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Planets with potentially breathable atmospheres

16 Jul 2017 15:33

I think so far I only have found -6 exponents on SO2 on cold deserts.  Sometimes temperate terras have -5.
 
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16 Jul 2017 17:13

O2 might be way too high. 

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16 Jul 2017 18:11

Nope, not really. O2 is tolerable at that partial pressure and inspired percentage.

However still, Death with one breath with H2S at those levels.
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16 Jul 2017 18:24

And I think that's the first time I've seen H2S be the only party pooper.  Dang!

Added:  Oh, the NH3 (ammonia) would also be very toxic at that concentration. (CDC toxicity page.) I should get around to adding that to the chart.  The other gases as well.
 
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16 Jul 2017 18:38

Alright.

How about this one?

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17 Jul 2017 18:58

Wow, you keep hitting these really close cases!  This one is pretty interesting.  Lots of hydrocarbons (C2H2 is acetylene, C2H4 is ethylene, and CH4 is methane), all fairly nontoxic but flammabe/explosive in certain mixtures with oxygen.  I'm pretty sure that is not an issue at these concentrations though.    

We'll ignore the cold temperature, and then the only problem I do see is the CO2, which would give you a rather unpleasant few minutes to an hour before losing consciousness and then death.  

If the CO2 partial pressure were lower by about a factor of 3 I would call this breathable!
 
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17 Jul 2017 20:12

Might be too much O2....

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18 Jul 2017 00:10

I'm going to say here "congratulations!", cause you found one!   :D

The oxygen pressure of 0.483atm is in the breathable range (0.1 to 0.6).  And at first glance, one might think the CO2 is too high at 0.0876atm.  But the trick is to use altitude. 

For example, if you move up in altitude to where the total pressure is cut by a factor of 3, (around 15km above sea level on this planet), then the O2 pressure is 0.161atm, and CO2 is 0.0292.  This is in the safely breathable range!  It would just be mildly uncomfortable -- some shortness of breath, and very cold!

Excellent!
 
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18 Jul 2017 00:43

*watsisname perches on the side of a mountain on Starlight's planet, breathes in the crisp blue air, and marvels at the night sky above the clouds*  Hopefully without freezing his lungs.

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18 Jul 2017 07:46

Wow! I actually found one! Amazing to see what you think of this. 
 
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18 Jul 2017 13:56

Freaking COOOOOL!!! Time to celebrate! I need to start staking out property on your planet hehe. What will it be called? I've been dieing for a cigarette and it will be so nice to be able to finally have a smoke on a different planet, wow, wow, wow! BTW, Inspired Oxygen at 84.3% can be dangerous. 60% is the limit for oxygen therapy, and I don't think getting to a higher altitude can fix that. Still... This planet should be inducted into the Hall of Habitable Homeworlds.

Atmospheric Analysis: .573atm total atmospheric pressure @ -91.968°C (-133.5°F)
------------------------------
CH4 .274% .00157atm
Methane, nontoxic, yet it is extremely flammable and may form explosive mixtures with air. Methane is violently reactive with oxidizers, halogen, and some halogen-containing compounds. Methane is also an asphyxiant and may displace oxygen in an enclosed space. Not including Water Vapor, Methane accounts for 20% of the total radiative forcing from all of the long-lived and globally mixed greenhouse gases. Methane has been detected or is believed to exist on all planets of the solar system and most of the larger moons, even Halley's Comet. With the possible exception of Mars, it is believed to have come from abiotic processes. On Mars it may be a byproduct of electrical discharges from dust devils and dust storms, or that it may be the result of UV radiation. Or from life way below the surface LOL. Titan has thousands of Methane lakes and it rains Methane. It was also detected on extrasolar planet HD 189733b. Its origin is unknown, since the planet's high temperature (700 °C) would normally favor the formation of carbon monoxide instead.

C2H2 .102% .000583atm
Acetylene, used for oxyacetylene gas welding and cutting. Might be solid at low temperatures, but only at a normal 1 atm, so it is a vapor on your planet. Very small temperature and pressure window to remain as a liquid. Occurs naturally in the atmosphere of the moon Enceladus, coming from chemical reactions underground at high temperatures and released in thermal venting. At around 2 atm pressure and higher it can decompose explosively from intense heat or a shockwave into benzene, carbon and hydrogen. Copper catalyses the decomposition of acetylene, so don't store it in containers with copper fittings.

C2H4     340 ppm     .000195 atm
Ethylene, the oil-making gas, is a colorless flammable gas with a faint "sweet and musky" odor when pure. Worldwide production exceeds that of any other organic compound, mostly for plastics. It is also an important natural plant hormone, and is used in agriculture to force the ripening of fruits. The famous Greek Oracle at Delphi (the Pythia) went into her trance-like state as an effect of Ethylene rising from ground faults. Like all hydrocarbons, ethylene is an asphyxiant and combustible. It is listed as an IARC class 3 carcinogen as there is no evidence at present that it causes cancer in humans.

H2S     82 ppm    4.69*10^-5 atm
Hydrogen sulfide, toxicity is comparable with that of Carbon Monoxide. Detoxification is effected by oxidation to Sulfate, which is harmless. Hence, low levels of Hydrogen Sulfide may be tolerated indefinitely. At some threshold level, believed to average around 300–350 ppm, the oxidative enzymes become overwhelmed. Eventually the gas is converted to sulfite in the mitochondria by Thiosulfate reductase, and the Dulfite is further oxidized to Thiosulfate and Sulfate by Sulfite Oxidase. The Sulfates are excreted in the urine. Diagnostic of extreme poisoning by H2S is the discolouration of copper coins in the pockets of the victim. Treatment involves immediate inhalation of Amyl Nitrite, injections of Sodium Nitrite, or administration of 4-dimethylaminophenol in combination with inhalation of pure Oxygen, administration of bronchodilators to overcome eventual bronchospasm, and in some cases hyperbaric Oxygen therapy. **Chronic exposure to low level H2S (around 2 ppm) has been implicated in increased miscarriage and reproductive health issues.** In 2014, Levels of Hydrogen Sulfide as high as 83 ppm have been detected at a recently built mall in Thailand called Siam Square One at the Siam Square area. Shop tenants at the mall reported health complications such as sinus inflammation, breathing difficulties and eye irritation. After investigation it was determined that the large amount of gas originated from imperfect treatment and disposal of waste water in the building. In June 2016, a mother and her daughter were found deceased in their Porsche SUV. The medical examiner determined the cause to be hydrogen sulfide intoxication from the vehicles battery located under the driver seat. In January 2017, three utility workers in Key Largo, Florida, died one by one within seconds of descending into a narrow space beneath a manhole to check a section of paved street. **In 2005, it was shown that mice can be put into a state of suspended animation-like hypothermia by applying a low dosage of Hydrogen Sulfide (81 ppm) in the air. The breathing rate of the animals sank from 120 to 10 breaths per minute and their temperature fell from 37 °C to just 2 °C above ambient temperature (in effect, they had become cold-blooded). The mice survived this procedure for 6 hours and afterwards showed no negative health consequences.** Several groups of bacteria can use Hydrogen Sulfide as fuel, oxidizing it to elemental Sulfur or to Sulfate by using dissolved Oxygen, metal oxides or Nitrate as oxidant. The Purple Sulfur bacteria and the Green Sulfur bacteria use Hydrogen Sulfide as an electron donor in photosynthesis, thereby producing elemental Sulfur. In fact, this mode of photosynthesis is older than the mode of cyanobacteria, algae, and plants, which uses water as electron donor and liberates oxygen. Hydrogen Sulfide has been implicated in several mass extinctions that have occurred in the Earth's past. In particular, a buildup of Hydrogen Sulfide in the atmosphere may have caused the Permian-Triassic extinction event over 250 million years ago. High levels of hydrogen sulfide are lethal to most animals, but a few highly specialized species (extremophiles) do thrive in habitats that are rich in this chemical.

Explosive limits - 4.3–46%
Detection - 0.00047 ppm is the odor threshold, the point at which 50% of a human panel can detect the presence of an odor without being able to identify it.
Recommended exposure limit - 10 ppm, less than 10-minutes
Permissible exposure limit -
    10 ppm is the OSHA permissible exposure limit (8 hour time-weighted average).
    10–20 ppm is the borderline concentration for eye irritation.
    20 ppm is the acceptable ceiling concentration established by OSHA.
    50 ppm is the acceptable maximum peak above the ceiling concentration for an 8-hour shift, with a max duration of 10 min.
Immediately dangerous to life -
    50–100 ppm leads to eye damage.
    100–150 ppm the olfactory nerve is paralyzed after a few inhalations, and the sense of smell disappears, often together with awareness of danger.
    320–530 ppm leads to pulmonary edema with the possibility of death.
    530+ ppm causes strong stimulation of the central nervous system and rapid breathing, leading to loss of breathing.
Lethal Concentrations (median)
    713 ppm (rat, 1 hr)
    673 ppm (mouse, 1 hr)
    634 ppm (mouse, 1 hr)
    444 ppm (rat, 4 hr)
Lethal Concentrations (lowest published)
    600 ppm (human, 30 min)
    800 ppm Lethal for 50% of humans for 5 minutes' exposure.     
    > 1000 ppm cause immediate collapse with loss of breathing, even after inhalation of a single breath.

C2H6     5.28 ppm     3.02*10^-6 atm
Ethane, occurs as a trace gas in the Earth's atmosphere, currently having a concentration at sea level of 0.5 ppb. At room temperature and Earth's atmospheric pressure is a flammable gas. When mixed with air at 3.0%–12.5% by volume, it forms an explosive mixture. Ethane can displace oxygen and become an asphyxiation hazard. Ethane poses no known acute or chronic toxicological risk. It is not a carcinogen. Ethane is a greenhouse gas. It has been detected as a trace component in the atmospheres of all four giant planets, and in the atmosphere of Saturn's moon Titan. It was once widely hypothesized that Ethane produced on Titan rained back onto the moon's surface, and over time had accumulated into hydrocarbon seas or oceans covering much of the moon's surface. Infrared telescopic observations cast significant doubt on this hypothesis, and the Huygens probe, which landed on Titan in 2005, failed to observe any surface liquids, although it did photograph features that could be presently dry drainage channels. In December 2007 the Cassini probe found at least one lake at Titan's south pole, now called Ontario Lacus because of the lake's similar area to Lake Ontario on Earth (approximately 20,000 km2). Further analysis of infrared spectroscopic data presented in July 2008 provided stronger evidence for the presence of liquid Ethane in Ontario Lacus. Ethane is also on the surface of Pluto.

CO    4.22 ppm    2.42*10^-6 atm
Carbon monoxide, the silent killer, because it is indetectable to humans and can kill within minutes. It already claims hundreds of lives each year, and survivors of CO poisoning can be left with psychological and neurological symptoms. It is toxic to hemoglobic animals (both invertebrate and vertebrate, including humans) when encountered in concentrations above about 35 ppm, although it is also produced in normal animal metabolism in low quantities, and is thought to have some normal biological functions. In the atmosphere, it is spatially variable and short lived, having a role in the formation of ground-level ozone. Aristotle (384–322 BC) first recorded that burning coals produced toxic fumes. An ancient method of execution was to shut the criminal in a bathing room with smoldering coals. What was not known was the mechanism of death. Worldwide, the largest source of Carbon Monoxide is natural in origin, due to photochemical reactions in the troposphere that generate about 5×10^12 kilograms per year. Other natural sources of CO include volcanoes, forest fires, and other forms of combustion. Outside of Earth, Carbon Monoxide is the second-most common molecule in the interstellar medium, after molecular Hydrogen. Because of its asymmetry, the Carbon Monoxide molecule produces far brighter spectral lines than the Hydrogen molecule, making CO much easier to detect. Interstellar CO was first detected with radio telescopes in 1970. It is now the most commonly used tracer of molecular gas in general in the interstellar medium of galaxies, as molecular Hydrogen can only be detected using ultraviolet light, which requires space telescopes. Carbon monoxide observations provide much of the information about the molecular clouds in which most stars form. Beta Pictoris, the second brightest star in the constellation Pictor, shows an excess of infrared emission compared to normal stars of its type, which is caused by large quantities of dust and gas (including Carbon Monoxide) near the star.

0.1 ppmv        Natural atmosphere level
0.5–5 ppmv    Average level in homes
5–15 ppmv    Near-properly adjusted gas stoves in homes, modern vehicle exhaust emissions
17 ppmv        Atmosphere of Venus (result of the photodissociation of carbon dioxide by electromagnetic radiation of wavelengths shorter than 169 nm.)
100–200 ppmv    Exhaust from automobiles in the Mexico City central area in 1975
700 ppmv        Atmosphere of Mars
5,000 ppmv    Exhaust from a home wood fire
7,000 ppmv     Undiluted warm car exhaust without a catalytic converter

Explosive limits - 12.5–74.2%
Detection levels - odorless & colorless
Recommended exposure limit - Time Weighted Avg 35 ppm  
    C 200 ppm
Permissible exposure limit - TWA 50 ppm
Immediately dangerous to life - 1200 ppm
    > 667 ppm may cause up to 50% of the body's hemoglobin to convert to carboxyhemoglobin. A level of 50% carboxyhemoglobin may result in seizure, coma, and fatality.
Lethal Concentrations (median)
    8636 ppm (rat, 15 min)
    5207 ppm (rat, 30 min)
    1784 ppm (rat, 4 hr)
    2414 ppm (mouse, 4 hr)
    5647 ppm (guinea pig, 4 hr)
Lethal Concentrations (lowest published)
    4000 ppm (human, 30 min)
    5000 ppm (human, 5 min)

Ar    3.34 ppm    1.91*10^-6 atm
Argon, the lazy gas, is the third-most abundant gas in the Earth's atmosphere, at 0.934% (9340 ppm). It is still considered a dangerous asphyxiant in closed areas, since it is difficult to detect, it is colorless, odorless, and tasteless. One person has died from asphyxiation in an argon-filled section of an oil pipe under construction in Alaska, so, don't even worry about it.

SO2    3.25 ppm    1.86*10^-6 atm
Sulfur dioxide, used by the Romans in winemaking when they discovered that burning Sulfur candles inside empty wine vessels kept them fresh and free from the vinegar smell. Its antimicrobial action also helps to minimize volatile acidity. Sulfur dioxide is responsible for the words "contains sulfites" found on wine labels. It is found on Earth and exists in very small concentrations and in the atmosphere at about 1 ppm. On Venus it is in the atmosphere at about 150ppm. Early in the life of Mars it was nearly as high as 100ppm. The atmosphere of Io is 90% Sulfur Dioxide and trace amounts are thought to also exist in the atmosphere of Jupiter. In low concentrations SO2 causes endothelium-dependent vasodilation. In higher concentrations it causes endothelium-independent vasodilation and has a negative inotropic effect on cardiac output function, thus effectively lowering blood pressure and myocardial oxygen consumption. The American Conference of Governmental Industrial Hygienists reduced the short-term exposure limit to 0.25ppm. The OSHA Permissible exposure limit is currently set at 5 ppm for up to 8 hours. Exposure to SO2 is associated with premature birth. 3.25ppm is totally within the safe range, so, finally a planet without too much SO2! Just don't play outside too long ;)

Lethal dose or concentration:
LC50 (median concentration)
    3000 ppm (mouse, 30 min)
    2520 ppm (rat, 1 hr)
LCLo (lowest published)
    993 ppm (rat, 20 min)
    611 ppm (rat, 5 hr)
    764 ppm (mouse, 20 min)
    1000 ppm (human, 10 min)
    3000 ppm (human, 5 min)

US health exposure limits (NIOSH):
PEL (Permissible)
    TWA 5 ppm (13 mg/m3)
REL (Recommended)
    TWA 2 ppm (5 mg/m3) ST 5 ppm (13 mg/m3)
IDLH (Immediate danger)
    100 ppm

Ne    3.11 ppm    1.78*10^-6 atm
Neon, very abundant on a universal scale; it is the fifth most abundant chemical element in the universe by mass, after Hydrogen, Helium, Oxygen, and Carbon. It is the second-lightest noble gas, after Helium. On Earth it occurs at around 18.2ppm. Neon poses no threat to the environment, and can have no impact at all because it's chemically unreactive and forms no natural compounds (it can form an exotic compound with fluorine in the laboratory). No known ecological damage is caused by this element. Happy Trails!

NH3    2.05 ppm    1.17*10^-6 atm
Ammonia, boils at −33.34°C and freezes at −77.7°C (at 1atm) into white crystals. On your planet since the pressure is .573atm (58.06kPa), it will boil at around -44°C. [https://en.wikipedia.org/wiki/Ammonia_(data_page)] The Permissible Exposure Limit for ammonia set by OSHA is 50 parts per million (ppm) averaged over an eight hour period. The odor detection level ranges from 5 to 53 ppm. At 30ppm you might want to wear a mask though. It causes eye irritation at around 110ppm, and they killed a cat with a tube directly inserted into its lungs with 1,000ppm. So, your planet is completely safe from Ammonia harm. Ammonia is also found throughout the Solar System on Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto, among other places: on smaller, icy worlds like Pluto, ammonia can act as a geologically important antifreeze, as a mixture of water and ammonia can potentially have a melting point of as low as 173°K if the ammonia concentration is high enough and thus allow such worlds to retain internal oceans and active geology far longer than would be possible with water alone. Another cool thing is your kidneys produce Ammonia to neutralize excess acid in your body.
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Planets with potentially breathable atmospheres

18 Jul 2017 14:14

WOW! Thats quite impressive post you have there. How would we go about colonizing this planet? 

As for the name of the planet, I dunno yet. Does the ISS have 100% Oxygen in its air? I heard that once... 
 
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18 Jul 2017 14:19

The International Space Station is a multinational program, jointly led by the US and Russia. While the US and Russia had to compromise on many design decisions, the makeup of the breathing atmosphere was not one of them. The decision to pressurize the ISS to one atmosphere with a standard mix of nitrogen and oxygen was probably one of the easiest design decisions agreed upon by those two countries. The Mir space station, the Soyuz capsules, and the Space Shuttle were all pressurized to one atmosphere. Making the ISS breathing atmosphere be anything but one standard atmosphere would have required extensive redesigns of the Soyuz capsule and the Shuttle, and would have precluded reuse of the Mir environmental control systems.

The real question then is why the breathing atmosphere in Mir, Soyuz, and the Space Shuttle is a standard atmosphere, both in terms of pressure and composition. There are significant advantages to a reduced pressure, pure oxygen environment. Such an environment reduces spacecraft mass, structural integrity issues, and complexity. A pure oxygen environment eliminates the need to carry nitrogen tanks, eliminates the need to carefully monitor the oxygen/nitrogen mix, and eliminates the possibility of the bends (decompression sickness). The reduced pressure means the spacecraft can be a bit less bulky as well. There are additional advantages, particularly with respect to EVAs. Both the Soviet Union and the US initially planned to use pure oxygen breathing atmospheres.

The Mercury, Gemini, and Apollo breathing atmospheres were pure oxygen. The Apollo 1 fire modified how that pure oxygen atmosphere was attained, but it did not change that the breathing atmosphere was transitioned to pure oxygen shortly after launch. The issues associated with a pure oxygen breathing atmosphere made NASA shift to having some nitrogen in the Skylab breathing atmosphere, but not much. The Skylab breathing air was 75% oxygen, 25% nitrogen. The use of a pure breathing atmosphere in the Apollo spacecraft continued to the very end, which created challenges for the Apollo-Soyuz test mission.

The Soviet space program switched from a pure oxygen atmosphere to standard atmosphere very early on. Valentin Bondarenko died in a pure oxygen fire three weeks before Yuri Gagarin's historic flight. Having a standard atmosphere mix drastically reduces the likelihood and severity of fires, and also greatly simplifies the pre-launch process. A pure oxygen atmosphere requires extensive pre-breathing to purge nitrogen from the bloodstream. A standard atmosphere meant the cosmonauts could enter the capsule without wearing a helmet and they were physiologically ready to go.

NASA eventually learned these lessons, too. The Space Shuttle used a standard atmosphere. Having a standard atmosphere in the ISS was the only logical decision.
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18 Jul 2017 14:43

How interesting. Thank you for that information.

Do you have an idea of how Humans would colonize the planet I found?
 
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18 Jul 2017 15:31

Well, that's a more complicated question. I have heard the minimum number of humans needed to produce a genetically viable civilization would require around 9000 individuals. Not sure of the gender balance either.

Lets say the atmosphere doesn't need any modifications and all equipment needed for safety can be provided by the Weyland-Yutani corporation. Then you must first take into account Reliability Theory: if 2 components each need to work for a system to work, and each has a 0.9 probability of working, then the probability of the series working is 0.9*0.9 = 0.81.  With probability 0.18, one will fail. With probability 0.01 both will fail. The more things that have to go right for a system to work right, the more fragile the system becomes. Even if your component reliability is 99%, a critical path of about 70 pieces brings chain reliability below 50%. You need system architectures that fix this problem: ways to build reliable systems out of unreliable pieces. There are two basic ways to do it:

  1. Redundancy: build a lot of such things that try to make it work in parallel. Different architectures, many instances of each architecture etc. This is the lean startup model: make each experiment so cheap that you can "spray and pray"... if enough entrepreneurs are working on enough interesting problems, a few hits will create enough economic growth to make the whole sector as a whole turn a positive ROI. This is unfeasible for space stuff because there is no realistic way to bring the cost of each instance down to lean startup levels. But just as a note, NASA DID try what you might call "agile space" through the 90s.
  2. Get there horizontally: the question makes it sound like this a single "mission." That's a poor way to think about it. Rather than building a single wobbly Jenga tower 2 million blocks high, you build a pyramid. By the time the top reaches 10 feet, the bottom will have spread out to be 100 sq ft. It is stable all the time. You keep the angle of the pyramid safe by building out horizontally as you try to raise its height. For space, "horizontal" may be a lot better. What do I mean by that? You completely colonize the moon and make the process of going back and forth as routine as a bus trip. Make it civilizational muscle memory. Done? Do the same for the whole solar system. Once the whole Solar System has shrunk from "impossibly scary" to "backyard" suddenly Alpha Centauri starts to look a lot more accessible. Your planet would be at the top of a very very very large systems architecture pyramid.
     
One way to understand the distinction is this: vertical strategies attempt to plant a human civilization "seed" somewhere else (and for THAT, I just prefer transmitting the human genome by radio, along with some of our civilization history, and hope some aliens are smart enough to do the rest). Horizontal strategies will attempt to grow civilization itself, and envelop those target zones. First with an interplanetary Internet that then grows into an Interstellar Internet. Then it "thickens" into a materials/logistics supply chain. Finally, it is robust enough that we can travel along it.

The first step to "horizontal" grow-the-infrastructure strategies is already being considered: an Interplanetary Internet:
The Interplanetary Internet
And oh yeah, somewhere along the way, we will have to build stable clanking replicators:
Clanking Replicators
By the time the first humans get to Base Pluto, we should have one going there.

Back around 2003 when there were furious debates about whether the Moon was a meaningful stepping stone on the way to Mars, many old-school space technologists were furious that effort was being invested in going back to the Moon. The critics of using the Moon as a stepping stone don't get the basic premise of horizontal engineering. The Moon was one delicate achievement in the 60s-70s. It needs to become a robust achievement before Mars can be meaningfully tackled.  The "verticalists" would rather do one delicate Mars run to prove a point than fully build out a space-based civilization more slowly. My doom-and-gloom prediction is that none of this has even the remotest chance of happening. We are going to fail at a much more basic challenge: keeping civilization functioning here on Earth. Robotic AI or Avatars have a better chance than we humans do.
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