Drake Equation??? Humbug!!!!!

lunarmark · 2004-09-07 06:35:40

Hi Lunarmark!
>> Who is this Sterling Webb person? I can't place him.
And why, in the case of his hypothetical planet exactly twice the diameter of Earth, should the mass be 12 times greater when the volume is only 8 times as great? Why does the average density of the hypothetical planet have to be 1.5 times Earth's average density?.... <<<

Shaun,

(Stirling web is a bloke on another mailing list, we had a similar thread going on there, and I though his reply was quite well layed out..)

The thing to remember is, that as the diameter of the planet increases the total mass goes up in an even bigger way, since the core actually represents a larger part of the mass of the planet, so whilst the diameter may be double earth it would be much much denser therefore there would be a lot more gravity.

It is widely belived that the bigger the planet the more water would be depositied there. Some of the water originates in the original enstatite material which formed the earth/planet. Other water might have come from comets or water laden meteorites which struck the earth early on, bu again a bigger planet might endure more impacts.

So we can assume that a x2 Earth would have much more water, or at least have had more water. It stands more chance of staying on the surface due to the higher gravity and magnetic field etc.

The point that was made about the distance of the x2 planet away from it's sun being critical is a good one. you would either end up with a super venus or a very large Europa. However a bigger warmer planet may very well mean the habitable zone may actually be wider with planetry systems with bigger planets.

Of course we could still be talking about mini Jupiters here so its all academic at the moment!

karov · 2004-09-07 10:18:01

About the moons` habitability and the dependency of livability of a planetary mass object from stellar light sourse:

http://www.sfwa.org/members/Nordley/Gra … ravity.pdf

, this of course puts in the account, prelliminary taken as "most probable", only the earth-type life - based on chemical reactions and hence, building blocks, thus restricted in complexity and subjective time speed by the maximum figures - property of the involved chemicals... and especially the liquid water based protein/NA-life, confined in our comperativelly narrow PHASE DIAGRAM borders.

The conclusion is that a world to be habitable by earthly lifeforms no at all needs a sun-like star at ~1 AU distance. For example if the plane of rotation of the Jupiter`s huge mag-field wasn`t excentric in accordance with the orbits of the Gallileans - they would have thick atmospheres as Titan ( orbiting within the Saturns mag-field with right angle) and regardless the distance to the Sun, if these atmospheres were thick enough ( several bars?) - at the surface liquid water temperatures would dominate! With insolation 25 times lower than the earth`s one, the local life needs 25 times more effective chlorophile-like pigment to ensure bisphere as vigorous as ours, but this is not necesarry in general... The internal heat reserves of any planetary mass object are really enormous, a life-cycle which utilizes it can last even longer than one depending on the stabile short phase of any Main sequence star...

see also, http://www.gps.caltech.edu/faculty/stev … ...ets.pdf

=====================================
About the tidally locked planets, you may see that they orbiting M-stars or in principle even Brown dwarfs, can have gaseous atmosphere and liquid water in have at least 0.15 bars of CO2. Other atmospheric content, too...

http://www.seismo.unr.edu/ftp/pub/gille … /joshi.pdf

Environments with right temperature/pressure for earth-type life are quite abundant here in the Solar system, as well as out there...

karov · 2004-09-11 07:12:11

Ocean-planets:

http://arxiv.org/ftp/astro-ph/papers/03 … 308324.pdf

see, especially for the Habitabilty zone - 4.2 Planetary albedo -- which fenomenon extends the Habitable Zone to regions closer to the star. According to Kuchner`2003 - the naturally increased albedo prevents the planet from transforming into gass ball for billions of years even if it is pretty close to the star.
=====================================

The same way the greenhouse effect and non-radiant stellar power sourses could ensure in the opposite diresction away from the star liquid water surface temperatures even in the interstellar void.
==========================================

If the jovian gallilean moons were at the same distances to brown dwarf at least Io and Europa would have been in the HabZone, non-counting the effects of thick titan-like or other massive atmosphere. For example: http://www.universetoday.com/am/publish … am....2004... the eventual companion of this brown dwarf - the 5 times jupiter mass planet is still radiating at 1000 C surface temperature due to formational gravitationally sqweezed heat. This heat will last for short in geological scale, but if it powers life emerging and innitial development, this life could hide in liquid water ocean beneath the ice-crust later, when the gas giant cools down.

Habitable Zone - i.e. liquid water conditions - could be found in plenty of places in the universe, and it seems that the actual stellar irradiation plays insignifficant role.

Shaun Barrett · 2004-09-15 08:15:22

Hi again, Lunarmark!
I'm still having trouble with this guy, Sterling Webb, and his estimate of the mass of a SuperEarth exactly twice the linear dimensions of Earth.
He maintains that this hypothetical rocky planet, exactly 8x Earth's volume, will have 12x the mass. This immediately gives us an average density for SuperEarth of 1.5x Earth's average density.
Earth's average density is 5.5 g/cu.cm. Thus, according to Mr. Webb, SuperEarth's average density must be 8.25 g/cu.cm. (1.5 x 5.5 g/cu.cm). Interestingly, the density of elemental iron is only 7.874 g/cu.cm, which means Mr. Webb's SuperEarth couldn't be 12x Earth's mass, even if it were made entirely of pure iron!
When I did this simple calculation, it occurred to me that perhaps the immense pressures and temperatures at Earth's core, which is widely believed to be a mixture of iron and nickel, might produce some kind of super-dense metal. But apparently this is not the case. Iron and nickel are relatively incompressible, even under those conditions. In fact, due to impurities in the mix, such as sulphur, Earth's core has a density some 10% less than that of pure iron.

You have said; "The thing to remember is, that as the diameter of the planet increases the total mass goes up in an even bigger way, since the core actually represents a larger part of the mass of the planet, so whilst the diameter may be double earth it would be much much denser therefore there would be lot more gravity."
I don't think this is correct. I've done the arithmetic and found that if all of Earth's dimensions are doubled, including the diameter of the core, the ratio of the core volume to the total planetary volume remains the same. Therefore, there's no reason to assume that, as the planet's diameter doubles, the total planetary mass should increase beyond what you might expect from the increase in volume, which would be 8x.

As I've shown above, even if the hypothetical SuperEarth were to be entirely nickel/iron core material, with no rocky mantle and crust, it still wouldn't attain a mass 12x that of Earth.
To reach that kind of mass, you would have to assume that a significantly higher percentage of denser metals were available for planet-building in the region of space in which the SuperEarth formed. I'd be prepared to bet Mr. Webb hasn't made reference to any such special circumstances. And, if he did, then he is simply engineering things to suit his own purposes, since there is no evidence to support such a supposition.

I know I'm making a big deal out of Sterling Webb's little thought experiment! Why am I going to so much trouble to find flaws in his reasoning?
It's because I'm getting sick and tired of all the 'gloom merchants' who seem intent on shooting down anything and everything to do with space exploration. Just lately, we had another sermon from Jeff Bell, savagely criticising Dr. Zubrin and, by implication, the Mars Society, its membership, and its aspirations. His logic was faulty, too. And he is obviously emotionally attached to the proposition that the human exploration of Mars, and even the notion of a sample return mission, should be abandoned. If he had presented a well-reasoned case for such views, I would have reacted differently. But he didn't.
Now, along comes Mr. Webb. He seems to be trying to place unrealistic limits on the size of rocky planets which might harbour life. I wouldn't mind if his imaginary scenario made sense, but I don't believe it does.
Who are these people?!! Why do they try, at every turn, to belittle the exciting prospects for humanity in outer space? I could try to say they're part of a propaganda campaign to turn people away from 'the final frontier' - a kind of undercover Luddite conspiracy - but I'll resist that temptation!

However, at the very least, we need to expose the glaring flaws in their logic and their science. This is a 'heads up'. Keep your 'Bulls*** Detectors' primed and ready!
:laugh: :;):

rgcarnes · 2004-09-15 12:13:10

Thanks Shaun,

I'm certain that I, and surely many others, appreciate the attention you've paid to these matters.

The B-S detectors of many of us are saturated now days. Please keep up your efforts while you still can.

lunarmark · 2004-09-20 08:38:35

You said:

>Who are these people?!! Why do they try, at every turn, to belittle the exciting prospects for humanity in outer space? I could try to say they're part of a propaganda campaign to turn people away from 'the final frontier' - a kind of undercover Luddite conspiracy - but I'll resist <
>>

Conspiracy, hmm maybe, (or are we just the engineers that have to get the mad idea's to actually work), yes!

Good points though...

Mars_B4_Moon · 2022-08-09 11:13:28

How helicopters are shaking up the hunt for life on Mars
https://www.nationalgeographic.com/maga … fe-on-mars

‘All or nothing’: Scientists search for extraterrestrial intelligence
https://whyy.org/segments/all-or-nothin … elligence/

The Odds of Life and Intelligence - Maths of the Drake Equation
https://www.youtube.com/watch?v=iLbbpRYRW5Y

Mars_B4_Moon · 2022-09-02 10:43:43

Frank Drake, astronomer famed for contributions to SETI, has died

https://arstechnica.com/science/2022/09 … -has-died/

Mars_B4_Moon · 2022-09-13 07:22:46

I'm still not sure if Life will be found currently on Mars, maybe evidence of past life or maybe something still living inside a Cave

After this you have Europa or Exoplanets

‘Super-Earth’ discovery by Australian astronomers ‘has potential to transform understanding of planetary atmospheres’
https://www.spacechatter.com/2022/09/12 … iese-486b/

Mars_B4_Moon · 2022-10-27 10:47:36

Search for Life on Mars Panel

1 hr 40 mins

25th Annual International Mars Society Convention

https://www.youtube.com/watch?v=VVCPeDIsIiA

Mars_B4_Moon · 2023-03-10 10:27:08

Aliens haven't contacted Earth because there's no sign of intelligence here, new answer to the Fermi paradox suggests
https://www.livescience.com/aliens-tech … al-signals

Humanity Is Among The First Spacefaring Civilizations?
https://www.youtube.com/watch?v=uTrFAY3LUNw

Exploring the Drake Equation: We Talk About Aliens
https://lowell.edu/2023/03/07/exploring … ut-aliens/
Are we running through the six with our woes…. alone? The Drake Equation says no. On this episode of Star Stuff, our fearless hosts delve into a probabilistic argument created by Dr. Frank Drake in 1961, used to estimate the number of active, communicative extraterrestrial civilizations in the Milky Way Galaxy.

Mars_B4_Moon · 2023-03-30 08:21:06

Moons Orbiting Rogue Planets Could be Habitable

https://www.universetoday.com/160673/mo … habitable/

Mars_B4_Moon · 2023-05-10 05:32:30

NASA Uses Powerful Transmitters to Talk to Deep Space Spacecraft. Will Other Civilizations Receive Those Signals?

https://www.universetoday.com/161278/na … e-signals/

Mars_B4_Moon · 2023-05-24 17:16:09

The Genesis Lab: Exploring Life's Origins and Illuminating a Key Term in the Drake Equation

https://www.seti.org/genesis-lab-explor … e-equation

The Fermi Paradox: Searching For Dyson Spheres

https://www.bitchute.com/video/Uf9SZgeVDqI/

Isaac Arthur

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#51 2004-09-07 06:35:40

Re: Drake Equation??? Humbug!!!!!

#52 2004-09-07 10:18:01

Re: Drake Equation??? Humbug!!!!!

#53 2004-09-11 07:12:11

Re: Drake Equation??? Humbug!!!!!

#54 2004-09-15 08:15:22

Re: Drake Equation??? Humbug!!!!!

#55 2004-09-15 12:13:10

Re: Drake Equation??? Humbug!!!!!

#56 2004-09-20 08:38:35

Re: Drake Equation??? Humbug!!!!!

#57 2022-08-09 11:13:28

Re: Drake Equation??? Humbug!!!!!

#58 2022-09-02 10:43:43

Re: Drake Equation??? Humbug!!!!!

#59 2022-09-13 07:22:46

Re: Drake Equation??? Humbug!!!!!

#60 2022-10-27 10:47:36

Re: Drake Equation??? Humbug!!!!!

#61 2023-03-10 10:27:08

Re: Drake Equation??? Humbug!!!!!

#62 2023-03-30 08:21:06

Re: Drake Equation??? Humbug!!!!!

#63 2023-05-10 05:32:30

Re: Drake Equation??? Humbug!!!!!

#64 2023-05-24 17:16:09

Re: Drake Equation??? Humbug!!!!!

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