How can they terraform Mars when there is no magnetosphere?

Question

Scientists sometimes speak of terraforming Mars. They say that by creating machines to pump out greenhouse gasses they can warm it up, which would melt the ice and bring back rivers, lakes and oceans. This wil then create a thicker atmosphere. They say that by adding algae and other plants they can create oxygen, Then they can add animals and humans could live there.

But scientists have also said that Mars has a thin atmosphere today because its iron core cooled off and solidified. Without the movement of liquid iron to generate a magnetic field its magnetosphere disappeared. Then solar winds blasted the atmosphere off of Mars.

Since remelting its iron core is probably way out of the realm of possibilty, what will prevent Mars from getting bombarded with radiation and its atmosphere blasted away again? Or at least its inhabitants getting radiation sickness?

wilde_space · Accepted Answer

You are right. We could theoretically create a thicker atmosphere, but it would be gradually lost to the solar wind, and we would have to keep pumping gasses into the atmosphere to keep it up. There's also the issue of radiation from space.

If we do colonise Mars, it's best to sick to self-sustaining bases.

bestonnet_00 · Answer

The atmosphere loss is more to do with the low gravity than the lack of a magnetosphere and takes places over millions of years, we could easily just keep topping it up as we go.

Radiation won't be a problem either because the atmosphere will be quite thick enough to stop it without need a magnetosphere.  Earth's atmosphere is 10 tonnes per square metre so for Mars to have similar surface pressure it is going to need a thicker atmosphere because of the lower gravity so even if you go with a lower surface pressure you'll probably get 10 tonnes per square metre with no problem (and 5 tonnes per square metre would be quite good enough to protect everyone on the surface from radiation).

The area where not having a magnetosphere will actually cause problems is that orbiting spacecraft won't get the protection that Earth's magnetosphere provides although in those cases large space stations can just have 5 tonnes per square metre of slag packed around them (or less if you use the right materials) and small spacecraft are just going to have to go unshielded (except for a small room to shelter from solar flares but which would actually increase cosmic ray exposure) and use methods to limit exposure like getting to Mars quickly (nuclear rockets can reduce radiation exposure that way).

Gabriel · Answer

What about using magnetotactic bacteria to grow a giant magnet through or at the poles of Mars? Evidence suggests that that type of life is now or has already been there and there is much iron present.

lithiumdeuteride · Answer

These do seem like nearly insurmountable obstacles to large-scale terraforming.  It may be that we are never able to overcome them.  Or perhaps if humanity reaches the level of technological sophistication to re-melt a planet's core, we won't even need to terraform anymore.  We may be able to engineer a human who can survive on Mars.

Irv S · Answer

Pretty far out, but a fusion electric power plant, 
and a superconducting DC distribution systemm routed about the equator, 
might restore that field.
It's 'tech.' we don't quite have yet, .. but we are talking 'long term'.

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How can they terraform Mars when there is no magnetosphere?

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