On Mon, Oct 17, 2016 at 2:09 AM, Richard Aiken <xxxxxx@gmail.com> wrote:

A temp of -60 C [roughly Mars conditions] requires 112,000 meters (~69 miles) deep.

I googled "Larry Niven canyon" and turned up the Larry Niven Wiki, which refers to the planet as an "originally uninhabitable Mars-like world."

Sixty nine miles deep seems a BIT unstable, even for crazy Humans to settle.

So let's doodle some more . . .

If we bump the sea level pressure up to 0.34 atmospheres (just below the lower limit for unassisted breathing) and leave the temp at -60 C, then we need a depth of -12,500 meters to reach 0.90 atmospheres.

Only half again the depth of the Marineris. Much better.

Richard Aiken

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