6 minutes ago, beecee said:

Terraforming Mars is one of the great dreams of humanity.

It is?  I thought it was basically a big science fiction subject.  

I have heard the importance of a magnetic field to keep an atmosphere, but then I think of Venus which has an absurdly dense atmosphere and almost no magnetic field.  So how important can it be.  If this last part is considered a hijack please disregard, that was not my intention.

The atmosphere of Venus is mostly CO2, so it’s heavier. Venus also has a strongly circulating ionosphere, which creates a magnetic field - it’s not an internal source.

47 minutes ago, Bufofrog said:

It is?  I thought it was basically a big science fiction subject. 

I thought much of what is/was science fiction, is always a dream...as putting boots on the Moon once was.

48 minutes ago, Bufofrog said:

 I have heard the importance of a magnetic field to keep an atmosphere, but then I think of Venus which has an absurdly dense atmosphere and almost no magnetic field.  So how important can it be.  If this last part is considered a hijack please disregard, that was not my intention.

As per what swansont says, and not sure if this counts or not, but it's rotational/spin velocity is pretty slow...a day on Venus is longer (243 Earth days)  then its year ( 225 Earth days) 

1 hour ago, swansont said:

The atmosphere of Venus is mostly CO2, so it’s heavier. Venus also has a strongly circulating ionosphere, which creates a magnetic field - it’s not an internal source.

Thanks, that makes sense.  Maybe the CO2 and heavier gases like H2SO4 are what is left of the atmosphere.

28 minutes ago, Bufofrog said:

Thanks, that makes sense.  Maybe the CO2 and heavier gases like H2SO4 are what is left of the atmosphere.

That’s my understanding. There’s a little nitrogen, and the oxygen is all bound up in heavier molecules.

4 hours ago, swansont said:

That’s my understanding. There’s a little nitrogen, and the oxygen is all bound up in heavier molecules.

Would the slow spin rate have any bearing?

6 hours ago, beecee said:

Would the slow spin rate have any bearing?

No idea.  I wouldn’t be surprised if it impacted the motion of the ionosphere (the primary source of the magnetic field), since you’d expect a decent temperature gradient, but we have a decent temperature gradient here on earth. Proximity to the sun is another variable, and I don’t know how that all combines.