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

[Baruch]

It would be so massively cool to find a any type of microbe.

I agree it is very unlikely, but man... if we did, life is suddenly everywhere.

It is everywhere.  But not as we define it.

[Cavebear]

Just out of curiosity, if Mars couldn't hold an atmosphere earlier on its own, what makes anyone think it could hold a terraformed one?  I've never understood that part.  It isn't the atmosphere that is the problem.  It's the lack of size and (maybe) lack of magnetic core.

[Gawdzilla Sama]

Just out of curiosity, if Mars couldn't hold an atmosphere earlier on its own, what makes anyone think it could hold a terraformed one?  I've never understood that part.  It isn't the atmosphere that is the problem.  It's the lack of size and (maybe) lack of magnetic core.

Mars slowly lost its atmosphere over a few million years or so according to the models I've seen. Erosion by solar wind isn't fast.  If we got a new atmosphere up it should last at least that long.

[Cavebear]

Mars slowly lost its atmosphere over a few million years or so according to the models I've seen. Erosion by solar wind isn't fast.  If we got a new atmosphere up it should last at least that long.

OK, but doesn't it also take a long time to CREATE an atmosphere?  We need to find a way for one to stay.  Asteroid bombardment?  Comets?  Planetary core heating?

[Gawdzilla Sama]

OK, but doesn't it also take a long time to CREATE an atmosphere?  We need to find a way for one to stay.  Asteroid bombardment?  Comets?  Planetary core heating?

Comets, or icy bodies in the inner solar system. Probably don't need to go further than Jupiter or Saturn for beau coup ice. It will be expensive, a scaled-up Manhattan Project.

[Cavebear]

Comets, or icy bodies in the inner solar system. Probably don't need to go further than Jupiter or Saturn for beau coup ice. It will be expensive, a scaled-up Manhattan Project.

But I will say again, could Mars HOLD an atmosphere for as long as it would take to create one?  There is an aspect of perpetual motion if you can't.  I mean, suppose you had to crash down asteroids that could add to a Mars atmosphere to maintain it.  Dodging asteroids isn't fun.

[pr126]

Total Recall.

[Gawdzilla Sama]

But I will say again, could Mars HOLD an atmosphere for as long as it would take to create one?  There is an aspect of perpetual motion if you can't.  I mean, suppose you had to crash down asteroids that could add to a Mars atmosphere to maintain it.  Dodging asteroids isn't fun.

It took millions of years to lose it, it might take a hundred years to get a new one going. Not only does crashing icy bodies into Mars provide water and other gases, like nitrogen, it also adds a wee bit of heat, and every little bit helps.

We could have a "daisy chain" of pusher ships that get the bodies going in the right direction and then go to the next one on their list, repeat as needed. A hundred of those might deliver a thousand bodies a month, depending on the orbital dynamics. Again, expensive, but extinction is cheap.

A gunny sergeant once asked me how fast I could run?

"How scared am I?"

[Baruch]

OK, but doesn't it also take a long time to CREATE an atmosphere?  We need to find a way for one to stay.  Asteroid bombardment?  Comets?  Planetary core heating?

You are killing the meme ... let the space cadets play ;-)

https://www.youtube.com/watch?v=UU7TdtLzPrA

[trdsf]

But I will say again, could Mars HOLD an atmosphere for as long as it would take to create one?  There is an aspect of perpetual motion if you can't.  I mean, suppose you had to crash down asteroids that could add to a Mars atmosphere to maintain it.  Dodging asteroids isn't fun.

Since Mars is geologically inert -- no apparent continental drift of any sort anymore -- and has a minimal magnetic field, it hasn't a way to both retain and regenerate its atmosphere.  Now, there's a speculative plan that an artificial magnetic shield at Mars' L1 point with the Sun would both provide the necessary magnetic shielding to prevent the atmosphere being stripped by the solar wind, but also allow the planet to warm enough to release the CO₂ at the poles, which would then allow it to warm enough to melt the remaining water.

The problem then becomes one of Martian gravity -- it can hold a nitrogen-oxygen atmosphere (barely), but it can't retain water, even if the surface temperature and pressure are raised to something approximating that of Earth.  So there would probably be atmospheric resupply missions every few centuries, capturing a comet or some such and bringing it in very carefully or in small chunks.  Alternately, adding mass to the planet so the escape velocity rises would turn the trick, or some combination of the two.

[Gawdzilla Sama]

Maintaining the atmosphere would be minor compared to establishing it.

For a SWAG let's say 0.01% of the atmosphere is lost every hundred years. How hard would it be to bring that back up to standard in, say, ten years of ice mining? Not much, really. And if the NeoMartians don't do then the colony fails do to lack of will.

[Baruch]

Maintaining the atmosphere would be minor compared to establishing it.

For a SWAG let's say 0.01% of the atmosphere is lost every hundred years. How hard would it be to bring that back up to standard in, say, ten years of ice mining? Not much, really. And if the NeoMartians don't do then the colony fails do to lack of will.

Will?  Triumph of the Will?  Nazis on Mars (how appropriate) rather than Nazis on the Moon?  Iron Sky indeed.

[Unbeliever]

Since Mars is geologically inert -- no apparent continental drift of any sort anymore -- and has a minimal magnetic field, it hasn't a way to both retain and regenerate its atmosphere.  Now, there's a speculative plan that an artificial magnetic shield at Mars' L1 point with the Sun would both provide the necessary magnetic shielding to prevent the atmosphere being stripped by the solar wind, but also allow the planet to warm enough to release the CO₂ at the poles, which would then allow it to warm enough to melt the remaining water.

The problem then becomes one of Martian gravity -- it can hold a nitrogen-oxygen atmosphere (barely), but it can't retain water, even if the surface temperature and pressure are raised to something approximating that of Earth.  So there would probably be atmospheric resupply missions every few centuries, capturing a comet or some such and bringing it in very carefully or in small chunks.

That might be prohibitively expensive and time intensive. It could maybe work if there was sufficient motivation, though.

Alternately, adding mass to the planet so the escape velocity rises would turn the trick, or some combination of the two.

I wonder how much mass could be added to Mars without disrupting it's orbital motion?

[trdsf]

Maintaining the atmosphere would be minor compared to establishing it.

For a SWAG let's say 0.01% of the atmosphere is lost every hundred years. How hard would it be to bring that back up to standard in, say, ten years of ice mining? Not much, really. And if the NeoMartians don't do then the colony fails do to lack of will.

That's actually not a bad guess â€" you're within a few orders of magnitude, and it would be a sensible safety margin with regard to planning atmospheric maintenance.  When Mars' magnetic field collapsed and the solar wind was able to reach the Martian atmosphere, it still took millions of years to blow it away, and that was about 3.7 billion years ago when the sun was much younger and more active.  It's currently losing its atmosphere at the rate of 100 g/s... but it has 2.5x10¹⁹ g of atmosphere left, even at its low pressure, so it's not like it's wisping away at an alarming rate.

[Cavebear]

Since Mars is geologically inert -- no apparent continental drift of any sort anymore -- and has a minimal magnetic field, it hasn't a way to both retain and regenerate its atmosphere.  Now, there's a speculative plan that an artificial magnetic shield at Mars' L1 point with the Sun would both provide the necessary magnetic shielding to prevent the atmosphere being stripped by the solar wind, but also allow the planet to warm enough to release the CO₂ at the poles, which would then allow it to warm enough to melt the remaining water.

The problem then becomes one of Martian gravity -- it can hold a nitrogen-oxygen atmosphere (barely), but it can't retain water, even if the surface temperature and pressure are raised to something approximating that of Earth.  So there would probably be atmospheric resupply missions every few centuries, capturing a comet or some such and bringing it in very carefully or in small chunks.  Alternately, adding mass to the planet so the escape velocity rises would turn the trick, or some combination of the two.

Mars needs a larger iron core and more mass.