 |
 | Home | Contact Us | FAQ | Search & Site Map | Link to Us |
 | Sign In | Join | Other 45 Sites in Network |
| HomeDiscussion GroupsSpace ScienceAstronomyAmateur AstronomySpace FlightSpace StationShuttleSpace HistorySpace PolicySETI SpaceKB.com Contact UsLink To UsSearch & Site Map |
Space Forum / Space Flight / August 2003artificial gravity a different idea...maybe?
Hi Folks Just joined the group for the purposes of posting an idea. I have been doing a little reading today about artificial gravity and haven't seen magnetism mentioned at all. This may sound stupid but couldn't the floor of a spacecraft be magnetized and the crew wear suits that would be attracted to that floor? It would be more practical in a spacestation, which runs on photovoltaic, cause the electro magnetic floor would be a drain on electricity. Please let me know what you think. > I have been doing a little reading today about artificial gravity and > haven't seen magnetism mentioned at all. This may sound stupid but > couldn't the floor of a spacecraft be magnetized and the crew wear suits > that would be attracted to that floor? Notwithstanding the issue that strong magnetic fields tend to interfere with the proper operation of electrical equipment, there is the fundamental issue that magnetism only affects magnetic materials, whereas the primary characteristic of gravity and inertia is that both of them affect =ALL= forms of matter equally. Furthermore it is not the magnetic _FIELD_ that generates force on an object, but the magnetic field _GRADIENT_: ferromagnetic materials are attracted to a magnet because the field strength _INCREASES_ as one gets closer to the magnet, so that moving them closer to the magnet increases the magnetic field energy stored in the ferromagnetic object and the perturbation it makes in the surrounding field. If you put a chunk of iron in a perfectly UNIFORM magnetic field, it would feel no =NET= force at all --- it would merely feel a torque that would align it with the field, and even that only if it was asymmetrical. Hence, for your proposal to work, one would have to generate a constant magnetic field _GRADIENT_ of `X' tesla per meter throughout the volume of the crew space, i.e., it would need to be strongest at the floor, and linearly decrease with distance from the floor. Also, the so-called "magnetic lines of force" will appear to be diverging outward from some point or line source below the floor. This creates a number of problems: 1.) Maxwell's equations plus practical materials considerations impose physical limits on how large a volume over which one can produce a uniform magnetic field gradient. 2.) Since most healthy humans tend to be non-spherical, their magnetic suits will tend to align their bodies along the magnetic field lines --- which as I said, will appear to be DIVERGING from some point or line below the floor. This will mean the floors will have to be sharply curved unless their is a very strong uniform background field imposed along with the uniform field gradient. 3.) Unless all their tools are non-magnetic, they will attempt to align themselves along the magnetic field lines. Imagine trying to use a wrench or screwdriver that is constantly trying to twist itself out of your hand and line up perpendicular to the local magnetic field. 4.) Ferromagnetic materials are highly nonlinear; hence, if you put two chunks of iron in a magnetic field, their induced magnetic moments will cause them to exert complicated and difficult to predict forces on each other if you get them close together. Likewise for two humans wearing ferromagnetic suits. > It would be more practical in a spacestation, which runs on photovoltaic, > cause the electro magnetic floor would be a drain on electricity. I don't think you realize just how LITTLE power the solar panels on the space station will put out. The =TOTAL= power capability of the ISS is only 110 kilowatts, or roughly a mere 150 horsepower --- about the equivalent of three or four automobiles running flat out. The power requirements for your scheme would be ENORMOUS unless the magnets are superconducting --- and even them, the cost would be large, since it costs a LOT of power to keep a superconductor cold enough to superconduct (cryogenic refrigerators consume tens or even HUNDREDS of watts of power for every watt of heat they pull out of the cryostat!). In summary, their are multiple reasons why this idea would be both impractical and undesirable over the entire volume of a space station. It =MIGHT= perhaps be possible in a very small "exercise room" is a space station with MUCH more power to spare than the ISS, but I do not see that happening any time soon. -- Gordon D. Pusch perl -e '$_ = "gdpusch\@NO.xnet.SPAM.com\n"; s/NO\.//; s/SPAM\.//; print;' > Hi Folks > Just joined the group for the purposes of posting an idea. [quoted text clipped - 8 lines] > > Please let me know what you think. You would just need permenant magnets embedded in the boots. The real reason for artificial gravity is that there are serious health consequences to living in a zero-gee environment for any length of time. Plus, it helps keep your stuff sorted. Karl Hallowell khallow@hotmail.com > You would just need permenant magnets embedded in the boots. The real > reason for artificial gravity is that there are serious health [quoted text clipped - 3 lines] > Karl Hallowell > khallow@hotmail.com The health consequences could be avoided by putting a load on the body, for example using bunge cords to pull the shoulders to the feet. This is similar to the treadmill they have that they run on. To really reproduce gravity and to perfectly match earth conditions you need a spinning habitat. This can be cheaply and easily done I don't know why this is an issue at all. The ship has to have a cylindrical habitat and this cylinder has to spin. The people on the inside surface can enjoy almost real gravity. Zoltan > The health consequences could be avoided by putting a load on the > body, for example using bunge cords to pull the shoulders to the feet. > This is similar to the treadmill they have that they run on. This won't put a load on your circulatory system though. I don't know how much of a problem that would be if bone loss is somehow avoided. > To really reproduce gravity and to perfectly match earth conditions > you need a spinning habitat. This can be cheaply and easily done I > don't know why this is an issue at all. The ship has to have a > cylindrical habitat and this cylinder has to spin. The people on the > inside surface can enjoy almost real gravity. It doesn't even have to be a cylinder rotating on its axis. It could be two sections linked with a bridge, spinning end over end. This would give you a wider "radius", meaning lower rotation and less coriolis effects. However, it'd kind of screw up low-gravity research, and would make less efficient use of available space, and require more material to be launched. You could just put living areas in a separate rotating section, but that's a lot more complex. With current technology, the two parts would probably have to be physically separate. Experiments would have to be done by remote (which could largely be done from ground), or the astronauts would "commute". A better solution: two complete stations, one with rotation gravity, one exclusively for low-g experiments. Crew would rotate between them periodically, say every two weeks. Pretty far-fetched, considering how we are doing with just one station. This reminds me of a book I read...I think it was Imperial Earth. Part of it covered a trip from Titan to Earth. As I recall, the ship was under constant acceleration, but not enough to prevent bone loss, and the main character had to build up endurance so he could function on Earth. The ship featured a ring around its circumference, and a common exercise was to run or ride a bicycle around this ring. One would start out slow, with "up" being the direction the ship was accelerating, but as one gained speed, apparent gravity would increase and point outward, perpendicular to the axis of the ring.  SignatureChristopher James Huff <cjameshuff@earthlink.net> http://home.earthlink.net/~cjameshuff/ POV-Ray TAG: chris.huff@tag.povray.org http://tag.povray.org/ >> You would just need permenant magnets embedded in the boots. The real >> reason for artificial gravity is that there are serious health [quoted text clipped - 6 lines] > The health consequences could be avoided by putting a load on the > body, for example using bunge cords to pull the shoulders to the feet. Are you sure about this? Have there been any studies on these lines? I could certainly see this helping with skeletal issues, but is the skeleton the only thing that dislikes long-term zero-gee ? Lex >>> You would just need permenant magnets embedded in the boots. The real >>> reason for artificial gravity is that there are serious health [quoted text clipped - 10 lines] >I could certainly see this helping with skeletal issues, but is the >skeleton the only thing that dislikes long-term zero-gee ? The entire human body doesn't like long term zero g. Christopher +++++++++++++++++++++++++ "Kites rise highest against the wind - not with it." Winston Churchill >>> You would just need permenant magnets embedded in the boots. The real >>> reason for artificial gravity is that there are serious health [quoted text clipped - 12 lines] > > Lex I seem to recall seeing an article where a test animal subjected to rapid vibration (!) reported had less bone density loss than normal 0g effects... Cheers, Richard > To really reproduce gravity and to perfectly match earth conditions > you need a spinning habitat. This can be cheaply and easily done I > don't know why this is an issue at all. The ship has to have a > cylindrical habitat and this cylinder has to spin. The people on the > inside surface can enjoy almost real gravity. Possibly the little detail that the "cylindrical surface" needs to be about a =MILE= in diameter to get the rotation rate down below 1 rpm @ 1 gee, since if it rotates faster than 1 rpm, the majority of human beings tested upchuck. (Even at 1rpm, a significant fraction of the people tested upchuck; you need to get the rotation rate down to about 0.25 rpm in order for the general population to not upchuck.) -- Gordon D. Pusch perl -e '$_ = "gdpusch\@NO.xnet.SPAM.com\n"; s/NO\.//; s/SPAM\.//; print;' > Possibly the little detail that the "cylindrical surface" needs to be > about a =MILE= in diameter to get the rotation rate down below 1 rpm @ 1 gee, > since if it rotates faster than 1 rpm, the majority of human beings tested > upchuck. (Even at 1rpm, a significant fraction of the people tested upchuck; > you need to get the rotation rate down to about 0.25 rpm in order for the > general population to not upchuck.) The best bit about this post is the knowledge that, in the future, there will be dozens of bright young engineering students taking their "Orbital Habitats Design" classes, and sitting dozing whilst someone sketches various torii and explains the social importance of the "vomit coefficient". :-) Of course, .25rpm would mean you'd have to bring the torus out to, what, 2 miles? Makes it an even less enticing prospect... Signature-Andrew Gray shimgray@bigfoot.com >> Possibly the little detail that the "cylindrical surface" needs to be >> about a =MILE= in diameter to get the rotation rate down below 1 rpm @ 1 >> gee, since if it rotates faster than 1 rpm, the majority of human beings >> tested upchuck. (Even at 1rpm, a significant fraction of the people tested >> upchuck; you need to get the rotation rate down to about 0.25 rpm in order >> for the general population to not upchuck.) >The best bit about this post is the knowledge that, in the future, there >will be dozens of bright young engineering students taking their >"Orbital Habitats Design" classes, and sitting dozing whilst someone >sketches various torii and explains the social importance of the "vomit >coefficient". >:-) >Of course, .25rpm would mean you'd have to bring the torus out to, what, >2 miles? Makes it an even less enticing prospect... But 2 miles of wire is cheap. -ash for assistance dial MYCROFTXXX > ... the "cylindrical surface" needs to be > about a =MILE= in diameter to get the rotation rate down below 1 rpm @ 1 gee, > since if it rotates faster than 1 rpm, the majority of human beings tested > upchuck. (Even at 1rpm, a significant fraction of the people tested upchuck; > you need to get the rotation rate down to about 0.25 rpm in order for the > general population to not upchuck.) Umm, no, it's not =THAT= bad. Many studies put the upper range of "comfort" at 3 or 4 rpm. Some put it as high as 6 rpm. The most useful summary I've found -- one of the few that discusses "comfort" as something other than an on/off switch -- is from Ashton Graybiel, based on extensive research in ground-based centrifuges and rotating rooms: "In brief, at 1.0 rpm even highly susceptible subjects were symptom-free, or nearly so. At 3.0 rpm subjects experienced symptoms but were not significantly handicapped. At 5.4 rpm, only subjects with low susceptibility performed well and by the second day were almost free from symptoms. At 10 rpm, however, adaptation presented a challenging but interesting problem. Even pilots without a history of air sickness did not fully adapt in a period of twelve days. Graybiel, Ashton (1977). "Some Physiological Effects of Alternation Between Zero Gravity and One Gravity." _Space Manufacturing Facilities (Space Colonies): Proceedings of the Princeton / AIAA / NASA Conference, May 7-9, 1975_, pages 137-149. Edited by Jerry Grey. American Institute of Aeronautics and Astronautics. SignatureTed Hall >> ... the "cylindrical surface" needs to be about a =MILE= in diameter >> to get the rotation rate down below 1 rpm @ 1 gee, since if it rotates [quoted text clipped - 5 lines] > Umm, no, it's not =THAT= bad. Many studies put the upper range of "comfort" > at 3 or 4 rpm. Some put it as high as 6 rpm. Even a 50 meter radius is =NOT= what one would call a "small" cylindrical section! -- Gordon D. Pusch perl -e '$_ = "gdpusch\@NO.xnet.SPAM.com\n"; s/NO\.//; s/SPAM\.//; print;' > Possibly the little detail that the "cylindrical surface" needs to > be about a =MILE= in diameter to get the rotation rate down below 1 [quoted text clipped - 3 lines] > down to about 0.25 rpm in order for the general population to not > upchuck.) How much up can an upchuck chuck when an upchuck does chuck up? Enquiring minds want to know. > -- Gordon D. Pusch RRS > The health consequences could be avoided by putting a load on the > body, for example using bunge cords to pull the shoulders to the feet. > This is similar to the treadmill they have that they run on. Yes, and it has not been effective against bone loss. The load isn't enough in either intensity or duration. It has been suggested that shorter, more intense, strength-training exercises might be more effective for maintaining bone structure -- more effective than the lengthy aerobic workouts on treadmills and rowing machines that they do now. On the other hand, they need the aerobic exercise to maintain their cardiovascular systems. SignatureTed Hall > The real reason for artificial gravity is that there are serious > health consequences to living in a zero-gee environment for > any length of time. What are these health consequences? What is the g threshold or range over which they occur? What are the timescales over which they occur? (I'm thinking of it in terms of possible asteroid colonies, or where asteroid industrial facilities would require a number of resident technicians etc.) >> The real reason for artificial gravity is that there are serious >> health consequences to living in a zero-gee environment for >> any length of time. > > What are these health consequences? Loss of muscle mass and reduction of bone density among other effects. <http://astrobiology.arc.nasa.gov/news/expandnews.cfm?id=988> > What is the g threshold or range over which they occur? No-one knows. Nobody has ever lived at 0.5G. There may not be a threshold, it may be a proportional effect. There have never been animal experiments in the range between 0 and 1G simply because we don't have a centrifuge (yet) in orbit. > What are the timescales over which they occur? (I'm thinking of it > in terms of possible asteroid colonies, or where asteroid industrial > facilities would require a number of resident technicians etc.) Zero G is not a problem for short durations, say a week or two. Beyond that it becomes an increasing problem. As you can see from reports about the condition of astronauts returning after extended stays in zero G, they need a few weeks to recover to the point where they function normally again. Regaining the original bone density takes much longer (years). SignatureManfred Bartz > Zero G is not a problem for short durations, say a week or two. > Beyond that it becomes an increasing problem. As you can see from > reports about the condition of astronauts returning after extended > stays in zero G, they need a few weeks to recover to the point where > they function normally again. Regaining the original bone density > takes much longer (years). What I've been wondering for some time now: A person constantly living in zero G, would he suffer any illness from that loss of bone mass etc.? Imagine a space habitat where people are born, live and die. I think they would need some kind of training to make sure they can perform other things than pressing a button now and then (which we on earth get a minimum of by just walking around), but would there be a need for this massive training done i.e. on the ISS? Or, pushing this further: A child being born and growing up in 0g. Would it just adopt to this conditions and feel fine, although probably unable to withstand 1g at all? OK, probably nobody knows about that... ;-) Jochem Signature"A designer knows he has arrived at perfection not when there is no longer anything to add, but when there is no longer anything to take away." - Antoine de Saint-Exupery > > The real reason for artificial gravity is that there are serious > > health consequences to living in a zero-gee environment for > > any length of time. > > What are these health consequences? Loss of bone and muscle density (the bone density loss is the real nasty one, think osteoporosis). > What is the g threshold or range over > which they occur? We don't know. All we know is that they don't happen at 1 g and they do happen in micro-g. What happens in the range in between is just speculation. > What are the timescales over which they occur? Duration of only a few weeks don't seem to cause major problems, several months seems to be where things start getting bad,. Currently we haven't studied durations longer than about a year, but indications are that it just keeps getting worse (bone loss continues). >(I'm > thinking of it in terms of possible asteroid colonies, or where asteroid > industrial facilities would require a number of resident technicians etc.) The problem doesn't seem to be so much being able to live, but in transitioning back to 1 g, where strong bones and muscles are needed. If you live most of your life in zero-g, indications seem to be that you'd be just fine. >> What are these health consequences? > [quoted text clipped - 7 lines] > and they do happen in micro-g. What happens in the range in > between is just speculation. As far as I know this is not a direct consequence of zero-g (or micro-g) but a consequence of missing that load on bones and muscles our body is evolutionary optimized for. One could imagine that a person living in micro-g but doing really hard work with frequent heavy loads on bones and muscles would do quite well. And the other way round, people in 1g just laying in bed for months *do* suffer loss of bone and muscle density quite similar to those in zero-g. Jochem Signature"A designer knows he has arrived at perfection not when there is no longer anything to add, but when there is no longer anything to take away." - Antoine de Saint-Exupery > > We don't know. All we know is that they don't happen at 1 g > > and they do happen in micro-g. What happens in the range in [quoted text clipped - 7 lines] > just laying in bed for months *do* suffer loss of bone and muscle > density quite similar to those in zero-g. Yes, it is all about the absence of load on bones and muscles, and that causes atrophy in both. The real problem is that excercise does not seem to be able to completely counteract these effects. Astronauts who have been in orbit for the better part of a year or longer than a year usually spend a lot of time excercising (many hours per day). I don't know all the specifics but I believe that while excercise does help, even exercising a lot nearly every waking hour does not completely counteract the effects. Also, I believe that the bone and muscle loss in zero-g is quite a bit faster than for bed ridden individuals. Compared to zero-g, ordinary movement in 1 g is like continuous, low impact excercise. Every time you lift your arm up you're using your muscles and bones to lift the weight of your arm against gravity, and that's a lot more excercise than pushing around the mass of your arm in zero-g. > The real reason for artificial gravity is that there are serious > health consequences to living in a zero-gee environment for > any length of time. > What are these health consequences? What is the g threshold or range over > which they occur? What are the timescales over which they occur? Here's a summary: http://www0.arch.cuhk.edu.hk/~hall/ag/Dissertation/2_1.htm SignatureTed Hall > > The real reason for artificial gravity is that there are serious > > health consequences to living in a zero-gee environment for [quoted text clipped - 6 lines] > > http://www0.arch.cuhk.edu.hk/~hall/ag/Dissertation/2_1.htm For long-term settlements in space, we must also be concerned about the effects of microgravity on foetal develeopment. From http://www.health.xq23.com/stem_cells/Primordial_germ_cells.html "1: J Exp Zool 2002 Jun 1;292(7):672-6 Influence of simulated microgravity on avian primordial germ cell migration and reproductive capacity. Li Z, Song Y, Ma Y, Wei H, Liu C, Huang J, Wang N, Sha J, Sakurai F. Department of Biochemistry and Molecular Biology, China Agricultural University, Beijing 100094, China. Fertilized eggs of chicken and quail were incubated under the simulated microgravity condition provided by a clinostat. The number of Primordial Germ Cells (PGCs) was counted in early embryogenesis, and the reproductive capacity of quail hatched following the simulated microgravity was investigated.Simulated microgravity caused significant decline of PGCs in the blood of early chicken embryos and in the gonads. The numbers of spermatogonia in the hatchling testis were also fewer than those in the control groups. Therefore, simulated microgravity may retard gonadial development and reduce the reproductive capacity. J. Exp. Zool. 292:672-676, 2002. Copyright 2002 Wiley-Liss, Inc." I suggest that an experiment be performed in low-Earth orbit: deploy 3 identical automated packages, each containing freshly fertilized bird eggs. The packages are deployed as an assembly, linked by tethers. The spinning assembly separates, putting each package at a different radius. One set of eggs develops at 0.17 gee (Lunar gravity), one at 0.38 gee (Martian gravity), and one at 0.55 gee. Return the hatched chicks to Earth and check their development. > I have been doing a little reading today about artificial gravity and > haven't seen magnetism mentioned at all. This may sound stupid but couldn't [quoted text clipped - 3 lines] > It would be more practical in a spacestation, which runs on photovoltaic, > cause the electro magnetic floor would be a drain on electricity. You could do that a lot cheaper with velcro. The point of artificial gravity is not that it makes it easier to get around (actually, it makes it harder) but that it prevents adverse health effects of zero-g, such as bone loss and muscle loss. > Hi Folks > Just joined the group for the purposes of posting an idea. [quoted text clipped - 8 lines] > > Please let me know what you think. Unfortunately, this only solves part of the problem. Velcro has been suggested (and used?) to make one's feet adhere to a surface. However, this doesn't prevent calcium loss in bones or make toilets flush any better. Best regards, Len (Cormier) PanAero, Inc. and Third Millennium Aerospace, Inc. len@tour2space.com ( http://www.tour2space.com ) > Unfortunately, this only solves part of the problem. > Velcro has been suggested (and used?) to make one's > feet adhere to a surface. However, this doesn't > prevent calcium loss in bones or make toilets flush > any better. If velcro DID make toilets work or flush any better, I'd be worried. "Johnson.." schrieb: > the floor of a spacecraft be magnetized and the crew wear suits that would > be attracted to that floor? > It would be more practical in a spacestation, which runs on photovoltaic, > cause the electro magnetic floor would be a drain on electricity. > Please let me know what you think. Hallo May be you need a powerful magnetic field to hold a person on the ground. So the problem is: should the person be able to lift his feet? Also the design of today spacecraft uses all walls for equipment. Perhaps you include a little switch inside the shoes, so when the leg is lifted, the switch will turn off the magnetic field in the shoe. But as I think, some astronauts love it to fly from one corner to the other, of course, I will enjoy that. This can be more interesting for bigger spacecrafts, not so big that you get an effect when parts are rotate. But, what will happen outside the spacecraft, when you have a megnetic field running. Would this act like a particel collector? This will bombard your hull and can cause heavy damage. So you can construct a magnetic field around the space ship, that operate like such a collector, then maybe some micro meteorits collapsed inside this field and lose their energy there. Possible to lower the cosmic rays this way? lin free fall basket ball > Hi Folks > Just joined the group for the purposes of posting an idea. [quoted text clipped - 8 lines] > > Please let me know what you think. |
Reply to this Message |
 Sign In
 Join
 My Latest Posts My Monitored Threads My Blog My Photo Gallery My Profile My Homepage Start New Thread Enable EMail Alerts Rate this Thread
|
©2009 Advenet LLC Privacy Policy - Terms of Use
This website includes both content owned or controlled by Advenet as well as content owned or controlled by third parties.