombardment. Surprisingly, water on the Moon is deeply embedded in rocks, suggesting water was part of the Moon's composition from the very beginning. If the Moon formed as a result of a collision of a planet with the early Earth, then it stands to reason that the early Earth also had water in abundance (2). In that case, the 'late veneer' theory is redundant anyhow. But the collisions themselves offer a suggestion as to how the Earth migrated:
Perhaps it's as simple as saying that the Earth got knocked off its perch, and the asteroid belt marks the spot of this catastrophic event. More likely, the close flyby of a larger, rogue body played a part - simultaneously providing the gravitational push for a substantial migration by the Earth, and the accompanying system of moons and comets that could have resulted in sizeable impacts during the flyby.
I think these latest findings lead us towards the conclusion that the Earth initially formed, water and all, much further away from the Sun than its current location. Furthermore, the asteroid belt is a by-product of whatever event drove the Earth deeper into the inner solar system. Such a situation would explain the Earth's abundance of water, the fact that the water did not come from comets, and the abundance of water located on even minor main belt asteroids far from the Earth.
Comet from the Kuiper Belt Has Earth-like Water (Oct 2011)
Comets in the solar system have variable origins. Over recent years scientists have looked at the water composition of comets in order to answer the question of where the Earth's water originated from. This is a trickier question than you might think. If the Earth formed in its current location (and note I say 'if') then the intense bombardment of the solar wind from the early hot Sun should have driven off all the volatiles from the Earth's primordial surface, including water. The fact that the Earth has abundant water, rather than being arid like Venus and to a lesser extent Mars, is a mystery.
The generally accepted answer to this mystery is the 'later veneer theory', whereby water was deposited onto a dry Earth as a result of the impacts of many, many comets and asteroids over a vast period of time. But this theory has been questioned recently because the isotopic composition of water in the half dozen comets so far analysed has been different to that of Earth water. If they are a representative sample of smaller bodies in the solar system, then the water must have come from somewhere else: Firstly, there aren't enough comets in the solar system to have created the Earth's oceans, and secondly, the isotopic composition seems to be wrong anyway.
The latest comet to be analysed in this way has opened a door of hope on the Late Veneer Theory:
"New measurements from the Herschel Space Observatory show that comet Hartley 2, which comes from the distant Kuiper Belt, contains water with the same chemical signature as Earth's oceans. This remote region of the solar system, some 30 to 50 times as far away as the distance between Earth and the sun, is home to icy, rocky bodies including Pluto, other dwarf planets and innumerable comets." (3)
The problem is where comet Hartley 2 originally came from (4). The Kuiper Belt is effectively a second asteroid belt beyond the planet Neptune, much larger than its famous cousin which lies between the orbits of Mars and Jupiter. It is a part of the solar system astronomers are only just starting to understand, and regular readers of this site will recognise that it has thrown up a large number of anomalies and new questions.
Many of these new findings are suggestive, in my opinion, of a different scenario for the early solar system than is presently held by the mainstream scientific community. The new puzzle is why bodies originating close to the Earth have a different isotopic composition to the water found on our planet, whereas one originating in the distant Kuiper Belt has exactly the same. So where this new discovery throws the Late Veneer Theory a bit of a lifeline (5), it does not explain why the Earth has more in common with a Kuiper Belt Object that has strayed back into the inner solar system, than it does with the nearby asteroids and other neighbouring cosmic debris. Comet Hartley 2 seems misplaced, to say the least:
"However, the new results also raise new questions. Until now, scientists assumed that the distance of a body’s origin from the Sun correlated to the deuterium-to-hydrogen ratio in its water. The farther away this origin lies from the Sun, the larger this ratio should be. With a “birth place” within the Kuiper belt and thus well beyond the orbit of Neptune, Hartley 2, however, seems to violate this rule. “Either the comet originated in greater proximity to the Sun than we thought”, says Hartogh, “or the current assumptions on the distribution of deuterium have to be reconsidered.” And maybe Hartley 2 is a so-called Trojan that originated close to Jupiter and could never overcome its gravitational pull." (6)
Competing theories like mine, originating in Zecharia Sitchin's controversial explanation for the cosmic catastrophes of the early solar system, may offer answers to this mystery, which don't require rewriting the laws of physics. There's the potential here to prove a very important point about the origin of Earth. Let me explain: Earth may have formed in one of two locations, (1) where it is now (what everyone assumes), or (2) at the distance of the asteroid belt (Zecharia Sitchin's solution (7)). How can we tell? Scientists think that water in the solar system contains different ratios of hydrogen to deuterium isotopes, depending upon the formation distance from the Sun, and that gives us the potential ability to determine where things should sit in the solar system.
Now, if the Earth formed at the current distance, then the early waters were blasted off the surface of the Earth by the sun's solar wind, which was stronger initially than it is now. Like volatiles being blasted off comets as they approach the Sun, the Earth should have lost its water. It should have been dry when it solidified. As we know, it's actually wet.
So the water either came from impactors like comets and asteroids, or...the Earth formed further away from the Sun than it is now. At the distance of the asteroid belt, water would not have been blasted away.
When scientists look at the isotopic ratio of water contained in various bodies in the solar system, they are building up a picture of the early solar system. As it turns out, things have not gone as expected. Comets studied so far have not had the same ratio as Earth, so that brings into question whether the Earth gained water from them. This latest comet, which is really a Kuiper Belt Object, is the first to contain the same ratio as the Earth.
Some scientists suggest that the bombardment of the inner solar system that took place 3.9 billion years ago (the 'Late Heavy Bombardment') consisted of a swarm of giant comets from the Kuiper Belt displaced by the migration of Jupiter and Saturn. Such a concept is supported by the recent discovery of the debris of a giant comet in a neighbouring star system whose chemical signature matches meteorite fragments found here on Earth. A pattern may be occurring here:
4 billion years ago, some 600 million years after our solar
system formed, scientists think the Kuiper Belt was disturbed by
a migration of the gas-giant planets Jupiter and Saturn. This
jarring shift in the solar system's gravitational balance
scattered the icy bodies in the Kuiper Belt, flinging the vast
majority into interstellar space and producing cold dust in the
belt. Some Kuiper Belt objects, however, were set on paths that
crossed the orbits of the inner planets.
"The resulting bombardment of comets lasted until 3.8 billion years ago. After comets impacted the side of the moon that faces Earth, magma seeped out of the lunar crust, eventually cooling into dark "seas," or maria.
"Comets also struck Earth or incinerated in the atmosphere, and are thought to have deposited water and carbon on our planet. This period of impacts might have helped life form by delivering its crucial ingredients." (8)
Despite the ready supply of water in comet clouds seen forming around other stars (9), the problem remains that the population of the Kuiper Belt is insufficient to have supplied enough water to have filled the Earth's oceans. What could have swept through the Kuiper Belt to have displaced all those missing KBO asteroids? Surely not distant Jupiter and Saturn? This is where the Dark Star concept could really provide the answer (10). But caution is needed: the dataset here remains small, and we will only be able to piece the puzzle together properly when a larger sample of comets and asteroids has been properly studied.
This website has argued for years that the evidence in the solar system increasingly points to a migrating Earth scenario. It seems, on the face of it, to be a rather far-fetched idea. As with so many things, we take the Earth's stability for granted, when in fact its history is pock-marked with catastrophe and monumental change. We assume that the Earth was formed at the same distance from the Sun and has stayed there ever since. But why should that be?
It is said that extraordinary claims require extraordinary evidence. The evidence for the early migration of the Earth (or possibly the Earth/Moon binary system) takes the form of the water in various parts of the solar system. This water, which consists of a mixture of isotopes, carries its own signature, which various according to where in the solar system the water first formed. Similarly, isotopic signatures can be derived from the elemental composition of rocks, helping scientists to slowly piece together the puzzle of the early solar system. Results are proving surprising.
The arguments involved become complex (and I have tried to do them justice in my book Dark Star (10), as well as on in-depth analysis on this website) but the picture that emerges from the evidence is that the water on Earth and the Moon is unexpectedly abundant, given how close they are to the Sun, and that the idea of water being brought to the Earth and Moon by comets is an insufficient explanation for what we see here.
I have therefore argued that the best explanation for what we see is that the Earth system initially formed where the asteroid belt is currently now, and migrated in to its current position following an early catastrophic event (involving the Dark Star). The more distant location for the early Earth provides us with a strong explanation for why the Earth has so much non-cometary water on it: it was too far from the Sun for the early solar heat to have driven the volatile water off. Such a scenario is in keeping with Zecharia Sitchin's theories of where the Earth formed.
Further grist for this particular mill is now provided by recent studies of moon rocks which, when combined with the newest theories of Moon formation, lead the scientists in exactly the same direction. Here's the quote from New Scientist:
"So if the moon's water came from Earth, where did Earth's water come from? The impact that formed the moon happened within about 100 million years after solid bodies began to form in the solar system – an eye-blink in astronomical timescales. [Alberto] Saal [of Brown University, R.I.] doubts that Earth could have accumulated enough water from asteroid strikes in that time. "The implication, although I cannot absolutely prove it, is that probably the Earth formed with water," he says. The trouble is that our planet is currently too close to the sun for it to have retained water as it coalesced from the swirling disc of material that was to become the solar system.
Saal thinks that Earth may have formed near where the asteroid belt is now, which is far enough from the sun for water to condense. The planet would then have migrated inward. It'll be a tough theory to prove, because Earth's geologic activity has been recycling rocks, and thus erasing the evidence, for billions of years. That's what makes moon rocks so valuable.
"All that we know now is because we have a fossilised record of what happened 4.5 billion years ago on the moon," says Saal. "We couldn't get that conclusion from looking at the Earth." (11)
It appears that the interior waters of the Earth and Moon have the same source (12), leading to the conclusion that they were always there from the beginning of the life of Earth. I would imagine, then, that should the Inward Migration Hypothesis be correct, then we should find similar water compositions among the asteroids in the main belt. After all, if the Earth started its life there and was catastrophically expelled, then shouldn't at least some of those asteroids have been part of the early Earth? The composition of some meteorites suggests planetary origins, or at least that the were once fragments of very large planetessimals early in the life of the solar system:
"What is most unusual about these rocks [designated GRA 06128 and GRA 06129] is that they have compositions similar to Earth's andesite continental crust - what makes up the ground beneath our feet," says University of Maryland's James Day, lead author of the study. "No meteorites like this have ever been seen before." (13)
A smoking gun may be around the corner as space agencies and mining companies turn their attention towards asteroids. Scientists working with the data from WISE are currently piecing together the history of the asteroid families, projecting back in time to glue the pieces of the original 'vases' together (14). It seems evident to me that Sitchin's work is receiving further vindication from cutting-edge science, and that these endeavours will soon offer his idea some long-awaited proof.
Sceptics argue that there is no evidence that a planet larger than Mars ever existed in the zone currently occupied by the asteroid belt. Furthermore, the very presence of mighty Jupiter in this region makes the probability of the formation of a terrestrial planet not just low, but virtually impossible.
"“There’s a not a single piece of concrete evidence that would suggest that there ever was a full-sized planet in the asteroid belt,” said Nick Moskovitz, a planetary scientist at M.I.T. “In the region of the Main Belt, it’s dynamically impossible in the presence of Jupiter’s gravitational influence for small bodies to collide and stick together to form a full-sized planet.”
"In truth, the mass of the Main Belt — which extends just past the orbit of Mars to about three and a half times the distance from the Earth to the Sun — has not changed much over the 4.5 billion year life of the solar system. Moskovitz says the belt that we see today is the result of a population of bodies that have spent the subsequent 4.5 billion years interacting and colliding with one another." (15)
I'm generally sceptical when sceptics make such sweeping generalisations. The history of science is awash with examples of such bold statements proving laughably erroneous years later. One only needs to review the remarkable variety of extra-solar planets discovered in the last decade or so to see how theoretical positions held by astronomers beforehand subsequently required serious revision.
Written by Andy Lloyd, author of 'The Dark Star' (2005) 'Ezekiel One' (2009) and 'The Followers of Horus' (2010)
© 10th Jan 2011, 7th & 20th Oct 2011, 20-27th May 2013
1) Kristina Grifantini "Where DID Earth's Water Come From?" Sky and Telescope, p22, January 2011, with thanks to Lee
2) 'Water found on the Moon' http://www.wired.com/wiredscience/2008/07/water-found-on/# 9th July 2008, with thanks to Lee
3) JPL Press Release, "Space Observatory Provides Clues to Creation of Earth's Oceans" 5th October 2011, http://www.jpl.nasa.gov/news/news.cfm?release=2011-312&cid=release_2011-312 with thanks to David, see also http://www.bbc.co.uk/go/em/fr/-/news/science-environment-15181123
4) Technical Data about Comet Hartley 2: http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=103P;orb=1;cov=0;log=0;cad=0#discovery
5) Thomas Moore, Scientists Find Ocean-Like Water On Comet, October 05, 2011 http://news.sky.com/home/technology/article/16083250 with thanks to Lee
6) Astrobiology Magazine "Proof that Comets Brought Oceans to Earth" http://www.astrobio.net/pressrelease/4261/proof-that-comets-brought-oceans-to-earth with thanks to Lee
7) Z. Sitchin “The Twelfth Planet” Avon 1976
8) JPL Press Release "NASA's Spitzer Detects Comet Storm in Nearby Solar System" 19th October 2011 http://www.jpl.nasa.gov/news/news.cfm?release=2011-322&cid=release_2011-322&msource=11322&tr=y&auid=9719493 with thanks to David
9) University of Michigan Press Release, "Nearby Planet-Forming Disk Holds Water for Thousands of Oceans", 20th Oct. 2011, http://www.sciencedaily.com/releases/2011/10/111020171448.htm with thanks to Monika
10) Andy Lloyd "Dark Star: The Planet X Evidence" Timeless Voyager Press 2005
11) Lisa Grossman "Moon Water Came From Young Wet Earth" 9th May 2013 http://www.newscientist.com/article/dn23515-moon-water-came-from-young-wet-earth.html with thanks to Lee and Beau
12) A. Saal, E. Hauri, J. Van Orman & M. Rutherford "Hydrogen Isotopes in Lunar Volcanic Glasses and Melt Inclusions Reveal a Carbonaceous Chondrite Heritage" Science 1235142, 9 May 2013, http://www.sciencemag.org/content/early/2013/05/08/science.1235142
13) Science Daily "Half-Baked Asteroids Have Earth-Like Crust" 8th Jan 2009 http://www.sciencedaily.com/releases/2009/01/090107134526.htm with thanks to Lee
14) T. Phillips "New Asteroid Families Discovered" May 2013 http://science.nasa.gov/science-news/science-at-nasa/2013/29may_asteroidfamilies/
Dorminey "Main Asteroid Belt No Remnant Of Exploded Planet" 31st Jan 2013