Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: crimsonknight3 on 16/06/2012 14:58:37
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Quite often on the nights i can't sleep i daydream about solutions to the problems of inter-stellar travel and while most of my ideas end up being more science fiction than plausible, i have always wondered if a gyroscope would work (e.g. stay in the same position) in the earths gravitational pull/further out into space.
The reason i wonder this is simply because i think it would work well as a way to maneuver craft faster than using thrusters. If a gyroscope rotating at a high speed was contained in a sphere and it stays in the same position, then you could use some sort of mechanics to move the craft around the sphere = a fast maneuver though of course this would need *some thrusters + a lot of propulsion to be able to slow down or change course.
I've thought on other ideas such as a fusion generator creating plasma that is ejected at high velocity but in my daydreaming i can't ever seem to think of a viable fuel source that wouldn't take up a large amount of space.
Also another problem i have in my daydreaming is the fact that if we ever have the capability to travel AS fast OR faster than light, how would we solve the problem of stellar debris, very small or big meteorites and other objects floating around out there? The only idea I've had yet is if we could somehow capitalize on dark matter, if it truly is pushing the galaxies away from eachother that would mean it is anti-gravity, pushing things away rather than pulling them in, if you could use dark matter you would have the ability to push objects away from the front of the craft.
I don't know much about science at all, just a lot of little bits and pieces here and there, like i understand how to slow a craft down in space you would have to put equal force to slow down as you did to speed up unless there is a gravitational force at work, thank you in advance for reading my ramblings it would be amazing to hear some real intelligent people pick apart my ideas:)
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Do gyroscopes work in zero g? Yes, they would continue to spin in the same orientation. They work by something called conservation of angular momentum which is one of the fundamental laws of physics: once something starts spinning, it maintains its orientation and spin unless you act on it with an outside force to redirect the spin axis. So if you put a gyroscope in your spaceship, you can easily track how the orientation of your ship changes.
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So it would work for orientation but not as a means of maneuvering which does answer that question, wish i'd asked sooner. However gyroscopes DO work on my original principal on earth? They try to stay upright if you try and move the housing around them? I remember this toy that you had to try and twist your wrist in circular motions to speed up the gyroscope inside at which point it exerts force as it tries to spin
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So it would work for orientation but not as a means of maneuvering which does answer that question, wish i'd asked sooner. However gyroscopes DO work on my original principal on earth? They try to stay upright if you try and move the housing around them? I remember this toy that you had to try and twist your wrist in circular motions to speed up the gyroscope inside at which point it exerts force as it tries to spin
They don't really try to stay "upright". If they are very well made, they are really just trying to resist any change in the direction of their axis of rotation.
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As per usual mechanical stuff has been replaced by frikkin lasers ... https://en.wikipedia.org/wiki/Ring_laser_gyroscope
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The Voyager probes use gyroscopes to help aim the antenna back towards Earth without the need of using thrusters.
If you were building a spaceship with a fixed location of the exhaust ports, you could use the gyroscope to make rapid orientation changes of the spacecraft, without having to use thrusters (and thus loosing propellant). However, if you are doing multiple course changes, there would also be benefit of building the entire spacecraft as light as possible, so the added mass of the gyroscope may be counter-productive.
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A lot of spacecraft use gyroscopes to change attitude. They are just named reaction wheels. Every so often the spacecraft has to burn precious attitude control fuel to allow the reaction wheels to be brought back down to the middle of the speed control range, due to the drift from the spacecraft circling the sun, the imperfections in the bearings, the motion of the sun around the galaxy, the motion of the galaxy and other effects. Every broadcast satellite and GPS, Iridium satellite has at least 2 sets of them, to keep the antenna pointed at a fixed point on the earth.
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The Voyager probes use gyroscopes to help aim the antenna back towards Earth without the need of using thrusters.
If you were building a spaceship with a fixed location of the exhaust ports, you could use the gyroscope to make rapid orientation changes of the spacecraft, without having to use thrusters (and thus loosing propellant). However, if you are doing multiple course changes, there would also be benefit of building the entire spacecraft as light as possible, so the added mass of the gyroscope may be counter-productive.
A large mass is inevitable though if we are talking about travelling between stars, however in the solar system size becomes more managable depending on the speed of the craft but then if used in a space craft rather than a space station, multiple course changes will always be needed. I was thinking about propulsion and firstly, if for instance, we had more efficient fusion generators, using the super heated hydrogen (the little knowledge of fusion generators i have is basically injecting hydrogen into a super-heated 'donut' which uses magnetic force to prevent the fusion heating up the wall of the generator and once the fusion reaction has reached a certain point, it becomes self sufficient until it runs out of fuel) would venting the super-heated gas created create a viable propulsion system? Even if you used the super-heated gas to create steam to create electricity there would still be gas left to be vented? Though as of yet i can't really think of a way of getting rid of the immense heat if the craft were trying to stay stationary unless there is a way of 'containing' the super-heated gas (if im right in thinking said gas is plasma?) then we have already discovered alloys of metals that can withstand the heat of the sun, would something similar manage to contain compressed plasma for a realistic amount of time?
Also i know this is straight out of a sci-fi tv show (stargate universe) but it inspired my imagination, the ship in that series 'destiny' flies through the upper layers of the sun to 're-fuel' itself, it would be possible with the right technology to 'scoop' off some of the hydrogen from stars, which to me seems a good renewable (but not infinite) source of fuel, though as of yet i don't have a viable way of protecting an entire craft, the only thing i could think of when trying to sleep last night (which is getting worse, taking me more than 4 hours to fall asleep now) was to use a scoops of a similar design as the planes that provide fuel to jets in the air, a scoop that extends out whilst the ship stays just along the corona which the heat is less intense... More pondering tonight, i was trying to think of a way that the craft can repel the massive forces the sun puts out and ive been considering a very strong electro-magnetic force, although that makes a big risk for sensitive electronics.
As for faster than light travel though impossible to us now, it does in my mind seem possible, i saw mention in a program that there is a type of atom or particle (cant remember) that can and does travel faster than light, so if its possible on a molecular level surely its possible that all matter has the capability to travel faster than light right? As all matter is made up of the same stuff, protons, electrons, neutrons etc etc... If a black hole can bend and absorb light that means light is susceptible to the same physics as all matter so i thought it might work in reverse.
Its such a shame that the world doesn't work as one united force, I keep saying to people that as long as mankind is fractured in separate countries and regions under separate governments with different goals, we will never achieve a level of scientific understanding great enough for us to travel to other planets in a realistic timescale. I just hope its in my lifetime and before i get too old, i've always had a wish to be cryogenically frozen and woken up in 100-200 years time, like those alive now who wish they were born 20-30-40 years ago as they feel they belong there. If i had a better memory, with a better mind, i would start a career in physics, im only 23 and im about to be a father and ive done nothing with my life because of health limitations. I would love to be at the forefront of science trying to better our understandings about the universe and potentially (as there are theories) other universe's, but alas i have a bad memory and a bad habit with problem solving, if i have a problem it becomes the center of my life until i figure it out so now i just blot out my problems and go with the flow. Sorry for the large amount of writing, i've never been good at writing blogs but its nice to get my ideas out into a community of people who are intelligent and want to help other people learn and understand this existence.
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I always thought that Iridium satellites tumbled hence the flashes that delight amatuer stargazes and horrify proffesionals.
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Gyroscope Capabilities
Gyroscopes can be used to change the direction your spaceship is pointing, but it won't change the direction your spaceship is traveling. With current technology, to change the direction of travel involves firing a rocket, or taking an orbital slingshot around a massive object like a planet.
Sub-Light Travel: Rockets & Fuels
There are some current projects that are attempting to produce energy from controlled nuclear fusion, for example the Joint European Torus (JET) and the US National Ignition Facility (using lasers). If/when controlled nuclear fusion is achieved in a compact size, this would make a great space rocket, as the fuel is fairly light and compact; it is efficient because it burns at a high temperature. At present both these experimental projects take up a large warehouse and large conventional power stations to make them work. Managing the high temperatures of fusion is one of the big problems of fusion.
Ignoring the temperature problems, scooping gas off the sun would yield a mixture that is about 90% hydrogen and 9% helium. You can fuse the hydrogen, but it takes very high temperatures (more temperature problems). Deuterium is "easier" to burn, but it is more common in comets or in the atmosphere of a gas giant like Jupiter. Tritium is even easier to burn, but it is radioactive, and you have to make it as you go.
If you can't sleep, why not read some science fiction:- one story I read suggested flying to a comet, and strapping on a fusion rocket. The comet acts as a fuel source and as a shield against gas and dust in space. (It won't be much protection against a meteorite, but these are rare in space.)
For rockets, anti-matter is the most powerful potential fuel we know, but so far scientists have only managed to bottle a few anti-atoms together, which is not enough for a practical fuel tank.
Faster-than-light travel
There was a report that neutrinos had been observed traveling slightly faster than light, but that has now been traced to a loose connector on some equipment.
Travel at the speed of light is not a theoretical challenge: in principle you could locate the position of every atom in a person's body, encode that onto a laser beam, and send that to a receiver which would reconstruct every atom in its original position. Far beyond current technology, but not forbidden.
Travel beyond the speed of light is also theoretically possible: There are some hypothetical particles called tachyons that can only travel faster than light, but they have never been observed.
The challenge that is beyond current physics is to make the transition between traveling slower than light and going faster than light. If you try to do it by rockets, it would take all the mass in the universe and you still wouldn't be going faster than light.
We don't have a solution to this today, so many science fiction writers gloss over this aspect of interstellar travel, or speculate about travel through another dimension, which is theoretically possible (even if we have no idea how...).
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Thank you evan_au that answers a lot of my questions and ideas that have been rattling around for a long time!! I've read, and seen tv programs, suggesting there are more than the dimensions we know of and theoretically being able to bend time but i've never given them much thought as it seems like we would need a vast improvement of knowledge to even disprove those theories, though i did see an interesting tv program once stating that creating a 'portal' at a current point in time, you could enter the portal in the future and come out at the time it was first created, and according to the physicist on the program (i cant remember his name but i enjoy his programs) said that scientists have proved that it is possible but the massive power requirements and technology are far beyond us at this point in time.
As for the sleeping reading generally keeps me awake longer as if i get into a good book i end up not putting it down. I think the sleep thing is more subconcious than anything, a lot of stress in my life at the minute (considering i dont work i feel silly saying that lol)
I did think that maybe gas giants would be an easier source but gas giants are usually made up of a mix of gasses that would need processing and on a space craft that would take up precious space, not only that but the one constant when travelling to other stars is the stars themselves, not all stars have planets and neither do they all have gas giants so the stars themselves would be a more reliable source, however travelling in our own solar system they would be a good fuel source.
Is there ways to produce hydrogen? I know that you can get hydrogen from water using electric current but at what point if ever does the water regain hydrogen? If there was a way of producing hydrogen then it would make a renewable fuel that can be produced on the craft in transit, rather than relying on rare elements you may or may not find during exploration?
Travel at the speed of light is not a theoretical challenge: in principle you could locate the position of every atom in a person's body, encode that onto a laser beam, and send that to a receiver which would reconstruct every atom in its original position. Far beyond current technology, but not forbidden.
This is what i've never understood about teleportation technologies, if its a case of saving the atoms of a person, then transmitting them, then reconstructing them, in my mind wouldnt that make an exact replica of the person rather than 'moving' them... To teleport them you would need to destroy the atoms as they entered the 'memory' of the teleporter however that screams accident waiting to happen, if you abort a teleportation early.
The challenge that is beyond current physics is to make the transition between traveling slower than light and going faster than light. If you try to do it by rockets, it would take all the mass in the universe and you still wouldn't be going faster than light.
I understand that A. In order to go faster than light you would have to either artificially make the mass of the craft finite in order to be AT or travel faster than light and B. that in order to slow down you would have to use the same amount of force in the opposite direction.
If tachyons are proven and they ONLY travel travel faster than light, then could they thoeretically be used as a force? Rather than a craft using a fuel for long distance travel, use dark matter + anti-gravity + FTL atoms like tachyons, for travel, I mean i know that all 3 of those are only really thoeretical right now (except dark matter which we know is there as we can see its effects) Dark Matter could be used to create anti-gravity and the craft could latch onto tachyons to pull it up to speed?
The theories in my mind are getting a little jumbled now, one of my old ideas was to use dark matter as propulsion as it could theoretically push you away from a mass at relatively high speed but i chucked that idea as though you could use the same dark matter to slow down would require that your aim is very accurate because if your off you could just keep on going and never reach an object with sufficient mass to slow you down.
It sounds silly but i always thought deutirium was fictional (seen it in too many games i suppose) Its created from water isnt it?
We don't have a solution to this today, so many science fiction writers gloss over this aspect of interstellar travel, or speculate about travel through another dimension, which is theoretically possible (even if we have no idea how...).
I find it great that although they are science fiction writers, a lot of the ideas DO seem theoretically plausible. Some theoretical physics i saw on a tv program (same one i keep mentioning) that all matter is in two places at the same time where it is and where it is going, do you think its plausible to suggest that if matter can exist in two places at once, we will eventually be able to wedge the gap between the matter and push the atoms so that instead of being close they would be far away, thus teleporting without the need for transmitting a persons data? Only calculating the position of their atoms then pushing them to another location?
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Also I re-watched one of Brian Cox's programs yesterday and if gravity affects time, would the effects get more noticable the further away from earth, or would they dissipate the further from earth you get? If time goes faster in earths orbit (satellites etc) Obviously time on earth is our only point of reference however what I don't understand is if earth can affect the fabric of space-time with it's gravity, what effects would something with a massive mass or tremendous gravity have on time? If a black hole is strong enough to bend light and not let anything escape wouldn't that mean that near its event horizon time would virtually stand still? Also wouldn't we feel the effects of other gravitational disturbances such as a supernova, that would send out a gravitational wave? So why haven't we yet?
(he was talking about a current experiment with lasers in a massive L shaped tube which is meant to measure the effect of the gravitational waves that two neutron stars orbiting eachother theoretically send out)
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I decided to start studying physics by reading through physics for dummies + a little study in maths, i was good at maths at school but have a very bad memory for methods. I came across this
"In practice, it’s very hard to get the speed just right, which is why geosynchronous
satellites have either gas boosters that can be used for fine-tuning
or magnetic coils that allow them to move by pushing against the Earth’s
magnetic field."
I know the force needed to move an object on the surface would be higher but is it possible to use magnetic coils on the surface to lift an object weighing say, 1000kg?
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Of course, they work in micro or zero gravity. Space travel depended on these devices for guidance & other tasks. Without gyro's, the capsules would've just been uncontrollable. Not only are they important for space travel but are also found in about all of the US military's missile(Patriot, Tomahawk,etc.) stockpile.
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One of the original questions from OP was whether gyroscopes can be used to manoeuvre a spacecraft more rapidly than thrusters. This is entirely true and is how NASA's Swift satellite, deployed in 2003/4 to study gamma ray bursts, could swivel rapidly ("swiftly", hence the name) to point at objects of interest: https://swift.gsfc.nasa.gov/