Test For Success

hello I'm John pitch you know the trouble with balloons is you never know just how much one of these will really take well that's too bad but balloons are cheap and you can always try another one with satellites it's different uh they cost on the average about $50,000 a pound and that's too much money to guess about before you put one of them into orbit you want to know just exactly how good it really is and that's the purpose of this laboratory space science 63 with John Fitch is a presentation of the National Aeronautics and Space Administration today's program tests for Success this is one of the test floors at the Gard space flight center in Green Belt Maryland here most of our scientific satellites go through a rigorous series of pre-launch tests I'd like to have you meet Mr John C new who's head of the test and evaluation division Mr new can can you tell me just how much can you really find out about a satellite how well it's going to behave before you put it into orbit well actually we learn a lot about its performance here in this laboratory we can recreate the conditions of the launch and of injecting the satellite into an arbit and actually the conditions of outer space we have facilities here for example that can recreate the conditions of vibration that you get during launch of uh despinning when it's in orbit uh getting in to orbit and the conditions of uh of outer space could we see some of these um procedures surely let's go down to our vibration laboratory and we can see the actual conditions being recreated there at that plant during the launch of a satellite there are two principal conditions that we're concerned with one is the uh vibration that comes from the Roar and and noise as the booster lift the satellite up into space and the other one is the fact that the booster is beginning to acquire velocity it's changing rapidly in motion and this is acceleration I think I've heard our astronauts refer to both of these I recall one of them mentioned how bumpy it was when he first got started and and of course also the being forced back into his um couch as the rocket picked up speed well those are the effects of vibration and acceleration now in in this particular room here we we are concern ourselves with the vibration effect we have here a satellite it's of the observatory class one of our large classes of satellite it's sitting on a vibrator a a machine which uh recreates uh reproduces this motion and it in turn is sitting on a large uh block of concrete now this uh block of concrete weighs 300,000 lb see and it's separated from the rest of the building that is true separated from the rest of the building and in fact it sits on some very large Springs these Springs are of about the same size as are are used in a underneath a box car on a railroad I see you mean this vibrator would actually shake the rest of the building it would it would shake the entire building here and of course would disturb uh some of the other tests that we're carrying out here so we had to isolate it and uh it's isolated The Noise by means of this large room and so forth does it uh does the vibrator move the satellite up and down a great deal or very fast well uh the the motion is is not too much perhaps a an inch is the maximum motion but the the the rate at which it goes back and forth becomes quite rapid it moves uh oh at the rate of maybe five times a second to as rapidly as 3,000 times a second and this is in fact of course the the vibration effect uh it's so fast in fact John that one could not see it with the naked eye we uh usually monitor these vibration tests by means of instruments and also by means of Motion Picture film uh which we can slow down and actually look at a detailed part in the satellite and see its motion here we see a structural model of a satellite being vibration tested you'll notice the motion in the lower platform and the movement of the particular component now we've jumped up to the next Shell what cause is that well that's due to the different resonances that occur at different uh vibration levels here we see a satellite that's gets a rocking mode uh due to this vibration this is a detail closeup of a particular satellite and you can see that there's quite a bit of relative motion between the various structural members of the satellite system we also have instrumentation of little accelerometers that measure these motions this is a a scene of a particular experiment and you'll notice in this that the experiment actually fails and there's quite a sudden change in the motion level as there it occurred as I mentioned earlier the other part of the launch phase environment is that of acceleration here we see a technician just completing the mounting of a satellite on this large centrifuge huge this is a rotating Arm about 20 ft in diameter as it begins to move around it will create the accelerating force similar to the launch vehicle uh going into space this acceleration is measured at so many G's so many times the Earth's gravity that's correct on this particular centrifuge we can reproduce the equivalent of 50 G's this is much higher than what the uh satellite would actually experience well now that we've tested the satellite for the problems that it faces in being launched what's the next step well a spacecraft is uh spinning uh when we take and launch it away from the second stage it goes on a a ballistic course and to make it go on a straight line we spin it up very fast uh like the a rifle bullet yes that would be similar now it's very important that the spacecraft be very accurately balanced uh during this operation and that's what we're doing with this satellite that you see here it's being checked for its balance now actually it's a little bit unbalanced and we have uh determined by means of this machine the amount of unbalanced and we take a uh a weight such as this and actually we'll attach it uh to the satellite to see uh if this corrects that unbalance so uh soon as this stops why uh I'll show you how we take and attach this test weight uh it's just uh applied to the satellite is we see here then this will be spun up again and checked to verify that this is in fact the correct uh weight to correct the Unbound that's very much like uh balancing an automobile Tire isn't it yes it's very very similar to that in fact we actually use a lead weight here and attach that to the actual satellite that will be launched now does the satellite continue to spin uh when it's in orbit well uh actually not we would want the satellite to be turning only very slowly there so to do that we have uh uh antennas that may have to come out or weights and this when they come out they slow down the satellite now that's a little hard to show it on this machine but I have some films of that John why don't we look at those and we can see that operation best from those films good this is a sounding rocket which has previously been balanced we see the cylindrical nose con being kicked forward by means of Springs at the top of the spinning sounding rocket we see the transmitting antennas that begin to erect suddenly just sort of thrown out there by centrifugal force that is correct and in the center we see a much longer uh transmitting antenna that's beginning to unwind for that long black cable yes but with all of these tests how is it possible that a satellite can ever fail once it's in orbit well of course it depends upon how well we've done our homework how well we've done our testing here in the laboratory you know we had a case of a of a sounding rocket that we were launching and it failed and this disturbed us quite a bit we thought it might have been a random failure but we uh shot another one and it had the same kind of failure now this made us come back here into the laboratory and look very closely at the uh test methods that we were using and in fact we found that this satellite which set on top of the uh rocket motar uh did not in fact have a little centering button that was used uh in the actual launch and we thought this might be giving us a problem that when it was vibrated it would impact so we changed it to exactly the way it was on the launch and lo and behold when we tested it in the laboratory that way we got the same kind of failure that we had gotten out in the field so we were very pleased in being able to find the cause of the failure and we've launched uh several of those sounding Rockets since then and they've all been successes so not only do you test things here but you're actually sort of testing out your tests uh this is correct uh we conduct research ourselves into the test methods and the proper way of trying to recreate these conditions here in the laboratory and unless we have tested them right we know of course they won't necessarily be a success out in space well getting back to our story now that we've got our satellite uh into orbit and the bearings are off and the antennas and solar paddles are out is that about complete the conditions you have to simulate oh no we're now approaching the most important part and that's the space environment now we have several Chambers space chambers that we use for this we've seen some small ones around the laboratory uh let's look at one of our mediumsized ones I think the boys are putting a satellite uh into one now let's go upstairs and look at one of these now John but now can you actually uh simulate the en Enon out in space here well we attempt to do this uh to the extent that our technology will allow us to do it today and this mediumsized chamber which we we see here is an example of uh of how we do that uh the the satellite itself is lowered down into place inside the chamber and we have a large uh cover here which rolls forward and closes this chamber up and makes it absolutely pressure tight then what do you do well we then have pumps uh on this chamber that begin to pump out all of the air that we have in uh inside the chamber to create the vacuum condition of outer space now how uh good a vacuum can you actually create here on Earth well that's one of the real advances in the technology that has come from the space age uh we used to think of uh vacuums and uh all uh just a few millimeters of mercury was very difficult today in this chamber we can produce a vacuum of 1 * 10 - 9th mm of mercury now that uh that term may not mean much to you but that's a, billion a change of a, billion times and that's very few molecules of air left in inside the chamber well aside from the vacuum what other conditions are there to recreate well we have in Space the the vacuum condition which we've mentioned we have the fact that it's very cold out in space when you're not uh looking at the sun the background is very cold and we recreate this uh condition of coldness by means of what we call a shroud and you'll see that around the uh walls of the chamber the black area and we have pipes uh into this material that we pump liquid nitrogen liquid nitrogen is at a temperature of 173° below zero measured on the Centigrade scale and that's very very very cold now you mentioned that sometimes it's uh in sunlight and I suppose it would receive some heat from the Sun yes the satellite when it's uh in full view of the sun receives a great deal of thermal energy uh from the Sun and we reproduce that uh if it's just a question of heating it sometimes by means of infra infrared lamps the like the heating lamps you use at home but often times we have to reproduce the actual wavelengths uh in the sun's uh energy and this we do by special lamps called uh Mercury Xenon lamps or a particular type that we're using here in in our Center well now does a satellite simply sit inside of this chamber or do you actually operate it well that's one of the interesting parts of this experiment that we conduct here uh we actually operate uh the satellite the same way it'll operate out in space we uh exercise its little radio and we send it commands by mean of the ground control equipment and in fact John we actually have the same people who will control the satellite when it's being launched and gets out into orbit those same technicians are right here today uh actually operating this satellite just as though it we're out in space so you're testing the people as well as the satellite that's correct and we try to send them through a training program so they're trained to recognize the uh little idiosyncracies the the peculiarities of each individual satellite we don't build very many of them just one or two or three now can the satellite also send back its information from in here the wood in space uh we let the satellite operate and it tells us what the uh uh satellite is doing and how it's performing also collect information about what the uh the environment in the chamber is and we collect all of this together and by means of computers which we can see in our computer control room we actually take and uh operate the uh uh satellite so that uh we compare the data from the satellite and the data from the chamber uh this prints out on a on an actual printed record so that the space scientist can see exactly how his satellite is performing and compare it with the expected conditions see well now you mentioned that you have um other space Chambers in addition to this uh medium siiz one I believe you called it yes uh this is about 12 ft in diameter and we have some that go up to as large as 30 ft in diameter right over here we have our largest facility for checking out a satellite it's called our Dynamic test chamber what does that mean well we can test the mechanical motions movements of those parts of a satellite which do in fact move out in space it's a very large chamber as you can see it's some 30 ft in diameter and 60 ft tall got to be able to put a pretty good siiz satellite in there well that's true the lid uh closes by moving over the top of the vessel and then we create in here a rather mild conditions of vac this chamber is large enough that a man can get inside of it and operate and we have an air lock which permits the entry of a man oh can we go inside yes uh we can enter the air lock and this permits a man to get inside the Chamber of course we have to set up uh many of our tests inside I was going to say you'd need to wear a space suit if you had to come in when there was a vacuum well that's true John if there was a vacuum in here a man would enter in a space suit well if you're primarily interested in checking out the the mechanical Parts how it moves then why do you need a vacuum in the first place well that's interesting part of about satellites you see a solar uh panel has a very large surface and if we just moved it here on uh in the Earth's atmosphere there would be a great volume of air that we'd have to displace out in front of it or we take something like uh this uh material here uh this is the material that will be used in the Echo balloon now we're interested in the uh strength of this material and how much weight it'll support and how it will uh deploy or open up when we get it out in space if we just check this here uh in the Earth's atmosphere with all the air it would distort it quite a bit so we remove all the air uh enough so that at least we get rid of the mechanical effects and then can check out the entire ecosystem now we we of course couldn't see it in here uh right now so we' have taken some movies of this would you like to see some movies of this very much all right in this scene you will see a section of the echo balloon material unfolding as the uh balloon material comes down from the top you can see the small package on the bottom this is being used to test the strength of the material it's very light flimsy material as to whether it will adequately carry that instrumentation package right next to our large dynamic test chamber we have its twin sister we call it our space environment simulator now it is of the second generation uh a large chamber big enough to handle our largest Observatory class satellite in it we create all of the conditions of space the vacuum and the sun's energy and uh um the coldness of outer space now how good a vacuum can you get in this one well this one actually we get down to the 10th scale uh uh this is 10 times uh better than the one that we had seen earlier we do that by means of uh various pumping systems this is a a diffusion pump which we have here how does that work well we use oil in this diffusion pump uh this oil is heated up and uh it's very hot down here uh as that oil Vapor ra uh Rises then uh it's condensed up at the top and it falls back through a series of baffles and this sucks the gas molecules out of the chamber and they're carried on out through the vacuum line I gather you have more than one kind of pumping system yes we do uh in addition to the the diffusion pumps we have mechanical type pumps let's move over to our control panel and we can see the other types of uh pumping systems which we do use they all work at the same time or no they actually work in series we start off by uh uh the mechanical pumps let me kind of explain what we're looking at this is a control panel for our entire uh chamber and pumping system uh this is the chamber itself these are the shrouds or curtain walls which uh we had seen in an earlier chamber these are our various pumping systems uh clustered around uh here is the diffusion pump which we had seen earlier now we really start out by first removing the bulk of the air by means of mechanical pumps of two types that we have here after we get down to uh oh maybe a millimet of mercury or a little lower we then turn on these diffusion pumps and they begin to capture uh the gas molecules as I had explained in addition uh in this large system we use another type of pumping system called a cryo pumping system we use a very uh cold gas actually uh helium in this case it's about about 80° colder than that liquid nitrogen I had talked about and uh that is in carried in a little panel off on the side and as the gas molecule comes over here and Strikes that panel it's frozen just as though you'd freeze water vapor and this captures that gas molecule and does not allow it to go back into the system we use uh all together here about 18 diffusion pumps in pumping down such a large system we have about 50,000 cub ft that we're pumping down we're not only removing the original air that's in the system but also the gas that comes off of the satellite itself when it operates you see in the space environment now what about simulating the sun in this chamber well we can simulate the Sun and that's shown by means of uh of this diagram here we have a total of 127 lamps that shine down from the top these are all arranged so they fit together it's much like the uh honeycomb you see in the Beehive you see and this total area that we can cover here is about 20 ft in diameter you know uh earlier I was wondering how a satellite could ever fail after it passed all these tests but seeing all these various vacuums and heating systems and extreme cold now I'm beginning to wonder how a satellite ever passes the test in the first place well that's uh that's a good question some of our experim have asked the same one actually this uh business is quite different than what we ordinarily see in in the American economy where we're Mass producing articles in the space business we're only producing one or two of a kind and in Satellite work we uh we build first what we call a prototype model uh this is complete in every detail and we test it to check out the design of that satellite system and in fact we tested about 50% uh more difficult than uh and more extreme conditions than what the satellite itself will experience but then too we uh we never rely on just one system here we try to put them in parallel where we can so we build uh two flight units the the actual flight one we expect to launch and a backup in case something should go wrong and we test both of those systems uh in full scale testing uh here in this laboratory as you've seen so you always ply one of these latter two systems uh this is generally the case we actually had one uh one satellite system the Explorer 10 where we actually launched the Prototype it proved to be that good well what happens when something actually uh does go wrong inside of a chamber well uh this is a failure and uh we of course have to fix that we might uh go look at that now in our failure analysis laboratory we attempt to examine what uh has been the cause of a failure as we uh found out in in one of our Chambers the satellite was not working properly it's now very important that we determine why it didn't operate properly this means in general that we have to come in and diagnose in in in detail uh just what it was that failed to operate now satellite is made up of tens of thousands of Parts some of them have as many as 15 or 20,000 parts so it's it's quite a detective game to find out which part had failed we very often can isolate this to a a particular transmitter or a particular uh experiment that has not operated properly and then from there we have to examine very closely uh usually with a microscope because we are uh building our satellites today out of very small uh parts so one tiny little part could jeopardize an entire project that's correct and uh this could defeat uh the entire satellite now we see in this particular microscope here a very small tube this is a subminiature tube that uh is used in the transmitter of this particular uh satellite and we can see in the picture that the very fine grid wire that makes up a part of this tube actually fail during the vibration test and this was what caused uh this particular transmitter to uh become inoperative now in some of our other uh satellites and uh component parts we are starting to use uh solid state devices things like transistors and uh doodes and in this particular setup that we see next uh we see a diode being examined and in this uh picture we see a very fine particle of dirt uh which became lodged inside the glass capsule uh that that makes up this component and it was this very fine Speck of dirt that caused this component to fail how did it get in there well this uh got in there during the manufacturer of this device and quality control is extremely important now as we examine these parts we find uh it's very important to uh keep clean and and to be careful as we examine them because often we can we can defeat the examination in this next uh example we see an entire circuit a subminiature circuit that uh is uh being examined and we can see a hair uh here in this picture that has lodged onto the circuit and has caused it to fail once again something during the manufacturer of this particular circuit well well it seems to me that the detective work you do in this laboratory must be an really important part of your entire testing procedure well it is it's here that we find out the reasons that uh a part fails it's uh it's here that we find out why a satellite might not work in space but we correct each one of those and substitute a part that we know will work and it's here that we move the satellites from the failure columns to the success columns and we can say that everyone that has gone through this program has been a success in space well thank you very much Mr new we've been visiting the test and evaluation division here at the Goddard space flight center where each satellite must meet and pass its test for [Music] success [Music] I I [Music]