Magnetic Effects In Space (1973)

[Music] during the summer of 1973 three astronauts Alan Bean Jack LMA and Dr Owen garot were launched into space where they spent almost two months in the sky laab spacecraft the world's first laboratory in space [Music] the crew performed a variety of scientific experiments and demonstrations the onboard scientist officially designated a scientist pilot was Dr Owen garot a former professor of electrical engineering and an astronaut since 1965 during the mission Dr Garett conducted a number of demonstrations specifically for the use of science students back on Earth Dr garot discusses some of his Skylab experiences with high school students Skylab is perhaps the most unusual laboratory that you can imagine living in weightlessness meant that you didn't walk from point A to point B instead you Flo and to do that you simply pushed yourself off and drifted over to the spot that you were headed for now here you see some of our weightless gations that we went through during a little time we took away from our work schedule now this weightlessness also made it possible for us to conduct some science demonstrations that we simply couldn't do here on Earth because of the strong influence of gravity one of our demonstrations involved the Earth's magnetic field and this completely surrounds the Earth making in effect uh the Earth itself a giant magnet one of the many things that this field does is to protect us from dangerous solar particle radiation coming not only from the Sun but also from the outer reaches of our galaxy Skylab moves through the steady magnetic field of the earth making almost 16 revolutions every 24 hours as you see skylab's orientation with respect to the nearby magnetic field is constantly changing the uniqueness of the Earth's magnetic field has led some to the conclusion that this field may have been a vital Factor even in the development of life here on Earth we also know that even minute changes in the Earth's magnetic field both its strength and in its direction can seriously interfere with some aircraft instruments and also ship's compasses and this can lead to endangering lives when their navigation is performed by reference to the strength and direction of the Earth's magnetic field this field also is basically related to the appearance of Aurora or Northern and Southern Lights as we call them and interacts with the solar wind also which is a new discovery of our space age let's take a look at some of our TV footage and see a Skylab demonstration in which some of the effects of the Earth's magnetic field are demonstrated I'm sure most all of you at least at one time or another in your past have had the occasion to use a compass it's of course made from just a little magnet and North End always points toward the North Pole and you can use it to determine for example your way out of the woods or your way on a hike and that sort of thing well perhaps many of you haven't ever thought about whether or not the Earth's field extends farly out into SP for example here we are up in Skylab some 270 Mi above the surface of the Earth and indeed the Earth's magnetic field does extend out this far and in fact a good deal further but we can demonstrate that as well and perhaps you would uh enjoy seeing such a demonstration uh here's a group of little magnets that I have uh these are about 2 in long and about 2/10 of an inch in diameter and uh when we put these uh just floating out in midair like I'm doing here you can see that they take on a very definite orientation for example there is one I've released it right out in the center now and you can see it is settling down to a specific orientation that's the direction in which the Earth's magnetic field is running here right along parallel to this little bar magnet and we can of course use this to determine the direction of the Earth's field right up here at the location Skylab is is at now as we travel around the Earth if we could watch this for a longer period we would see this little magnet make several rotations as we circle the Earth because the direction the Earth's magnetic field is changing and here's another thing that we can do you see we must not get too close to it with another magnet because when we do uh the two of them interact and they very much perturb uh and influence the other one now uh let me just make a couple other little uh demonstrations here for you first of all we found you see that one magnet aligns very nicely with the Earth's field and if you watch very carefully you can see this dipole oscillate back and forth now we're moving the other magnets so that they do not influence it now perhaps you'd find interesting in one of your science classes to try to compute the period of that uh uh little uh Compass or another way to do it you can measure the period from this oscillation and compute the strength of 's magnetic field right up here at the Skylab orbit uh to do it you'll need to know a little bit about this magnet uh but you can uh estimate that approximately from the fact that it's a 2 in long 2/10 in diameter magnet and make a calculation to determine what the period for that ulation should be now here's another little question that uh might uh be appropriate for some of the younger uh members of our audience suppose I take two of these magnets and I put them together like this now if I put these out here and let them float you see they have almost no tendency at all to line up with the Earth's field there's just a little bit remaining but almost no tendency at all and so perhaps you can explain that or if you can't you can ask ask your science teacher and here she can tell you why it is with two magnets like this uh we seem to lose that tendency to line up with the Earth's field well we saw the period of one oscillation a minute ago let me uh try it uh with uh two magnets end to end like this and you see they also ulate it's not like the two side by side two end to end will still oscillate and maybe you can see that and uh you can measure this period and from that period uh you could again calculate the Earth's field or you can determine something about the inertias of these combination of two magnets and I'll leave that for another calculation for your science class now we'll give you a closeup look at the oscillation of one magnet back in the center and now we'll use two to oscillate and you see the period of this oscillation is a good deal more slow when we have two of them together and we can extend that even to three three rods if we like and there the period is very clear and can be measured rather accurately now if I put uh three side by side we again see they all have a different period and they move a little too fast there there we go before resuming our Skylab demonstrations I'd like to give you an opportunity to measure the period of the oscillations of the different combinations of magnets that we've just been looking at now after you've measured these periods and the film has ended your instructor will supply you with the other data that are needed to calculate either the moment of inertia or the strength of the Earth's magnetic field from our Skylab location up in space now here's how I would suggest that you make the measurement of the period of these oscillations now this little pen that I'm going to show you here will represent the dipole that you've just seen and in my other hand I've got a stopwatch and so the way I would measure that period is to wait until a dipole has tipped to one extreme fits motion and more or less stopped ready to turn around and at that point start your stopwatch and then measure at least one or if there is time perhaps two or even three oscillations of the dipole and then stop the stopwatch now I've just simulated there for example measuring three of the oscillations and my stopwatch reads 10 and 1 half seconds and so the period dividing 10 and a half by three gives us 3 and 1/2 seconds for oscillation of the dipole and then you'll want to go back of course and measure that period for each of the various combinations of magnets that we've just been looking at first let's make a dry run start your stopwatch precisely when you see the dot and hear the tone count the oscillations one two and then stop the watch when you see the dot again and hear the tone okay now we're going to repeat the footage for the single magnet so you can make that measurement when you're through right down the measurement on your paper and then we can measure the period of the oscillations for two magnets now let's measure the period of three magnets side by side and write that number [Music] down then finally fin we'll measure the period of the three magnets when they're placed end to end in a long single dipole when you completed that we'll have four measurements recorded on our paper and we'll use these measurements in our calculations when the film is ended now in another demonstration we will observe the effect of a magnet attached to a nut similar to this one that we cause to spin like a top in space now we're going to tape a little magnet to the nut just like this use a little piece of gray tape just the way we did on board the spacecraft and we're going to observe the effect of this magnet on the spinning of the nut note that the polarity of this flat magnet is not along its long axis as it is with the little bar magnets instead the North and South poles are located on the flat sides what we'll see is first of all when we launch it in an orientation parallel to the Earth's magnetic field that the spin is fairly stable you see once again it continues to spin pretty nearly stably about the direction in which it was launched but what happens if we allow the nut and the magnet to float freely in space let's take a look at the case in which the attached magnet has an orientation or a polarity in which its dipole is not in the same direction as that of the Earth's magnetic field but the next thing I want to show is uh when I tip these in a direction perpendicular to that if it's not spinning Watch what it does you see it tips right over and turns parallel to the Earth's field so that it spin access or its access through the disc is oriented with the Earth's field just the way it was before that's its normal tendency is to tip right over and align its own Di pole with the direction of the Earth's field now I'm going to spin it about this direction and we'll see what its reaction is all right now it's more or less spin axis perpendicular to the Earth's field at this point when we have to watch it for just a minute here but the thing that I want you to observe is the fact that its spin axis is tipping over in another Direction you see how it's now tipped over to the point where it's almost facing the camera and now it has it's tipped about 90° but not toward the Earth's field which is off to my right instead it is tipped over towards the camera now this is called precession and we'll go back and check the Earth's field once more we'll see whether or not it's changed take another of our little magnets it may have changed a little bit but not a great deal in the time that we've been uh talking but these magnets are already influencing each other as you can see and they'll align themselves just like that in the direction of the Earth's field now this concludes our demonstrations of magnetic effects in space we've observed first of all the oscillations of various combinations of little bar magnets and then next we've seen the precession of a spinning object in this case a small gyroscope represented by this spinning nut with a magnet attached after you've completed the suggested calculations you will know that the Earth's magnetic field extends far out into space above the Earth and you will have calculated its magnitude and observed its changing direction we've also seen the very first demonstration of precession ever observed in this marvelous new Laboratory that we call space and in this laboratory of course gravitational forces no longer perturb our experiments perhaps your own curiosity and Imagination will suggest even more sophisticated experiments to you which can be demonstrated on later flights e e e for