# space station with artificial gravity, can it be done cheap?

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#### jurgens

##### Guest
ok dude, im going to give you a more thorough response as to why it wouldn't work. I couldn't before because I was studying for my finals. Also, wait for the picture to load first.<br /><br />Ok first of all, excuse me for the crude drawings, im not too good with ms paint. Secondly, ok what you have is the station rotating. The station has a tangential velocity of V, and requires a centripetal acceleration of a. Lets say you want to have 1/3g at the rim, then your a = 1/3g or, v = sqrt(r/3g). Now, let's say you want to "dock" the shuttle on the outer rim of the station. First of all, the shuttle will require a velocity equal to v relative to the station in order to match it's speed. Secondly, and this is the part that requires WAY TOO MUCH FUEL, is that the shuttle will be required to have an acceleration in the direction of the station equal to a. That means, the shuttle will have to be constantly thrusting in order to stay motionless relative to the station. Now, getting the shuttle to have a constant acceleration of 1/3g takes too much fuel. That's your number one problem.<br /><br />Secondly, say you could do that, say you have some really cool propulsion system that uses very little fuel and can give you a constant 1/3g acceleration. Now you're problem is that you need to catch the shuttle. You need something to grab it's "wheels"(I say "wheels" because they could easily be something designed just for docking) So now you have grabbed it's docking mechanism and you are pulling in the shuttle to attach to the outer rim... Well say you get it on, and let's say this shuttle weighs about 30,000kg... You'r outer support structure would be required to support F = ma, F = 30,000 * g/3 = 98kN. You would need to support 98kN of weight! Now these stations usually don't have very strong outer surfaces, so you'r docking mechanism woud just be ripped off and the shuttle would be flung out away from the station. Not to mention each time that would happen, the a

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#### jurgens

##### Guest
oops, I forgot to add the picture

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#### ve7rkt

##### Guest
<font color="yellow">The way the 2001 docking system was made, all you have to do is align yourself with the front of the station, provide a small amount of thrust to get yourself rotating at the same speed as the station, and just go forward. Not to mention, who says you can't have more then one ship docked on the station??? You can easily have a very large amount of ships docked to a station of that design.</font><br /><br />Well, I say so, because if the docking port isn't on the station's axis, you can't do step one, align yourself with the docking port, because the docking port is always moving and always changing direction.<br /><br />If the hub counterrotates, you can festoon it with docking ports wall to wall in every direction and have whatever you want docked to each one. If the hub rotates along with the station, no matter how large the hub is, there will only be two points where you can dock, and those will be on the axis, in line with the axis.<br /><br />Please tell me how I'm wrong, it's the only way I'll learn. <img src="/images/icons/smile.gif" />

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#### jurgens

##### Guest
>Well, I say so, because if the docking port isn't on the station's axis, you can't do step one, align yourself with the docking port, because the docking port is always moving and always changing direction. <<br /><br />Have you not watched 2001 a space odyessey?<br /><br />Yes the station is rotating, but so would the incoming ship. All that you have to do is match the angular velocity of the station. Not to mention, you can park you ship anywhere inside of it... All you have to do is get it in there first.

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#### holmec

##### Guest
Hey, check out this article on a new study on this subject:<br />http://www.space.com/businesstechnology/050518_tech_wednesday.html<br /><br />They are studying periodic exposure to aritficial gravity in the course of a day for astronauts on long voyages. Finally!<br /><br /> <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

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#### holmec

##### Guest
I thought there was a miscommuication. Here is what I mean:<br /><br />I'm having trouble loading a pic. <br /><br />put your ship inside the wheel and turn it around. It lands on the inside of the wheel, it starts at 0 velocity, goes down then as the wheels make contact friction accelerates the ship to the speed of the station in rotational velocity.<br /> <br />You can use nubers if you want, but it would have to be a really big station for this to work. So the real question is wheather such a large station is feasable, and it probably isnt.<br /><br /> <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

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#### holmec

##### Guest
trying again <br /><br />This way the ship is not upside down. From the perspective of a person on the station. <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

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#### jurgens

##### Guest
you have the same exact problem, not a good idea... Ill explain later though, I have an astronomy final to study for.

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#### frodo1008

##### Guest
jurgenS: Wow! I didn't think of that, but you are correct. Even if you could only have one ship leave and one ship land at the opposite ends of the hub, it would NOT mean that you could not have more ships docked within the hub. After all, large airports that have hundreds of aircraft only have several runways.<br /><br />Now, this might require hubs that were somewhat large, but the hub areas are the lowest gravity areas of a spin stabilized partial gravity station. Therefore, construction of a large hub area would be the least challenging part of building such a station (at least from the structural strength perspective. There is nothing stating how long such a hub has to be along its axis. It could be as wide as at least the width of one of the largest ships you would expect to dock with the station, and as it would be circular it would need to be big enough to have two such docked ships pass one another (probably on top of each other, remember minimum gravity in this volume). Then you could make this hub as long as you want to accommodate as many docked ships, as you would need for the size of the station!! There would be no need to even try to dock on the rim of the station, which at best would be very difficult.<br /><br />At any rate I would think that the first of such stations would not be any larger than it would take to have moon level gravity at 2 rpm. Or even higher gravity, say Mars level at higher rpm. NASA has done research that shows that (at least as far as trained astronauts go) the adverse affects of the spin itself are not even apparent at as high as 6 rpm. So relatively higher spinning stations (which would be considerably smaller than slow spinning stations) could be built. Such smaller stations would not need to be docked to by any more than two spacecraft at the same time to take care of such station’s needs.<br /><br />As space tourism gains momentum then larger stations designed for a greater number of ordinary people would have to

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#### frodo1008

##### Guest
stutch: In both my earlier post and jurgenS post the entire station would indeed rotate. The docking facilities would directly lead to the spokes running out to the various different rims (at different distances to facilitate having different gravities on the same station). In a rotating space station the spokes to the rims really ARE the tethers, just that they would also allow direct access to the rim portions and would be much stronger that just pure tethers.

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#### ve7rkt

##### Guest
<font color="yellow">Have you not watched 2001 a space odyessey?</font><br /><br />Yes. I loved the Station V scene. Hated almost everything else about the movie (blasphemy, I know), but I loved the part that's important for this discussion. <img src="/images/icons/smile.gif" /><br /><br />It was a long time ago, though, so I'll state what I remember, and PLEASE correct me if I'm wrong: the Orion shuttle lines itself up with the station's axis, rotates at the same speed as the station, enters the rectangular slot docking bay... and then we cut scene to the hotel, so we don't actually see the docking itself.<br /><br /><font color="yellow">Yes the station is rotating, but so would the incoming ship.</font><br /><br />Of course. If the incoming ship didn't rotate at the same speed as the station, the docking port would be twisted and ripped off as soon as it touched, like pulling the cap off a beer bottle. Complete with fizzy foam, except it's from your lungs.<br /><br /><font color="yellow">All that you have to do is match the angular velocity of the station.</font><br /><br />That's the problem. If the docking port is off-center, so far as I can tell, you CAN'T match it. It will be rotating, and you can match that rotation, but it will also be revolving, moving in a circle around the station's center, and you can't match that.<br /><br /><font color="yellow">Not to mention, you can park you ship anywhere inside of it... All you have to do is get it in there first.</font><br /><br />Now that's an idea, and maybe a good one: the ship enters along the axis, gets grabbed by something like the crane-harness-thing that lifts the Shuttle orbiter, and pulled off to the side where it's positioned onto a docking port or The Hangar Airlock To End All Airlocks (tm) or something; reverse the process to depart.

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#### mental_avenger

##### Guest
<font color="yellow"> Problem is, if the hub is rotating along with the rest of the station, any docking port not actually on the axis is moving in a circle around the axis. </font><br /><br />Depending on the size of the wheel, the station will be spinning very slowly, perhaps only ½ revolution per minute. In a relatively small diameter hub, the lateral displacement would not be very large. It sould be a simple matter for an incoming ship to park in the center of the hub, rotate to match the rotation of the station, and then be captured by docking clamps to one of several docking stations.<br /> <div class="Discussion_UserSignature"> <p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="2" color="#ff0000"><strong>Our Solar System must be passing through a Non Sequitur area of space.</strong></font></p> </div>

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#### mental_avenger

##### Guest
<font color="yellow"> The big problem with 2001 docking, is that it only allowed for one vehicle. My idea allows for an airport like operation. </font><br /><br />And what sort of traffic do you expect? Remember, we are talking about lift-offs from Earth, and returns to Earth. It will be a long time before we exceed the 1-2 hours needed to clear a single ship from the dock.<br /> <div class="Discussion_UserSignature"> <p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="2" color="#ff0000"><strong>Our Solar System must be passing through a Non Sequitur area of space.</strong></font></p> </div>

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#### holmec

##### Guest
>Ok first of all, excuse me for the crude drawings, im not too good with ms paint. Secondly, ok what you have is the station rotating. The station has a tangential velocity of V, and requires a centripetal acceleration of a. Lets say you want to have 1/3g at the rim, then your a = 1/3g or, v = sqrt(r/3g). Now, let's say you want to "dock" the shuttle on the outer rim of the station. First of all, the shuttle will require a velocity equal to v relative to the station in order to match it's speed. Secondly, and this is the part that requires WAY TOO MUCH FUEL, is that the shuttle will be required to have an acceleration in the direction of the station equal to a. That means, the shuttle will have to be constantly thrusting in order to stay motionless relative to the station. Now, getting the shuttle to have a constant acceleration of 1/3g takes too much fuel. That's your number one problem.<br /><br />Secondly, say you could do that, say you have some really cool propulsion system that uses very little fuel and can give you a constant 1/3g acceleration. Now you're problem is that you need to catch the shuttle. You need something to grab it's "wheels"(I say "wheels" because they could easily be something designed just for docking) So now you have grabbed it's docking mechanism and you are pulling in the shuttle to attach to the outer rim... Well say you get it on, and let's say this shuttle weighs about 30,000kg... You'r outer support structure would be required to support F = ma, F = 30,000 * g/3 = 98kN. You would need to support 98kN of weight! Now these stations usually don't have very strong outer surfaces, so you'r docking mechanism woud just be ripped off and the shuttle would be flung out away from the station. Not to mention each time that would happen, the angular momentum of the station would change quite a bit which would screw things up. <<br /><br />1/3g??? Who can live in that? You may very well need 1g or higher for the body.<br /><br />Ok, no station l <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

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#### holmec

##### Guest
If you have more than one station, or have colonies on moon and mars, you have traffic that increases with time as more and more humans live off Earth. <div class="Discussion_UserSignature"> <p> </p><p><font color="#0000ff"><em>"SCE to AUX" - John Aaron, curiosity pays off</em></font></p> </div>

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#### frodo1008

##### Guest
holmek: In the first place I surely hope that people can get used to 1/3 g ( or even 1/6 g) as these are the respective gravities of Mars and the moon. Most people on these threads seem to want humanity to eventually learn to colonize and exploit the moon and Mars. Heck, most people would want humanity to eventuall be able to live and work on the moons of the outer planets, and none of these even approach a size large enough for Earth normal gravity (1.0 g). The very idea of having a spinning space station with partial gravities is to do research on long term habitation at the gravities of the moon and Mars. There may indeed be health issues, but hopefully these can be overcome. However, without such stations research into human habitation on these important bodies for long times will be impossible (unless of course, we can come up with some method of negatine the affect of gravity, but I think this would a far future item if ever).<br /><br />Initially, spinning stations would be built from the central core outward. During this phase of construction docking would have to be at the central core itself. However, as the spokes themselves grow symetrically outward the ends of the spokes could (I think at least) then become docking areas. They would have to be structuraly capable of doing this docking, but I don't see any show stoppers in the abilities of whatever types of shuttles are then available to be able to match the rotational velocities of the growing stations. Eventually even with completed stations such docking would be possible. This would then mean that BOTH methods of docking would then be available on a completed station!!

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#### gunsandrockets

##### Guest
"Therefore, construction of a large hub area would be the least challenging part of building such a station (at least from the structural strength perspective. There is nothing stating how long such a hub has to be along its axis."<br /><br />Exactly.<br /><br />Building upon this idea, I have come up with an idea for a space station configuration I call, Axle & Gravity Well. Start with your long zero gee axle. I forsee truss structure walls forming a square cross section hollow Axle. If the Axle is open on each end, rather than making the hollow Axle large enough for the passage of two ships at once, ships could just enter one end of the Axle and leave by the other end of the Axle. That way ships could more easily dock at the center of rotation, minimizing balancing issues for the Station in motion.<br /><br />The long Axle, aside from providing a docking area for visiting spacecraft on the inside and support structure near the center for the habitation area, could also support on the outside of the truss solar power panels and radiators. During the initial construction phase a lightweight zero gee habitat structure, such as the Bigelow Nautilus inflatable module, attached parallel to the Axle would form the first living area for the station.<br /><br />Now comes the Gravity Wells. Instead of the classic 2001 style spokes and rims for the habitat area, use instead just two spokes which are directly opposite of each other, each spoke then forms a "gravity well". The Gravity Wells would start out small, and gradually increase in length by the addition of identical modules laid end to end. Docking of new modules would be done in zero gee while the Station is not rotating. The Station would spin up again for normal operations after the addition of a new pair of modules.<br /><br />As the length of each Gravity Well increases, the rotation of the Station is reduced so that the bottom of the Wells would never exceed one gee force. Even though the whole length of a We

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#### scottb50

##### Guest
I would hope not. What happens when they crash? I would kep Microsoft as far away from Space as possible. <div class="Discussion_UserSignature"> </div>

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#### poodown

##### Guest
whats the fun of making gravity?? one of the amazing thinsg about space IS the microgravity...it might not be as practical but its all apart of the experience ive heard many astronauts say that microgravity is one of the best things! I say keep the micro gravity! gravity is overrated! <img src="/images/icons/smile.gif" />

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#### gunsandrockets

##### Guest
Windows? I suppose.

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#### mental_avenger

##### Guest
<font color="yellow"> Some advantages of this Axle & Gravity Well configuration include scalibility, simplicity and increasing livibility. </font><br /><br />Your configuration would be too limiting. A space station of the size we are talking about will probably have several hundred people on board eventually. They will want to interact, socialize, and live together as much as possible. That means that most of them will want to be living at the same gravity. Switching between gravity levels will probably be neither comfortable nor healthy. That is the purpose of the wheel design, putting the majority of people in the same gravitational environment. The gravity level for the majority of Station personnel will no doubt be determined by testing and experimentation, eventually arriving at the best level for long term health.<br /><br />The spokes of the wheel will provide plenty of room for alternate gravity levels. They may be used for certain activities, experiments, for and acclimation of passengers moving between different gravity environments, between the Earth and Mars, for instance.<br /><br />There is one other advantage to the wheel design. The wheel rim, connecting the spokes, will add stability and rigidity, which will lessen structural fatigue caused by flexing, and will also help reduce oscillations.<br /> <div class="Discussion_UserSignature"> <p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="2" color="#ff0000"><strong>Our Solar System must be passing through a Non Sequitur area of space.</strong></font></p> </div>

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#### gunsandrockets

##### Guest
"Your configuration would be too limiting. A space station of the size we are talking about will probably have several hundred people on board eventually. They will want to interact, socialize, and live together as much as possible. That means that most of them will want to be living at the same gravity. Switching between gravity levels will probably be neither comfortable nor healthy."<br /><br />Pardon me if I beg to differ.<br /><br />ANY station with gravity would be healthier than the current zero gee situation. <br /><br />My intention was a practical design for near term construction and use. Currently the ISS, a zero gee station, is intended to have a crew of six and a mass of 419 tonnes. Do you realize the scale of your ideal station of several hundred people? How soon do you believe we could amass several thousand tonnes in orbit to build it?

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#### mental_avenger

##### Guest
<font color="yellow"> Pardon me if I beg to differ. </font><br /><br />You don’t have to beg, this is an open forum. <img src="/images/icons/wink.gif" /><br /><br /><font color="yellow"> ANY station with gravity would be healthier than the current zero gee situation. </font><br /><br />You can’t know how frequently (daily, hourly) moving between radically different levels of gravity would affect humans. It would almost certainly be uncomfortable at best, and might require a great deal of conditioning to tolerate well. We won’t know until extensive testing is performed. However, we DO know that humans tolerate a constant gravity level very well, they were designed for it.<br /><br />While your idea might be useful as a small, scientific research facility, IMO, it wouldn’t be the best configuration for a permanent space station used for refueling, repairs and maintenance of spacecraft to and from Earth, or for layover/acclimation of passengers.<br /> <div class="Discussion_UserSignature"> <p style="margin-top:0in;margin-left:0in;margin-right:0in" class="MsoNormal"><font face="Times New Roman" size="2" color="#ff0000"><strong>Our Solar System must be passing through a Non Sequitur area of space.</strong></font></p> </div>

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