Discussion Kepler Mission, Finding Lots of Uncolonizable Planets

[Admiral_Ritt]

T_Neo

Yes, Kepler did find all the Easy "close in" planets but that was early in
it's mission, I'ts coming up on 3.5 year of operation. and it does favor
larger planets a bit. BUT: with this method the estimate is that about 1,500 stars
that have planets should show up. So the operational window
to find Earth twins is running out.

It is possible that other solar systems have terrestrial planets that are not
aligned with the other planets so we cant spot them. However statistically
that should not make a difference, as even it they are on an odd orbit
the only requirement is that their orbits cross their sun, from our perspective

REGARDING RED SUNS

This Wpedia explains it better than me, [ame="http://en.wikipedia.org/wiki/Habitability_of_red_dwarf_systems"]Habitability of red dwarf systems - Wikipedia, the free encyclopedia[/ame]

There's alot of them granted but they are a poor bet for colonization.

Magnetic Fields are created by Liquid Iron Core, in combination with
flow of this material caused by rotation.

Mars magnetic Field is gone because it's core has solidified to a point where
it's remaining strenght does not reach the surface. that puts smaller
planets squarely on the NOT SUITABLE for colonization catergory due to
early core solidification.

Mercury has a magnetic field and it has a liquid code probably because of
gravitational heating due to it orbit near the sun. The slow rotation causes
a small field, something like less than 5% as strong as earth's

I really think if the Kepler mission had a good candidate for an earth twin
they would not wait for 3 orbits to comfirm it. They would say they have
a 80% chance and ANNOUNCE......that's why I think they are giving us
findings and not mentioning that these new finds are not only not
colonizable, they are not even suitable for a base.

 

[T.Neo]

However statistically
that should not make a difference, as even it they are on an odd orbit
the only requirement is that their orbits cross their sun, from our perspective

That is a pretty big requirement. Only a small number of exoplanets transit their stars, as seen from Earth. Their relative inclination has to be closely aligned to us.

This excerpt states that the probability of an alignment for a close-in planet is 10%, but that this drops down to 0.47% at 1 AU from a Sol-sized star. This would indeed indicate a bias toward detecting close-in planets.

This Wpedia explains it better than me,

The Wikipedia article on the subject is rather poorly written...

Mars magnetic Field is gone because it's core has solidified to a point where
it's remaining strenght does not reach the surface. that puts smaller
planets squarely on the NOT SUITABLE for colonization catergory due to
early core solidification.

That is a horribly brash conclusion to jump to. The category of 'smaller planets' could describe a planet smaller than Mercury or smaller than Jupiter. It would be more useful to talk about planets that are smaller than the lower mass bound for habitability. First, we need to determine what that lower bound actually is. I don't have any publications on hand but I've seen figures of 0.3 Earth masses required to maintain an atmosphere and sufficient internal heat over geological timescales.

Also, mass is not the only difference between Earth and Mars; Earth has a density of 5.52 g/cm^3. Mars has a density of 3.93g/cm^3, only 70% that of Earth. This may affect the rate at which the planet cools, especially if it correlates with concentration of radioisotopes within the core.

Mercury has a magnetic field and it has a liquid code probably because of
gravitational heating due to it orbit near the sun. The slow rotation causes
a small field, something like less than 5% as strong as earth's

The question was not about the strength of the Mercurian magnetosphere, but how the strength of a planetary magnetosphere correlates with rotation rate.

I really think if the Kepler mission had a good candidate for an earth twin they would not wait for 3 orbits to comfirm it. They would say they have
a 80% chance and ANNOUNCE......

It would make sense if they were biding their time. They need to confirm things first; the transit method has a high rate of false detections and especially with these sorts of discoveries, you do not want to announce something prematurely and look stupid afterwards.

not mentioning that these new finds are not only not
colonizable, they are not even suitable for a base.

Of course they're not mentioning colonisation. We can't even send a probe to the nearest star yet, let alone colonise a system that is hundreds of light-years distant. These people are scientists and they want their work to be percieved seriously (and rightly so).