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Earth's Water Didn't Come From Outer Space
sciencehabit writes "Where did Earth's oceans come from? Astronomers have long contended that icy comets and asteroids delivered the water for them during an epoch of heavy bombardment that ended about 3.9 billion years ago. But a new study suggests that Earth supplied its own water, leaching it from the rocks that formed the planet. The finding may help explain why life on Earth appeared so early, and it may indicate that other rocky worlds are also awash in vast seas."
Um ... By definition, no.
Guns don't kill people; Physics kills people! - John Lithgow as Dick Solomon on Third Rock From The Sun
"ugly bags of mostly water" IIRC
A hot mantle isn't something that happens by chance. When a planet forms, it involves large chunks of *stuff* coming and binding together - that is, coming from a dispersed position of high gravitational potential to a compressed position of much lower gravitational potential. All of that GPE has to go somewhere, and most of it went into thermal energy, hence the heat at the Earth's core. Mars is much smaller than Earth = less GPE to liberate = less core heat. Of course the fact that Mars is too small to hold on to a substantial atmosphere also plays a part.
What I'm saying is that any sufficiently large rocky planet almost by definition has substantial core heat. It's not really much of a coincidence that the Earth has a hot mantle. Probably, any large rocky planet of about the same age as Earth (i.e. orbiting a population I star) has plenty of core heat left.
qntm.org
Reading the conclusions of the fine article, I notice "...the more probable source for early water oceans [on Earth] is the collapse of the planet's steam atmosphere..." and "... these oceans may not persist over billions of years on smaller planets against the processes of atmospheric escape and continuing impact blow-off..."
It is a clue also that the title is about early oceans. This paper has nothing to do with the origin of Earth's present oceans but rather discusses early, pre-bombardment phase water and also more massive rocky planets.