before it, it is a marvel technology, a remarkable instrument of humanity's search for knowledge. late in august 1981, four years out from earth, voyager two reached that most beautiful of planets, saturn. the first of the two voyagers, had flown by saturn. in november 1980, sending spectacular closeup pictures,. 140,000 million kilometers back to earth. voyager one discovered hundreds of rings all very different different. voyager two would fly even closer. saturn and its moons, its mission to expand upon the revelations of voyager one. the flight of the voyager is an ongoing project with. several major assignments in future years. there. control center is the jet propulsion laboratory in pasadena, california. scores of reporters came there from all over the world for the week of voyager saturn encounter as they reflected excitement over the space probe that was as strong among ordinary people as scientists for a long time trying to explain. and they followed voyager progress, a daily press briefings in a packed auditorium. on august 24th, the day before the flyby, reporters saw movie made from stills took on its approach of spokes in saturn's wide b ring. the time lapse sequence has now been dr. brad smith, head of the team assigned to interpret voyager pictures described the film an hour ago and there's a lot going on in this time sequence. i feel the spokes are trying to tell us something. it may be days or weeks before we really understand what they are trying to tell us. by that time you would all be gone. so we're going to share it with you this morning and all of you out there can do instant science right along the rest of us in trying to see what's happening. there's a lot of complex activity going on. one tends to see some spokes looking as though they're sharing out others, seem to be forming. others seem to be fading away. so why don't we just go to it and we can all analyze the problem. go through it twice fairly fast and then twice a little more slowly. you have to be careful of projection effects. it appears that some of the features actually. to it. dr. smith also showed a new and spectacular color picture of the rings. now, this is greatly exaggerated color, but what we were concerned about with these were these within the ring when you when you look at a at a normal color version of the b ring, it looks fairly uniform. but when you really push and particularly get down into the ultraviolet, then we see that these are real changes across the ring. so here's the sea looking blue relative. the other rings, it's a little bit dark. the cassini looking relatively and then this this structure here where this region is a little bit bluer and this is a little redder than average. so even the big ring there are differences in the in the spectral reflectivity it is not a homogeneous ring in that sense tightening each in the laboratory is on television production mission. scientists were interviewed by voice of mission control. dr. al hibbs. gibson asked dr. smith about those color variations and the rings. were sufficient to. one of the possibilities that could account for this is kind of different. is it does it imply these are quite different minerals or are they being exposed. different kinds of things. well, that's that's what we don't really understand. all we see is a effect that could mean different composition among the particles between the big rings ring, or it could be a purely superficial effect something happens to the ring particles, perhaps a color color dislocations in the in the crystal structure that the due to high energy particle bombardment slightly cause the surface of the particles so different in the ring systems. but smith and his fellow scientists were sure of one thing, and now, you know, counting of rings in voyager one, we had estimated that there hundreds perhaps even up to a thousand. now we're getting higher and we're finding that many of the rings that we're seeing is thought were single rings. and the voyager one photography are now turning out to be multiple in some cases 30 tiny individual ringlets where we thought there was only one. so what we're finding is that we shouldn't be seeing a thousand, we should be seeing thousands there is far more structure there than we thought from the voyager one. dr. smith. a disappointment. voyager had discovered three new saturnian satellites. two of them seem to keep the thin ring contained, like sheepdogs chasing strays into the pack. this led to a theory that the gaps between various saturnian rings were kept clear by other satellites. but unfortunately, dr. smith told him no new satellites were found to explain and have now, after searching than here supposedly would be located in some portion of this of this particular or the dark gaps in the top and bottom of that close up. so in fact, it was found that it was within those two dark gaps that we conducted the search for this 30 kilometer object. as i said, fortunately, we didn't find one. and so that leaves us unable at the moment anyway to explain the mechanism to these wide gaps. it was the only good theory we had at the time. and it's another theory, i hope, another theory will. august five, 1981, at last, after four years, the day of voyager two was closest approach to second largest planet at dawn, california time, the spacecraft was still about 800,000 kilometers away that evening. and the 825 voyager would fly over saturn's cloud tops and begin its long swing around the dark side side. by now had had a chance to examine voyager as pictures of the moon. hyperion the us attorney and the satellite. that's an american discovery. the first picture of the moon as it turned out was of its flat edge and suggested a cylindrical shape. but later pictures showed odd flat shape akin to a potato, a peanut, a hamburger. and while the axes of other saturnian moons in line with the axis of a mother planet hyperion has tilted the other way. the scientists couldn't tell why. voyager had taken time lapse pictures of saturn earlier in its approach, a film made from these pictures showed new information on saturn's. there. dr. edward stone voyager project scientist explained that scientists were looking for rotating cyclone like storm systems in saturn's northern hemisphere. sure enough, we have found them. we found them spinning off behind a larger structure. and it's those storms which evidently are very important to the development of the weather system on saturday and presumably also on jupiter. so i think that major objective we do the detailed analysis of those storm systems, exactly how rapidly they rotating, what their speeds are and relate to the high speed jet streams that we may have a very important piece of the story for the weather system on saturday. the hours ticked away and voyager raced on towards saturn as this animated film dramatically the pull of the planet's gravity steadily increase. the speed of the spacecraft. when the day began, voyager was traveling at 13 and a half kilometers per second, at closest approach. it would be moving nearly twice fast or more than 24 kilometers per second. during last two and a half hours before closest approach, voyager performed a fast awaiting ring encounter task. some 2 hours of watching the star delta scorpio go through the rings, the number length of the light flashes were disclosed. precisely how many rings there are, as well as their positions and widths. voyager then moved to its approach, flying 100,000 kilometers above the cloud tops. the spacecraft entered the planet's earth and sun disappeared. its view. voyager's radio voice was cut off by the planet. it would be heard again if all went when the spacecraft emerged, the shadow. but scientists have to wait more than an hour for renewed voyager transmissions to reach earth and receiving stations in australia. if all had gone according to plan australian station reporting into the deep space control center, the status and operations of that as it picked up the signal, as it came through and all was well, champagne was born of the celebration project manager esther davis was happy. hey, why? after its long journey, voyager two had been off target at closest by only 2.7 seconds and 48 kilometers south of the power station. but suddenly, scientists on duty discovered that something was wrong. we'd like voyager was telling them it had problems going, getting closer. now what the scientists discovered was that the scan platform, which the cameras would not move to follow through all isotropic and up. so the next morning, august 26, with voyager moving on past saturn escort demonstrated the problem for reporters. this whole thing is the scan platform that we're dealing with it moves in two directions. this is the asthma. asthma direction and that's that that's the direction of rotation where we're having a problem where it appeared to get stuck during the time period it loads an elevation and that direction appears to move without any difficulty and move properly. so we investigate and with these tests the movement of the scan platform attests last stating moved at a very slight bit to see if we could move it test earlier this morning. we're increasing this amount of movement, this excursion and the gearbox that drives of this is this device i'd looking area here where are all of the gearboxes it's a bit of clockwork kind of thing a lot of gears and drives this game platform through the series of pipes axes. speculation was that had flown through a swarm of small electrified particles that found its gears and navigation systems a very powerful tool. dr. stone was how much the cameras had missed after being put out of action. the things, therefore, that really knew part of voyager that is imaging the right side of the rings that at very close approach has been completed. the part which we will miss, obviously the imaging of the dark of the ring and of course that's unfortunate. but we did do some dark side quite a bit dark side imaging of the ring on voyager one and my phone doesn't come back when the spacecraft can't be oriented for one reason or another. can you put a percentage number on. how much of a mission goals have been achieved? i would have to say essentially of them. the only think the major area where we're missing some key data is probably on enceladus, having gotten only one of our three high resolution mosaics and 10th is where we got one or two. meanwhile, voyager had continued to send back taken before the closest approach and stored for later transmission. one such picture concerned that thin outer f ring this voyager one picture had made it seem like rings braided together. dr. stone discussed the new voyager two f ring picture without him and the f ring in this picture and this is one of the things that surprises does not show this beautiful braided destruct. well, you may remember that bon one. we had just one image where that was very structure. it may turn out that is not the characteristic of the entire ring, but it is a very localized effect. and so we will need to we're imaging great deal more of the ring to try to trace out its characteristics. here's another one of that same region. and then here we're getting again detailed structure of the the ring system cells. there they are. some of these like that one where one can see between in there, you can see the near and narrow dark, a gap. and next to it, a series of shallower, less dark ridges, if you like. evidently, there are variations in the thickness of the ring. we're looking at the light scattered off the lighted side of the ring. and that's, again, telling us something very important about how that gap is formed. i'm sure it's telling something of that nature. august seven, by day's. voyager two would be nearly two and a half billion kilometers past, cruising around 12 kilometers per second, specifying the word from project manager asker davis was that the scan platform had been made to move, but not as much as he'd like. so we cannot yet say we can move it reliably and we've restored some kind of normal operation. so that's still our our objective. we're not yet at a place where we're saying we're fixing the problem. we're still trying to define the problem and understand what it is. there are going to be a lot of tests, as i over the next few days. a bit upbeat and positive. a lot of work to do yet to get where we want to be. morning. yesterday i got. the question given the scan platform had stopped. what was my estimate percentage of success with the voyager two encounter. and i did not really have a quantitative estimate at that. well, i've had 24 hours since then to give the question some thought, and i have a number for you. the number is 200% for. at the same press conference, a dramatic partial picture of the moon tethys was shown the heavily moon wants to be photographed soon after the spacecraft flew around behind saturn, voyager managed to the partial picture in spite of its jammed platform. even more interesting were the pictures of unsullied. brightest moon in the solar system with a surface so starkly white that it radiates 100% of all the sunlight that falls on it. voyager two had sent back in some of those pictures taken just about the time of its closest approach to saturn, just before scan platform jammed and. some of this has stayed quite by washing clean. dr. eugene shoemaker, that turns out. there's a region along the satellite here which was intensely about 3 billion years ago, allowing most of the craters to relax while at the same time in this region over here the craters are not relax so that we discovered quite unexpectedly that that the satellite was heated non uniformly like earth and its moon and senators and neighboring diani pulling each other back forth each time they pass, creating and heat. this may be a clue as to how the tidal heating takes place. it may take place when there's sudden rupture of the satellite. perhaps by impact, allowing of the two different parts of the satellite, frictional heating under the tides and then a discrete region will be warmed up and actually may liquid in the interior because we think some of these surfaces actually have had water flowing out on the surface and the crust then becomes very soft and craters will collapse. more. august 28, voyager two was 3 million kilometers beyond saturn. with luck, there still might be pictures of the planet's dark side. meanwhile, this was the last official day of the encounter. when it was over, reporters would pack up and go home. the final morning press conference began. good news come a little smile on my face today because there's a good chance that saturn will be on our tv screens by the end of day. the bearer of the news was richard lester, deputy project manager. progressively. in each of the three diagnostic tests performed on the scan platform, the the stickiness and the slower than normal performance that we've seen has gotten better. the tentative and this isn't a whole lot of data to work from is that the platform gets better with use. after our initial problem a few hours later there was indeed a saturn picture the screen. dr. stone and al hibbs discussed it in their daily interview perspective. but i think to start with, we ought to point out we have a picture finally from the voyager. it doesn't look like much to begin with. this picture is part of a sequence which was deliberately underexposed aimed at a portion of the dark of the rings and indeed the dark side of the rings is right in the middle of the picture. yes. see the shadow of saturn cast on the rings. and of course, we're looking at the dark side of the rings as so the rings are not very bright, even where they're not behind saturn. this is a wide angle, camera shot and is an indication that, in fact, we did reorient the scan platform and will allow us to continue observing saturn for the next few days. really quite an exciting picture to see. it is on elsewhere in the laboratory. scientists were finding new surprises in their immense treasure of incoming data. one concerned that finn f ring which seemed to keep changing in the latest pictures. it was not a braided ring. as voyager had seen it. not a single as voyager two had seen it earlier in the week. but many strands. an interesting theory about the black spot on the leading edge of iapetus from an australian scientist. voyager two had learned that iapetus has mass than had been predicted. that could mean the scientists suggested that the moon contains methane, along with its ice and rock. solar radiation and other bombarding the surface could react with the methane and black as pitch hydrocarbons. and now there were second or third thoughts about the possibility additional shepherding satellites. they were in favor again or, the new theory centered around the rings and the inky division. named for its founder or doctor is richard tirrell. jeffrey kinsey were two scientists who helped interpret pictures. well, at least for this agreement, we call it the kinkier ever thinking in the yankee. and i say these these kings here are a pretty good fit to the theory that's been advanced to explain the brains in the airframe which basically involves gravitational pulls by force and shepherding satellites. and this might be taken as an indication that this division contains, some such small shepherding units, that is an embedded movement of a sort, it would probably have to be pretty small. we'd never be able to see it because these these braids, these things are so close together and small, maybe a mile in diameter. so voyager one had found rings of the cassini division once thought to be a gap. voyager two was finding more before we had the idea of the cassini division, a division, and then we saw a close up and we saw it's really a bunch of rings bracketed by two divisions, smaller divisions. now we're looking at each one of these divisions, and they're not even simple. they've got rings inside them and those rings have complicated structure. when asked for their final analysis of saturn's rings system to and because he said there is final analysis, i think a lot of people were sort of under the impression as we get higher and higher resolution the rings we all of a sudden reach the point where it will say, aha, we found it. this is what explains the structure things. i think what we're finding, we get higher and higher resolution. the theories that we developed to understand the rings are getting more and more complicated, just as the structure in the becoming more complex, trying to get a deep understanding right now from more or less. the first look data i mean there's overwhelming amount of data even with problems we had in the second half of the encounter, it's still it's it's sort of like drinking out of a fire hose to it. there's so much data at you so fast that you can't really formulate your theories and i'm not sure at times one scientist advanced a new theory to explain the different colors in the rings color. he suggested is determined by particle size the smallest our nearest the planet the largest at the outer edge. but he said the composition of, all the particles seems to be the same. does he sided with those who believe all the ring material came from a single celestial body that broke apart. oh, dr. smith talked about the possibility following up on the new ring data, thinking we hope that we've obtained the right observations. now with voyager two. but if we haven't we still have another chance when space telescope goes into orbit around the earth in 1985. it has sufficient resolution to reveal these spokes at the level of which we need to study them. that unfortunate lee is about the only phenomenon going on within the rings where future ground based observation or near earth observations will help us out. with voyager saturn flyby. as with voyager one's, there were remarkable photographs that went beyond science to the esthetic wonders. the distant heavens. dr. stone, pleased with the saturn encounter, looked ahead to what he hoped would be a long and more exciting discovery, or the last of the voyagers or voyager two is now on its way to uranus. it arrives at uranus in january of 1986. uranus is about half the size of saturn, but a giant planet compared to the inner planets one of which we live on. very interesting thing about uranus, though, that it's spin axis is pointing will be pointing basically at the sun when we arrive in 1986. so that we approach uranus, we will see the north pole and we'll see in the sky a eye pattern of nine narrow rings and the five known satellites orbiting the same bull's eye pattern. we will fly by uranus, returning data with quality comparable to that which we achieved just in the last week at saturn. head on to neptune, which is 30 times as far from the sun as the earth. encountering neptune in august of 1989. and we have a plan to essentially fly over the top of neptune's north pole, the closest planetary flyby, the whole mission on to its moon triton, which may be a twin of the moon titan at saturn. remarkably, with that 1989 flyby of neptune, american spacecraft will have closely investigated every planet our solar system except pluto. there have been no missions to that farthest planets, but scientists believe neptune's moon triton is so similar to pluto that much be learned after all. both voyagers will continue operating until their fuel runs out the turn of the century. when that happens, their antennas will begin to drift and lose contact with earth. before that time, voyager one should find the edge of our solar system where our solar wind is replaced by intergalactic winds with emissions accomplished. the voyagers will have just begun an infinite journey. bertrand and paterno is research fellow at the hoover institution and a
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