- #1
Nik_2213
- 1,218
- 493
I'm trying to model an Earth-sized exo-planet, ~1.1g, with 'failed' Runaway Moist Greenhouse...
Slightly smaller core than Earth's, with thicker mantle and crust. So, larger than Earth, but not by much.
Sitting near inner-edge of 'Hab Zone' of Early-K-type star, orange-ish rather than Sol's yellow.
Day length ~31 hours due 'solar tides'.
There's sufficient magnetic field to prevent rapid atmospheric 'stripping' as happened on Mars...
Due timing of system's 'Late Heavy Bombardment' equivalent, the planet is 'mostly arid', no vast oceans, just enough for a few 'seas' and Great Lakes.
If was cool enough for such...
And, without ample water to help lubricate tectonics, no 'Terran' multiplicity of subduction zones.
Just one (1) big 'hotspot'. A 'Large Igneous Province'. Think Mars' Olympus complex. Not so tall, though as, despite thicker crust, limited by ~1.1 g gravity.
Still, enough to build 'Shield' the size of Australia, with sundry dormant cones and caldera, some smoking / fizzing vents...
The 'LIP' has out-gassed enough CO2 and H2O to top-up basic N2 'atmosphere' and start planet towards a 'Runaway Moist Greenhouse'.
The lowlands' water evaporated to salt flats and brine pools, think Med's 'Messinian' period, briskly bootstrapping 'Runaway'...
But, then the supply of water ceased, the 'Runaway' stalled...
Okay, another big eruptive 'pulse' from the 'LIP' might provide enough extra atmospheric CO2 + H2O to 'Go the Distance', turn planet to a 'Lesser Venus'.
But, for now, the summits of the cones and rims atop 'LIP' are still 'condensing'.
The volcanic sulphur has long-since washed out of atmosphere.
There are many springs, even a few streams draining acidic pools and volcanic lakes. These run down-hill, either soak in or simply evaporate...
Hmm...
I need pressure & temperature across lowlands to be 'dire', utterly inhospitable, yet conditions atop LIP to be 'condensing' at not more than 2~~3 Bar.
Yes, 'SCUBA ' range, perhaps with a partial Heliox mix...
Sorry, I've tried to 'Do the Math', but it keeps beating me: Is there an 'Atmospheric Scientist' in the room ??
Slightly smaller core than Earth's, with thicker mantle and crust. So, larger than Earth, but not by much.
Sitting near inner-edge of 'Hab Zone' of Early-K-type star, orange-ish rather than Sol's yellow.
Day length ~31 hours due 'solar tides'.
There's sufficient magnetic field to prevent rapid atmospheric 'stripping' as happened on Mars...
Due timing of system's 'Late Heavy Bombardment' equivalent, the planet is 'mostly arid', no vast oceans, just enough for a few 'seas' and Great Lakes.
If was cool enough for such...
And, without ample water to help lubricate tectonics, no 'Terran' multiplicity of subduction zones.
Just one (1) big 'hotspot'. A 'Large Igneous Province'. Think Mars' Olympus complex. Not so tall, though as, despite thicker crust, limited by ~1.1 g gravity.
Still, enough to build 'Shield' the size of Australia, with sundry dormant cones and caldera, some smoking / fizzing vents...
The 'LIP' has out-gassed enough CO2 and H2O to top-up basic N2 'atmosphere' and start planet towards a 'Runaway Moist Greenhouse'.
The lowlands' water evaporated to salt flats and brine pools, think Med's 'Messinian' period, briskly bootstrapping 'Runaway'...
But, then the supply of water ceased, the 'Runaway' stalled...
Okay, another big eruptive 'pulse' from the 'LIP' might provide enough extra atmospheric CO2 + H2O to 'Go the Distance', turn planet to a 'Lesser Venus'.
But, for now, the summits of the cones and rims atop 'LIP' are still 'condensing'.
The volcanic sulphur has long-since washed out of atmosphere.
There are many springs, even a few streams draining acidic pools and volcanic lakes. These run down-hill, either soak in or simply evaporate...
Hmm...
I need pressure & temperature across lowlands to be 'dire', utterly inhospitable, yet conditions atop LIP to be 'condensing' at not more than 2~~3 Bar.
Yes, 'SCUBA ' range, perhaps with a partial Heliox mix...
Sorry, I've tried to 'Do the Math', but it keeps beating me: Is there an 'Atmospheric Scientist' in the room ??