[cynicom]

To have been awash with water, Mars had to have two things, the needed temperature range and sufficient atmosphere.

[ngc6656]

The puzzling part of this is that Earth's oceans, and now probably the water that was on Mars, both date from this period. Where did it come from?

The only reasonable answer is comets.

It is reasonable. Who first proposed comets as the source of Earth's water?

[bikerman]

Martian lawn sprinklers.

[Simmy2.5]

Now the question is, does Mars have enough water now to sustain a self contained colony.

[JoeSixPack1]

I was always suspect of those evil hydrogen clouds roaming the galaxy but questioned which star system was hording all the oxygen clouds???

[Joe Boucher]

in a word, GOD.

[MosesKnows]

But where did the water come from?

There is no water. Rather than ask where it came from why not first ask, where did it go?

[MosesKnows]

The impact blasted the Earth's atmosphere into space

Was there an atmosphere to blast into space? I thought the impact is what caused earth to have a moon and an atmosphere.

[aruanan]

The formation of the planets was an inefficient process and for millions of years the Earth and the other planets were bombarded by what astronomers call planetesimals — essentially leftover chunks from the birth of the solar system, up to a few hundred kilometres in diameter.

Don't you just love moronic sentences like this?

[governsleastgovernsbest]

I find the article very interesting because I had never previously considered the question of where Earth's water came from. Guess I assumed it somehow occured here naturally, just like other compounds. What a strange notion to imagine it came from comets.

But when you look at the vast oceans, is it really possible that all that water comes from melted comets? I really can't believe that. Are there other scientific theories, in particular ones that envision that water was somehow created on Earth?

[mewzilla]

But where did the water come from?

The Culligan Man?

[Arthur McGowan]

So if the earth had been just a little closer or farther from the sun, no people. If we had been hit by just a few more comets, no dry land, and no people. Hmmm.

[PGalt]

Interesting article. Thanks for posting it.

[DCPatriot]

Two parts hydrogen and one part oxygen?

[patriot_wes]

"Venus, Mercury and Mars, the other approximately Earth-sized planets, likely suffered similar collisions around the same time. (How convenient) Comets were formed farther out from the sun than Earth, but in such abundance that they also rained down in the early solar system.

There you go, public school in; junk science out.

[NeonKnight]

It cost NASA $1B to prove what could be concluded from a good telescope photo.

Personally, I am all for reaching beyond the limits of Earth. We will do it of course, whether I like it or not. Our pioneering spirit is instinctual, and necessary to our survival. We will continue to spread our seeds as far and wide as possible.

NASA just isn't the answere. We should invest our exploration dollars in private enterprises, offering grants and rewards for specified achievments. Safety would improve, the ins companies would see to it. Obstacles would be quickly overcome, as companies raced to reach their goals.

Companies might also supplement their govt payroll thru commercial advertising. I have no problem with a "McOrbiter"...thats where you go before transferring down to the "Wrigglies" Bubble Dome, and entering the "Phillip Morris" Decontamination Chambers (Which would also be the only place under the dome that smoking is permitted.)

[norwaypinesavage]

Where did the water come from? "The only reasonable answer is comets."

So then, where did the water in the comets come from?

[William Terrell]

What causes free hydrogen and free oxygen to combine to make water in the first place?

[Bloody Sam Roberts]

Q: Where did the water on Mars come from?

A: Where did the water on Earth come from?

[uglybiker]

So, where did the water on Mars come from?

There are theories......