This is huge: *current* liquid water on Mars.

[Gawdzilla Sama]

An atmosphere WOULDN'T be "established" on Mars without more gravity to hold it there.  I'm not sure what you mean by "the inaminate option".

You refuse to say how long it would take for the atmosphere to erode. Are you saying that it would erode faster that it could be established? If so, that's just wrong, unless you know of a mechanism I don't.

[Cavebear]

You refuse to say how long it would take for the atmosphere to erode. Are you saying that it would erode faster that it could be established? If so, that's just wrong, unless you know of a mechanism I don't.

Yes. yes. yes. yes. yes. yes. yes. yes.  That's what I've been saying.  And I'm saying that because Mars doesn't hold an atmosphere for a reason.  No magnetosphere!

[Gawdzilla Sama]

MARS STILL HAS AN ATMOSPHERE!

[Gawdzilla Sama]

Yes. yes. yes. yes. yes. yes. yes. yes.  That's what I've been saying.  And I'm saying that because Mars doesn't hold an atmosphere for a reason.  No magnetosphere!

So, after a few billion years the atmosphere is completely gone, right?

[Cavebear]

So, after a few billion years the atmosphere is completely gone, right?

It is gone as fast as you create it.

[Gawdzilla Sama]

It is gone as fast as you create it.

Nonsense. If that were true there would be no atmosphere on Mars now. Instead, after billions of years, we still have some atmosphere. NOT INSTANT LOSS. That's absurd.

[Cavebear]

Nonsense. If that were true there would be no atmosphere on Mars now. Instead, after billions of years, we still have some atmosphere. NOT INSTANT LOSS. That's absurd.

There is virtually no atmosphere on Mars.  Is that what you have been basing all this discussion on?  The Mars atmosphere is about 0.6% of Earth's mean sea level pressure because that is all the planet's gravity can hold!  Mars can't hold the atmosphere you want to create for even a few years.    Everything I search says it just CAN'T WORK...

[Gawdzilla Sama]

There is virtually no atmosphere on Mars.  Is that what you have been basing all this discussion on?  The Mars atmosphere is about 0.6% of Earth's mean sea level pressure because that is all the planet's gravity can hold!  Mars can't hold the atmosphere you want to create for even a few years.    Everything I search says it just CAN'T WORK...

It currently has not much atmosphere.

You mention "Mars can't hold the atmosphere you want to create for even a few years." but I don't see a reference.

[Cavebear]

It currently has not much atmosphere.

You mention "Mars can't hold the atmosphere you want to create for even a few years." but I don't see a reference.

You made the previous claim it could for billions of years.  I don't have to prove that.

So prove it.

[Gawdzilla Sama]

Mars still has an atmosphere. QED

So, if we establish an atmosphere there, what do your sources say will be the lifespan of that? "Instantly" is a non-starter.

BTW, have you met Robert Zubrin? http://www.marssociety.org/home/about/mars-direct/

[trdsf]

I like you, but apparently I have to repeat myself a lot too.  You can't create an atmosphere on Mars that will last any length of time unless the core increases in mass and therefore the gravity of the planet to hold any atmosphere we create by any means. 

Every method of creating an atmosphere on Mars amenable to humans would be very temporary unless the mass of the planet can hold what is created.  Surface solutions will all be temporary, if not being lost to space as fast as created. 

You can't get over the problem that Mars just isn't massive enough to hold an atmosphere.  That's why it doesn't have one suitable to humans.

The reason it doesn't have a substantial atmosphere is because it doesn't have a magnetic field.

It has sufficient gravity to hold a nitrogen-oxygen atmosphere; it can't hold hydrogen, helium, water vapor (although it can have pressure and temperature high enough to retain water).  The following diagram shows the gravity and pressure relationship for maintaining an atmosphere; anything below the world can, absent other factors, be retained.



This is also why Martian methane is such an interesting find: it really shouldn't have any left by now, which means there's a current source.  Methane is a byproduct of some biological processes; it's also a byproduct of physical ones, but finding it at least leaves Martian life in the 'possible' column.

[trdsf]

With regard to the lack of a magnetic field, I posted earlier in this thread about a theoretical way to provide Mars with one without re-melting the core.

It's mega-engineering, but it's theoretically possible within this century.

[Unbeliever]

Why even do all that work to terraform a planet when we can just build orbital habitats to suit us? We don't need planets!

The High Frontier: Human Colonies in Space

[Gawdzilla Sama]

Why even do all that work to terraform a planet when we can just build orbital habitats to suit us? We don't need planets!

The High Frontier: Human Colonies in Space

If they have anti-gravity, sure, that might work. But I think it will be a while before Dr. Sumgui has the bugs out of that system.

[Unbeliever]

They just need to spin, and voila! gravity (sort of).