Rosetta Results: Comets "Did Not Bring Water To Earth"

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."

Comments

Re: Oh it's asteroids now?

[Anonymous Coward]

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 it. It's not like the scientific models pop magically into being, there's someone behind it, who has sufficient training in the field in question, to make reasonable guesses on how things might fit the empirical data based on his/her previous experience.

Re: Actually...

[Anonymous Coward]

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.

If you read the article in Science

[The Real Dr John]

you'll see they have pretty solid evidence that this particular type of comet (Jupiter family) had a deuterium/hydrogen ratio in water that is very different from earth, whereas many asteroids (chondrites) have about the same D/H ratio. All they were saying was that this type of comet was not responsible for delivering most of earth's water, which seems reasonable based on their evidence (see figure 3 from the article).