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More space news!


tkdguy

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Re: More space news!

 

Rather ridiculous' date=' actually. We are GOING to send humans to Mars. At that point, there's simply no way to avoid contamination. Even if Mars has microbiology, we're going to kill it sooner or later.[/quote']

 

Yes, but from a scientific standpoint, you don't want to be contaminating your samples with Earthlings while you're still trying to figure out if there are Martians.

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Re: More space news!

 

In today's Science: Kepler 47, a system where at least two planets orbit nicely around a fairly tight binary star system, reasonably solar-like star and an M dwarf. The outer planet, though not Earthlike, seems to orbit wholly within the Habitable Zone (a 303-day orbital period).

 

(tkdguy reported this upthread, but I didn't read the journal paper until today.)

 

Following astronomical convention, the two stars are designated (capital) A and B. The planets are designated (lower case) b and c (so Kepler 47b and Kepler 47c orbit Kepler 47 AB.)

 

There is (in the supplemental material) one "orphan" transit, that is, a transit event that doesn't work for either of the two planets discovered through their transits. This suggests that there is another planet in the system with an orbital period longer than 3 years or so, which is very easy to believe.

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Re: More space news!

 

I read an article about David Brin wherein he briefly mentions the waterworld theory, which says that most worlds in the habitable zone are likely to be submerged in lots and lots of liquid water, unlike Earth which is actually towards the inner edge of the habitable zone. This has ramifications for the Drake Equation since we might expect alien fish to have a harder time communicating or getting offworld. Has this theory been written up in detail anywhere? I haven't been able to find anything with some brief googling.

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Re: More space news!

 

I read an article about David Brin wherein he briefly mentions the waterworld theory' date=' which says that most worlds in the habitable zone are likely to be submerged in lots and lots of liquid water, unlike Earth which is actually towards the inner edge of the habitable zone. This has ramifications for the Drake Equation since we might expect alien fish to have a harder time communicating or getting offworld. Has this theory been written up in detail anywhere? I haven't been able to find anything with some brief googling.[/quote']

 

I have heard about that, but not in something I'd characterize as in the scientific literature. The difficulty is that's a question more about planetary evolution than anything else. Some modelers have trouble assembling a planet of Earth's size with both a big moon and as much water as the Earth now has, because the giant impact most people think is needed to make the Moon pretty efficiently removes all the volatiles (which includes water) from the post-impact bodies. That means you need to add volatiles back in, which now you have to do via the bombardment by icy planetesimals from beyond Jupiter. Recent thoughts about that bombardment suggest those episodes came at a few specific times when the giant planets' orbits shuffled around and passed through resonances with each other, which caused considerable "pumping up" of the remaining icy planetesimals and disrupted nearly all their orbits. But bombardment like that is indiscriminate; just about everything in the inner part of the Solar System should have received a bombardment of icy things. The Moon probably never had the mass and atmosphere to retain water, so that's not an issue. Venus seems to have repaved itself about 0.8 Gyr ago, erasing all older terrain features; that surface is still pretty inaccessible anyway even with best tech now. So what about Mars? How much water did Mars have, and when, and how was that lost (which couples to the evolution of its atmosphere)? What gets found by the robot missions could have serious impact on those "water world" ideas, because Earth and Mars really ought to have had comparable geologic/astronomical histories, altered chiefly by Mars's lower mass and Earth's greater insolation. And only Mars seems to present a the chance of examining that geologic history in a way we can interpret.

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