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Comment by Tuna-Fish | Hacker News Reader

Few thousand would be lowballing it rather lot. An impact of that magnitude would melt the entire surface, boil the oceans, and strip off the atmosphere. It would take hundreds of millions of years for earth to recover, if it ever would.

Also, Mars is not that hospitable to life. The best option I see would be putting as much people and industry in orbit as possible, and try to live from asteroids.

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> An impact of that magnitude

It wouldn't be an impact. For the moon to reduce its orbit to the point that it impacted the earth it would be moving rather slow as orbital objects go.

It would be more of a gradual merging as chunks of rock and ocean moved between the two bodies.

Exactly. See: http://en.wikipedia.org/wiki/Roche_limit

Basically, in this scenario the moon would either come down in chunks or would form a set of rings.

Yes, I was thinking a -3.8cm per year rate, and did contemplate the "squishing" that the moon Io has to deal with. Just pulled the timeframe from my rear end, probably would take that long just to get the process started. :/

> Mars is not that hospitable to life

I've always found it rather interesting how the combined mass of Mars and Venus is just about the same as Earth's. Can't we move Venus out to a higher orbit where it would impact with Mars and produce an Earth 2?

I've thought the same thing... assumed we'd need alien help. Someone very powerful, like species 8472 but friendlier.

As inhospitable as Mars is, asteroids and space stations are far worse!

Yep, and faced with an end-of-life event we'd probably make a go of it, no?

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