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Is This a New Earth?
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| 11ryanc | Date: Wednesday, 18.11.2015, 22:01 | Message # 1 |
 Observer
Group: Users
United States
Messages: 19
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| Thus far, I've found a plethora of pressurized terras with multicellular life within a single search in a galaxy just outside the Milky Way. These 2 stands out the most though. The Earth characteristics were striking.
As far as I can tell, with this one. Atmospheric pressure is no greater than standing on a moderate sized mountain top to ski off of. Gravity is fairly close to 1g. Orbital period is a little under a year, a day being about 20 hours in duration. It does not appear to have a tidal lock. There is a small Selena moon within close orbit. Green grass, blue seas, clouds. Falls within a binary red dwarf system.
Almost sounds too good to be true..
The somewhat low mass is what has me most concerned. Though the planet's overall size is smaller as a whole. Does it seem feasible to presume there's a strong enough magnetic field regulating the radiation exposure?
Screenshots: http://imgur.com/a/pAxaB
Moving along, I also found another similar planet not too far apart from the aforementioned. The planet's mass is identical to that of the Earth, as is the overall size. Somewhat greater at that. Atmospheric pressure is a bit denser than the other planet aforementioned, though still below what we have at sea level here on Earth. The regression is that the gravity exceeds 1g by a small amount. It orbits around an oceania moon. Star is an orange dwarf. Both worlds harbor marine and terrestrial life.
Screenshots: http://imgur.com/a/mvWJ2
What are you're guy's inquiries? Let's assume there's no terminal bacteria, or intermediate threat from the locals. Which of the 2 looks like a safer bet to land a human, who just so happens to feel inclined to wear a sweater and take his helmet off for a walk.
Intel Core i7 4790k, MSI Z97 PC Mate, EVGA GTX 950, 16GB 1600 MHz, SanDisk SSD Plus 120GB, 2 TB WD Green, 2 TB Seagate Barracuda, Cooler Master Elite 350 Mid Tower
Windows 7 Ultimate x64 SP1
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| Alek | Date: Wednesday, 18.11.2015, 23:04 | Message # 2 |
 Pioneer
Group: Users
United States
Messages: 326
Status: Offline
| In complete honesty, I think that the second one is a safer bet due to the higher gravity, so like you said, less chance of being killed or harmed by radiation. Yes it might be a bit harder to walk, but think of this: If you get used to it, and your body learns to deal with the higher gravity, you'll be way stronger when you get home 
Living among the stars, I find my way. I grow in strength through knowledge of the space I occupy, until I become the ruler of my own interstellar empire of sorts. Though The world was made for the day, I was made for the night, and thus, the universe itself is within my destiny.
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| Watsisname | Date: Friday, 20.11.2015, 00:12 | Message # 3 |
 Galaxy Architect
Group: Global Moderators
United States
Messages: 2613
Status: Offline
| The second planet is arguably a better prospect for habitability than the first. It is larger and massive (current research points to super Earth's being more habitable than Earthlike planets or smaller worlds), and it has a slightly greater surface temperature and pressure.
Is the higher surface gravity a problem? I doubt it. +0.16g is noticeable but not severe. You can adapt.
And as for surface pressure, 0.75atm is equivalent to being at about 8000 ft or 2400m on Earth. You'd definitely feel it if you were transported there immediately, but most people can adapt to such pressure very easily.
Also, it's not the air pressure that really affects your blood oxygen content so much as the partial pressure of oxygen, which means the composition of the atmosphere matters, too. You could have a higher pressure with a smaller O2 concentration and be fine, or a lower pressure with higher O2 concentration and also be fine, as long as the mixture isn't too flammable or toxic...
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| Bells_Theorem | Date: Friday, 20.11.2015, 01:45 | Message # 4 |
 Explorer
Group: Users
United States
Messages: 188
Status: Offline
| At 5.8 and 11 billion years old respectively, I'd say Earth is the new earth. 
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| 11ryanc | Date: Thursday, 26.11.2015, 22:20 | Message # 5 |
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Observer
Group: Users
United States
Messages: 19
Status: Offline
| What pressures are within human tolerance to begin with? I've heard somewhere that life can be possible at 0.47 atm, though it's debated. I'm honestly impressed, and surprised how much the pressure differs at semi high elevations, and how well those inhabiting adjust. I never hear about the maximum pressure tolerance though. What seems like a feasible max? Have any tests been conducted?
Intel Core i7 4790k, MSI Z97 PC Mate, EVGA GTX 950, 16GB 1600 MHz, SanDisk SSD Plus 120GB, 2 TB WD Green, 2 TB Seagate Barracuda, Cooler Master Elite 350 Mid Tower
Windows 7 Ultimate x64 SP1
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| Watsisname | Date: Friday, 27.11.2015, 05:03 | Message # 6 |
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Galaxy Architect
Group: Global Moderators
United States
Messages: 2613
Status: Offline
| I don't think it's as clear-cut as that. The highest permanent human settlement on Earth is at 16,700 feet, which is equivalent to 0.54atm, or 54% of the blood-oxygen content as at sea-level. Humans can survive exposure to much higher altitude, such as the top of Everest (33% as at sea level), but not for very long, as the brain becomes oxygen starved.
The problem of reduced oxygen pressure on humans is a bit more subtle, complex, and insidious than this, though. Everyone has a different tolerance and acclimatization potential for altitude. Some people can do ascents of Everest without supplemental oxygen and be reasonably okay, if they take the early ascent slow and the final section and descent very fast. But others will develop HAPE or HACE and even die at altitudes less than half of that. Even ascending from sea level to just 5,000 feet can cause some people altitude sickness, while others barely feel it at all.
So I hesitate to generalize any specific "minimum pressure" for human tolerance. It depends on the person and the duration. It also depends on the partial pressure of O2, not the total pressure. If given oxygen, the body can cope with much lower pressures than this. You can even survive exposure to vacuum for a little while, though that certainly is not very comfortable.
The hyperbaric bound is interesting, too. The first problem is the toxicity of O2 at high pressure. Divers have to account for it and change their air mixture beyond a certain depth. With lower partial pressure of O2 you can withstand greater pressures, though I'm not sure where that boundary lies.
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