Comet water discovered to be nearly identical in composition to Earth's oceans

 Suggests comet bombardment contributed to forming oceans

This photo of Comet Hartley 2 from the November 2010 flyby performed by NASA's Deep Impact spacecraft shows jets containing water vapor ejecting from the core.

From the European Space Agency: Did Earth’s oceans come from comets?

Comet Hartley 2 observed by ESA’s Herschel

This illustration shows the orbit of comet Hartley 2 in relation to those of the five innermost planets of the Solar System. The comet made its latest close pass of Earth on 20 October, coming to 19.45 million km. On this occasion, Herschel observed the comet. The inset on the right side shows the image obtained with Herschel’s PACS instrument. The two lines are the water data from HIFI instrument. Credits: ESA/AOES Medialab; Herschel/HssO Consortium

ESA’s Herschel infrared space observatory has found water in a comet with almost exactly the same composition as Earth’s oceans. The discovery revives the idea that our planet’s seas could once have been giant icebergs floating through space.

The origin of Earth’s water is hotly debated. Our planet formed at such high temperatures that any original water must have evaporated. Yet today, two-thirds of the surface is covered in water and this must have been delivered from space after Earth cooled down.

Comets seem a natural explanation: they are giant icebergs travelling through space with orbits that take them across the paths of the planets, making collisions possible. The impact of comet Shoemaker-Levy 9 on Jupiter in 1994 was one such event. But in the early Solar System, when there were larger numbers of comets around, collisions would have been much more common.

However, until now, astronomers’ observations have failed to back up the idea that comets provided Earth’s water. The key measurement they make is the level of deuterium – a heavier form of hydrogen – found in water.

Comet Hartley 2’s orbit in context

The left panel shows Comet Hartley 2’s orbit. The central panel shows a larger portion of the Solar System, including the Kuiper Belt. The Kuiper Belt is one of the two main reservoirs of comets in the Solar System. Comets like Hartley 2 are believed to have formed here and to have migrated inwards. The right panel shows the Oort Cloud, the other main reservoir of comets located well beyond the outer Solar System.

All the deuterium and hydrogen in the Universe was made just after the Big Bang, about 13.7 billion years ago, fixing the overall ratio between the two kinds of atoms. However, the ratio seen in water can vary from location to location. The chemical reactions involved in making ice in space lead to a higher or lower chance of a deuterium atom replacing one of the two hydrogen atoms in a water molecule, depending on the particular environmental conditions.

Thus, by comparing the deuterium to hydrogen ratio found in the water in Earth’s oceans with that in extraterrestrial objects, astronomers can aim to identify the origin of our water.

All comets previously studied have shown deuterium levels around twice that of Earth’s oceans. If comets of this kind had collided with Earth, they could not have contributed more than a few percent of Earth’s water. In fact, astronomers had begun to think that meteorites had to be responsible, even though their water content is much lower.

Now, however, Herschel has studied comet Hartley 2 using HIFI, the most sensitive instrument so far for detecting water in space, and has shown that at least this one comet does have ocean-like water.

HIFI

The Heterodyne Instrument for the Far Infrared (HIFI) is a high-resolution heterodyne spectrometer. It works by mixing the incoming signal with a stable monochromatic signal, generated by a local oscillator, and extracting the frequency difference for further processing in a spectrometer. HIFI will have seven separate local oscillators covering two bands from 480-1250 gigaHertz and 1410–1910 gigaHertz. HIFI was developed by a consortium led by SRON (Groningen, The Netherlands). Credits: ESA (image by C. Carreau)

“Comet Hartley’s deuterium-to-hydrogen ratio is almost exactly the same as the water in Earth’s oceans,” says Paul Hartogh, Max-Planck-Institut für Sonnensystemforschung, Katlenburg-Lindau, Germany, who led the international team of astronomers in this work.

The key to why comet Hartley 2 is different may be because of where it was born: far beyond Pluto, in a frigid region of the Solar System known as the Kuiper Belt.

The other comets previously studied by astronomers are all thought to have formed near to Jupiter and Saturn before being thrown out by the gravity of those giant planets, only to return much later from great distances.

Thus the new observations suggest that perhaps Earth’s oceans came from comets after all – but only a specific family of them, born in the outer Solar System. Out there in the deep cold, the deuterium to hydrogen ratio imprinted into water ice might have been quite different from that which arose in the warmer inner Solar System.

Herschel is now looking at other comets to see whether this picture can be backed up.

“Thanks to this detection made possible by Herschel, an old, very interesting discussion will be revived and invigorated,” says Göran Pilbratt, ESA Herschel Project Scientist.

“It will be exciting to see where this discovery will take us.”

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Chris Smith

So God put the water here by chucking a lump of ice at it after it had cooled? ;-).

kim;)

Interesting !!!
Mr Watts have you seen this? [ I would have left it on your “Tips and notes” pages but dialup just won’t load it anymore 🙂 ]
Huge ‘Ocean’ Discovered Inside Earth
http://www.livescience.com/1312-huge-ocean-discovered-earth.html

I seem to remember that recently comets made from just ice were discovered by seeing specks in photographs of aurora. These were about the size of houses, and being all ice, simply melt and become part of the earth’s atmosphere. It was estimated from the rate of occurrence that all the water of the earth could have come from this source over a period of about 1 billion years. Or is my memory failing me.

Bloke down the pub

Observations. What do they expect to learn that way?

Huth

20 October which year?

John Silver

The cosmos is a source for infinite speculation.

mattweezer

Here we go again, every time Scientists make an observation then speculate about origins it sparks a huge debate between religion and science and poo starts to get flung in every which way. All I know is I really don’t care where they think water might come from. Focus on the observation and leave the rest to us to conclude…please! I don’t care anymore about scientists thoughts on origins. In the end water doesn’t taste better because it came from a comet or created by someone, though I suppose it could alter your appreciation of it a bit. For all those who want to hotly debate this, I recommend you go enjoy a cold glass of water instead, it will be more beneficial in the end and you will save yourself some frustration…cheers!

Joe Lalonde

Anthony,
I love when a good comet helps to prove my research!
Water was here long before this theory of being bombarded by comets of water.
What do you think kept toxic gases compressed when this planet was cooling?
Massive amounts of water that has been lost to space at a rate of 1.25mm/10,000 years.
Why do you think we have all this salt left over around the planet under a billion years old?

Alan the Brit

I like the sound of that. The theory has been hanging around for years & seemed plausible. However, a question, if the water on Earth evaporated due to the heat generated in its formation, why would it have “disappeared” as opposed to merely being stored in the atmosphere ready to reform as water as soon as the Earth cooled?

Tom_R

Isn’t water outgassed from volcanoes? I would think the most likely explanation is that water ice was buried in the formation of Earth and released late enough to remain and eventually form oceans as the Earth got cooler. Venus didn’t get it’s CO2 from comets.

The article states: “The origin of Earth’s water is hotly debated. Our planet formed at such high temperatures that any original water must have evaporated.”
But actually those who favor the idea that most of the Earth’s seawater came from internal sources (volcanic steam and outgassing from the Earth’s crust) say something else. They say that the primordial Earth’s atmosphere was much denser then, so that the boiling point of water at sea level was much higher. Hence, liquid water may have existed even at temperatures exceeding 212° F / 100° C.
(P.S., Ian Plimer notes this in his “Heaven and Earth” — a must-have title for the AGW-skeptic’s bookshelf)

TheBigYinJames

It’s only a hop, skip and jump from this to “Comets cause catastrophic sea level rise, we must rid the solar system of comets”

Disputin

A nasty, sneaking, heretical thought: is it absolutely known that Earth was once completely molten (aside from the major moon-forming impact, that is)? Consider a pile of space rubble accreting under gravity. The centre gets heated and melts, gradually expanding the melt front, but will it actually reach the surface? I don’t have much problem envisaging a rubbly, dusty surface over a molten inner, with volcanoes erupting and gradually forming a crust, but with the water still liquid on top.
As I said, just a thought.

(snip) Our planet formed at such high temperatures that any original water must have evaporated. (/snip)
“Evaporated”, or “evaporated and left the earth permanently”?
It makes sense that any water would have evaporated, but it does not make sense that it would not condense again at some later time.

Ray

It’s Yamal all over again… 1 comet makes the case.

John Barrett

I don’t get this at all. It sounds too much like “Was God a Spaceman?” I mean water doesn’t breed and I seriously doubt that any comet that DIDN’T destroy the earth would deposit enough ice to fill the oceans.
Isn’t it more likely that it comes from hydrogen from volcanoes burning in the atmosphere, or something ?

Kaboom

A single comet vs. multiples that didn’t check out .. I think the most basic math obviously dismisses the hypothesis unless low deuterium count comets have significantly higher probability of hitting earth than their high deuterium count brethren.

Dixon

Anthony, you are doing a fantastic job in making these things available so quickly.
Comets seem a pretty logical source of water on Earth to me. The old portents of doom have also always seemed a highly likely candidate for massive climate change to me – all that water boiling off in the upper atmosphere. How big a comet would you need to actually impact – even then, what would be left – a nice lake? Would we even notice a few chunks of ice arriving pretty much continuously? .
Why would anyone expect the ratio of deuterium in the oceans to be the same as deuterium in comets? I’m no expert, but the rates of reaction of deuterated organic compounds are dramatically different to hydrogen-based organic compounds, since all known life is hydro(gen)-carbon based, surely the presence of life would dramatically alter the H to D ratio in seawater? You get a lot of kinetics in 4 billion years…

Douglas DC

What about the various icy moons? Similar or not? Worth a look…

Adam Gallon

I’ll probably be the 37th post to mention “Panspermia”.

Alan the Brit

Of course the God was an Astronaut thing does rather fit, someone called Slartibartfast probably had a hand in it, he won an award for the fjiords you know! 😉

DirkH

John Barrett says:
October 6, 2011 at 7:21 am
“I don’t get this at all. It sounds too much like “Was God a Spaceman?” I mean water doesn’t breed and I seriously doubt that any comet that DIDN’T destroy the earth would deposit enough ice to fill the oceans.”
Think many (“house-sized”) small water comets coming in all the time.
http://csep10.phys.utk.edu/astr161/lect/comets/smallcomets.html

SiliconJon

My issue with the “water came from comets” is that it ignores a likely common cause. I say water on earth came from the same source as the comets and the comets are just some minuscule left overs. I’ve say water is created in some sort of solar or other cosmic process, and recent discovery of a star emitting jets of water shows this to be at least one origin of galactic H20 supplies.
Water is abundant in this universe, which will sadly make so many science fiction plots ridiculous.
Scientists discover water cloud in galaxy…
http://www.filtersfast.com/blog/index.php/2011/08/scientists-discover-water-cloud-in-a-galaxy-far-far-away/
Star Found Shooting Water “Bullets”
http://news.nationalgeographic.com/news/2011/06/110613-space-science-star-water-bullets-kristensen/
Black Hole Holds Universe’s Biggest Water Supply
http://www.wired.com/wiredscience/2011/07/black-hole-holds-universes-biggest-water-supply/

Jeff in Calgary

“Our planet formed at such high temperatures that any original water must have evaporated. Yet today, two-thirds of the surface is covered in water and this must have been delivered from space after Earth cooled down.”
Must have been delivered from space? There are other options. Maybe the water changed state from gas to liquid. Or maybe it was made from a chemical reaction that combined hydrogen and oxygen.

kwik

What difference does it make?
Wheter a big pile of rock was forming first in space, and then bombarded by other lumps of ice, or, one big lump of rock and ice was formed in one go……

JeffC

evaporated doesn’t mean destroyed … does water vapor escape into space ? if not then the evaporated water would simply have hung around in the atmo waiting for cooler times …

Jim Cripwell says:
October 6, 2011 at 3:37 am
I seem to remember that recently comets made from just ice were discovered by seeing specks in photographs of aurora.
There was such a proposal, but analysis of the images show that the ‘ice’ specks were just that: artificial specks or defects in the imagery.

Gail Combs

Ted Wagner says:
October 6, 2011 at 7:06 am
(snip) Our planet formed at such high temperatures that any original water must have evaporated. (/snip)
“Evaporated”, or “evaporated and left the earth permanently”?
It makes sense that any water would have evaporated, but it does not make sense that it would not condense again at some later time.
____________________________________________________________________
My thoughts exactly. To they have the calculations showing the earth’s early water vapor managed to obtain escape velocity???

Me

Maybe the water was blasted into space by an asteroid impact with the Earth and formed a comet.

Dave Springer

The Oort Cloud has a drive-thru window.
“May I take your order, sir?”
“Yes please. I’d like one global ocean with everything.”
“Very good sir. Would you care for fries with that?”
“No thank you but a few extra packets of kelp would be great.”
“Thank you sir. Your order comes to $1,000,000,000,000,000 and will be ready in a billion years at the next window. Have a wonderful day!”

Pascvaks

If there are ‘good’ icy comets, might there not also be ‘bad’ dry-icy comets? Don’t ya just love ‘settled’ science? It’s soooooo unsettling.

Jimmy Haigh

Maybe comets come from Earth’s oceans.

A G Foster

There are temperature constraints imposed on the reconstruction of H2O history, and much depends on whether we suppose cold or hot accretion. The smaller the molecule, the faster it travels at a given temperature. Water molecules have an escape velocity temperature intermediate between O2 and N2 on the one hand, and He and H2 on the other. So oxygen and nitrogen remain, while hydrogen and helium don’t hang around very long. Presumably the earth had to cool down before water could be retained in the atmosphere, to a temperature cooler than the upper atmosphere, which is hot enough to send hydrogen and helium into space. –AGF

SiliconJon says:
Water is abundant in this universe, which will sadly make so many science fiction plots ridiculous.

Reminds me of those wonderful scriptures speaking of the massive, incomparable flood that occurred between Genesis 1:1 and 1:2.
For this they willingly are ignorant of, that by the word of God the heavens were of old, and the earth standing out of the water and in the water:
Whereby the world that then was, being overflowed with water, perished – 2 Peter 3:5, 6

Tom_R

>> Disputin says:
October 6, 2011 at 7:03 am
A nasty, sneaking, heretical thought: is it absolutely known that Earth was once completely molten (aside from the major moon-forming impact, that is)? Consider a pile of space rubble accreting under gravity. The centre gets heated and melts, gradually expanding the melt front, but will it actually reach the surface? I don’t have much problem envisaging a rubbly, dusty surface over a molten inner, with volcanoes erupting and gradually forming a crust, but with the water still liquid on top.
As I said, just a thought. <<
The Earth is STILL completely molten, except for a very thin solid crust, and a core that's well beyond the melting point of iron but is solid because of the pressure.
In any case, most of the Earth's atmosphere and liquid water must have been lost in the collision that created the moon (if that theory is correct). That Earth has only about 25% of the nitrogen in Venus' atmosphere points to a catastrophic event after most or all of the atmosphere was in place. Earth, being formed farther from the sun, should have formed containing more volatile material than Venus.
I would suspect that early Earth lost all of it's primordeal atmosphere, including the water vapor, before it cooled. The H2O and CO2 were probably outgassed after the Earth cooled. I can't see any validity in a theory that says that H2O had to come from comets but CO2 didn't have to, and I'm not familiar with comets containing a significant amount of CO2. The oxygen is from plants converting CO2. The argon is from decay of potassium 40. There should also be a lot of helium from alpha decay and it's absence points to a hotter upper atmosphere in the Earth's past.
But I still want to know where the nitrogen came from. Was it a gas that stayed with the Earth when it was formed? Was it trapped inside the Earth as a gas (or a liquid or solid?) as it was formed and later outgassed? Was it originally from nitrogen in the form of methane ice? Was it from the decay of carbon 14? Does anyone know if there is appreciable nitrogen released by volcanoes?

Tom_R

>> Leif Svalgaard says:
October 6, 2011 at 9:27 am
Jim Cripwell says:
October 6, 2011 at 3:37 am
I seem to remember that recently comets made from just ice were discovered by seeing specks in photographs of aurora.
There was such a proposal, but analysis of the images show that the ‘ice’ specks were just that: artificial specks or defects in the imagery. <<
Also, frequent house-sized comets would leave a visibly changing landscape on the moon with no atmosphere to prevent a full-speed collision.

Blade

“Comet water discovered to be nearly identical in composition to Earth’s oceans … Suggests comet bombardment contributed to forming oceans”

I recall last winter looking out the picture window at two feet of smooth virgin snow blanketing our property. Nearby the neighbor kids were playing and one of their errant snowballs landed right in the midst of our perfectly unblemished wintry landscape. I noticed how this snowball immediately vanished beneath the accumulation and soon so-one would ever be able to tell if it ever existed.
I note for the record that at no time did it ever cross my mind that our yard had been filled the night before by neighborhood kids tossing snowballs from their snow filled yards into our empty one.

Nick Shaw

Am I to assume then, that water soaked comets continue to bombard the earth (and I’m not talking about big ones we can see but, millions of little ones)? It’s only reasonable to make this assumption. It’s not like somebody suddenly deflected all the comets away once the earth had “enough” water.
Could that not be the reason sea levels are rising and nothing to do with warming of the climate?
Could there come a time when the earth does, indeed, become Waterworld?

Peter Melia

The photo of the comet shows what seems to be an awful lot of water being ejected.
How old is the Comet?
Has the water been issuing since the comet started?
How much water is left?
Etc.

Gary Hladik

A G Foster says (October 6, 2011 at 10:13 am): “Water molecules have an escape velocity temperature intermediate between O2 and N2 on the one hand, and He and H2 on the other.”
So if most of Earth’s water didn’t come from comets, that would imply yet another Goldilocks requirement met by our planet, making extraterrestrial life even less likely?

William Abbott

The small, house-sized, comets are observed phenomena. The images are not defective, altered or explained away as specks.
http://sdrc.lib.uiowa.edu/preslectures/frank99/index.html
http://smallcomets.physics.uiowa.edu/www/faq.htmlx
http://smallcomets.physics.uiowa.edu/
Earth’s orbit travels through a flux of very small comets and one enters the earth’s atmosphere about every minute or so. The H2O recently discovered on the moon is more intriguing than the supposed absence of impact craters from these small comets. The height of noctilucent clouds at 80 to 100 km, well how does anybody think water vapor get up that high?
The problem with University of Iowa’s Louis Frank’s observations isn’t that they are invalid or refuted – they are so wildly disruptive to every branch of science they are rejected out-of-hand as impossible: The observed comet flux accounts for the earth’s oceans in ten to twenty million years, maybe less. What earth science can bear up to that time-line?
I want to see a post on small comets. If Anthony would help me I’d have a go at it myself.

LarryD

Check out Small Comet Theory.
Inferring from their observations, I was not at all surprised when the Mars probes found signs of a lot of water on Mars, past and present.
Nor was it any great surprise that the Moon had water.
The lack of water on Venus is also explained, the small comets don’t survive much further inward of Earth.
The remaining unanswered question is, where do they originate?
And it would be nice if someone put up a powerful enough radar satellite to detect them and plot their course.

Tom_R

>> William Abbott says:
October 6, 2011 at 11:31 am
The small, house-sized, comets are observed phenomena. The images are not defective, altered or explained away as specks.
http://sdrc.lib.uiowa.edu/preslectures/frank99/index.html
http://smallcomets.physics.uiowa.edu/www/faq.htmlx
http://smallcomets.physics.uiowa.edu/
Earth’s orbit travels through a flux of very small comets and one enters the earth’s atmosphere about every minute or so. The H2O recently discovered on the moon is more intriguing than the supposed absence of impact craters from these small comets. <<
Really? How do you explain the absence of thousands of new impact craters on the moon if it were being impacted by house-sized comets every minute or so (or even every hour to more than account for the lower gravity and smaller cross-section)?

Hoser

Yeah, right. One data point.

OK, is this another example of Science getting it backwards?? How about the earth going through a catacysm where the water and minerals… were ejected and formed at least some of the comets?? This gentleman has an interesting theory possibly better than mainstream Science Theories!! Explains a whole bunch of anomalies that are problems for the consensus.
http://creationscience.com/onlinebook/

Vince Causey

The problem is one of trying to shoe horn the facts to fit the theory. First they say that the inner solar comets could not have seeded Earth’s ocean’s because they don’t have the same deuterium signature. Then they find a comet from the kuiper belt which does, and in order to fit the theory, all the comets that provided the Earth’s water must now have come from the Kuiper belt only. But why should it be that inner solar comets never contributed water but Kuiper belt comets did? There is an inconsitency there that needs an explanation.

kramer

This article reminds me of the following which I read a few years ago:

In the spring of 1986, I published my explanation of the black spots in a scientific journal: The Earth’s atmosphere was being bombarded by house-sized, water-bearing objects traveling at 25,000 mph, one every three seconds or so. That’s 20 a minute, 1,200 an hour, 28,800 a day, 864,000 a month and more than 10 million a year. Spelled out in this way, the numbers truly boggle the mind. These objects, which I call “small comets,” disintegrate high above the Earth and deposit huge clouds of water vapor into the upper atmosphere. Over the history of this planet, the small comets may have dumped enough water to fill the oceans and may have even provided the organic ingredients necessary for life on Earth.
http://smallcomets.physics.uiowa.edu/wp.html

A G Foster

Pontification: The “firmament” of Genesis seems to have been a metallic hemisphere hammered out by God to keep all the water out. This hemisphere was put into place after day and night were separated. Day and night alternated a few times before the sun was created, showing that the ancient Israelites, like the Babylonians and everyone else, did not know that the sun was responsible for daylight. After all, the notion that the sun circles the earth presupposes that the earth is round, and this notion was taught to the Jews by the Greeks–as late as the Book of Enoch the Jews still believe in a flat earth.
The idea that the whole universe was made of water trying to leak in from the sky and from the ground allowed for the flood myth: water came from everywhere and simply dissipated. It was not till Ecclesiastes that Greek science prevailed here: the Preacher complains that even the rain is not new, but recycled–he understands that the ocean is a constant store of water and that the global hydrological budget is finite. The Flood and the Flat Earth certainly do go hand in hand. –AGF

Chuckles

Seems to say that water is water?

A G Foster

Talk about space junk. No satellite would be safe. –AGF