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Chat,

I am counting every second also, this could be one of the most exiting space landings for a long while if it comes off, (and it is a high risk landing), it will be simply stunning. There are a lot of unknowns however, like will the chutes be big enough to slow it down, have they calculated the atmospheric drag well enough (beagle 2 didin't!), even will there be enough light to see. fingers definatley crossed!

The magnetic field point is an interesting one..

To keep an atmosphere in a high radiation enviroment you need a magnetic field.

To have a magnetic field, the planet would need a molten core, therfore it would have to be earth sized (since anything much smaller would have a cooled :. solidified core by now)

The other thing though, is the type of radiation, presuably it would from be 'juptier orbit trapped protons etc' (ie particles) in which case a magnetic field will stop it, but high energy xray/gamma/cosmic showers not so sure!

so its unlikely unless of course there exsits a mechanism whereby a small moon still has a liquid core due to 'tidal action', and manages to keep its atmosphere. this could be what is happening on Titan. Titan is [very] cold however.

Gennaro,

Dont worry I have never seen the same star age listed twice!, or indeed a stars distance listed twice the same, they seem to differ on a regular basis depending on the author. (goes to show how little we actually know about distant stars!)

The element issue you mention with the moon Is about right, I think without it, our geology on earth would be somewhat different!

The moon also helps life in other ways too, it must have blocked quite a few large meteors/comets in its day (i.e its a cosmic hoover!), some of the craters on the moon are staggeringly massive. They would have set life back a long way had they hit us.

The other thing is the nice stable smooth orbit and short day/night we enjoy is partly down to the moon, (its gravitational mass helps keep our  climate from being too extreeme). In addition tidal action must have conributed to life in some way e.g currents and water flow essential to spreading life around, as well as perhaps adding to continental plate movemt by 'tidal' force on the earths crust.

it would be interesting to see a model of the earth with a moon and without and see how the earth is different, my bet is earth would be quite a different place without the moon.

If this is the case then it changes the Drake equaton, because the chances of an exo-planet similar to ours having a moon of similar size, composition and distance with all the other factors is I would have thought quite low.

Its not even safe to assume that all planets like ours would probably have a moon, since the moon was formed by a giant collision with the earth, that has its own probabilites attached too, what if the impactor had hit Mars or Jupiter, RESULT:  bigger earth and a completley different Earth....

Indeed We MIGHT find all sorts of things.

But we KNOW that life (that is all the life we have studied) needs a stable band of temperatures otherwise all known life either goes dormant or dies!

This isnt to say that other forms of life couldnt potentially exist but at the moment we have to go by what we see in the world around us, and Venus and mars appear sterile, (at least to anything other than Bacteria - possibly).

There is a big difference between an eviroment that can support life and one in which life can thrive & evolve into complex intelligent forms.  (There are organisms on Earth that could potentially [survive] on mars, at least for a while, but could it evolve into humans in 3 billion years time - no)

I would argue that early life is actualy quite fragile (and there appears to have been many near extinction events in earths history).

If you factor in the fact that a habitable planet needs an orbit actually [very] similar to Earth's maybe with a moon and enough water then the potential number of alien habited worlds is even less.

The truth is we dont know enough about the number of planets like our own to make an accurate judement It could even be for example that if it wasn't for the other 8 planets we might have way too much water for intellegent life to form (i.e no land mass=no humans) or if earth was smaller we would have no atmosphere -  so we might even need a solar system that is exactly same as ours for life to start! even less odds!

You say our planet is probably not a freak, I think it probably is a freak. Look at the reletivly close distance to Mars and Venus, and look how different they are to us!

We are only habitable because we have a moon exactly the right size to keep our orbit stable, otherwise seasons would vary greatly, and day night might end up like Venus's 255 days or so, which would hinder life's development.

Its also our magnetic field (which is still very strong compared to others) which shields life from most harmful solar radiation (i.e protons etc) this also prevents the atmosphere from being stripped like Mars.

All these things to me make Earth a special place, and maybe suggests that we are indeed, largley one of a kind.

I would say that 'life'  is probably widespread as bacteria but when you consider it took billions of years for intelligence to form, even with our very stable planet.

- we aint gonna find anyone else anytime soon.

Saw the transit myself, fantastic. A real treat!

'Venus is the god of love, mars the god of war - the planet mars is tranquil, Venus is a violent hell - Hello, wrong name alert '

What I dont understand about venus, is if it has no magnetic field (as such) then how does such a massive atmosphere stay attached to the planet?

Surley accepted wisdom is that a magnetic field repels/diverts the solar wind away, stopping the atmosphere/gas molecules from being stripped off (this is essentially why mars has next to no atmosphere)

I have always thought Venus to be a far better candidate than Mars for life (lets face it, Mars has practially no atmosphere!!)  - Venus however is a veritable chemistry set perfect for forming life (at least higher in the atmosphere), youv'e got methane, water co2 sulphur etc at decent pressure. Even at the surface whilst its typically over 400 celsius, -well below the surface it may very well be cooler?

There are bacterial forms on earth that survive many hundreds of degrees I see no reason why Venus couldnt support some sort of life, (earth is very similar in geology and size).

I am just staggard at the complete lack of any decent missions to the Venusian surface. Surley in this day and age, it should be possible to land a probe that can take the heat?

All it needs is a Titanium insulated pressure vessel with a coolant inside! The trick would be to store enough coolant (e.g Solid Co2 or Liquid Nitrogeon) to last the misson. And to start with, land it on a mountian top!

Personally I would land a lander with a bell shaped 'enviromental dome', that a hardened rover could crawl around underneath (and this dome could protect it), you could even have some sort of cooled enviroment under the dome, (like a diving bell) this would allow more delicate machinery to examine the surface soil, without heat and acid spoiling the day.

As an extensive collector and Studier of meteorites myself, I can tell you these Martian meteorites are from mars without question, recent evidence from the Mars Rovers also backs this up, but it was pretty certain before then anyhow. here's why...

The Martian meteorites are subdivided essentially into three groups Shergottites, Nakhalites, Chassignites. These are all Basaltic (or cumulative Basaltic) rocks, which differ completley to all the other meteorite types, so they clearly belong to a seperate parent body, than all the other falls.

Next the Isotopic Ratio's match Mars rock studied directly by space probes exactly (different elemental ratios exsist depending on the parent body, i.e each one has its own unique signiture), Gases trapped in the rock, match the Martian atmosphere.  Orbital back calculations from witnessed Martian meteorite falls suggest martian origin.  Dating of the rocks by radioisotope decay, dates them far too young to be from asteroids, which all stopped being volcanic billions of years ago due to their small size) Now we have direct observational and isotopic evidence from the Mars Rovers that indicate the Bounce rock is a Shergottite type rock.

Lastly the mechanism that ejects rock from the surface of mars is actually quite straight forward, a meteor striking the surface at a certain critical angle can easily eject debris into martian orbit (and beyond) this has been studied by many people, and just as rock (meteorite) has reached earth from the moon, so to has it reached us from mars. Earth and Venus have thick atmosphere and higher gravity so its less liklely that rock from these planets would escape but still not impossible.

There are few things in  science that we can be certain of, but given this amount of evidence, its looking pretty good!

:band:

rgcarnes,

Frstly C1 chondrites, do not come from mars! TO SUGGEST THEY ARE IS SIMPLY WRONG.

What evidence is there that the isotropic ratio's prove this? [none!]. for a start C1's predate mars' surface completley by many billions of years.

& how do you explain the CAI inclusions? which match spectrographic signitures of stars? (i.e they contain pre solar  inclusions) Secondly C1 chondrites have spectrogtraphic similarities to cometry material, so are you telling me that comets with long period episoidal orbits origiante not from the outer extreems of the solar system, but the inner planets? no way, physics would have to be broken for that to be the case, orbital mechanics rules that out for sure.

No - This idea belongs to the 'crop circle brigade' if you ask me - Its utter rubbish.

Thanks for that.

what about one other source of methane?, I wonder if methane could be produced from a the impact of  a carbonaceous meteorite(s)  i.e a comet a impact?  since they contain 5% typ carbon as well as a large amount of voitile organic/aromatics and water.

if you had a large comet(s) that vaporised in the upper atmosphere, you would liberate a large amount of carbon based molecules maybe the methane can be expalined in this way? 

Just a thought.

You can look into the recent past to an answer to this, when NASA announced it had found a fossilised microbe in a Martian meteorite a few years ago (although this has since proved to be controversial)

what happened? - nothing!

There where no religious outcrys, there was no mass hysteria in fact 99% of the population didnt care, justg carried on 'watching TV and eating Pizza' - as always!

I really think finding non-intelligent life will have little effect on mankind, we (man) aren't even too bothered at finding new life forms (species) on our own planet!!

No I reckon there will be a few news headlines then, life goes on as normal... :band:

It is worth sounding a note of caution here, there could easilly be a chemical answer for the methane, Mars has a highly oxidising/reducing soil,  for example the methane might be trapped deep at the pole from past volcanic activity and released during melting... or there may be some residual thermal activity still going on, -  even our moon, may still have a warm core, which could allow accasional outgassing, (though this is controversial).

Thermal cooling of planetary bodies is poorley understood, it is entirley possible that the Methane is volacnic in origin and mars's interior is warmer than thought.

c'mon,

If there was large amounts of life on mars we would have seen it by now, enough photo's & microscope shots have been taken, to see any larger life forms.

The only (last) hope for life on Mars rests on finding 'tiny primitive bacterial life forms' for which you need a [much] better microscope.

They might concievably find fossilised bacteria, (maybe), but I'd say on balance (with all the availible evidence), Mars is very Sterile (minus earth-Mars contamination by Space probe that is!)

i'ts a very interesting geology mission, but the  great Mars life hunt, is just a 'tactic' to get the probes there.

Call me a synic, but sometimes the truth hurts..