see space odissey......
A manned trip to Mars could end up blinding its astronauts suggests research by the American Academy of Ophthalmology. The report says that long amounts of time spent in space damages astronauts' eyes. It puts another obstacle in the way of manned Mars missions, which would be a three-year round trip requiring rocket power …
see space odissey......
see Star Trek....
you mean a rotating system it has to have a considerable radius otherwise the force acting at head level is considerably different to foot level and can't be compensated for so blood pools in the legs.
Does require an even bigger craft and thus even bigger rocket. It does seem to be a simple problem compared to shielding against cosmic rays and the like.
Or even space odyssey . . .
A much smaller radius sleeping section would help an awful lot; it only needs to have a large enough radius to ensure that astronauts can sleep in it without tidal forces in their inner ears reminding them that the room really is spinning.
Doesn't make it much less of an engineering problem though.
Send two craft tethered to each other by a long cable. Put the show into a gentle spin and - voila - instant artificial gravity in both.
What rate of spin (I have a feeling that even moon gravity would be a lot faster than "gentle"). How will spinning affect other systems? Will steering/manoeuvring this thing be more difficult?
Space engineering is hard.
that would be likely to disorient you even more than micro gravity due to the continuous rotation.
if you think back to the old gravitron fairground rides which used centrifugal force to hold you to the outer wall of the ride they were doing exactly what you suggest here, you became disoriented within a minute or so because you could still feel the effects of normal gravity working at differing angles to the artificial gravity being produced by centrifugal force.
in space that feeling may take longer to appear due to smaller amounts of gravity being present.
another downside of having something spinning is that it would make course changes very harsh on anything inside it while also increasing the complexity of making a course change due to gyroscopic effects (from memory a force exerted on something spinning will have its direction changed by 90 degrees if it spinning fast enough and will induce a very nasty wobble if it is not spinning fast enough)
I think you'd need a hub at the centre as well, for the communications dish that needs to stay pointed at Earth. That dish would have to be moved to the side when you re-join the three sections for orbital manouvering. There would be some weight penalty for the cable, and some fuel cost in generating and then shedding the angular momentum each time you re-join the modules into one.
I doubt any of these is more than an engineering challenge, especially if the G-force needed for keeping astronauts healthy is significantly less than 1G.
The biggest problem would be what to do in a solar storm. A rotating capsule would make it impossible to use the rest of the supplies between the atronauts and the sun as shielding. They could re-join into a single craft and orient it pointed at the sun with the crew quarters in the shadow - but there's that fuel cost every time you have to do it.
You've just doubled the cost of the mission. But then, who's counting? If we wanted "cost-effective" we'd have sent a robot.
Prediction: The US will eventually send a manned mission to Mars, because some jackass politician will eventually decide his dick isn't big enough. However, by then some media organisation will be able to fund robot probes to deliver "exclusive live coverage" of every part of the trip, including having a camera on the ground at the landing site when the door swings open for the first time. Thus, NASA's finest hour (as it will surely be called) will be turned into a demonstration of why robots are better than people for space exploration (or indeed deep-sea diving or any other hazardous environment). Oh, and it will also have a *really* intrusive advert spashed across the screen at the crucial moment.
I have always wondered why they have not created a craft with a slow spin to create some gravity.
But then again I am not a top scientific boffin so there may be other reasons this is not a plausible option!
Any boffinry types out there able to elaborate?
It's a question of priorities, the 'merkins went to the moon on 1/2 of 1 percent of their GDP, while at the same time they were spending nearly 7% of their GDP making Vietnam look like the moon.
Ohhh look, a picture from Vietnam
"What rate of spin (I have a feeling that even moon gravity would be a lot faster than "gentle"). How will spinning affect other systems? Will steering/manoeuvring this thing be more difficult?
Space engineering is hard."
I don't see why. I mean it's hardly rocket science is it.........
For given and strictly limited values of "Cost Effective".
Centripetal acceleration: a = (v*v) / r
√(ra) = v
For an acceleration of 10 m/s/s (Earth normal!), 100m tether: v = 22.4 m/s
314m circumference, so that's a rotation rate of 0.07 revs per sec.
So 4 rpm for Earth-normal centripetal gravity.
If we can build that multinational modular hodge-podge up there, we should also be in a position to build a proper space station and/or spaceship which has a spinning habitable section.
In fact, in the case of the spaceship you might as well spin the whole thing. It is not like it will need docking/undocking operations before the end of the flight. Even if it does, spinning up something along its axis to sync to another spinning object is not a particularly difficult engineering problem.
Even that may not be necessary. You can have the docking apparatus be able to separate from the main ship body via one more dock/airlock to the spinning section. You undock at that junction to accept an incoming ship, slow down the docking bay relative to the main body, stop, dock to the incoming ship, spin up together with the docked ship (shifting some ballast to stabilize as needed - just put fuel and water reserves there), equalize rotation and dock back.
That solution was envisioned as early as Von Brown and Tciolkovski. Is it me being thick and having too much coffee in my blood system. Or am I missing something?
What happened to spinning the spacecraft to generate artificial gravity?
If the lack of gravity is the main culprit then any manned mission would have to have a rotating section to keep the astronauts' feet on the ground.
Why do you say the rocketry currently beyond our capability?
With the right political will, humanity could have put people on Mars in the 1980s.
Read Zubrin's "The Case for Mars". It's all there
send them to specsavers
as an aside the invisible man would also be blind, since light would pass through his transparent retinas
Or more simply, design the ship as a short stubby can and spin the entire thing on it's axis, it's going to have to be built in space anyway.
So it looks like whatever ship is built for the task needs some way to generate even a minimal amount of gravity-like force.
Or spin the whole thing round when out of Earth's gravity.
Long lonely periods in spaceaway from your wife might also be a contributory factor? :)
"I'm sorry Dave, I can't do that. Its not in my programming."
In that situation I'd really want artifical gravity - imagine having the erm... end result floating around the space ship.
Hand covering eye icon, because... well. 'nuff said.
that for safety reasons, there must be an assistant and it is critically important they swallow?
Perhaps a rotating section of the spacecraft could solve this problem. I know that simulating gravity without causing motion sickness needs a very large diameter (100m) wheel but if the crew only used it when lying down, it should be possible to use a much smaller size.
Various tests have been done to simulate the effects of zero G on the body by having volunteers stay in bed for hundreds of days. I don't remember reading anything about it causing eye trouble.
So maybe sleeping in a low gravity chamber could help reduce the build up of pressure from spinal fluid.
Gravity is still Earth normal not zero G
Before we found out about increased risk of blindness/vision problems, a well-known side effect of zero G enviornments was the atrophying of muscle (including the heart) and bone tissue. That's why you always see those shots of astronauts strapped down to a treadmill so they can run to keep up some of their muscles so they won't fall over the instant they get back to Earth.
So even if being a couch potato all the way to Mars and back would help with the vision loss (which I don't think it would), it would only exaggerate the muscle and bone loss. So you would come back to Earth needing years of physical therapy and probably have shaved a few years off your life from the deterioration of your heart muscle.
Isn't it also possible that 6 months in a box where you never need to look further than about 10 feet in front of you might have an effect on eye muscles as well?
If little Johnny doesnt stop it, he will go blind.
I can't imagine NASA designing an interplanetary spaceship without this feature. It's such an obvious solution to the known problems caused by long periods of free-fall.
Design the ship such that it can spin around its major axis while on its journey, with the living compartments close to the sides. The astronauts thus get a simulation of gravity that should be good enough to prevent physical degeneration during the journey, with only a very short period of free-fall when the ship flips 180º to begin its deceleration.
Spinning the ship on its axis might be a solution, but it is one that needs to be tested. This is because unless you get the design right the occupants can get nauseous .. see "Artificial Gravity and the Architecture of Orbital Habitats" by Theodore W. Hall.
The basic conclusion is that big radius, low RPM=good (for example, one study said that the comfort zone was achieved by 1rpm and 100m radius). The point is made that all our research habitats in space have been designed to test the effects of zero G. There haven't been any studies in space on the use of spinning habitats.
Basically .. most of the spinning ships envisaged in books and films have had too narrow a radius. The 2001 space station probably had it right, but this wasn't going anywhere. And I bet passengers were puking up as the shuttle spun up to enter the station.
of small radii generating a MUCH greater differential force head to foot so that blood pools in the lower limbs.
I would have expected NASA to construct the manned section of the vessel as a toroid or cylinderand rotate the section such that the centripital force approximates 1g.
Is it just me or wasn't this approach WIDELY publicised in 2001: A Space Odyssey?
Surely NASA could come up with something that would create a facsimile of gravity. I know it's not a proper hi-tech sexy sci-fi solution but I think most people would spend an hour a day on a hamster wheel if they knew it'd stop them going blind.
- 3 year trip
- long periods of boredom
- no wives/girlfriends on board
I can think of another self-inflicted activity which might account for the blindness...
The crew may start out with no significant others on board, but eventually...
...so NASA might opt instead to start with a crew who are already in stable relationships.
Either that they fall out with each-other, as couples sometimes do.
Or worse, suppose a bit of action were to occur… and 9 months later the crew numbers increment by one?
I feel sorry for the poor squirt when he/she gets back to Earth.
"And where were you born Suzie?"
Girl points to the ceiling and announces "On a space ship!"
(in the back room) "He he he… alien! Suzie's an alien!"
I thought Clarke had this problem solved way back in 2001.
"especially spinal fluid – rising to the head and putting pressure on the brain and eyes"
Just curious but how can this be the cause? If they are weightless (and even in LEO they are just that) there is no up or down so how can fluid "rise" anywhere?
The systems in the human body were designed for a 1g acceleration/gravity influence at all times, pulling fluids towards the feet. If there is no such influence on the body, as in microgravity, the fluids pool in the head since the compensation mechanisms are fighting nothing.
We, human beings, are made to stand up. So we evolved in a way that our body pumps everything UP, to counterbalance the gravity.
Remove gravity and the upper part of our body has to deal with a rise in pressure (no gravity to help here) of all the fluids. I can only imagine that our tiny little blood vessels that irrigate the eye get no so happy about it... :D
Better solution. Put a nuclear rocket engine in orbit, fly to Mars in about a month, less if it happens to be in a favourable position at a time. This also helps reduce the risks from radiation, micro-meteorites and various random failures as a result of equipment decaying over time.
Actually, put 2 nuclear rocket engines in orbit, so that if the first suffers a failure while it's idling in Mars orbit, the second can come to the rescue. Use SpaceX's cheap rocket lift capability to put the required parts and the manpower needed to build it in orbit and you can probably have one for the same cost as the planned return to the moon.
If you can do the trip in 1 month, you are accelerating for 2 weeks, and decelerating two weeks. So there is little or no zero-g.
One proposal I've read of is for the astronauts on the first Mars mission to orbit without landing. I can't see the point. What can they do that an unmanned orbiter can't do?
Well, the obvious solution is to make the crew mixed-sex, isn't it? Will also solve the problem of tools slipping out of hairy palms and creating a health hazard...
Why not? It's not like the rest of us need to see *through* their eyes. Systems could easily be adapted to make the journey practical.The only argument I can see against this is that it would draw attention to the utter futility of a manned martian mission in the first place.
"utter futility of a manned martian mission in the first place."
Why bother debating about an unrelated biological issue, if we don't yet have the technology to propel the spaceship?
How do we know the technological advances that would solve the propulsion problem won't also help solve the other problems too?
just include a guitarist in the crew
everything revolves around them
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