Loss of vision in space

[katateochi]

I just saw an article on one of the (many) problems of lengthy space flight; It appears that prolonged periods in micro gravity environments causes a build up of cerebrospinal fluid (CSF) which as well as having a potential for brain damage, also causes damage to eye sight.  Astronauts who've spent extended periods on the ISS have reported significant reduction in their visual acuity, in the context of long term space flight (ie to Mars) this could become a really serious problem. 
Here's the article http://www.sciencealert.com/we-finally-know-why-astronauts-lose-their-vision-in-space-and-it-s-bad-news-for-mars-missions

Two thoughts came to mind; 
1) Couldn't they put astronauts in a centrifuge (basically gently spin them with their heads at the pivoting point) to simulate the forces that would naturally drain CSF away from the brain?
2) perhaps this is why Kerbals have such large heads? Maybe a physiological adaptation to their space faring lifestyle! 
 

[Tullius]

13 minutes ago, katateochi said:

Couldn't they put astronauts in a centrifuge (basically gently spin them with their heads at the pivoting point) to simulate the forces that would naturally drain CSF away from the brain?

A problem with artificial gravity by using a centrifuge is the difference in "gravity" between your head and your feet. With the head at the pivot, i.e. at 0g, and your feet at 1g, does this really help or will it create other problems?

And if you build your centrifuge large enough that that effect becomes negligible, you need a pretty big spacecraft. The idea to create the centrifuge by tethering the last rocket stage to your spacecraft and spinning the whole thing up is not some random stupid idea, but actually the most sensible and feasible idea to construct a centrifuge sufficiently large to not suffer from the above effect.

[Green Baron]

The centrifuge would have to be large enough so that the difference between head and toe is not that big. Otherwise forces would cause the one to constantly swat the other or himself. Imagine you start with an arm movement in 0g and end in 1g outwards plus acceleration towards the movement of the centrifuge .... stuff for very hilarious scenes :-)

Good ting these discussions come up now. Radiation, nutrition, low g, ..... many problems need solutions.

Edited November 30, 2016 by Green Baron

[Elthy]

What i didnt understand: Was the effect permanent or did it reverse after return to 1g?

[James Kerman]

Quote

'Irreversible' damage

The results showed that long-duration astronauts had significantly greater post-flight increases in the volume of CSF within the bony cavity of the skull that holds the eye, and also in the volume of CSF in the cavities of the brain where the fluid is produced.

The sample size is small, and the results have not yet appeared in a peer-reviewed journal. But Prof Alperin says the research points to a "primary and direct role of the CSF in the globe deformations seen in astronauts with visual impairment syndrome".

"If the ocular structural deformations are not identified early, astronauts could suffer irreversible damage," he said, "as the eye globe becomes more flattened, the astronauts become hyperopic, or far-sighted."

Prof Alperin has received a $600,000 grant from Nasa to study the condition.

He outlined the findings at the annual meeting of the Radiological Society of North America (RSNA) in Chicago.

http://www.bbc.com/news/science-environment-38132481
https://www.nasa.gov/hrp/bodyinspace

[Elthy]

From the linked article in the OP:

Quote

causing untreatable nearsightedness that lingers for months even after they’ve returned to Earth.

That reads like its not forever...

[linkxsc]

Heres my question. We have 2 datapoints on this. 1g and 0g. For earth and space stations repsectively.

Is this still a problem at .3g or .1g? 

Everyone loves their centrifuges big, but do we really need 1g to counteract this problem? Or could we manage with just .1g, to mitigate the problem completly... wouldnt help with the bone and muscle problems, but we have workout regemins for that.

All i see is more reason for a long term moon base for testing.

Edited November 30, 2016 by linkxsc

[kerbiloid]

Centrifuge Accommodations Module was cancelled, nobody knows

[Ten Key]

Nearsightedness and farsightedness are not exactly life threatening conditions these days.

[justidutch]

1 hour ago, Ten Key said:

Nearsightedness and farsightedness are not exactly life threatening conditions these days.

Perhaps not, but a "build up of cerebrospinal fluid" … "within the bony cavity of the skull that holds the eye, and also in the volume of CSF in the cavities of the brain where the fluid is produced" does not exactly sound overly desirous to me.

 

Where they should really be doing extensive research, though, is in the excessive flatulence experienced by those travelling in space 

[Gkirmathal]

20 hours ago, Green Baron said:

The centrifuge would have to be large enough so that the difference between head and toe is not that big. Otherwise forces would cause the one to constantly swat the other or himself. Imagine you start with an arm movement in 0g and end in 1g outwards plus acceleration towards the movement of the centrifuge .... stuff for very hilarious scenes :-)

Good ting these discussions come up now. Radiation, nutrition, low g, ..... many problems need solutions.

Not necessarily, if you'd have a smaller radius + higher RPM centrifuge which is only used as sleeping module (laying down) between 8h x 8h shifts. Then it could be done IMO.

But I have no idea if the effect of 8hx8h; micro gravity vs centrifugal gravity, would be be enough to offset the detrimental effects of a full micro gravity voyage. Might be enough to keep the body healthy, or it might be that we need longer duration's in a centrifugal gravity environment, it also might be we need exposure 100% of the flight.

Who knows...no space agency ever tested this on in LEO for any duration which would give good statistical results.

[Wjolcz]

3 hours ago, Gkirmathal said:

Not necessarily, if you'd have a smaller radius + higher RPM centrifuge which is only used as sleeping module (laying down) between 8h x 8h shifts. Then it could be done IMO.

But I have no idea if the effect of 8hx8h; micro gravity vs centrifugal gravity, would be be enough to offset the detrimental effects of a full micro gravity voyage. Might be enough to keep the body healthy, or it might be that we need longer duration's in a centrifugal gravity environment, it also might be we need exposure 100% of the flight.

Who knows...no space agency ever tested this on in LEO for any duration which would give good statistical results.

I was actually thinking about it. Wouldn't a simple cylinder (not necessarily big enough to have ~1G feeling in the whole body when standing up) work well when spun during the "night time"? The astronauts would simply lay down (maybe with their head slightly higher than their feet to stimulate the heart) during the sleep and everything would probably be fine.

I mean, there obviously are people in space industry who thought about this, but it seems pretty logical. 1G is 1G, doesn't matter if you stand or lay down, right?

Edited December 1, 2016 by Veeltch

[Ten Key]

46 minutes ago, Veeltch said:

I mean, there obviously are people in space industry who thought about this, but it seems pretty logical. 1G is 1G, doesn't matter if you stand or lay down, right?

Actually, it does. Both NASA and the ESA use prolonged periods of bed rest as experimental stand ins for long duration spaceflight.

http://www.esa.int/Our_Activities/Human_Spaceflight/Bedrest_studies/New_bedrest_adventure_adds_artificial_gravity

[kerbiloid]

I would guess that the night-only gravity is not an option.
The first problem of 0-G is that the blood lifts from the legs and pours into head and chest, while on the Earth gravity pulls it down.
Awaken people are mostly vertical, while the sleeping ones are horizontal. So, the artificial gravity must be from head to feet.

The same with bones. Sleeping doesn't make bones to enforce. Only vertical pose in head-feet gradient.

[Wjolcz]

2 hours ago, Ten Key said:

Actually, it does. Both NASA and the ESA use prolonged periods of bed rest as experimental stand ins for long duration spaceflight.

http://www.esa.int/Our_Activities/Human_Spaceflight/Bedrest_studies/New_bedrest_adventure_adds_artificial_gravity

That seems different though. They are tilted head-down to spread the blood pressure evenly around the body (and make the head swell) to simulate 0G environment.

If you start rotating the cylinder-shaped spacecraft and keep the feet lower than the head when laying down then the whole body experiences 1G and the pressure is higher in the lower body which would make the heart perform more work to pump the blood, thus keeping it in a healthy state.

It probably wouldn't fix the muscle and bone mass loss problem, but still better than nothing. Maybe it could even prevent the build up of the cerebrospinal fluid?