Rosetta Results: Comets "Did Not Bring Water To Earth" 135
An anonymous reader writes with findings from the Rosetta mission which suggests water on Earth probably came from asteroids, and not comets."Scientists have dealt a blow to the theory that most water on Earth came from comets. Results from Europe's Rosetta mission, which made history by landing on Comet 67P in November, shows the water on the icy mass is unlike that on our planet. The results are published in the journal Science. The authors conclude it is more likely that the water came from asteroids, but other scientists say more data is needed before comets can be ruled out."
The wet ones did! (Score:5, Funny)
They got it wrong. The dry comets are lighter and so are still flying around. The wet ones were heavier and so fell to Earth.
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Re:The wet ones did! (Score:5, Funny)
That whooshing sound you heard was not a comet passing over your head, it was the joke.
Re:The wet ones did! (Score:5, Funny)
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Mass has everything to do with it. You're thinking "weight", dumbass.
Re:The wet ones did! (Score:4, Informative)
Weight is defined as the force of gravity that is acting on an object. When you are in orbit, weight is serving as the centripetal force that is keeping you on a circular orbit. So if an object was weightless, it would fly off in a straight line instead of orbiting. GP is almost right. The weight of the space ship is going to be much greater than the weight of the astronaut inside simply because the spaceship is more massive (and F_g = GMm/r^2, so weight increases linearly with the mass of the orbiting object), but the astronaut feels weightless because he/she has the same acceleration as the space ship.
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Some on with mod points please mod Calvar up. He has it exactly correct.
Re:The wet ones did! (Score:4, Informative)
No, it doesn't.
F_g = GMm/r^2
F_c = mv^2/r
Combine the two, and you get
GM/v^2 = r
So the orbital radius of an object around the sun depends only on the mass of the sun and the velocity of the object. The mass of the object doesn't matter. This is high school level physics, buddy.
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Either way, GGP's assertion that mass is relevant but weight somehow isn't makes no sense.
Water came from asteroids... (Score:1)
Didn't planet earth come from 'asteroids'?
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Oh it's asteroids now? (Score:4, Interesting)
Why does the water have to have come from comet/asteroid/whatever impacts? Maybe it just kind of seeped out of rocks or something. Hydrogen and oxygen are pretty common.
Re: Oh it's asteroids now? (Score:5, Informative)
The theory is that the protoearth lost all its water when the impact that formed the moon happened. That impact reliquified the planet, driving off the lighter elements. Ergo we had to be reseeded somehow.
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So, the scientists are obsessed with this 'water came from comets/asteroids' because they believe Earth lost it once and had to receive it again?
Sounds far fetched to me.
Ofcourse scientists are obsessed about things like this. This method of operation is the quintessential Scientific Method. You create a model based on what you know and the model will predict certain things that you can look for. This is exactly the same reason the large particle accelerators exist, the Standard Model (Particle Physics) predicts the existence of particles and a method to find them and that method is the accelerator.
If something you find doesn't fit the model, you either trash it or modify i
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Because Earth has very unusual moon. Some good models exist to explain how it came it existence, and how the present system evolved, and can explain the isotope and elemental composition data we have for the Moon, and explain all currently discernible features of the system rather well. But they start with a massive planetoid collision on the early Earth that lofted enough material (combined from Earth and the impactor) to create that little twin planet of the Earth called Moon. Available evidence favors t
Sounds unlikely to me (Score:2)
Water is pretty heavy. The collision would certainly have vapourised all water on the surface and underneath and even converted a lot of it to H2 + O2 , but the rest would simply have hung around in orbit as ice and rained back down eventually.
Re:Sounds unlikely to me (Score:4, Informative)
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Using that logic there would have been no water to start with since the earth was "really really hot for a while" when it formed you dimwit.
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Why don't you just point us to the numbers that are agreed upon by all planetary scientists? Clearly you're an expert on this.
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"Genda and Abe (2003, 2005) showed that Earth is unlikely to lose much of its water as a result of the Moon-forming impact, although loss of a significant amount of atmosphere is possible. " http://www.ncbi.nlm.nih.gov/pm... [nih.gov]
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You made the assertion pal - you back it up. But then given you're the moron who thinks hawking is only kept on because of his disability I think its safe for say your so full of it its coming out both ends.
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Except theres no reason for it to have lost much at all during the moons formation. Most of the water would have remained in orbit as ice or locked up in orbiting solidified rock.
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How can they know for certain the moon came from an earth impact vs just a passing proto-planet without a well defined orbit that got caught in our gravity?
There is so much about the universe that is not understood at these timespans, I have a hard time believing that anything can be known for certain at this point in science. http://en.wikipedia.org/wiki/G... [wikipedia.org]
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And by probably i mean at the level of confidence of any AGW prediction model. ie a bit. Yet every man and his dog knows that scientist having everything correct with AGW and your a coal/oil denier shill if you disagree. Yet every armchair scientist that hasn't even bothered to read the wiki about $TOPIC know why everyone working in the fie
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And by probably i mean at the level of confidence of any AGW prediction model. ie a bit. Yet every man and his dog knows that scientist having everything correct with AGW and your a coal/oil denier shill if you disagree. Yet every armchair scientist that hasn't even bothered to read the wiki about $TOPIC know why everyone working in the field is so clearly wrong.
That's why the agw fanatics generate negative opinions about science. It's apparent to everyone but them that they have gone over the edge.
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How can they know for certain the moon came from an earth impact vs just a passing proto-planet without a well defined orbit that got caught in our gravity?
Well, the wiki really explains it better than I could. I'm not an expert, I just know it's the currently favored theory, IE it's the best match for observations, not that it's a perfect match.
It's also possible that at least 'some' water remained after the impact, and the return of 'enough' water was via various methods.
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The whole reason I linked the wiki is because of the "Difficulties" section.
IE, despite what this Slashdot article implies, this is not really fully accepted theory yet. There are a large number of holes in the theory that the moon came from the earth that have yet to be reconciled.
Re: Sounds unlikely to me (Score:2)
Escape into space is one thing, but also far enough outside of Earth's orbital position that its gravity wouldn't keep the water in an intercept orbit for eventual return? I'm not able to find anything with my naive google searches.
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It wouldn't have "seeped out", but you're on the right track. hydrogen + oxygen + energy = water. and water + energy = hydrogen + oxygen. We understand a lot of the surface chemical processes on this planet. We don't understand all the subterranean processes, but we have an idea.
Non-terrestrial bodies can carry water. Landing on a single comet and saying "no comets have Earth-like water" is like saying "We've only found life on Earth, therefore no other life exists."
I think some people have a very
Re: Oh it's asteroids now? (Score:3)
>> hydrogen + oxygen + energy = water. and water + energy = hydrogen + oxygen
>does not compute
Technically it is:
2H2 + energy = 4H
O2 + energy = 2O
4H + 2O = water + energy
Then the equations are reversable.
Actually... (Score:5, Informative)
The more informative article from the ESA website [esa.int] says that the Deuterium/Hydrogen (D/H) isotope ratio is significantly higher (more than three times, in fact) than that of water found on Earth.
However, The comet in question is not of the same type and composition as *all* comets. In fact, comets (even those that generally share orbits with the one sampled) vary widely in their D/H ratios. As such, the paper does not claim that comets didn't bring water to Earth, merely that comets like the one sampled (comet 67P/Churyumov–Gerasimenko) by ROSINA did not bring water to Earth.
From the better TFA:
Re: Actually... (Score:2, Insightful)
So what they're saying is that this comet, which obviously never struck Earth, was not responsible for delivering any of our water.
No argument here.
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So what they're saying is that WHOOSH.
No argument here.
There. FTFY. Not sure if you were being obtuse in attempt to be amusing or if you're just dumb as a box of rocks. Either way, have a wonderful day!
FTFY
I see. so you subscribe to my second theory about GP. Gotcha.
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Isn't it also possible that no comets will have the right D/H ratio due to that fact the there is no guarantee all the comets that hit earth had the same d/h ratio.
Anything is possible. Even time travel into the past (with certain limitations).
However, since the article I linked (and quoted/bolded the relevant text) states that they have sampled a comet that has a composition matching the D/H ratio as found here on Earth, it seems reasonable to conclude that other comets, some of which hit the Earth and some of which did not, have Earthlike D/H ratios.
What is more, since all material in the solar system coalesced from the same molecular cloud that collapsed into our
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Anything is possible. Even time travel into the past (with certain limitations).
No, Time travel to the past isn't possible at all. That would be acting like there is a physical place called the past to travel to which is physically separate from all the moving mass in the universe that we call the Present. That would require constant instantaneous non-big-bang creation of all the mass in the universe over and over again at a Planck-time like interval.. Care to show evidence for that actually happening?
It doesn't matter how some scientists choose to interpret certain equations, they are clearly misinterpreting how they actually relate to reality.
Actually, people a lot smarter than you have posited that it is, in fact, possible [wikipedia.org]. It's quite unlikely, and completely beyond our abilities, but not impossible. Note that I said "possible" not feasible.
I don't see the problem (Score:5, Interesting)
Deuterium/Hydrogen (D/H) isotope ratio is significantly higher (more than three times, in fact) than that of water found on Earth.
Q: How do you separate heavy water from light water?
A: Distillation. Light water boils off / evaporates more easily, because the molecules are lighter, and leaves the heavier water behind.
Why shouldn't this be true of vacuum sublimation as well?
Leave a chunk of dirty ice orbiting the sun in a hard vaccuum for a few million years, with the water quietly sublimating away. Seems to me the result would be that last remaining chunk of dirty ice would have a substantially larger fraction of heavy water molecules than the water on the planet where the deep gravity well hangs on to the lighter molecules.
Is it enough to explain a 3:1 enrichment? No clue. But I'd like to see that the analysis was done and what the scientists' estimates were.
(Not to say they ignored it. The last time I raised a similar question about a scientific paper reported here it turned out that the scientists HAD examined the issue.)
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The current view is that comets live most of their lives very far from the Sun. The ones that are nearby are there because their orbit changed recently.
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In the same matter I wish cosmology would create less theories based on on a single observation as one observation can neither prove or disprove theories.
Cosmology didn't claim that this observation proved anything, nor did it spark any new theories. OP made an unsupportable claim in the title. Which is complete hyperbole and not even close to what the researchers reported. Which is why I posted what you replied to.
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Well, clearly, if the comet has a higher D/H ratio, and Earth's water came from comets, then much of our deuterium has gone somewhere. Thus proving that the dinosaurs had an advanced technological civilization based on deuterium fusion. Too bad they didn't have a space program capable of deflecting asteroids.
As for comet 103P/Hartley 2, that was probably used as a refueling stop by extraterrestrials.
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Well, clearly, if the comet has a higher D/H ratio, and Earth's water came from comets, then much of our deuterium has gone somewhere. Thus proving that the dinosaurs had an advanced technological civilization based on deuterium fusion. Too bad they didn't have a space program capable of deflecting asteroids.
As for comet 103P/Hartley 2, that was probably used as a refueling stop by extraterrestrials.
Finally! Someone with some common sense! Good show, old chap!
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Thus proving that the dinosaurs had an advanced technological civilization based on deuterium fusion.
Historical documents [google.com] show that tyrannosaurs used their relatively small arms to operate the controls of fighter jets, so it stands to reason that dinosaurs figured out economical fusion power. I wouldn't be surprised if all the fossils we've found are just the dinosaur lawyers and telephone sanitizers.
Why does the isotope ratio of one comet matter? (Score:4, Interesting)
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Also the life on earth has been processing the water for a few million years - splitting the water to be make sugars and splitting sugars to make carbon dioxide and water. The ratio in water we have now is due to the water from life (I'm avoiding the Dune reference with Water of Life :-) ) which is based on the availably hydrogen in the environment which is attached to hydrocarbons and other molecules as well as water. I think they physicists need to talk to a biologist about the facts of life :-)
What we
The comet is dry as bone (Score:2, Interesting)
The press release should have said: The comet is dry as bone, Earth water must have come from somewhere else.
So far no water ice has been found and the pictures shows a completely dry hard rock. That they keep calling it an "Ice mountain" is just crazy. There is no proof that there is ice on a comet. Only that there is hydroxyl in the coma. Saying "We know of no other way for there to be hydroxyl in the coma without there being ice in the comet" is just bad science. Especially when there have been lab exper
*sigh* (Score:2)
Previous measurements of the deuterium/hydrogen (D/H) ratio in other comets have shown a wide range of values. Of the 11 comets for which measurements have been made, it is only the Jupiter-family Comet 103P/Hartley 2 that was found to match the composition of Earth’s water, in observations made by ESA’s Herschel mission in 2011.
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it tastes funny.
Re: Water is Water (Score:2)
You're not wrong about water being H2O, the difference is in the H part. Hydrogen is one proton orbited by one electron (an oversimplification, but work with me here). An isotope of hydrogen called "deuterium" also has a neutron in its nucleus. So, both deuterium and protium (the "normal" isotope of hydrogen, without the extra neutron) are hydrogen, but deuterium has more mass due to the neutron. Water can be formed with either isotope; water formed from deuterium and oxygen is sometimes called "heavy w
Water is Water and no water is still no water (Score:2)
My point was that there has never been any proper proof of there being either water or heavy hater on comets only hydroxyl (OH) in the coma. There are several ways the hydroxyl could have gotten there, so you cant say there has to be water in the comet core for there to be hydroxyl in the coma.
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I think you may have replied to the wrong comment.
If you read the article in Science (Score:4, Insightful)
Clarification (Score:5, Interesting)
There seems to be a lot of confusion and conjecture in the comments about the grandiosity of the claim. This does not necessarily rule out all comets. Maybe an attempt at a better summary of the article would be helpful:
Background:
- Not all water is the same. Some water is heavier due to a presence of a certain amount of deuterium.
The general consensus is:
- When the solar system formed, the components for water were created.
- These components eventually formed with the early Earth and a water cycle was created.
- Yes, the early Earth was hot, but heat and elements were plentiful and Earth managed to hold onto some of these elements and would have had water evaporating and raining back down again.
- The planet Theia *collided* into the Earth. A certain amount of the debris coalesced into the moon. Imagine Pluto smashing into your house.
- The heat from the collision would have evaporated/released all elements lighter than X, which includes water. (ed: perhaps water on the moon is more closely related to early earth water coalesced and re-condensed?)
- Sometime later, the Earth received much more water than would have been sustained from such an impact.
- The weight (deuterium ppm) of this "new" water is different (much lighter) than the weight of "old" water, and generally any other water in the solar system.
So where did this "new" water come from?
This article suggests:
"We have light water in some comets and very heavy water in other comets. We have to assume the mixture of all these comets is something that is heavier than what we have on Earth, so this probably rules out Kuiper Belt comets as the source of terrestrial water."
And I believe this means:
It would have taken many of these Kuiper Belt comets to contribute a great deal of water to the Earth. If we use probe measurements to confirm other measurements and calculate the *average* weight of water on a number of Kuiper Belt comets (along the order of magnitude necessary be a main source of "new" water for the Earth), then we see that the amount of deuterium in Earth's water would have been much greater -- i.e. the water would contain an average weight of all impacts needed to saturate.
Thus this rules out Kuiper Belt comets being the main source of "new" water for Earth. Their water in general is simply too heavy on average. As soon as enough Kuiper Belt comets impact the Earth to come close to the amount of water needed, the calculations show that the level of deuterium would be much, much higher than what we see.
And the article itself turns to conjecture with:
So where do we look for lighter water? Maybe asteroids?
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It's one thing to say "this comet's water suggests (sample size =1) that cometary water isn't the water on earth". That says NOTHING about where the water actually came from, only where it didn't.
It's a pretty clear that "welp, we didn't find it here" *doesn't* therefore mean "it must be there" unless there are a total of two possible alternatives.
I haven't bothered to read the OP determine if the leap of logic is the OP's or the summarizer's.
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- The planet Theia *collided* into the Earth. A certain amount of the debris coalesced into the moon.
Is it know for sure that the collision would have completely liquefied the planet? It makes some logical sense that the impact hitting on one side of the planet would have produced or left a bulge on the other side. This could be where Pangaea came from then. Obviously if the entire planet became liquefied then there would be no bulge. But if a portion of it was left as a crust it could be an explanation for how the continents started out as one super continent so long ago.
Clarification (Score:2)
- The heat from the collision would have evaporated/released all elements lighter than X, which includes water. (ed: perhaps water on the moon is more closely related to early earth water coalesced and re-condensed?)
In this scenario, wouldn't much of the released elements have returned thanks to gravity?
Also if we're bringing Theia into it, maybe Theia is the source of the water?
ad infinitum (Score:3)
... and... where did the asteroid get the water? Smaller asteroids?
Without doing any research on the topic, yet smug in my own opinion (hello slashdot family!) I don't know why we'd ascribe a smaller rock-like mass as responsible for delivering simple molecules to a bigger rock-like mass.
Silly Buggers (Score:2)
Everybody knows water comes from rain.
But seriously, there is a giant body close to earth, that is chock full of hydrogen, and if you burn off that hydrogen by oxidation you get water.
If we also can get carbon into play, we have most of the ingredient in the cycle f life
To be more specific: (Score:2)
To be more specific, they speculate the water on Earth did not come from Comet 67P. Instrumentation showed evidence that Comet 67P is not on Earth and has never been on Earth.
A independent panel of scientists is reviewing the data.
Why does the water have to come from space? (Score:2)
I find it much more plausible that our oceans were derived from internal water than that asteroids deposited it. I mean, really, how much water could your average m
Let's get more samples (Score:2)
Not exactly... (Score:2)
One single sample? (Score:2)
So, we have one comet as sample.
That comet is aons old.
At some point in time "young" comets where supposed to seed the earth with water.
How can that single "old" comet prove that "young" comets did not do that?
Soo, since one comet doesn't match our water. (Score:2)
This automagically means that all comets are out of the picture?
This seems very short sighted.
We need a sample of comets in the vicinity that likely existed in the time of our Earth's formation.
Sample size? (Score:1)
A sample size of one, seems a bit short of that needed to generalize to all other comets... 8-P