And yet, we cant stay away from it.
Astronauts on board the ISS help scientists learn about theeffects spaceflight has on the human body.
Spoiler alert: theyre not great.
How long can the human body endure the harsh space environment?NASA
A human mission to Mars would take roughly three years, according toNASA.
But what would that kind of journeyand even longer durations in spacedo to the human body?
How long could a person endure life during a deep-space voyage?
And in the worst-case scenario, what would happen if someone were stranded indefinitely on the ISS?
Heres what they had to say.
The simple answer: it depends.
How long can this be extended?
In this case, people could survive in space for quite a long time.
Without countermeasures such as exercise, their time would be leisurely and enjoyable.
Their only goal would be to enjoy the experience, which could be quite pleasant.
If outside the relative safety of low-Earth orbit, deep-space radiation might have substantial effects.
Some of these effects would be cumulative: an increasing risk of cancer with increasing time in space.
In parallel with these issues is the little-understood impact of weightlessness on the distribution of fluids in the body.
These might be harbingers of actual neural damage from extended time in space.
If others onboard are available to assist, these people might survive for a long time.
But to what end?
These are among the major risks of which we are aware.
There will likely be others that arise as people spend longer times in space.
This is a challenge.
If they go with work to be done and the intention of returning to Earth, the answer changes.
Even with the current best exercise and nutrition countermeasures, radiation and isolation will take their toll.
With little supporting evidence, I would place this limit at about four years.
With artificial gravity it may be much longer.
In this case the limitations may be predominantly due to psychology and radiation.
The surface of Mars is about one-third of deep space due to Mars body and atmosphere.
So one way to answer is to ask how much risk a person is willing to accept?
If unlimited risk is acceptable then the answer has to do with probabilities of occurrence of the various diseases.
Radiation causes DNA damage and creates radicals due to ionizations in tissue leading to increased oxidative stress.
These are precursor changes to various health diseases.
Late effects take some time to appear dependent on which bang out.
This shows that a person can remain in space for over 1.2 years.
Could someone stay longer?
However, the health risks become increasingly severe.
Lets consider a 1,000-day mission to Mars, which would be the expected duration with our current technology.
In microgravity, muscles and bones weaken due to the lack of regular weight-bearing activity.
Even more concerning is the radiation exposure.
Vision problems because of fluid shifts in microgravity may persist even after returning to Earth.
The altered immune system response during long-duration missions also raises concerns about fighting off infections or handling medical emergencies.
Missions longer than this would push the limits of human endurance.
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