Without resupply, how long can humans live in space?

[neilsox]

One year is likely as this has been done in nuclear submarines. Ten years, perhaps, if we have start with 100 tons, each, of oxygen and water, so we can replace contaminated air and water, when the recycle equipment is no longer able to remove some of the trace contaminants. Ten tons of food will feed 2 people, one kilogram per day for 5000 days, more if we can recycle the fiber from their poop. I'm thinking mostly freeze dried food. Fresh frozen at -39 f = -39 c is likely practical for 50 years, but we are talking, perhaps 1000 tons with the deep freeze equipment, and the energy source, assuming we we will be too far from the sun to use photovoltaic panels. We may need 100 tons of replacement parts to keep vital systems working for 50 years, lots more to keep non-essential systems operating. What else do we need and are my estimates reasonable? Neil

 

[csmyth3025]

It mostly depends on how much "stuff" your willing to send into space with them using multiple launch vehicles - which loosely translates to how much money you're willing to spend.

A good CELSS (Controled Ecological Life Support System) would be very helpful - but that also adds mass (and spare parts). There's a breakpoint at which the mass of a completely closed-loop life support system is less than taking multiple tons of expendables with you. I dont know where that point is, though. First we have to actually make such a system. As far as I know, that hasn't been done yet (except, perhaps, on paper).

Chris

 

[bdewoody]

Like Chris said it depends on how big a vessel you are willing to build. But as you increase mass you also increase the need for fuel which in turn increases mass again. So the two factors are; how much food, water and air do you take and how fast do you want to travel. Allowing for the fact that however fast you end up going after you have coasted most of the way to your destination you must expend the same amount of fuel to slow down.

 

[ZenGalacticore]

Don't confuse mass with size.

The planet Saturn would float in water.*

Therefore, with super-strong but super-light materials, we could build very large spacecraft with very small mass.

*Think of it this way: When the Sun goes red giant in 5 billion years, the outer atmosphere of the Sun will probably encompass the Earth's orbit; but while the Sun will be bigger, it will not be any more massive. Most of the same mass will merely be expanded. In fact, it will be larger while being a bit less massive.

 

[csmyth3025]

Don't confuse mass with size.

The planet Saturn would float in water.*

Therefore, with super-strong but super-light materials, we could build very large spacecraft with very small mass.

Methinks woody already knows whereof thou speaketh. He's probably applying that age-old (John Wayne) river ferry captain's maxim: "If ya wanna take all that stuff with ya, Pilgrim, yer gonna hafta hire yerself a bigger boat."

Chances are that we'll try to build our big spaceships out of the same super-strong but super-light materials that we use to build our small spaceships. Once we fill our bigger spaceship up with all the stuff we can fit in it, it's sure to have more mass than the smaller spaceship. Of course many years from now that may change when we start using our small spaceships to haul gold ingots from planet to planet.

Chris

 

[Rmachandran]

In the Space maximum we can live for 48 Hrs. The Space has no earth quality and it is tough that the vessel you travel has all the chemical content in the room you live that is equal to earth. Earth has the magntic force that is absent in space. These Electromagnetic force alone can give you natural feed such as proteins, Fertile your body etc which is absent in space. The vein in human body will smash once it is compressed by vacuum in space, and first the human in space will fell in coma in 24 hours and the body will stay for 24 hrs and reduce to ashes slowly.

 

[adrenalynn]

Umm... no, no, and please seek help.

 

[bdewoody]

Don't confuse mass with size.

The planet Saturn would float in water.*

Therefore, with super-strong but super-light materials, we could build very large spacecraft with very small mass.

Methinks woody already knows whereof thou speaketh. He's probably applying that age-old (John Wayne) river ferry captain's maxim: "If ya wanna take all that stuff with ya, Pilgrim, yer gonna hafta hire yerself a bigger boat."

Chances are that we'll try to build our big spaceships out of the same super-strong but super-light materials that we use to build our small spaceships. Once we fill our bigger spaceship up with all the stuff we can fit in it, it's sure to have more mass than the smaller spaceship. Of course many years from now that may change when we start using our small spaceships to haul gold ingots from planet to planet.

Chris

Thank you, Of course I was inferring that the increase in mass would be due to what cargo, fuel and food the voyagers would be carrying.

 

[EarthlingX]

This is an old NASA image, enough self-descriptive, i hope :

I think numbers are per day.


There might be some answers here too :

http://www.esa.int : ESA Education

http://www.nasa.gov : NASA Education


This is the closest on-line thing i found :

http://www.esa.int : Living off the land
...

There is a better, cheaper way to do things. Most of the 30 kg daily allowance consists of oxygen, either in the form of air for breathing or locked into water molecules. Very conveniently, the lunar regolith - the loose, powdery 'soil' that covers the surface of the Moon - is about 45% oxygen.

...

Rather detailed :
Advanced Life Support Requirements (pdf)

 

[dryson]

Resupply is not the main importance in keeping humans alive in space. Humans evolved within a specific gravitational environment called Earth. Once human's are removed from this environment the gravitational effect that keeps the body going diminishes as does the effects upon the body which would eventually cause death. In order to survive in space for a very long time a gravitational system must be employed to keep the human body system's going. A pressurized suit that the astronaughts wear during EVA activities would not help as the circulation system is not kept in a regular rythmic state. In order to survive in space for very long humans would need a device that would offer the same amount of resistance that gravity does on Earth to force the systems of the body to operate the same way that they do on Earth.

 

[neilsox]

Dryson is likely correct that optimum health requires approximately 1 g, but we are quite adaptable, so likely life expectancy is reduced by only about 10% in 1/6 g instead of one g. The quality of life is likely bad, and returning to one g after ten or more years likely makes the quality worse. I'm guessing as the tests have not been done yet. With present technology, we can tether two spacecraft together with a kilometer of tether; Spinning them about each other produces 1/6 g with minimal coriolis. Higher gravity with high reliability, likely requires better tether technology. Neil

 

[csmyth3025]

...With present technology, we can tether two spacecraft together with a kilometer of tether; Spinning them about each other produces 1/6 g with minimal coriolis. Higher gravity with high reliability, likely requires better tether technology. Neil

Based on your scenario and the formula: rpm= (9.81 m/s * g * 900)/(r * pi^2) where g=the decimal fraction of Earth gravity and rpm= revolutions per minute, the assembly you propose will require a rate of rotation of about 1.1 rpm to achieve 1/6 Earth gravity.

It's generally believed that most people can adjust to a rotation of 2 rpm without any problems due to the Coriolis effect on the inner ear. If you were to use this rate of rotation, you would only need a tether about 300 meters long to achieve a pseudo-gravity of 1/6 Earth gravity. A tether about 450 meters long would give you 1-g at 2 rpm.

As far as I know, there's no evidence to indicate that long term exposure to 1/6 Earth gravity will reduce one's life expectancy by 10%. As you said...you're just guessing.

Chris

 

[eburacum45]

Absolutely. Living in 1/6 gee might actually increase lifespan, as the heart doesn't need to pump so hard, and older people could lift their own weight more easily. The main problem with zero gravity is bone-density loss, but low gravity is not zero gravity, so bone density problems could be considerably reduced even in lunar gravity. No-one has experienced low gravity for more than a few days at a stretch, and they experienced no particular problems (as far as I can determine).