New Mars Forums

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!

Gravity would be the deciding factor, if a planet was too big it would have such a gravitational pull, that it would not allow life (as we know it to evolve).  14 times the gravity would be quite extreeme, I suspect that even water based life would have it's problems..

The other thing about a larger planet is that it would still be very geologically active, and a planet 14 times the size of Earth would be [very] volcanic...

Just right for starting life... But intelligent life might take too long to evolve before the star goes unstable, just a thought.

This paper is interesting ...

http://www.pubmedcentral.nih.gov/articl … 87]Fission in the core

Gives a mechanism by which fission can take place in the core.

Earth appears to have formed a lot closer to the sun than it is now, therefore the orbit it originated in means it is had lower oxygen levels in the rock (i.e Earth is made from Enstatite chondrite material) this means that Uranium metal would tend to form Sulphides instead of oxides (because of the low Oxygen ratio) and not be bound up in the mantle rock very much, but countinue into the core during differentiation.

Thus there could be a lot of Uranium (and similar heavy elements very near/in the core. enough to sustain extra heating compared to just the residual heat left over from formation.

if Mars had a similar mechanism (its a big if) and if mars maybe has a lower Iron content than thought, due to some historical formation event (we dont know much about Mars's interior or history) it is possible that mars would have a weak magnetic field but still be quite geologically active due to fission still taking place. Hence there may be volcanism still present.

There is an interesting article in New scientist (out know).

It is about the centre of the Earth, apparently there is far too much heat to be explained by the conventional 'still molten since it formed' theory, there is just too much heat in the earth to be caused by gravity or be left over from when the earth was formed.

One theory is that fissile radiactive elements ( being the heaviest elements, they they would sink to the core)  this would result in a nuclear chain reaction, so the heat could be generated from Nuclear processes!

If the same where true on mars then it could be a lot hotter in there than we think....

There are over 30 Martian falls (a 'fall' may contain many individual meteorites), and at a guess 50+ klios total weight. 
You can imagine with 70% of the martian meteoritic material locked up for research there is not a lot to go around.

But you can pick up a small piece of Martian meteorite (Such as Zagami) for around $20 upto many $1000 depending on the size of the piece!

Useful info Sites (Click links)

http://www2.jpl.nasa.gov/snc/]Mars Meteorites

http://www.marsacademy.com/intros/intro3_3.htm]Mars Society about Mars Meteorites

Fair point but,

If you took a large chunk of rock from earth, sent it through space, and it landed it on another planet, when you cut it and analysed it, it would show much evidence of life. Like organics, tell tale isotopic ratio's etc, maybe even some long dead organisms, since  every rock on earth contains microorganisms by the score... they really are everywhere.

Now We can ignore ALH 84001 (since this discovery has now been discredited, they went public way too early), typical sci-politics!

But If there was life on Mars hundreds of millions of years ago, (we have martian metoeorites that date from 3 BY to 130 MY) then there ought to be life (or signitures of life) in most martian meteorites, there is not. Even though Martian meteorites have been found with pristine interiors and some even contain (very) small amounts of martian water and trapped martian atmosphere,  why is there no evidence of any life form, even at the molecular scale?

Look at any surface rock on earth and you will find it covered in life, look at any Mars rock with a rover and it looks like the day it was made (minus wind errosion). If this elusive Martian life exists it
is certinaly keepeing a very low profile.

Wishful thinking is a very powerful driving force in science. This is why people still try to invent perpetual motion.

I agree if they did find life, it would certainly spell the end of any manned missions, imagine the health consiquences of finding alien bacteria!

I collect meteroites and have many Martian meteorite samples in my collection I havent noticed any biological side effects ...

**£%^!"£ Must Kill Earthlings, Must Kill Earthlings "!*£$!£!&$

:angry:

Safer to assume there is no life until we find a shred of evidence to the countrary.  The last bastion of hope of finding life, is if there is a hidden microbial life colony clinging on somewhere, somehow, but that myth is perpetuated by those that desperatly want to find it. A lot of people have a lot to gain and loose, and as ever with mankind, I am sure they wont get a little thing like the plain truth get in the way.

lets face it, Mars is like the moon only with red rocks and a hint of more atmoshpere, show me a more sterile looking planet?

Venus, I could undertand, even Titan and Europa, but Mars?
Nope no chance.

Fair enough, now there is even less evidence for life !

WOOOh wait a minute,

There are plenty of other reasons for Ammonia that don't require life. Volcanic activity can emmit it in bucket loads, lets not forget methane is present too another Volcanic side effect (and indeed another possible indicator of life). But the fact is they have already detected the possible rudiments of Volcanic/thermic activity.

They have not found life, at the moment just a nitrogeon compound, save the champagne. Exactly how much Ammonia, have they found? clearly it's a very small amount, so why would you have small localised Ammonia concentration in one place, and not everywhere else (if there was life would you not expect it to be 'global'.

To me it appears to just be a local Volcanic/thermal outgass breaking down into Ammonia, just as is seen on other planets including our own.

More about Ammonia...>>

Ammonia (NH3) is a colourless pungent gas that is familiar to us as the smell of urine. In fact probably no other compound can be identified by its smell and correctly named by as many people as ammonia. It can be detected in the air at a level of only about 50-60 ppm, and at levels of 100-200 ppm it sharply irritates the eyes and lungs. At even higher concentrations it makes the lungs fill with fluid and can quickly cause death. Ammonia takes it name from the worshippers of the Egyptian god Amun - the Ammonians, because they used ammonium chloride (NH4Cl) in their rites. Ammonium chloride (also known as sal volatile) occurs naturally in cracks near volcanoes, and when it is warmed it decomposes into the pungent ammonia. ???

Titan will be very interesting, especially when you think it will be only the second planet we have visited with a decent atmosphere (excluding mars - it being a near vacuume).

I have to say, my thoughts are that planets tend to be a little more dull than they first seem, earth looks green and lush from space, but if you landed in the Sahara... you'd think it barren.

So I am not expecting to see pictures of a methane beach, with waves lapping directly in front of the camera. More likley it will be a moon cratered landscape a cross between Mars and a foggy day in Scotland ! and all we will see is a misty rock if we are lucky. But there is just that chance that we will see 'Somthing Wonderful' as Aurthur C Clarke said in '2010' ...

:;):

well, fossils would be around both on an 'extinct planet' that had life, and a planet that currently has life, so I cant see as it would effect the equation in any way.

if we said roughly how many planets contain fossils, then it would be all the planets that once had and currently have any sort of  life, so likley there are many worlds with a fossil record, I am just not convinved that there are many worlds with intellegent life like ours that can actually communicate! the numbers are too small, unless  something happens to greatly increase the odds of life forming we are still in the single figures for worlds like ours.

I heard on the news recently that our solar system might only have been formed the way it is because there was a binary star system right next to our presolar disk, which influenced the formation of our solar system, yet more potential evidence that we live on quite a rare planet!?

Following the recent descovery by Cassini of a dense 'methane cloud' on Titan (or an area of intense methane activity) see
http://saturn.jpl.nasa.gov/news/press-r … a.cfm]Nasa press release

and http://photojournal.jpl.nasa.gov/catalog/PIA06405]Press release 2

And following the anomolous methane descovered in the Martian atmosphere, what are the implications for life, could this now be more likley due to volcanic activity or is the remote possibity of life on Titan more tenable??

Thoughts anyone?