And Then There Was Voyager

[Music] many of us expected this would be a mission of major discovery but none of us really expected the degree of discovery the degree of diversity which we found in the outer solar system we were lucky we had the unique opportunity to explore planets that man had never been to before but Voyager didn't only carry sophisticated instrumentation it carried the hearts and the minds of its creators and all of us who were privileged enough to see what it's all and it will be unique enough for a long time because there is anything else out there to explore for which you can get as much return in from the single system I think Voyager will be remembered as part of the few decades where human race left its planet and voyage will be a main chapter in that book Voyager kind of opened up the outer planets to everybody and I think they were vastly more interesting ly expecting up to and including and making a special nephew you only explore explore the solar system for the first time once [Music] and we did it you the outer planets are giant planets they're distinctly different than the smaller rocky objects in the inner solar system such as Earth Mars Venus and Mercury and Voyager was designed to open up to exploration these giant outer planets which are spheres of rotating fluid gas surrounded by 57 moons totally each planet has a unique ring system and they have magnetic fields which were immense compared to the magnetic field of Earth voyagers job was to explore those worlds in the outer solar system [Music] scientists at cape canaveral florida sent another unmanned voyager spacecraft on its way to jupiter and saturn today it lifted off flawlessly at 856 a.m. and had none of the problems of the Voyager launched two weeks ago this Voyager presumably will get to Jupiter in March of 1979 words are too scared Roger to had the problems in separating from the solid rocket kick stage the spacecraft today you know have a few problems but most of these problems were problems we experienced early on there is the voyager 2 spacecraft has a failed to receiver and and a sick back up receiver that's the most serious problem on board that spacecraft the way we communicate with the Voyager spacecraft is that we send commands to the spacecraft series of digital bits and computer language I go to the spacecraft and the language spacecraft to understand understand these gifts are transmitted from ground stations located around the earth where we call the Deep Space Network the 3d space network stations are located in Goldstone California outside of Madrid Spain and outside of Canberra Australia as the Earth turns we can maintain communicant in use communication with the point in space the spacecraft in turn there's kind of the reverse link coming back down the information that the spacecraft gathers goes into a transmitter on the spacecraft it's transmitted into those big ears on the ground of the Deep Space Network and transmitted back then on the ground to our control facility here in Pasadena the center on Voyager is like 10 the watt like 20 watts less power than an average light bill damn near front porch on the other hand when that signal has received on the earth it is literally a tiny tiny fraction of a lot that has received the amount of power received by the ground antennas is something like a billion of the amount of power used by my digital watch man is known about the planet Jupiter ever since he took a good look at the night sky it's not what you'd call a near neighbour though being more than 400 million miles away but after all these centuries we're getting a closer look than we've ever had and Voyager got up close when we looked at the time lapse moving from the atmosphere in motion things were changing every day little farms would pop up out of nowhere and get ripped apart were solid in stages and that made the mystery of the Great Red Spot and all those other or large spot even deeper because how could they last for so long in the midst of all that chaotic motion it was a startling discovery as voyager approached jupiter the first thing that inter intercepted with what's called the bow shock that they shocked with a supersonic solar wind becomes subsonic and that shocked the solar wind velocity which is a million miles per hour of roughly decreases 250,000 miles per hour that abrupt change in velocity causes the ionized gas to vibrate and we can sense we can hear the shock and we can hear the vibrations associated with that shock as a spacecraft flew through the shock Excel we had expected that the magnetic field might expects tend something like a million miles or so from the climate in fact it extends some three to four million miles from the planet now we understand because I 0 is injecting into the magnetic field some one to two tons of material every second that material as it's been with Jupiter is centrally expanding Jupiter's magnetic field and plating it to a much larger size than it would normally be we expected quite frankly the satellite to the outer solar system to be quite bland and geologically lifeless as we flew closer I would look less and less like anything we've ever seen the impact craters turned into a regular dark patterns and the colored patches red yellow painted on the surface as a matter fact as we flew closer we saw nothing at all that resembled an impact crater if Voyager 1 discovered 11 active volcanoes and nine of those were still active when Voyager 2 returned for months later I think the the event in the in the admission which really altered our view and our expectation for the rest of the mission was the discovery of the volcanoes an aisle that was such a dramatic and unexpected thing to find that it really told us that we could no longer be complacent we can no longer expect to understand or anticipate what we were really going to see voyager 1 flew in close to Iowa for a close-up flyby of Io to give good return from eyal and made its close encounters with the Galilean satellites after the closest approach of Jupiter if we look at Callisto it's one of the most heavily cratered objects in the solar system works Lee saturated with impact craters we looked at Ganymede and find two kinds of trains one is the terrain looks very much like Callisto but in addition Ganymede has a very complex intercepting network of false in a younger terrain which was evidently welled up to the interior and replaced it this old cratered terrain is so similar to crystal the case of Europa we see yet another style we see gargantuan thought patterns in which this ocean has frozen repeatedly broken open and fluids float up to the surface producing dark puddles of material within the faults weezer then broken again so there's intersecting and cross-cutting networks there were two small satellites discovered at Jupiter one of them found orbiting just outside a very thin tenuous ring of material that was discovered the Jupiter the imaging team members planned one single photo an 11-minute exposure that would be taken as the spacecraft plunged through the equator plane of jupiter and it just so happened that it was a ring there is dustin there seems to be no indication of water or ice within the ring so it's probably minute of rocky material an outer space spectacular that was the stuff of dreams only a generation ago began snapping into the sharp focus of reality today after its billion-mile journey from Earth to Voyager 1 spacecraft sent back pictures of man's closest look yet the ringed planets at the closest encounter of spacecraft and planet occurs later tonight when Voyager sails just 77,000 miles from Saturn's yellow clouds but already one playa de said in a strange world of Saturn's rings the bizarre as the common common place The Closer that Boyd you got to Saturn the more and more detail and structure Saturn's rings turned out to have and this just was an enormous surprise to everybody the rings were simultaneous with breathtaking a completely baffling and there was this far more structure than people had anticipated not only did we find many many concentric features of in the Rings but we found eccentric rings we found that the F ring which had been discovered by pioneer had braids in it and kinks and clumps all these things no one had ever even dreamed about before Voyager death of Saturn [Music] and then of course they were the folks that's where you discovered about a month or month and a half before encounter and these of these radial features in the Bering that come and go they are seen orbiting around the Rings and no one had a clue or at least not a yeah not a reasonable clue in the beginning as for what caused these features or even what they were that if you look at the rings of Saturn it for a period of time and watch this folks go around and round and you examined the appearance of the spokes on the ring that appearance changes and it changes with a period that is equal to the period of the spin of Saturn's magnetic field Voyager found that Saturn's magnetic field as pioneer 11 had already told us is his weaker that is it's only about 120 of the strengths of Jupiter's magnetic view that means its magnetic field doesn't extend as far from the planet about a million miles from the plan of what Voyager discovered was how rapidly that magnetic field is rotating the magnetic field of Jupiter rotates with a period just under 10 hours at Saturn it turns out the magnetic field rotates with a period of about 10 hours and 40 minutes so this was the first measure of the length of the day on Saturday turns out when we finally measured the magnetic field in the radio emissions that are tied to the magnetic field that the inside of Saturn is moving quite slowly it's moving more slowly than most of the storms in the atmosphere and the difference in those speeds translates to 500 meters per second for the winds which is over a thousand miles now and that made Saturn a lot windier planet than Jupiter and that was the big surprise for me and we win Voyager gotta voyager 1 approached Saturn in such a way that it who passed Titan before its closest approach to Saturn that trajectory then because of the tilt of the satellite system around Saturn caused the spacecraft to fly Lowell initially and then get deflected as it made its closest approach to Saturn going through the rain flame up out of the plane of the ecliptic we knew that Titan had an atmosphere we had no idea how deep it was or what it was made out of and what Voyager found was a nitrogen atmosphere with traces of methane and other hydra fibers and it was turned out to be quite as fast here we suspected might be an ocean of material called ething there could be all kinds of complicated hydrocarbons of different colors and different states and Isis some fluids there's all manner of hallucination about hydrocarbon goop that rains out of the atmosphere and falls on the surface aznar fact hiking remains one of the really exciting challenges for future exploration the case of limas we see a crater on Linus that's about forty percent of its diameter a little larger and that would have been enough to shatter the the object and of course when would this be the crater then because it would reassemble like a kind of a giant ball of sand and the case of kathy's there's another very large crater even larger than the one on my man but in that case notice the floor has is now rounded out so that it is curved as the rest of the object lunes the case is Diana you'll notice that most of the surface is pretty bland and only in this one region near the trailing hemisphere do we see a lot of detail on the surface here we see a lot of crisscrossing faults with wispy bright markings around them finally we look at Enceladus we're talking about very cold regions in here we are with this little tiny object showing geologic activity of the scale that in felda stud in which the ancient cratered terrain has been broken and has collapsed into the interior fluids and flowed out into those open gashes in the cross repeatedly yes I can see ya x-ray man well after we got courage or 12 Saturn we went back to NASA and said we have now satisfied all of the objectives for the MJS for the Voyager mission how about giving us money and giving us permission to target Voyager to tweak its trajectory just a little bit so that we can go on to Uranus with a penalty for this the data that we got quality of the mission of Saturn was a little bit less if we targeted for Uranus and it would be if we optimized percent and we buried all those facts to NASA we told them that it was maybe a sixty seventy percent chance that we thought it was worth it and I guess we were pretty persuasive because they bought the idea soon after boys are foods closest approach to SATA thanks while it was behind the planet if scan platform cop stopped at a mechanical failure and we weren't able to aim the cameras and the other point of all instruments on the spacecraft at the target after several years we concluded that in fact during the Saturn encounter we had moved this platform too much too fast and that if we used the platform in a consistently slow at a slower rate and if we constrained the total amount of angular motion that we applied to the platform and in fact we would be in a pretty safe condition Voyager to the amazing robot spacecraft that was launched eight and a half years ago and just kept on going past yet another milestone today as it became the first spacecraft to fly past the planet Uranus Uranus is not a very shortage etic place it looks more or less like a big blue ping-pong ball but we did see clouds in the atmosphere of Uranus and they did tell us something in fact Uranus is a tipped over version of Jupiter inside the cloud patterns are more muted but they have the same kind of banded structure that Jupiter and Saturn here now what that says is that the spin of a planet is the all-important process or thing that organizes whether Uranus is a very peculiar plan in the sense it's tipped on its side right now with the south polar region headed pointed at the Sun we had expected that the magnetic field pole would also be up near the rotational axis so the magnetic field would be pissed on its side what we found was to everyone's surprise it's a magnetic field rather than being pointed at the Sun with Chilton some 60 degrees from the rotation axis not only that but the center of the magnetic field was displaced from the center of the planet by almost a third of the radius of the planet the ordinances magnetic field is a bit stronger than that on on Saturn and it extends some 300,000 miles from the planet the rotation period that is the length of the day on Uranus is measured by how rapidly the magnetic fields rotating it is about 17 and a quarter hours the big problem going on to Uranus is that it's twice as far away from the earth as battering us in order to compensate for the darker environment we had to make sure that the spacecraft would be steadier and to make the spacecraft steadier we had to deal with the things that made the spacecraft moved my love is just flying through space the Iranian rings are inherently dark in fact they are no brighter than cold up so imagine trying to take an image of coal dust a twilight but it's even worse than that so we had to worry about the necessity of using long exposures and the fact that the spacecraft scan platform is not a stable platform and always move someone best image that we got in fact is the Iranian ring system we had to use image motion compensation what we saw in that image is a sheet of dust that extends throughout the Iranian ring system and this sheet of dust is punctuated by our features many of them there are more features in that picture then there are rings seen from inbounds so we have nine narrow rings seen in the inbound images and one newly discovered one the lambda ring as a matter of fact if we had our choice we never would have gone close to Miranda in order to get to Neptune we were obliged to go a particular distance from uranus in order to get the right gravitational deflection on the spacecraft well turned out that that distance was exactly the distance that Miranda's orbiters from uranus it is a very exotic and complicated place most of the regions that we viewed are heavily cratered cold rolling ancient arranged but embedded in these are very unusual circular patches almost like racetracks of groove trains that run around in circular bands surrounding very complicated crisscrossing structures from the interiors [Music] we address the question what can we do to hear the data better we did come up with a technique called a rang where we took existing antennas and electronically wired them together so then in the fact it had the appearance of being one larger antenna and we did that in Australia the primary receiving side Ernest and combined the DSN station with a borrowed antenna from the Australian radio Radio Astronomy community at parks standby park while we were moving from uranus and neptune and the ground we had two major things to do first of all we reprogrammed software on board the spacecraft need two things to stabilize the spacecraft that the pictures would not be seared and to add some new techniques of spacecraft that will allow it to pan and track the planet when we're taking pictures near the planet second thing we had to do is improve the communication capability we did that since the instep tune is twice as far away from communication standpoint is earnest we did that by enlarging the planet antennas on the earth and by adding several me such an antenna into our deep space network to help compensate for this [Music] it is mission accomplished for Voyager to the space probe is headed out of the solar system tonight after photographing parts of the universe no one had ever seen before now we had some hints from earth-based observations that Neptune had a few clouds and we thought was better than Uranus but we really weren't prepared for you spectacular weather activity that was found in fact nature is the windiest planet in the solar system and I was totally unprepared for that the winds are three hundred twenty-five meters per second that's the speed that the great dark spot is moving relative to the inside of mention everything's going to the east but the great start spot is going more thoroughly to the east than the inside of Neptune we had expected because Neptune does is not tipped on its side as a planet but is an upright planet that the magnetic field X was access would be aligned with the rotation axis that is the poles would be near the rotational pole we were surprised again the magnetic field is tilted by 47 degrees in the case of Neptune and its center of the magnetic field is offset by almost two-thirds of the radius of the planet its magnetic field is somewhat weaker only about half of that of Saturn for instance at the surface and its magnetic field extends only about 400,000 miles from land surface we did discover that the rotation period of the magnetic field is about 16 and hours and seven minutes faster than Uranus but slower than both Cupid ER and Saturn as we approach Neptune you're approaching the Sun and the earth almost directly behind us so we could see with virtually a full disk of Neptune and we aim to go right over the North Pole right up over the topic of Neptune very very close to neptune a trajet have been bent by gravity moves south and we intercepted Triton while it was behind Neptune and underneath it well as we got closer and closer to Triton it got smaller and smaller and smaller and at the same time brighter and brighter it turned out to be the brightest thing we've seen in the solar system north of the polar cap in the North just above the equator we find one thing we call the cantaloupe terrain it has a system of crisscrossing ridges which produced a set of almost squarish to ovoid dimples throughout the surface now we're talking about a surface which is 37 degrees above absolute zero this is the coldest thing in the solar system by far even the cold atmospheres of things like Neptune are warmer it was unthinkable to find activity going on a planet the surface temperature is that low I mean this is getting down a point where molecules thought it was about a month after the Reuter encounter that we were looking at stereo images way down in the southernmost part of brightness polar cap and we saw most of the features lined up as if they were on a perfect sphere in fact the two best examples turn out to be active eruptions in which material is being blown from the surface in a vertical column to an altitude of eight kilometres roughly five miles what you discovered six new moons at Neptune now two of them were found in the ring our core ring system orbiting a long two of the ring arcs so apparently shepherding the edges of those ring arcs in some way when we look at Neptune's ring systems as we can see here in this mosaic we see three continuous rings quite easily there is an outer ring it's the ring in which in fact the three arcs are embedded there's an inner ring which at in high phase geometry appears brighter than the outer ring that tells us right away it's dusty dustier than the outer ring and then we see an inner more diffused ring at something like 42 thousand kilometers from the center of the planet we believe now that we'll be able to communicate with Voyager essentially as long as its favor line two things will probably stop its life first of all it has a power source on board which the small nuclear power source called radioisotope thermal radioactive decay of plutonium which generates heat which in turn is converted into electricity in about 20 to 25 years we expect to be low enough so that there's not enough power the critical subsystems a spacecraft operating or at about the same time we could possibly run out of attitude control fuel at the fuel which goes through little thrusters which keeps the spacecraft stabilized in pointed at the earth now between the stars is a dilute gas ionized gas filling entered interstellar space is called the interstellar medium each star blows a bubble in that interstellar gas our own Sun does that that bubble in the case of our Sun is called the heliosphere we don't know how large that bubble is it may be that the distance to the edge of the bubble called the heel cause is a hundred times the distance from the earth to the Sun that is three times further than it is out please Neptune in which case 25 years Voyager 1 which will at that point the 130 times as far from the Sun of the earth could well be returning data from interstellar space for the first time there will be a part of her which will roam essentially forever in the gallery and that will be the Voyager spacecraft [Music] you