Using current technology what would be the harshest environment humans could survive in.
This could include other planets in our solar system even though we may not have the technology to get there.
The vacuum of space?
The surface of our Sun.
there’s a surface now????
ChrispenEvan said:
there’s a surface now????
Yep
Cymek said:
Using current technology what would be the harshest environment humans could survive in.
This could include other planets in our solar system even though we may not have the technology to get there.
I’ve been wondering for a long if a human being could survive virtually unprotected on the surface of Venus, given only a cooler to cool their incoming oxygen, water and food.
High pressure itself is not that much of a problem – it’s the decompression that’s the biggest problem so don’t decompress – high pressure only becomes a problem when it has a narcotic effect, and that can be countered by breathing either a liquid or a supercritical fluid. Liquid breathing is tough on the lung muscles, but has been trialled successfully on mammals, human babies in the womb can successfully breathe liquid. A supercritical fluid could have as little as 10 times the density of air, 1% of the density of water.
Then there is the cooling. All you really need to do is to keep the blood temperature to vital organs down. The brain is the most sensitive to high blood temperatures, as seen in the psychological effects of fevers. The blood temperature to the brain is easiest to reduce by breathing chilled oxygen, not by cooling the body, because the circulation distance from the body capillaries to the brain is much larger than from the lung capillaries to the brain. That said, blood temperatures to body organs does need to be kept down, just not as low as to the brain. I’ve done a bit of work on a nanotube-based heat exchanger that ought to work well for gas-gas cooling, though not well for liquid cooling because of liquid’s higher viscosity, so cool the breathed gas before liquefying it.
That said, I think the surface of Venus is a bit extreme for human life. A relatively unprotected human journey to the bottom of the ocean might be less traumatic because of the lower temperature. On the other hand, the pressure at the bottom of the Mariana trench is about 1000 atmospheres, as against 93 atmospheres on Venus. Scuba divers have managed 33 atmospheres, and 53 atmospheres for unprotected people in pressure chambers.
Taking the other end of the scale. Low pressure and temperature is not a huge problem. Everest climbers have survived on an oxygen partial pressure of 0.07 atmospheres, at temperatures averaging -25 degrees C. In Antarctica, explorers have survived at altitude (low pressure) at temperatures down to -90 degrees C. It’s well known that a human could even survive open space unprotected for a short time, keep in mind that the temperature there is irrelevant because of the law heat transfer rate.
Then there’s radiation.
> Then there’s radiation.
Before I get to radiation, let’s consider some other places in the Solar system, subsurface oceans of liquid water we could dive in.
Before going further, I want to immediately rule out the possibility of humans surviving in the subsurface oceans of salt water on Uranus and Neptune. The temperature there exceeds 2,250 degrees C and pressures exceed 200,000 atmospheres. In a word, no.
Europa, Ganymede, Callisto, Enceladus may have subsurface oceans of liquid water. Pluto may have, too, at greater depth. Ceres and Charon are probably solid right through unless, and it’s a big unless, they have small lakes of subsurface water kept warm by radioactive decay (like geysers and hot springs on Earth).
Let’s look at swimming in Enceladus as a typical example. The top of the water ocean is at a depth of about 30 km. Enceladus has a mass of 1.8×10^−5 Earths and surface gravity of 0.11 g. A back of envelope calculation gives a water pressure of about 330 bar at the top of the ocean. That’s higher than Venus but lower than the bottom of the Mariana trench. The temperature at the top of this ocean must be exactly -3 degrees, very mild, with the temperature increasing with depth until it becomes unacceptably hot.
¿What about subsurface unprotected on the Moon or Mars, relying on the gravity and the core’s radioactivity for pressure and heat. Not enough information, I don’t yet see any temperature variation with depth for the Moon or Mars.
Another idea I like is to encase a comet in plastic and bring it into the inner solar system to melt, resulting in a broth of water and organic chemicals that Earth-based life could swim in. The pressure would depend on the gas generated blowing up the plastic balloon (largely ammonia gas until bacteria could ‘fix’ it) and, by adjusting the distance from the Sun, the temperature throughout could be made quite pleasant for swimming.
Now, radioactivity. The effect tends to be cumulative. Alpha rays are trivially easy to protect against, beta rays not much worse. Gamma rays, cosmic rays, protons and neutrons are more difficult to protect against. Let’s assume negligible radioactives among food, water and air, which is easy to achieve. 4 Gy = 400 Rad = 50% lethal dose for acute radiation syndrome. Exposures on the ISS average 150 mSv per year, or about 4% of a deadly dose. The proton flux is the deadliest component of the van Allen Belts.
As for toxins, keep the food pure.
>Then there’s radiation.
increases mutations so all’s good.
transition said:
>Then there’s radiation.increases mutations so all’s good.
Only if you live long enough to reproduce, eg. if 20% of the population survives to age 20. That would be what?, perhaps an average of 0.4 Grays per year or a fraction more, 2.5 to 3 times the ISS dose.
For a human colony on the Moon’s surface, unprotected from radiation (extremely unlikely but work with me here), the radiation varies from about 110 mSv at solar minimum to 380 mSv at solar maximum. 380 mSv is very close to the 0.4 Gray maximum continuous radiation for colony survival. So a colony could survive on the surface of the Moon (just) even unprotected against radiation. For locations further from the Sun, and for subsurface locations, radiation would not be so deadly.
What about Venus? Does the atmosphere offer sufficient protection closer to the Sun even in the absence of a magnetic field? Um … (puts on thinking cap) … yes. The cosmic radiation at Venus’s surface would be less than at the top of its atmosphere by more than a factor of 8.5, perhaps much more than that. The radiation at the top of its atmosphere would be about 1.9 times that at the Moon, so a human colony on the surface of Venus would receive no more than 22% of the cosmic radiation of an unprotected colony on the surface of the Moon.
> Radiation
Um, avoid roaming unprotected on the surfaces of Ganymede, Europa and Io, they’re within Jupiter’s van Allen belt. Callisto is probably safe.
The surfaces of moons Mimas, Enceladus, Dione, Rhea are within Saturn’s van Allen belt.
Titan should be far enough out from Saturn to be safe from radiation, and the atmosphere would help a lot. By the way, Titan has an extremely pleasant surface pressure of 1.4 bar. It’s surface gravity is 85% of that of our Moon, no problem there. The temperature is a bit low at -180 °C, but heaters and thermal insulation should be able to cope with that.
> temperature
I used to think that nobody could survive a temperature above 100 degrees C. But there is this anecdote of survival at 126 degrees C.
“Sir Charles Brian Blagden FRS (17 April 1748 – 26 March 1820) served as a medical officer in the Army (1776–1780) and later held the position of Secretary of the Royal Society (1784–1797). He received the Copley medal, a scientific award given by the Royal Society London, for outstanding achievements in research in any branch of science. In 1775, he went into a room that had been heated to a temperature of 126 degree Celsius (260 Fahrenheit), taking with him a few friends, a small dog in a basket and a steak.The entire group remained there for 45 minutes. Dr. Blagden and his friends emerged unaffected. Dr Blagden was first to recognise the role of perspiration in thermoregulation.”
And even hotter.
One article says: “people have safely enjoyed heat at 160 degrees C … for three to four-minute bursts … in Informal competitions among young Finns … Heavy bathers in favour of the hottest temperatures always wear felt caps and slippers”.
Atmospheric pressure is of course assumed.
> What about subsurface unprotected on the Moon or Mars, relying on the gravity and the core’s radioactivity for pressure and heat. Not enough information, I don’t yet see any temperature variation with depth for the Moon or Mars.
There is a bit of information about the internal temperature of Mars. Its core temperature has been estimated at >1500 degrees C and ~3000 degrees C. If, and it’s a very big if, the thermal conductivity is uniform with depth, then an earthlike 20 degrees C occurs at a depth of about 165 km and a pressure (assuming basalt at a density of 2.8) of 17,000 atmospheres. That’s way too high a pressure. Let’s cut the pressure down to 1 bar, then a comfortable depth is under 10 metres of rock.
For the Moon, that’s 23 metres of basalt to get a pressure of 1 atmosphere. The Moon’s heat flux is about 21% of Earth’s, but that doesn’t matter because what does matter is that the superb thermal insulation of the Moon’s surface layer protects subsurface environments from the wild monthly surface temperature swings from -153 degrees C to +123 degrees C.
> Gravity – high and low.
I still find it remarkable that the gravities to be found on the surface of Solar System planets are so close to constant. For example, the surface gravity of Saturn is indistinguishable from that of Earth, only 6% different. The surface gravity of Uranus is identical to that of Venus and only 10% less than that of Earth.
It used to be that astronauts would quickly suffer from bone mass loss to the point of severe risk to life in zero gravity. But space medicine has now advanced to the point where some astronauts returning from the ISS after a year or more in space even have more bone mass than when they left Earth. So low gravity is not a problem any more.
For high gravity, I’m going to quote some old science fiction, “First Lensman” by E.E.Smith, written 1950.
“A lot of the adults died, 3 Gs is no joke, practically all of the babies keep on living. … They say that the third generation will be perfectly at home there.”
> Toxic atmosphere
I’m not considering breathing atmospheric gases here, I’m talking about skin contact.
N2, O2, CO2, H2O, no problem. CH4 fairly benign.
Atmospheres of solar system planets and moons sometimes also contain high amounts of CO, NH3, sulphur, SO2, Na+, H2S (and H2SO4 as a minor constituent). I’m not sure how dangerous these are to skin contact, is there a toxicologist in the house?
mollwollfumble said:
> Toxic atmosphereI’m not considering breathing atmospheric gases here, I’m talking about skin contact.
N2, O2, CO2, H2O, no problem. CH4 fairly benign.Atmospheres of solar system planets and moons sometimes also contain high amounts of CO, NH3, sulphur, SO2, Na+, H2S (and H2SO4 as a minor constituent). I’m not sure how dangerous these are to skin contact, is there a toxicologist in the house?
Skin contact with CH4. Totally benign – no treatment necessary.
Eye irritation at 100 ppm gaseous ammonia NH3 and chemical burns to skin at higher concentrations.
Here’s a shocker. Nobody knows what the absorption or toxicity of carbon monoxide CO gas is to dermal contact. http://www.atsdr.cdc.gov/toxprofiles/tp201-c3.pdf How could they not know ?!
Eye or skin contact with sulphur dioxide SO2 can cause irritation or burning. Eye irritation at 10 to 20 ppm. No data exists on dermal absorption !
Sulphur, contact with skin normally harmless, in order to get it as a gas needs either high temperature, very low pressure or both. So it can be ignored as a separate risk.
Sodium ions Na+ in the atmosphere. Dangerous or not?, when not accompanied by a corresponding negative ion. On planets this is normally the result of a cathodic-style loss of electrons, so would tend to be only in an environment that already has a dangerously low pressure. Let’s say that like sulphur it can be ignored as a separate risk.
Hydrogen sulphide H2S gas can cause eye irritation at low concentrations. “Male volunteers exposed to 100-150 ppm for as little as 2-15 minutes experienced eye irritation, and after 1-4 hours the pain was reported as sharp.” It “has only limited potential to be absorbed through the skin”.
H2SO4 is present in the atmosphere of Venus at a concentration of … zero … at ground level. Huh? OK, it’s not a problem. But the atmosphere of Venus does have 150 ppm of SO2.
mollwollfumble said:
Eye irritation at 100 ppm gaseous ammonia NH3 and chemical burns to skin at higher concentrations.
Here’s a shocker. Nobody knows what the absorption or toxicity of carbon monoxide CO gas is to dermal contact.
Eye or skin contact with sulphur dioxide SO2 can cause irritation or burning. Eye irritation at 10 to 20 ppm. No data exists on dermal absorption !
Hydrogen sulphide H2S gas can cause eye irritation at low concentrations. “Male volunteers exposed to 100-150 ppm for as little as 2-15 minutes experienced eye irritation, and after 1-4 hours the pain was reported as sharp.” It “has only limited potential to be absorbed through the skin”.
Given the abysmal lack of knowledge about dermal toxicity and dermal absorption of CO, SO2 and H2S, I’m tempted to run my own experiment to find out what they are.
What more can I say? Well, I can say that the old adage about “don’t look directly at the Sun” is vital in space, because the contrast between direct sunlight and the blackness of shadow is enormous. And I can talk about minimal protective equipment for harshest environments. The four items of equipment useful for a mobile human in an extremely harsh environment are: breathing equipment, thermoregulation/anti-vacuum, eye protection, and anti-gravity.
1. Breathing equipment. Keep in mind that a cylindrical bottle shape is far from optimal. The second image is a mini rebreather that extracts CO2 from exhaled air.
2. Thermoregulation / anti-vacuum. I’ve mentioned the Finnish felt hat above, that’s good for high temperatures up to 160 degrees C. A wetsuit/drysuit can act as thermal protection & anti-vacuum as well as anti-corrosive-atmosphere. Explorers in coldest climates use multiple layers of fur / fibres that trap air.
3. For eye protection I’d go electrochromic/LCD, the same crossed-polarization technology used in digital watches, rather than sunglasses (can’t see in shadows) or photochromic/transition lenses (dangerously slow to act). In some extreme environments consider eye protection against dangerous gases.
4. For anti-gravity in a high gravity environment, well, a walking frame seems to be the preferred technology on Earth. It’s a seat, carrier and walking support and is light-weight enough for climbing over rough terrain. For further distances, an off-road vehicle.
> For eye protection I’d go electrochromic/LCD, the same crossed-polarization technology used in digital watches, rather than sunglasses (can’t see in shadows) or photochromic/transition lenses (dangerously slow to act).
Much as it pains me to admit it, I have to retract that. Electrochromics are not good enough. To protect human eyes from permanent damage from looking at the Sun in space or in thin atmosphere requires sunglasses. Or, in the special case of Mars, a hat with a broad brim.
Sunglasses hide everything in shadow, and to overcome that (in all cases except when indoors or at night) a human would need either or both of – a torch, a video camera with screen. The torch is needed for lighting locally, and the video camera would carry near-infrared ability and contrast-reducing software to allow seeing further away in shadow.
mollwollfumble said:
> Gravity – high and low.I still find it remarkable that the gravities to be found on the surface of Solar System planets are so close to constant. For example, the surface gravity of Saturn is indistinguishable from that of Earth, only 6% different. The surface gravity of Uranus is identical to that of Venus and only 10% less than that of Earth.
It used to be that astronauts would quickly suffer from bone mass loss to the point of severe risk to life in zero gravity. But space medicine has now advanced to the point where some astronauts returning from the ISS after a year or more in space even have more bone mass than when they left Earth. So low gravity is not a problem any more.
For high gravity, I’m going to quote some old science fiction, “First Lensman” by E.E.Smith, written 1950.
“A lot of the adults died, 3 Gs is no joke, practically all of the babies keep on living. … They say that the third generation will be perfectly at home there.”
Perhaps I can be more precise than that.
0 to 0.1 G – hand over hand
0.1 G to 1.5 G – normal walking
1.5 G to 2.5 G – walking frame
2.5 G to 3.5 G – off-road vehicle
3.5 G to 4.5 G – add 1 G to human capability by using a G suit
4 to 6 G – a sitting untrained human without a G suit may black out
10 G – fighter pilots during aerobatics
17 G – has been endured without difficulty for a long period of time lying down
25 G to 46 G – endured in a rocket sled test, 25 G for 1.1 seconds with a peak of 46 G
45 G and above – endured many times by Paul Stapp, but eventually led to permanent eye damage
70 G – an average car crash
75 G – an impact to the head that may be fatal
100s of G – a slap to the face, no difficulty as a transient force
178 G – estimated to have been survived by David Purley in a motor racing crash
300 G – according to Snell, humans can survive a brief head impact of that magnitude, debatable
People survive in Frankston and Redfern and Baghdad and such…
mollwollfumble said:
mollwollfumble said:
> Gravity – high and low.I still find it remarkable that the gravities to be found on the surface of Solar System planets are so close to constant. For example, the surface gravity of Saturn is indistinguishable from that of Earth, only 6% different. The surface gravity of Uranus is identical to that of Venus and only 10% less than that of Earth.
It used to be that astronauts would quickly suffer from bone mass loss to the point of severe risk to life in zero gravity. But space medicine has now advanced to the point where some astronauts returning from the ISS after a year or more in space even have more bone mass than when they left Earth. So low gravity is not a problem any more.
For high gravity, I’m going to quote some old science fiction, “First Lensman” by E.E.Smith, written 1950.
“A lot of the adults died, 3 Gs is no joke, practically all of the babies keep on living. … They say that the third generation will be perfectly at home there.”
Perhaps I can be more precise than that.
0 to 0.1 G – hand over hand
0.1 G to 1.5 G – normal walking
1.5 G to 2.5 G – walking frame
2.5 G to 3.5 G – off-road vehicle
3.5 G to 4.5 G – add 1 G to human capability by using a G suit
4 to 6 G – a sitting untrained human without a G suit may black out
10 G – fighter pilots during aerobatics
17 G – has been endured without difficulty for a long period of time lying down
25 G to 46 G – endured in a rocket sled test, 25 G for 1.1 seconds with a peak of 46 G
45 G and above – endured many times by Paul Stapp, but eventually led to permanent eye damage
70 G – an average car crash
75 G – an impact to the head that may be fatal
100s of G – a slap to the face, no difficulty as a transient force
178 G – estimated to have been survived by David Purley in a motor racing crash
300 G – according to Snell, humans can survive a brief head impact of that magnitude, debatable
53 G – a head punch by an elite boxer
> Extreme Weather
E.E.(Doc) Smith has in the Lensman series a planet with the most extreme weather that I’ve ever seen in SciFi.
Judged by any earthly standards the planet Trenco is a peculiar one indeed. Its atmosphere, which is not air, and its liquid, which is not water, are its two outstanding peculiarities and the sources of most of its others. Almost half of that atmosphere and by far the greater part of the liquid phase of the planet is a substance of extremely low latent heat of vaporization, with a boiling-point such that during the daytime it is a vapor and at night a liquid. To make matters worse, the other constituents of Trenco’s gaseous envelope are of very feeble blanketing power, low specific heat, and of high permeability, so that its days are intensely hot and its nights are bitterly cold.
At night, therefore, it rains. Words are entirely inadequate to describe to anyone who has never been there just how it does rain during Trenco’s nights. Upon Earth one inch of rainfall in an hour is a terrific downpour. Upon Trenco that amount of precipitation would scarcely be considered a mist; for along the equatorial belt, in less than thirteen Tellurian hours, it rains exactly forty-seven feet and five inches every night—no more no less, each and every night of every year.
Also there is lightning. Not in Terra’s occasional flashes, but in one continuous, blinding glare which makes night as we know it unknown there, in nerve-wracking, battering, sense-destroying discharges which also make it impenetrable to any communication signal.
Because of the difference in pressure set up by the enormous precipitation, always and everywhere upon Trenco there is wind—and what a wind! Except at the very poles, there is hardly a spot in which or a time at which an Earthly gale would not be considered a dead calm; and along the equator, at every sunrise and at every sunset, the wind blows from the day side to the night side at the rate of well over eight hundred miles an hour.
The above quote is from the book “Galactic Patrol” but Trenco as a working environment for humans is described in the earlier book “First Lensman”. To overcome the wind when it is “scarcely more than an Earthly hurricane” and “highly variable in direction”, men would be tethered to a winch and “space line” and only stop work then the line hummed under the tension. No spaceport on Trenco could be built to withstand the strongest wind so it was allowed to blow around the planet under the wind’s influence.
Missed it! With all the talk about about harsh environments, we’ve missed the harshest of all.
I’ve been taking about deadly environments.
The harshest environments are those that aren’t deadly, they’re those that make you wish you were dead. EE Smith has two.
mollwollfumble said:
Missed it! With all the talk about about harsh environments, we’ve missed the harshest of all.
I’ve been taking about deadly environments.
The harshest environments are those that aren’t deadly, they’re those that make you wish you were dead. EE Smith has two.
scrub itch.
It was thinking is the hardest part about surviving on another planet/moon actually getting there and once there our current existing technology can keep you alive.
Cymek said:
It was thinking is the hardest part about surviving on another planet/moon actually getting there and once there our current existing technology can keep you alive.
Sort of. There’s always a question of the ratio of how much survival equipment can be carried there vs how much survival equipment can be manufactured at the destination. The Mars Direct project gives the best possible ratio IMHO. See: https://en.wikipedia.org/?title=Mars_Direct#First_launch
roughbarked said:
itch.
Humans can’t completely protect themselves from sound while mobile. This is what a harsh environment dominated by noise might be like.
“The door banged shut with a clangor which burst through space-suit and ear-plugs with all the violence of a nearby thunderclap. And that was merely the beginning. The engine started—an internal-combustion engine of well over a thousand horsepower, designed for maximum efficiency by engineers in whose lexicon there were no counterparts of any English words relating to noise, or even to sound. The car took off; with an acceleration which drove the Tellurian backward, deep into the cushions. The scream of tortured tires and the crescendo bellowing of the engine combined to form an uproar which, amplified by and reverberating within the resonant shell of metal … it’s the ungodly noise, I expected it and protected myself as best I could
“a craneman dropped a couple of tons of steel plate, from a height of eight or ten feet, upon the floor directly behind him. “I just about jumped right out of my armor,” is the way Samms himself described his reactions; and that description is perhaps as good as any. At any rate, he went briefly out of control”.
——
A harsher environment than that? What about a torture chamber?, think of the full range of different types of torture. That’s about the harshest environment that any human could survive in.