Coriolis Effect on Future Ships

[odysseus145]

An interesting article at nasa.gov about how humans adapt to a rotating enviroment <br /> <br /> <br /> <br />"Spinning Brains<br /> 07.23.04 <br /><br /><br />One day, astronauts might travel through the solar system onboard spinning spaceships. Can human brains adapt? <br />Next time you go to a playground, try this: Bring along a ball and a friend, and get on the merry-go-round. Try throwing the ball to your friend across the ride from you, or even just a few feet beside you, and see if they can catch it on the first attempt.<br /><br />They won't be able to, guaranteed. In fact, your throw will be way off. You'll feel your arm pulled strangely to one side as you make the throw, and once in flight, the ball will veer wildly.<br /><br /> <br />Physicists call this the "Coriolis effect," and it happens on any spinning platform. Hurricanes swirl because of the Coriolis effect, the spinning platform being Earth itself. Contrary to popular belief, Coriolis forces do not control your bathroom drains--Earth doesn't spin that fast. But playing ball on a merry-go-round is definitely a Coriolis experience.<br /><br />Right: Playing ball on a merry-go-round. Click to view the full-length movie (2 MB), which beautifully illustrates the Coriolis effect. Credit: University of Illinois at Champagne-Urbana. [More]<br /><br />Space travel could be a Coriolis experience, too.<br /><br />Researchers have long known that spinning spaceships like a merry-go-round could solve a lot of problems: In weightlessness, astronaut's bones and muscles weaken. It's tricky to eat and drink, and even use the bathroom. Inside a spinning spaceship, on the other hand, there would be an artificial gravity (due to centrifugal forces) that keeps bodies strong and makes everyday living easier.<br /><br />The problem is, spinning spaceships also come with a strong Coriolis effect. Tossed objects veer. Reach out to touch a button ... <div class="Discussion_UserSignature"> </div>

 

[nacnud]

There has already been some Russian studies of this where the volunteers were placed in a large centrifuge for a number of weeks at around 1.5g. They quickly adapted to the odd conditions and I have even seen a video of a game of darts where the contestants stood at 90 degrees to the dart board and still hit the bull <img src="/images/icons/smile.gif" />. Sorry but I don't have any references to this but remember Google is your friend. I don’t think that this effect is going to be much, if any, of a problem.

 

[jcdenton]

Interesting. Could this have anything to do with the fact that when you're spinning in space, you feel like the universe is spinning around you instead? <div class="Discussion_UserSignature"> </div>

 

[odysseus145]

Sorry about that. I fixed the link. <div class="Discussion_UserSignature"> </div>

 

[nopatience]

one thing that the article didn't directly address-would there be a huge difference between tests in space and tests on earth? Also the size of the ship would reduce the feel of spinning, would it not?<br /><br />are there any other ideas for artificial gravity besides spinning?

 

[mrmorris]

<font color="yellow">"...the size of the ship would reduce the feel of spinning..."</font><br /><br />The size of the ship has (almost) everything to do with how fast the spin needs to be. The other factor is what G is produced. No one knows what G force would be sufficient to significantly reduce or eliminate the long term effects of microgravity. It might be that a small fraction of a G would be sufficient. *Any* acceleration will give the body a defined up-and-down. A ship that rated with sufficient speed to generate lunar gravity (1/6 G) might even be sufficient. Generating this would require a much slower spin and greatly reduce materials strength requirements. <br /><br />The only options for artificial gravity (beyond science fiction ones) are spinning or straight-line thrust (i.e. a rocket accelerating at a constant 1G).

 

[nopatience]

<font color="yellow">straight-line thrust (i.e. a rocket accelerating at a constant 1G). </font><br />wouldn't that be interesting. How fast would you have to travel to stay at a constant 1G. and then when you stop, your ship would return to zero gravity. So on a trip to mars, you would have a day or so of zero grav. then 5 months of 1G, then another day or so of zero grav. Wouldn't that be easier then creating a spinning ship? (of course I have no idea what speeds are required for this effect- please enlighten)

 

[nacnud]

If you could accelerate at 1g halfway to mars turn around and decelerate the rest of the time there wouldn't be any worries about radiation, or problems at low gee or launch windows or even getting too board as journey times would be measured in days not months or years. <br /><br />As you can probably imagine the energy expenditures involved would be colossal. Until we discover a way of generating the energies involved we’re going to be using variations on a rotating ship design.<br />

 

[spacester]

Thanks so much for the link! <br /><br />Hooray! They're actually studying spin-g again. There's such a paucity of data. <br /><br />nacnud is correct: the constant thrust idea does not work, the fuel efficiency (Specific Impulse) is way too low with current and even foreseeable technology.<br /><br />Allow me to paste from a post in April 2003, referencing a December 2001 post . . . great threads, what a loss, all you get is my number crunching . . . <br /><br />* <br />For tons of information on the realities of artificial gravity, see:<br />This discussion about the effects of micro-g and the issues regarding artificial gravity and this for all the math you could ever want (scroll down to the conclusions) and then <a href="http://www.spacefuture.com/archive/the_architecture_of_artificial_gravity_theory_form_and_function_in_the_high_frontier.shtml"> this for an architect's view of what it would be like.<br /><br /><br />Here's the formula: <br />G = [R * [(pi*rpm) / 30]^2] / 9.81 <br />OR <br />R = (9.81 * G) / [(pi*rpm) / 30]^2 <br />Where: <br />G = Decimal fraction of Earth gravity <br />R = Radius from center of rotation in meters <br />pi = 3.14159 <br />rpm = revolutions per minute <br />* <br /><br />Now then, my point is simply that we don’t know the true effects of coriolis cross-coupling in a large radius habitat operating in a micro gravity environment. Of course you will have severe problems in a small radius habitat, all the research indicates that. Also, you cannot do a precise simulation in Earth’s gravity field. So we just don’t know. In my research, the best summarizing paragraph I have found is from the first link above: <br /><br />"In brief, at 1.0 RPM even highly susceptible subjects were symptom-free, or nearly so. At 3.0 RPM subjects experienced symptoms but wer <div class="Discussion_UserSignature"> </div>

 

[mrmorris]

<font color="yellow">"How fast would you have to travel to stay at a constant 1G."</font><br /><br />'G' is an acceleration, not a speed. In effect -- if you're under 1G of acceleration -- your speed is constantly increasing (or decreasing). It certainly isn't staying the same, so you can't be said to have 'a' speed.<br /><br /><font color="yellow">"So on a trip to mars, you would have a day or so of zero grav. then 5 months of 1G, then another day or so of zero grav. "</font><br /><br />The minimum distance from Earth to Mars is 54,510,620 km. A trip to Mars assuming near closest approach of 60 million km (although with 1G of accelleration -- this wouldn't be much of an issue), the total travel time would be just under two days. Calculators for this and other nifty things can be found here. Note that to calculate the time to Mars -- I took the time for two 30 million km pieces (half accellerating, the other half decelerating). If you just solve for 60 million km -- you'll get a much lower time -- but you'll speed right past Mars at a nifty pace.<br /><br /><font color="yellow">"Wouldn't that be easier then creating a spinning ship?"</font><br /><br />Nope -- as has already been said -- the propulsion technologies to do something like this are <b>far</b> in the future. With tech like this -- the solar system would be our playground.

 

[mrmorris]

I figured I'd calculate the approximate max speed for the hypothetical 1G acc flight. Given 24 hours of acceleration at 1G, the ship would be travelling at ~842.71 km/s. By comparison -- Voyager 1 (the fastest moving man-built object to date), is currently travelling at ~17.46 km/s.<br />

 

[nacnud]

Travelling at that speed you would have to be damb sure the brakes were going to work <img src="/images/icons/smile.gif" />. I have always found it a surprise that the times taken to travel around the solar system are so small at 1g acceleration. It's a pity that such a comfortable acceleration is going to take such a lot of energy to achieve.

 

[a_lost_packet_]

Great stuff in this thread guys.<br /><br /> <div class="Discussion_UserSignature"> <font size="1">I put on my robe and wizard hat...</font> </div>

 

[spacester]

mrmorris, that link you gave is pretty cool looking but um, it appears to be quite bogus. A quick look at the first two sections was not encouraging. I'll check more carefully later, gotta go for now. <div class="Discussion_UserSignature"> </div>

 

[mrmorris]

<font color="yellow">"ink you gave is pretty cool looking but um, it appears to be quite bogus. "</font><br /><br />I freely admit that I did not check the calculator's math. I located the sucker via Google just before writing the post. Never used it before that. If it's wrong, please post back with examples. Thanks.

 

[jmilsom]

Very interesting to read this post. I was just dwelling on this fact over the last few days. I knew of the problems of the Coriolis effect on rotating spacecraft and concepts of space wheels.<br /><br />That got me thinking. Recently a team in the UK has been able to produce a continuous thread of carbon nanofibre. This must have the Space Elevator people excited. But it could be used for a spacecraft or station. What if one were to build a space station in a Lagrange point that consisted of two living working compartments connected by long carbon nanofibre cables. Size dosen't matter as there is so much "space" out there. The compartments could be five kilometres apart rotating around a central point (like a bola). In this way you would get the gravity and the Coriolis force would be minimised.<br /><br />Any comments, arguments against or additions to such a concept? <div class="Discussion_UserSignature"> </div>

 

[mrmorris]

<font color="yellow">"it appears to be quite bogus. A quick look at the first two sections was not encouraging. "</font><br /><br />I did a couple of calculations by hand to test the first calculator on that page. Seems accurate enough. Looks like they were using 9.81 m/s and I just used 9.8 -- but the results match close enough.<br /><br />d = 1/2 a t^2<br /><br />d = 1/2 * 9.8 m/s * 10 sec^2<br />d = 4.9 * 100<br />d = 490<br /><br />Calculator shows 490.5<br /><br />d = 1/2 * 9.8 m/s * 172800 s ^ 2<br />d = 4.9 * 146313216000<br /><br />Calculator shows 146462515200.<br /><br /><br />If you have calcualations showing something else -- or showing problems with the others -- I'd like to see them. It'd be nice to book mark this to check things, but not if there are problems such as you suggest.

 

[mrmorris]

<font color="yellow">"Any comments, arguments against or additions to such a concept?"</font><br /><br />The concept isn't unheard of, and the distance need not be great to reduce the Coriolis effect to near-nothing. As with most ideas -- it solves some problems and creates others. In the end -- what will happen is that when the time comes to build a space station with artificial gravity -- a method will be chosen which provides the most benefits for the least cost and with the fewest downsides possible -- given the technology available at the time. Either that or (if the US builds it), it will be constructed using whatever method will provide the most jobs in some senator's state.<br /><br />Problems:<br /><br />-- People in the two sections can't easily move from one to the other. <br />-- Spinning this up and keeping it stable will be a challenge. Alterations to the spin plane *will* be needed over time, and this will normally have to be be added exactly equally on both compartments. Spin rotation can be changed by increasing or reducing the distance between the compartments -- but this won't have any effect on the plane. Impacts of micrometorites and such will cause alterations in the paths of the two bodies unequally.<br />-- Docking with this will be a challenge -- and will immediately introduce instabilities on the rotation as the weight of the docked ship will unbalance the pair. In a standard-concept station -- docking can occur at the hub -- not practical here.<br />-- Adding to the station once it's rotating is next to impossible.

 

[odysseus145]

<blockquote><font class="small">In reply to:</font><hr /><p>People in the two sections can't easily move from one to the other. <p><hr /></p></p></blockquote><br /><br />Could this problem be eliminated by having the facilities all on one end of the cable and a counterweight on the other end?<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>...and will immediately introduce instabilities on the rotation as the weight of the docked ship will unbalance the pair...<p><hr /></p></p></blockquote><br /><br />Could this problem be compensated for by altering the counterweight's distance from the center of rotation? <div class="Discussion_UserSignature"> </div>

 

[hansolo0]

Wasn't the ISS due to get a 'cetrifuge' of some sort, does this have anything to do with gravity (i.e. on a person) and is the ISS still going to get it?

 

[odysseus145]

<blockquote><font class="small">In reply to:</font><hr /><p>Wasn't the ISS due to get a 'cetrifuge' of some sort, does this have anything to do with gravity (i.e. on a person) and is the ISS still going to get it?<p><hr /></p></p></blockquote><br /><br />Yes it is but it will not be used for humans.<br /><br /><br />“The International Space Station's Centrifuge Accommodation Module will take life on a spin in space to achieve experimental results that can be brought down to life on Earth. <br /><br />Unique among ISS modules, this one will permit long-term study of the effects of varying gravity levels on the structure and function of generations of living organisms and test methods for countering the negative results of those variations. <br /><br />The Module will house the Centrifuge Facility, a more than 8-ft. diameter centrifuge drum or rotor, and a Gravitational Biology Facility, with racks for holding plants, animals and habitats. <br /><br />It also will have a Life Sciences "Glovebox," a box comprising about 18 cubic feet of work area into which will extend rubber gloves that permit crews to handle organisms to be used in research. <br /><br />Gravitational Biology Facility contents will include aquatic, insect and animal habitats, as well as a cell culture unit, a plant research unit and an egg incubator.<br /> <br />Microorganisms, cells, plants and animals will be subjected to gravity levels ranging from 1/100th to twice the Earth's gravity to better identify and capitalize on gravity's role in disease, aging and other processes that affect lives on Earth. The Centrifuge will also be used to separate biological materials of varying density. <br /><br />Under construction for NASA by the National Space Development Agency of Japan, the Module will complete the complement of station laboratories to be integrated into the ISS. It is targeted for a future launch aboard the Space Shuttle. The NASA/Ames Research Center Space Station Biological Research Project at Moffett Field, California <div class="Discussion_UserSignature"> </div>

 

[mrmorris]

mrmorris said: "People in the two sections can't easily move from one to the other. "<br /><br /><font color="yellow">"Could this problem be eliminated by having the facilities all on one end of the cable and a counterweight on the other end?"</font><br /><br />That's going to be one *big* counterweight. And if it's just deadweight, then that's a whole lot of mass put in orbit to little purpose. It's possible that we could use an asteroid as a counterweight. However -- if we have the technology to be moving asteroids around -- we can probably also build a bicycle-wheel station (BWS) large enough to minimize Coriolis forces and the Bolo-style station loses its only advantage.<br /><br />Alternately, the counterweight could have a purpose -- possibly use a nuclear power plant as the counterwight. One of the potential uses of carbon nanotubes is that of high-temperature superconductors. The tether could serve as the means for transmitting the power to the manned portion of the station. Again -- by the time we can throw a power plant into orbit -- we can probably build the BWS.<br /><br /><br /><br />mrmorris said: "...and will immediately introduce instabilities on the rotation as the weight of the docked ship will unbalance the pair..."<br /><br /><font color="yellow">"Could this problem be compensated for by altering the counterweight's distance from the center of rotation? "</font><br /><br />Rotating bodies don't take well to disturbances of that sort. I haven't done the math (and have no intention of doing so) -- but I seriously doubt this would work. To provide the type of compensation you're referring to, the situation would have to be something like:<br /><br /><br />Bodies A and B of equal mass are rotating about a common center -- each is 200m from the center of rotation.<br /><br />Body C (the spacecraft) docks with body A and increases the mass by 10%.<br /><br />Body B plays out some additional tether such that it is now 220m from the center of r

 

[odysseus145]

Thanks for the response<br /><br /><blockquote><font class="small">In reply to:</font><hr /><p>That's going to be one *big* counterweight. And if it's just deadweight, then that's a whole lot of mass put in orbit to little purpose. It's possible that we could use an asteroid as a counterweight. However -- if we have the technology to be moving asteroids around -- we can probably also build a bicycle-wheel station (BWS) large enough to minimize Coriolis forces and the Bolo-style station loses its only advantage.<p><hr /></p></p></blockquote> <br /><br />A station at a lagrange point would be close to the moon, so would it still not be feasible to launch a large counterweight from the moon?<br /> <div class="Discussion_UserSignature"> </div>

 

[yurkin]

<font color="yellow"> but the Earth/Moon L1 and Earth/Moon L2 points are closer. </font><br /><br />The E/M L2 is actually the only E/M L point further from the earth then the moon is from the earth. Luna, L4 & L5 are the same distance from us.<br />

 

[nexium]

I'm brainstorming craft/stations each shaped like an equalateral triangle with a winch in each corner, about a km of tether connecting each pair of winchs. Each station is powered by an ion engine capeable of accelerating the station at 1/1000 g. We use the ion engines (or equivelent) to spin up the pair until we get about 1/100g at each station. Instabilities will be like a very large ocean ship riding very long swells, with very slow movement in pitch, yaw and roll, perhaps all three simultaineously, mostly because the three tethers are elastic, and the vacuum of space does not dampen these oscilations. They should be only slightly annoying until we get almost to one g of spin. When a third craft docks increasing the system mass by 20% The winches and ion engines can help fine tune the docking. The first effect will be to dampen the oscilations, one or more of the tethers will begin to stretch, When the stretch tancient reaches the middle or perhaps the far end, the center of gravity will begin moving toward the station with added mass which will have reduced spin gravity after a delay due to the time (several minutes) the trancient takes to reach the far end and be reflected. The other station will slowly acquire more spin gravity. The yaw pitch and roll will return perhaps stonger, but the ion engines, climbers and winches can work at minimising/dampening them.<br /> Each of the three tethers should have a climber designed to carry two humans or equivelent supplies etc. I believe Dr. Edwards has the design nearly finalized for the space elevator. The climber will repair it's tether when micrometorites damage it. If a tether breaks, the direction of down will change by about 80 degrees (with over shoot) quite suddenly and dangerously unless there is some warning. Strong trancients could break the two remaining tethers unless there is a sizable safety factor. Please embellish, correct, refute and/or comment. Neil