Let's talk about MARS!

[Sektor31]

It's been postulated that Mars was once an Earthlike planet, but how long have the experts at work determined Mars' current state?

Also, if it WAS once Earthlike, could there have been an intelligent species living on it (ala Martians )?

[SyntaxVorlon]

Given the time it took to have intelligent life on earth, not knowing what sort of intelligence you mean, I'll assume civilization sized. Probably not. I've heard that at one time the atmosphere on mars was large enough to support life, but because of too little gravity, it lost its atmosphere for the most part.
It most likely does not have any remaining life, save for maybe a bacterium or two which thrive in very cold, high radiation, environments.

[Superman]

Nope, probably not.

[Asst. Asst. Lt. Cmdr. Smi]

Perhaps some plant life at most, but I don't think the possible earthlike conditions would hold long enough for anything more than that to evolve. If people believe there could have been such life, then future missions to Mars might look for fossils to find out.

[Kuroneko]

I've heard that at one time the atmosphere on mars was large enough to support life, but because of too little gravity, it lost its atmosphere for the most part.

Suprising. Granted, Mars's escape velocity is lower, but it is also colder, which would inhibit atmospheric loss, particularly for more massive gasses like O2 and especially CO2. Venus has 90% Earth's gravity, and yet has an atmosphere nearly a hundred times more massive, despite being much hotter. Mars not having much of an atmosphere suggests it probably didn't have much (or, at least the heavier gases) to begin with.

[kojikun]

Mars' size has NOTHING to do with its atmospheric density. Moons of Jupiter have denser atmospheres then Earth does and theyre much smaller then mars!

[TrailerParkJawa]

Mars' size has NOTHING to do with its atmospheric density. Moons of Jupiter have denser atmospheres then Earth does and theyre much smaller then mars!

Care to elaborate? Why is Mars' atmosphere so thin? I always thought it had to do with the gravitity being weaker.

[Kuroneko]

Mars' size has NOTHING to do with its atmospheric density. Moons of Jupiter have denser atmospheres then Earth does and theyre much smaller then mars!

None of Jupiter's moons have atmospheres even remotely comparable to that Earth. What you're probably thinking of is Titan, a moon of Saturn, which has surface pressure of 1.6 bars (Earth's is 1.01bars).

[kojikun]

bah. jupiter, saturn, whats the difference.

[Slartibartfast]

Had there been a civilization in Mars, there would be a HELLUVA lot of ruins and stuff, not some hill that if you look at it at a certain angle with certain shadows kinda looks like it might be a face or a pyramid.

[Kuroneko]

bah. jupiter, saturn, whats the difference.

Still, dismissing gravity as irrelevant is too hasty. Titan's escape velocity may be one-quarter of Earth's, but at 94K it is also more than three times colder. Based on this and tha fact that Titan's atmosphere is primarily nitrogen (like Earth's), I estimate Titan's atmospheric loss is about 4/sqrt(288/94) = 2.3 times higher than Earth's, but given that Earth is expected to be able to hold an atmosphere much longer than the Sun is expected to last, that's not really all that much.

[UltraViolence83]

I say we go to Mars and terraform it. Later, open a theme park. Charge admission to have patrons stand next to that hill-face thing and get their holophoto taken by it.

[GrandMasterTerwynn]

It's been postulated that Mars was once an Earthlike planet, but how long have the experts at work determined Mars' current state?

Also, if it WAS once Earthlike, could there have been an intelligent species living on it (ala Martians ;) )?

Current theories suggest that Mars may have been warm and Earthlike for less than a billion years after it formed and everything settled down. Then, due to it's very low mass, it's interior rapidly cooled off, and no more volatiles were outgassed to replace the stuff lost by Mars. So the planet very quickly froze, except for the occasional outflow of material from buried glaciers and permafrost melted by meteor strikes.

So the last time Earth and Mars had similar climates was about 3.8 billion years ago. And the most sophisticated form of life on Earth was bacteria, and we had the advantage of a lot of volcanic outgassing. Mars was already starting to lose that. So the absolute farthest Mars could've gotten was microbial life, and even that is somewhat doubtful, as the planet dried out and froze over pretty quickly. (More recent studies tend to indicate the planet may be much drier than we initially thought.)

[GrandMasterTerwynn]

Mars' size has NOTHING to do with its atmospheric density. Moons of Jupiter have denser atmospheres then Earth does and theyre much smaller then mars!

Wrong. Mars's size has a great deal to do with it's lack of atmospheric density. Especially when combined with the flux of solar radiation it recieves (which warms the gas, whose individual particles then tend to get bumped clear out of the atmosphere.) Mars lacks the gravitational pull needed to hold on to much of an atmosphere. And this lack of mass also means that Mars cooled down faster, so it quit outgassing earlier, so it couldn't replace what solar heating blew away. It's size and mass are the very reasons it has practically no real atmosphere to speak of.

And no moon of Jupiter had any atmosphere worth mentioning. Only Io has any atmosphere at all, and it's just dense enough to rival the high vacuums produced in laboratories on Earth.

The moon you're thinking of is Saturn's Titan. It has an atmosphere roughly 1.8 times as dense as Earth's and is actually pretty close to the planet Mercury in terms of size (though, owing to it's low density, it's closer in mass to Earth's Moon). However, Titan recieves a miniscule fraction of the solar energy that Mars does. This means the gasses are colder and don't have the energy necessary to escape Titan's feeble gravitational pull.

Move it to the orbit of Mars, however, and it would rapidly become another airless ball of rock, similar to the Moon.

[Peregrin Toker]

Had there been a civilization in Mars, there would be a HELLUVA lot of ruins and stuff, not some hill that if you look at it at a certain angle with certain shadows kinda looks like it might be a face or a pyramid.

What if the culture on Mars build its homes in subterranean caverns, harvesting subterannean fungi?? I know it sounds a little bit Space Opera-ish, but I just got the idea, no matter how weird it might seem.

[StarshipTitanic]

Aren't caverns made out of millions of year of water dripping? You won't get much of that on Mars.

[SWPIGWANG]

What if the culture on Mars build its homes in subterranean caverns, harvesting subterannean fungi?? I know it sounds a little bit Space Opera-ish, but I just got the idea, no matter how weird it might seem.

Energy source?

[Slartibartfast]

Had there been a civilization in Mars, there would be a HELLUVA lot of ruins and stuff, not some hill that if you look at it at a certain angle with certain shadows kinda looks like it might be a face or a pyramid.

What if the culture on Mars build its homes in subterranean caverns, harvesting subterannean fungi?? I know it sounds a little bit Space Opera-ish, but I just got the idea, no matter how weird it might seem.

If people went through all the trouble of excavating complex cities underground, it was because somehow the surface was way too dangerous or the weather or radiation or whatever made it nearly impossible to settle in the surface - this means that Mars was hardly Earthlike. Only in fantasy the dwarves choose to live underground for no obvious reason If all the "good things" were underground (mostly the atmosphere and lack of killer storms) and life EVOLVED down there (if the conditions on the surface were so harsh, it wouldn't make sense for sentient life to start up there) it might be possible... but aren't sunrays or lightning bolts or both necessary for such thing?

[Galvatron]

Also, if it WAS once Earthlike, could there have been an intelligent species living on it (ala Martians )?

Of course! How else would you explain this?

[Stormbringer]

Also, if it WAS once Earthlike, could there have been an intelligent species living on it (ala Martians )?

Of course! How else would you explain this?

Natural features combined with lighting. Haven't they rephotographed it and it's been shown to be curious natural feature?

[DPDarkPrimus]

Also, if it WAS once Earthlike, could there have been an intelligent species living on it (ala Martians )?

Of course! How else would you explain this?

Natural features combined with lighting. Haven't they rephotographed it and it's been shown to be curious natural feature?

It's a conspiracy, maaan! [/hippie voice]

[Rye]

Had there been a civilization in Mars, there would be a HELLUVA lot of ruins and stuff, not some hill that if you look at it at a certain angle with certain shadows kinda looks like it might be a face or a pyramid.

What if the culture on Mars build its homes in subterranean caverns, harvesting subterannean fungi?? I know it sounds a little bit Space Opera-ish, but I just got the idea, no matter how weird it might seem.

If people went through all the trouble of excavating complex cities underground, it was because somehow the surface was way too dangerous or the weather or radiation or whatever made it nearly impossible to settle in the surface - this means that Mars was hardly Earthlike. Only in fantasy the dwarves choose to live underground for no obvious reason If all the "good things" were underground (mostly the atmosphere and lack of killer storms) and life EVOLVED down there (if the conditions on the surface were so harsh, it wouldn't make sense for sentient life to start up there) it might be possible... but aren't sunrays or lightning bolts or both necessary for such thing?

There are colonies of shrimp on the ocean floor, and bacteria, (as shown on the blue planet bbc program) who get their energy from geothermal vents. No light gets down to those depths, and there isnt enough "marine snow" (dead animal and plant matter that sails down the sea and feeds alot of the life) that actually gets to the bottom to feed the creatures.

There are other extremes of life, of which i wont go into here, but it seems everywhere there is liquid water, more or less, life evolves to live there.

[Straha]

Also, if it WAS once Earthlike, could there have been an intelligent species living on it (ala Martians )?

Of course! How else would you explain this?

Natural features combined with lighting. Haven't they rephotographed it and it's been shown to be curious natural feature?

No, it's a martian taking a nap underneath the dirt, proving that there are martians, and that they are giants.

[GrandMasterTerwynn]

Also, if it WAS once Earthlike, could there have been an intelligent species living on it (ala Martians ;) )?

Of course! How else would you explain this?

http://nssdc.gsfc.nasa.gov/image/planet ... s/face.jpg

A trick of light, shadow, and piss-poor image resolution. The later Mars spacecraft re-imaged it as a weathered set of hills on a somewhat square-ish plateau.

[Sriad]

Also, if it WAS once Earthlike, could there have been an intelligent species living on it (ala Martians )?

Of course! How else would you explain this?

http://nssdc.gsfc.nasa.gov/image/planet ... s/face.jpg

A trick of light, shadow, and piss-poor image resolution. The later Mars spacecraft re-imaged it as a weathered set of hills on a somewhat square-ish plateau.

BAH!!! The later photos were obviously doctored!

As to Mars being "Earth-like" I'd like to point out that for the first couple billion years of its existance the Earth was a pretty piss-poor place to live.