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The syndrome impairing astronauts’ eyesight

washingtonpost.com

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Re: The syndrome impairing astronauts’ eyesight

#31

Post by akiselev »

nxzero wrote: post #24
jerf wrote: post #14

Earlier quoted context omitted.

It gets complicated, and the mass budget starts going up fast, if you want other things to be able to dock to it. Two space stations on the opposite side of a long rope (per the other reply) is also not a very compelling story to tell to Congress when you have to admit that astronauts won't be able to travel between those two space stations to speak of, unless, again, you really up the mass budget. We're space-poor.…

What about grabbing mass from the surface of the moon, junk that's floating around, etc.? Seems like this might be cheaper than getting it off Earth, right?

Except then you'd need to launch a full blown transport, mining, and manufacturing facility from Earth and assemble it just like the space station. I wouldn't be surprised if such a ship is heavier than the station you're trying to build, even if you strip out life support because the gear necessary to make silicon chips or machine hard metals is massive and numerous.

Re: The syndrome impairing astronauts’ eyesight

#32

Post by vixen99 »

PhantomGremlin wrote: post #3
andrewtbham wrote: post #2

It will not prevent travel to Mars. It's effects can likely be countered. Perhaps by artificial gravity. https://en.wikipedia.org/wiki/Artificial_gravity

Not everyone is ready to admit it yet, but IMO there is no long term future for us in space without something like artificial gravity. I remember back in the 1970s one of the Skylab astronauts came to my college to give a talk. I had read about some problems, so I asked him about the effects of prolonged weightlessness. He was very dismissive, he vehemently denied that there could be any problems at all. As they say,…

'no long term future for us in space without something like artificial gravity.' and without an answer to the radiation problem.

http://www.wired.com/2014/04/radiation-risk-iss-mars/

Re: The syndrome impairing astronauts’ eyesight

#33

Post by rbanffy »

imaginenore wrote: post #21
wolf550e wrote: post #9

Earlier quoted context omitted.

Yes, Zubrin has been advocating for this since 1990. https://www.youtube.com/watch?v=3UChuIqIKF4&t=1722 His explanation about the real situation with NASA and why the human spaceflight program has not accomplished anything is extremely disheartening. https://www.youtube.com/watch?v=3UChuIqIKF4&t=417

The real problem is you need to deliver so much material to orbit to create artificial gravity (a rotating space station) it's very expensive. We could create a simple rotating system with two pods connected by a long cable, but then it's not easy to dock to it, and there are balancing issues.

> you need to deliver so much material to orbit

Not that much. You'll need an inflatable module (so the wide part can still fit in the cargo fairing of an SLS) and a carousel that can be assembled inside it to rotate and give the crew enough gravity to counteract the effects of the zero-g environment. You'll need power to keep it rotating and radiators to get rid of the heat.

The unfortunate thing is that this cannot be tested attached to the ISS as the vibration would ruin the micro-gravity environment crucial for many experiments there.

Re: The syndrome impairing astronauts’ eyesight

#34

Post by rbanffy »

JoeAltmaier wrote: post #28
nxzero wrote: post #23

Earlier quoted context omitted.

If it was possible to build a gravity sleep chamber, it's very possible that exposing the human body to gravity and zero-gravity on a daily basis would be put more, not less stress on a body than zero-gravity alone.

That's just a random guess. We already lay down for 8 hours and stand up for 16. My random guess is, our fluids would recover with at least some artificial acceleration and why not when sleeping?

If you intend to replicate the effects of standing, you'd need to sleep standing.

Re: The syndrome impairing astronauts’ eyesight

#35

Post by doikor »

jerf wrote: post #14
hoorayimhelping wrote: post #12

Earlier quoted context omitted.

> The tricky bit is being able to launch enough mass to build something safe and comfortable to spin; Is it? I might have a completely busted mental model, but I thought you only need a module-sized mass on one end of a rod the length of things we've already assembled in space (e.g. an ISS truss) and a motor to spin it.

It gets complicated, and the mass budget starts going up fast, if you want other things to be able to dock to it. Two space stations on the opposite side of a long rope (per the other reply) is also not a very compelling story to tell to Congress when you have to admit that astronauts won't be able to travel between those two space stations to speak of, unless, again, you really up the mass budget. We're space-poor.…

At first we don't want 2 space stations spinning. We want 2 space crafts spinning and traveling to somewhere where we have enough gravity to survive (mars). All humans on one ship and cargo/return counter weight as other ship linked together by a tether and spinning for the travel duration.

But yeah we still need to lower the launch cost per kg to make it really feasible and super heavy launch vehicles which don't exist at all at the moment. Realistically we would want to launch 40+ tons directly to mars from earth (Falcon Heavy should be ~13 tons so we would need around 3x the power of that). We don't have anything with enough delta v to do that at the moment.

Re: The syndrome impairing astronauts’ eyesight

#36

Post by sarreph »

andrewtbham wrote: post #2

It will not prevent travel to Mars. It's effects can likely be countered. Perhaps by artificial gravity. https://en.wikipedia.org/wiki/Artificial_gravity

It may not prevent travel to Mars (for example, on a centrifugal space station), but considering gravity on Mars is 62% lower than here on Earth, I would postulate without some kind of gravity manipulation we are yet to develop (unless we have the energy to build centrifugal colonies on land) then manned missions on Mars would suffer a similar fate.

Re: The syndrome impairing astronauts’ eyesight

#37

Post by mtreis86 »

wizardhat wrote: post #26

Studies going as far back as the 80s show that people in submarines develop myopia: http://www.ncbi.nlm.nih.gov/pubmed/7457562 The leading theory is that being in a confined space causes the eye to adapt to viewing things up close rather than at a distance.

Anecdote: I saw an article about Native Americans, using a technique of quickly focusing from near to far and back as a means to increase their eyesight range, when I was around twelve years old. Called Eagle Eyes, or something. I have been practicing regularly for eighteen years now, and my eyesight has only improved. I have been looking at computers and books at least a third of my time since. Am I actively preventing myopia? Interesting.

Re: The syndrome impairing astronauts’ eyesight

#38

Post by jerf »

thaumasiotes wrote: post #15
jerf wrote: post #8

Earlier quoted context omitted.

Artificial gravity is easy. You "just" spin things. The tricky bit is being able to launch enough mass to build something safe and comfortable to spin; there's a limit to how small you can make your spinning habitat before the difference between "centrifugal force" and gravity is too pronounced for our long term comfort. That's part of why making it cheaper to launch per unit mass is so important. If we could put ten…

> there's a limit to how small you can make your spinning habitat before the difference between "centrifugal force" and gravity is too pronounced for our long term comfort There is no such difference. The constraint you probably have in mind is that you want the force of gravity at your head to be the same as the force of gravity at your feet. This is a problem with actual gravity too; see https://en.wikipedia.org/wi…

No, the vestibular system gets "annoyed", which is to say, permanently motion sick, if you spin something too small. Our vestibular system is not designed to deal with Coriolis force. You have to keep it below a certain threshold or you'd rather not spin at all... which is, in some sense, exactly why we don't spin the ISS, or, rather, designed something ISS-sized to spin. It's too small. You need a certain size in the rotation axis.

If the solution was just to spin our tin cans the problem would be solved.

Re: The syndrome impairing astronauts’ eyesight

#39

Post by jerf »

thaumasiotes wrote: post #16
jerf wrote: post #14

Earlier quoted context omitted.

It gets complicated, and the mass budget starts going up fast, if you want other things to be able to dock to it. Two space stations on the opposite side of a long rope (per the other reply) is also not a very compelling story to tell to Congress when you have to admit that astronauts won't be able to travel between those two space stations to speak of, unless, again, you really up the mass budget. We're space-poor.…

> Two space stations on the opposite side of a long rope (per the other reply) is also not a very compelling story to tell to Congress when you have to admit that astronauts won't be able to travel between those two space stations to speak of I don't get the complaint. Assuming travel from one station to the other is impossible, what's supposed to be wrong with having two smaller stations that don't cripple the healt…

Congress won't fund two stations.

Again, the problem isn't physics or engineering, it's that we're poor in space. This, and a lot of the other posts, are basically saying "What's so hard about having a job 10 miles away? Just drive there!" to people too poor to own a car, too poor to even dream of owning a car. Yes, it is a simple problem... if space wasn't so expensive to us. (I mean, not trivial, we'd still have to redesign a lot of stuff, but there's no reason to believe there's a fundamental problem.)

Re: The syndrome impairing astronauts’ eyesight

#40

Post by jerf »

ams6110 wrote: post #17
jerf wrote: post #8

Earlier quoted context omitted.

Artificial gravity is easy. You "just" spin things. The tricky bit is being able to launch enough mass to build something safe and comfortable to spin; there's a limit to how small you can make your spinning habitat before the difference between "centrifugal force" and gravity is too pronounced for our long term comfort. That's part of why making it cheaper to launch per unit mass is so important. If we could put ten…

Now all your space vehicles need to be able to hold together under 1G of force. That means a lot more structure and mass and the cost goes way up.

I didn't spec 1G of force. Though, as I, ahem, already said, I do suspect we'll need closer to .5G than .05G. But while it's not quite as evil as the rocket equation, you do get non-linear advantages as you go down the gravity scale. .5 is already much less than half as hard as 1G, and we could perhaps get away with .25.

Here we have a chicken and egg problem; how can we launch the variable-speed lab we really need to figure out how much gravity we need if we can't afford the 1G lab in the first place? Because proper science suggests we ought to be able to test the full range up to 1G. I'm spitballing .5 or .25, but scientifically speaking there's no guarantee the optimal won't be .8, 1.0, or, conceivably, even 1.1 or 1.2G. (Sure, the latter is unlikely, but I can't scientifically rule it out a priori.)

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