What if Mars was Earth or Venus sized?

[pmn1]

If Mars was Earth or Venus sized but still in its current orbit, what kind of conditions could you expect on it?

 

[Gravity_Ray]

I think if Mars was bigger, then its interior would have stayed warmer longer, and that would have allowed it to keep its magnetic field, which maybe would have allowed it to keep its atmosphere.

I think its size does have a lot to do with its current condition of cold and dead looking.

 

[yevaud]

Yes, correct. It's size (mass, actually) is too small to retain much of an atmosphere; a spotty magnetic field pretty much puts the death-knell on it.

However, Mars IS within the "Habitable Zone" of our solar system, so if it were Earth sized, it would likely have retained a substantial atmosphere that may well have been (could be?) conducive for human life.

 

[3488]

Hi pmn1,

Great question indeed.

Both Gravity_Ray & Yevaud are 100% correct.

Mars's relatively small mass, only 11% that of Earth or near enough twice that of Mercury meant that the interior cooled off relatively quickly (though there is some evidence of minor volcanic activity till recent geological times), but the main period of volcanism ceased before 2 GYA.

Relatiely low escape velocity due to a relatively small size & mass (Mars's global density is not that much greater than that of our Moon or the Jupiter moon Io) where as Venus's & Mercury's densities are high, only very slightly behind Earth's (Mercury has the greatest uncompressed density of any body in our solar system, Venus & Earth are internally compressed).

I hope this helps.

Andrew Brown.

 

[CAllenDoudna]

I always supposed it would be something like Canada, Russia, Tibet, or Bolivia. But I've been tinkering with a science fiction story set in a solar system similar to our own in which aliens terraform an Earth-sized Mars and kidnap a wagon train and take it there. In contemplating what they would go through it wasn't long till I realized a couple of interesting things:

1) They would have to revert to more nearly an Indian-level of technology and economy.

2) With each season on Mars being about five months long compared to three months on Earth the growing season would be about an Earth-year long and this lead to the fascinating possibility such an Earth-like Mars would have magnolias and oranges as well as cedar and maple.