40 Years Voyager - 2017 NASA Science Lecture

the von Karman lecture a series of talks by scientists and engineers who are exploring our planet our solar system and all that lies beyond good evening ladies and gentlemen how's everyone tonight excellent cool thank you all very much for coming out tonight we greatly appreciate it so in 1977 NASA's twin Voyager spacecraft embarked on an incredible journey after delivering delivering stunning images of Jupiter Saturn Uranus and Neptune the probes sailed on to study the boundary of our heliosphere Voyager 1 crest crossed that frontier in August 2012 becoming the first human-made object to enter interstellar space Voyager 2 is expected to enter that space in the coming years in this talk our guest will revisit the highlights of the last 40 years including the latest results from the interstellar medium tonight's guest earned his PhD in physics from the California Institute of Technology in 1973 and since then has been employed in the space radiation laboratory of Caltech where he is presently a senior scientist and member of the professional staff he is also a co-investigator on the Voyager mission the advanced composition Explorer mission and the Parker Solar Probe mission he has been the instrument manager for five previously flown instruments and is currently the manager for her instrument on the Parker Solar Probe which is scheduled to launch in 2018 his research interests include anomalous and galactic cosmic rays as well as solar energetic particles currently he is analyzing data returned from Voyager 1 in the local local interstellar medium and from Voyager 2 which is beyond the solar wind termination shock he is the co-author or author of more than 100 publications in refereed journals and in addition to his scientific pursuits he's an avid tennis player and bird watcher ladies and gentlemen please help me welcome tonight's guest dr. Alan Cummings thank you for that very nice introduction I'd say before we start I just was wondering how many people got an opportunity to see the farthest the documentary about Voyager it was on PBS last night and it was at the Langley theater last week and it's gonna be repeated I think on September 13 so it's it's a really good movie I'm not in it but nonetheless it's a good movie okay so as Mark said I've been working on Voyager since before launch and I've even given two of these von Karman lectures before one in 2007 and one in 2012 and I'm happy to say that a lots happened since the last we are Voyager 1 is an interstellar space let's have a hand for that and Wow forty years that's a tribute to a lot of people that have worked on this mission and are still working on this mission I read somewhere that through the Neptune encounter eleven thousand workers had been put into it and that was 28 years ago so does it it's a lot more than even that okay I wanted to give you a feel for the little bit of my history with Voyager and what I did and I was going to show you for example a picture of a stack of my notebooks for Voyager now the the first one I filled out was on the bottom and the current ones on top and I know those of you in the back can't tell how big a stack that is so I put a picture of myself next to it the county and well maybe I exaggerated a little bit anyway I could have probably found a better picture of myself but I was desperate for time time ran out on me and this is the best I could come up with and it was taken some time back when I had an encounter with a barbecue grill as you can see by that problem there and what I learned from that encounter was don't put your arm directly in the fire you know the hairs getting burned off your arm and some damage can occur as well and as a matter of fact it appears to me that it's shortened my left arm by about two inches but shoulders are pretty squared anyway if any of my tennis buddies are out there this is probably why my serving toss has gone out of whack lately okay let's look at the very first notebook this it's hard to tell what that notebook is it says something like TS at one is the best I can tell so here's the spine spines a lot easier to tell what's going on I blew it up over here MJS let one okay that's the first piece of information about the mission you're going to find it wasn't really called Voyager for a long time it was called MJS 77 it was that stood for Mariner space Mariner class spacecraft Jubran seven Jupiter and Saturday and launched in 1977 and so in fact I did not hear the name Voyager until near the time of launch in 1977 okay here is the first page of that notebook and I think I've blown it up over here yes okay so this is the very first entry November the 12th 1973 I met with wheel well actually bill Althouse he was an engineer and I'm a C and we went over what the current design of our low-energy telescope was which was four detectors two thin ones and two thick ones and there were going to be four telescopes per instrument and three instruments plus a spare set so and then we also talked about the tet telescope which is the electron telescope and it was just one telescope per instrument then a few days later I met with a bigger group Rabi vote is RV he was my thesis advisor actually and also their first principal investigator of our CRS instrument EC is edy stone and then we again and bill Blodgett and Tom Garrett Tom Garrett unfortunately is my colleague for a long time passed away in 1997 so the first word up there was think about detector testing and that is became my job because there were hundreds of detectors to select and test and make sure they were going to work in space and one thing I want to point out is that we had to build three instruments basically I mean we had to build the proof test model which came before and then we built the Voyager 1 and Voyager 2 instruments and that I was all done in five years 72 to 77 that is totally remarkable to me because I am the instrument manager on an instrument on Parker Solar Probe we just delivered its spacecraft we started in 2010 we've got one box and gonna be eight years before it's locked it was really remarkable what the Voyager team did the organization it took and everything to get that done okay and this is what we produced this is our CRS instrument cosmic-ray subsystem instrument on Voyager 1 and those let telescopes that we're talking about are labeled ABCD Tet is labeled Tet that's the electron telescope and these are high-energy telescopes which were produced by our Goddard College scattered Space Flight Center colleagues it's about a foot cubed and as a special bonus I have brought the spare telescopes here tonight the flight hardware is in a brown paper bag you can come up here later and go through the contents if you want if you don't if you promise not to drop anything ok now I'm going to start with a slide that has nothing to do with Voyager actually this is a picture from the group that celebrated after they landed Curiosity rover on Mars in 2012 they're very happy group they're all hugging and carrying on I mean it's fantastic now I want to compare and contrast that with the first data that we witnessed from our instrument in 1977 on Voyager 2 and this is our little group and I don't know about you but that does not look like a very happy group it looks like a worried group this is Rob you vote right there this is Rick cookers and was a graduate student back in the day and now as our engineer this is a Tom beard this anneal garrels recently passed away or any Fran's goat there's mark weeding back back in the corner there anyway this of course is me because this is all honest printer you know there's a paper printer coming out with all these numbers and stuff on it probably hexadecimal for all I know anyway I was the only one that could read that stuff upside down okay I want to talk about a one of the key persons on Voyager at the beginning this was Gary flandro and he was a graduate student at Cal Tech in 1965 and he worked over at JPL that summer and he figured out that the plants were all lined up on the right side of the Sun and you could actually visit a ball with this gravity assist technique so he discovered that on in the summer and he was evers a very pivotal discovery so NASA got interested and they hopped on that thing now that started out being a much grander mission with four spacecraft and go to Pluto too and everything but that got scaled back because of budgetary concerns and so they just decided we're just going to go to goober and Saturn that was the Meritor Jupiter Saturn thing and so that's the way we we left and sorry sorry about that I didn't want you to see that right now okay so these these were lost Voyager one went to Jupiter and Saturn and it was a very very high priority target was Titan a moon of Saturn Titan at a dense atmosphere and we just need to go there and see what was going on so it turns out if Voyager 1 hadn't done a good job at Titan then Voyager 2 was gonna have to repeat that and God would have been a real just MGS mission because Voyager 2 wouldn't gone on to Uranus and Neptune but fortunately everything worked out and they they did get to go Voyager - did you get to go to Uranus and Neptune these are the dates of the closest encounters at Saturn Voyager 1 got deflected up and out of the plane clipped ik plane and Voyager 2 got deflected down out of the Clippers plane and after the Neptune encounter ok so what I want to know the dates of the launch of voyagers I just consult my Voyager belt buckle which by the way I have on tonight this is OK the problem is I only had a brown belt to wear with this thing and I've committed some sort of fashion faux pas and I'm sure my wife's gonna kill me when I get home anyway on the back there it says August 20th 1977 for Voyager 2 and September the 5th for Voyager 1 that seems backwards but they wanted the first one to get to Jupiter to be called Voyager 1 so it actually went out 2nd on a faster trajectory alright this is a picture of the launch it's a big rocket Titan 3e centaur and one of the interesting things was I was in charge of those let telescopes as we know now and the front aperture was covered with a very thin aluminum foil three microns thick and we were afraid that a technician that the Cape could accidentally poke a hole in one of those things and so right before we sealed up the spacecraft for launch I got to go up in in there and look at him and I had a set of spares and I didn't find any holes actually but I did find one was loose and I did tighten it so good for me and that was very exciting to do that up in there with that was the last one to inspect it okay now another pivotal person is of course Edie stone the project scientist for 45 years and I could probably found a better picture of Edie as well but I was running out of time I was desperate and this is what I came up with he's given an award to someone who I've just cut right out of the picture there over to the left okay you'll see why I had to have that picture in a second so this is the spacecraft that was built and it's sitting right over here mock-up is very accurate mock-up I might say by the way that's CRS instruments right there Koz grains when I worked on it's got a big antenna on it and everybody sees the picture says okay how big is that antenna and I tell them to think of Ed stone think of Ed stone laying out across that antenna there's one ed stone there's two Ed stones and that's not quite enough so you need a pebble so I say it's two stones and a pebble and there you'll never forget the size of that at today's twelve feet across all right so you might wonder so this thing transmits data back to the earth and you might wonder how big the transmitter has to be on that do that and you know Voyager one is 139 astronomical units away which is 13 billion miles and the answer is 23 watts it's like a 23 watt refrigerator light bulb is all you need with the deep space network to accomplish this I need to shout out to the deep space network people you do a fantastic job you know there's Voyager just transmits this data continuously and it's always pointed at the earth and so if there's not some antenna to catch it it just goes on past and who knows what people are doing with it past the earth but there are three stations around the world one there's these sets of antennas around the world to always be in contact with it no matter you know what the time of day is one's at Madrid Spain ones in Canberra Australia one is in Goldstone California so they're spaced around and that we're great at encounter with the with everything was in the plane now it's a little trickier because Voyager 2 is deflected down and really only Canberra can handle that situation just check and see okay so yeah the next thing of interest for example on the left or the power is the power source it's the radio isotope thermoelectric generators and it's just a big plutonium one 238 source which has an 88 year half-life it decays so and the the surrounding material captures the heat that's generated from that decay and heats up thermocouples it's a very robust system and it's definitely needed for outer space I mean deep space travels where the Sun doesn't help you too much okay there is the Golden Record which is recording of lots of sights and sounds of the earth and the science boom is out on the right there and it's got most of the science instruments on it okay and the other thing is that it's got six computers the total of 68 kilobytes of memory that actually three three pairs three driven redone it pairs your iPhone with 16 gigabytes has is two hundred and thirty-five thousand times more powerful than that and yet this thing can just do everything it's amazing machine okay here's a picture of the front of the Golden Record with inscriptions on it their directions for how the aliens can find us if they intercept this thing there are there is a cartridge included and instruction there how to play it you need to be an alien to figure this out I'm sure of it but one thing that people did say and they were seriously but some people were serious about this some well respected people were worried that this was a big mistake why would we do this because aliens if they did you know it's not likely but if they did they might not be friendly and we're pointing out where we are here so my answer to that is that's just another reason we need better border security and immigration laws and you know maybe we need that wall after all I don't know it's got to be pretty tall though for an aliens okay so the other thing I I was watching the farthest and the something was said in there they hadn't really thought about and it really stood the hairs up on the back of her neck and that is that this record and the spacecraft may be the only evidence of our existence and it's still going to be going this base craft is going to go for billions of years around the galaxy but the earth is in danger because in a few billion years the Sun is going to go red giant expand out and burn earth to a crisp but would you will still be going now I got to thinking wouldn't it be just our luck if the Voyager was going around the center of the galaxy that it did and it got right back where the Sun was when the Sun decided to go red giant and it got burned up - not likely okay so I have a little movie showing the voyage of the voyagers in the plant the tour of the planets okay so it said destination in interstellar space this was made before that got accomplished so anyway here is a picture of the planets visited shown to scale relative size wise so Jupiter Saturn Uranus and Neptune and Earth's down there so that red spot turns out to be a giant hurricane it's been going for at least 300 years and it's a really big hurricane because two earths can fit inside it as you can see and now the other thing is that Neptune has this great dark spot it turns out that the Hubble space craft showed that that disappeared in about 1994 but some other one has come on since then as well okay so this is a 66 days out from Jupiter Voyager 1 was approaching took this made this movie and these were at that point better pictures than any ground-based telescopes could provide and I think it's just phenomenal what's going on in the atmosphere of Jupiter there are hurricanes those little arcades and they're going by the big hurricane and sometimes they make it through and then the next one not so good went right back in there so that was pretty phenomenal for the atmospheric scientists study Jupiter here's the picture though that really was the attention grabber for me the very first time I saw it I walked into a room where that was on a screen and I said what is that and it turns out it's Eyal moon of Jupiter and the first thing came to mind was what Caltech students have done it again they pulled a prank and they have substituted a picture of a poorly made pizza for Ireland but they had it was really I Oh and when when Voyager was launched I just assumed that all the moons are gonna look pretty much just like our moon sort of gray dull pock mark you know craters all over the place and here's one totally different and it's about the same size as Earth but it doesn't look like it and that's what Voyager found everywhere was everywhere you looked there was something different the diversity of the moons for example and I will show you that just a second and it turns out that the reason that surface looks like that is it's got volcanoes going on it which were discovered at the time of the Voyager 1 crossing found out there were nine active volcanoes going on and then Voyager 2 went by they found eight so io is a lot more active than a volcanic volcano is an earth and the tidal motion is like it's 330 feet whereas a big tides and that's what of course heats up the inside and causes the volcanoes here is another moon of Io I mean if Jupiter is called Europa and it's the crack cueball it's frozen ice and those are cracks in the ice it's you know you know in orbit around Jupiter but totally different than IO and totally different from the moon and it's thought have twice as much water on it than Earth does so it's a good candidate to go and try to find out if there's life down there okay and these are the beautiful rings of Saturn and it turns out that Saturn had a kind of an odd situation it has spokes in the Rings and these spokes are thought to be charged dust particles that are interacting with the magnetic field of Saturn and going around with the rotation of the core of Saturn okay here's one that is lucky to be you alive this is - a moon of Saturn it's a little moon but people immediately call it the Death Star because Star Wars that come out in 77 anyway that little mountain in the middle is about the size of Mount Everest and just barely made it okay so we got to Uranus and that's kind of disappointing from a planet's perspective that was pretty bland but it did have a big surprise and the big surprise was the magnetic field of yours and actually the fact that Uranus is rotating on its side its rotation axis is horizontal but the magnetic field axis here is trying to be vertical and there's quite a separation here like 60 degrees offset never seen anything like that most of time the magnetic field axis and the rotation axes are all lined up pretty close and the center of the dipole of the magnet field is not in the center of the planet there's another thing so but they don't have to all be pictures to be interesting and weird now Uranus has a moon though that is one of the strangest objects that was seen and it's called Miranda and it's 300 miles across and it should have just been frozen solid and just have a bunch of craters and that's it but it's not it it's it looks if I here's some close-ups I got that thing in there it's got these creations looks like somebody's been plowing the fields you turn these corners of Charon there's a canyons on it they're 12 miles deep it's very weird why that looks like way is I think still being debated a bit it could be geological activity or it could be that it got hit collided and reformed all right Neptune now Neptune was a little more interesting it has actually the fastest winds in the solar system 1300 miles an hour and it's surprising since it's so far from the Sun there's doesn't get much input from the Sun and as I said before that dark spot situation is different than it was the time that Voyager went by okay but it turns out that Neptune also had a weird banging field situation and it set the record for how far off from the center is the dipole axis it's actually more than halfway to the surface and it's also tilted by 47 degrees from the rotation axis and here is a moon of Neptune which was a big surprise this Knepp this moon is rotating are going around Neptune in backwards direction it's retrograde orbit which means it couldn't afford in place it must be a captured object and it is one of the coldest places in the solar system 35 degrees Kelvin and it's about 1,700 miles across here's the close-up those little black splotches turned out to be geysers and that was another big surprise this is a really cold place and yet it's it's got geysers their plumes and they were caught in the act by Voyager 2 now I don't know about you but those lines on the right remind me of something they remind me of where the 5 in the 405 and I hope if the Tritons can get their car started they're handling that situation better than we are okay all right I'm gonna go to this little movie that shows this guys are on Triton maybe a little hard just discerned but they got it it's this little thing here that this stuff is coming up about five miles up and then it's drifting off about 90 miles there's a series of images that we're taking okay so that boards are past all the planets and now what's next and that is of course interstellar space and you might know it as our Milky Way our galaxy and this is a drawing of it our Sun is out here where Mark read he's twenty-seven thousand light years to the center takes about 225 to 250 million years to go around the galaxy once and we're in this galaxy and the Sun blows a bubble in it I blow the bubble with what's called solar wind it's plasma submitted from the from the Sun and that's the drawing of it here's a actual little movie that shows the at least the existence of this so when this like comet is coming by this is from Soho I should have mentioned that little circle in the center or may I have to play this again is blocking the Sun and the bigger circle is keeping the camera from getting damaged so actually when you have an eclipse you are like we did the other day that you're actually an even better position here to study the corona because you don't have to block off that portion but anyway let's yeah let's see if I can play that I guess I want to point out something so you see the tail of the comet and as it goes around the tail switches to be Rayleigh out because this solar wind is blowing that out you also saw some explosions going on these chrome mass ejections and stuff that happens creates a lot of turbulence in the interstellar medium okay the combination the fact that the Sun is going around the galaxy and the fact that there is actually an interstellar wind of particles as well there's a solar wind but there's also an interstellar wind because stars exploded and they create a wind as well and that combination might lead to a comet shaped heater sphere where this is the interstellar wind and it blows in like this I say might because actually that is this current subject of current debate right now what the actual shape is some people arguing it might be spherical because it depends on what the interstellar magnet field is for one thing now here's a movie that shows a little of that how the structure of the bubble is so you've got the there's the inner center for we were just talking about got the Sun this is the solar wind blowing out it gets to there's a termination shock which comes to you first where it slows down and turns back down the tail and then when you get to the heliopause you get out into interstellar space and the heliopause divides the low energy plasma from the interstellar from the interstellar medium from the solar stuff so there's galactic particles out here and there's Heliospheric particles in here and the fields are different on the other side this is the sun's magnetic field in is in here and the galactic magnetic fields out there so this is the of course the heliopause were Voyager one crossed yeah you know I'll talk more about that later okay now if you don't have that movie handy at all times you can make a heliosphere in your kitchen sink and I think this is Ed stones kitchen sink actually but and I'm gonna I'll just I'll play the movie and then I'll explain the situation at hand whoops oh no that was a terrible thing to do why didn't that play okay here it is alright so the water comes from the faucet comes down hits the bottom of the sink and it goes radially out at that's sort of like the radial solar wind and then it goes out but it's losing pressure it can't push back on that water forever and it creates this little Ridge which then is the termination shock and then out beyond here where there is no influence from the what's the the water rushing down is the pristine interstellar space so let's take a look at that sometime it's it's pretty much similar in two dimensions all right now come to the pause and I'll put it in because the next section of the talk deals mostly with observations we made an interstellar medium after Voyager 1 cross the Helius pause on 25 august 2012 the cameras have long since been turned off so there are no photos to show you only squiggly lines for the most part so we all need to take a deep breath get our wits about us and move forward this next section is going to be like you went to a scientific conference and you're sitting among scientists many of whom will fall asleep themselves if you do get drowsy going forward I do want to make you aware that if that happens I tend to like to release a live animal into the audience that and it doesn't matter what kind of animal but I have found that mountain lions are really good at working out fortunately for you I don't have one of those handy but we'll see what I can come up with if it becomes necessary all right so I said that five years ago I gave the talk and it was on August 16 and that was actually 12 days before we crossed but we had gotten some interesting so this is one of the last slides I showed last time and this is a rate of particles that are energized in the heliosphere this is a scale for rate and this is time this is 2012 and this August 13 just happens to mark this tide either feel for what the date was but so we were just motoring along here everything seemed pretty normal like it always was and then suddenly this drop out happened and that was totally unexpected we had not seen anything like that before so these Heliospheric particles suddenly just drained away and then they came back up and then they went down so we had at the time of this talk last five years ago we had one and a half of these little episodes and it took us more than a year to decide we were in the interstellar space because things got confusing pretty quick now this is a little more challenging but anyway instead of one rate it got full rates here and the rates the different colors denote different types of particles the red ones represent particles that we think are accelerated in the interstellar medium by supernova shocks and we call it galactic cosmic rays and galactic cosmic electrons here two different rates so this was where we were we were one and a half notches into these you know these are they're called a CRS and TSP you don't need to worry about what that means there created in the heliosphere so this is the big difference but you would think looking at this so the Heliospheric particles dropped away they drop away again and there's three episodes then they really drop away and the galactic cosmic rays are increasing so it looks like moving across the boundary like galaxies on the side here and his fears back here and this is some in-between mess this goes on so we thought we had it and it's gonna be historic we got really excited and first man-made object crossed into the inner solar space and then there was a snag and the snag was this this this is the same thing I showed you these top two panels the low-energy Galacta he district' particles disappearing galactic cosmic rays jumping up but the magnetic fields in these lower three panels and what happened there was that the this is the magnetic field strength which does go up and down as if we might be going in and out of the interstellar medium but the fuel direction you can't see it very well here and I'll show it better on the next slide but it didn't change the direction is two angles lambda and Delta but as we went through this thing here it's it's pretty steady and so people begin to say well we're still inside the heliopause regardless of what you guys with the particles had to say about it and this shows clearly this is the real short time scale right right around this time where the magnet field magnitude gosh sorry little man you field magnitude went up that looked good look normal but this angle this angle didn't didn't cooperate so it would have been handy if the plasma instrument on Voyager 1 was working because the plasma instrument did fail in 1980 it's working fine on Voyager 2 when Voyager crew crosses is going to be a lot clearer and more interesting and interesting not more interesting but interesting because it would measure the density of the plasma and the density of the plasma is a measurement and that's shown here if you look at this this is where the Sun is or 1au where the earth is really but this is I'm sorry listen let's look at the right scale this is density we'll get to frequency in a minute this is a density as you get away from the Sun the dizzies going to go down that's why you can't push back on the interstellar medium as well it keeps dropping dropping dropping but he gets to the interstellar medium the thought is supposed to be sort of like 0.001 particles per cubic centimeter at the heliopause and then across the universe is going to jump up by maybe a factor of 80 so we didn't have that measurement directly but we got lucky because the Sun sent out a blast wave it went through the Uni pause and got to us and it rattled the cages it made plasma waves it made the plasma oscillate and there's an instrument on board called the PWS plasma wave system which can measure these oscillations and it just turns out that the frequency of those oscillations is directly related to the density if you know the density you know the frequency in fact you can see that this scale is dis co here and they this is the equivalent scale for frequency on the left so here's some data that was a drawing this is some data from the plasma wave instrument over period in 2012 and 2013 where there were three three of these episodes these would be a color spectrogram which shows you some where what the density is as you go up here so it started off being kind of low density but it in 2013 the next time it happened it was at a higher density and all these densities are much higher than the solar wind intensity that would be expected so that was the real evidence that we were in the interstellar medium these frequencies turned out to be in the audio range or a couple thousand Hertz and so if you could hear them they're not soundwaves but it would sound like this the pleasant wave team likes that but it's they're not family so it's a little line but I think they okay so go back to this slide and that just shows you we put the smiley face here because that means the density was correct for the interstellar medium okay and here's some more figures from the PDS team later the current data up to the almost current data and there were some more episodes there were episodes in 2014-2015 and a little bit here in 2016 seems like about once a year we get something but now the district's kind of leveled off that maybe you know what's the interstellar density is okay so most scientists believe Voyager 1 crossed the heliopause on August 25th 2012 at 121.6 au and I say most because there are a couple of doubters and they're pretty respected scientists they predict they have a different explanation for why the density went up they claimed that the actual the solar wind itself could be compressed most people don't think so and they did make a prediction and those predictions have not come true but I think they're still holding on to the hope that that they'll prove us wrong but ok now here's something directly from our instruments ers instrument and is something that we were very excited about doing we got the interstellar medium the this is the energy distribution of galactic cosmic rays in the local interstellar medium which we had no idea what it was could was going to be these are the upper points here so this is some low to high intensity and energy higher energy to the right and so these particles we knew high-energy particles can get near Earth the very highest energy but the low energy ones that solar wind is pushing out is pushing them out and you don't get them you don't see them at all it it blow you know a couple hundred MeV per nucleon whatever that means to you but in its so it could have just kept going like from here on up we could measure this part that when a it near Earth and it could have just gone up like that it could done anything we didn't really know and so now we know we and you know it bends over like this these are measurements made the maximum intensity is measured near Earth are shown here as Laura set of points and the upper points are the ones in the interstellar medium so now we know how much shielding the heliosheath is giving us sort of the heliosphere we're not ever seeing anything like that and it took us 40 years to find out but we got the job done okay now when we got to interstellar space we thought everything might be pretty pristine and pretty quiet and not much going on and if you look at this plot this is a plot of cosmic rays that's actually galactic cosmic rays mostly and we see we can see these this is a integral rate above a certain energy so there are energies which do get 2 to 1 au anyway this rate and this starts out in 1977 when Voyager 1 was launched it went down it goes up it goes down this is the solar cycle so the Sun is weird because it's magnetic field changes polarity every 11 years and in that imprints itself in the counting rate that we see anyway goes up and down up and down and then we got to the termination shock here marked TSX and then things change and it just started going steadily up towards the heliopause cross which is HPF whoops whoo I really went back there okay so at the heliopause and it's shown a little bit better here it just jumped up and now it's been pretty steady if you look in the right direction it turns out that this plot was made using telescopes that were pointed in a particular direction and it does show this flatline behavior it turns out that that direction is sort of parallel to the interstellar magnetic field if you look perpendicular to the interstellar magnetic field things are different and that's shown here this is a instrument another instrument on Voyager called LACP and it has its on a rotating platform it steps around it can scan around and look at all these different directions and so they picked out sort of three directions here the red and the green are directions mostly to parallel to the magnet field and it's pretty flat line there are these little bumps which have to do with these blast waves that come out in the Sun and interact and calls the plasma waves and the Disney measurements so we saw that before but most the time it's pretty pretty unremarkable pretty steady but perpendicular to the main field there all these changes that dropouts and I mean variation so I'm just showing you that that and people are trying to figure out what that is what why that happens and just wanted to let you know that even though you think it might all be pristine and nice out and calm and the interstellar medium there are still things that need figuring out okay now this is almost the end of the show and you put up with the squiggly lines I'm really proud of you I didn't see anybody go to say I didn't have to pull out this animal I have back here so what do you get at the end of a show he should get a cartoon and we used to get cartoons when I was a kid we got cartoons at the end of a movie I don't know whatever happened those I thought they were great anyway I'm going to treat you to a tune someone made about Voyager okay you apparently like that so I've got a another treat for you this is the alternate ending okay so the nearly final thing is I was wondering what the legacy of Wizards gonna be is it gonna be all its discoveries the first man-made object in interstellar space or is it something possibly even bigger than that and I'm gonna show you a video here of based on a photo that was taken and Valentine's Day in 1990 of wasn't one turn the cameras on look back and did a family portrait all the planets and earth was in a was there in that little circle this is Carl Sagan Lobby to have this photo taken and he called that picture of the pale blue dot he wrote a book about it and I want you to listen to what Carl has to say about that pale blue dot and think about I think it's pretty powerful okay let's see I think I go to the next slide to do this this slide is not video is not quite perfect because it don't worry about Neil he's not really in it that's here that's home that's us on it everyone you love everyone you know everyone you ever heard of every human being who ever was lived out their lives the aggregate or joy and suffering thousands of confident religions ideologies and economic doctrines every hunter and forager every hero and coward every creator and destroyer of civilization every King and peasant every young couple in love every mother and father hopeful child inventor and Explorer every teacher of morals every corrupt politician every superstar every Supreme Leader every saint and sinner in the history of our species lived there on a mote of dust suspended in a sunbeam the earth is a very small stage in a vast cosmic arena think of the rivers of blood spilled by all those generals and emperors so that in glory and triumph they could become the momentary masters of a fraction of a dot think of the endless cruelties visited by the inhabitants of one corner of this pixel on the scarcely distinguishable inhabitants of some other corner how frequent their misunderstandings how eager they are to kill one another how fervent their hatreds our posturings our imagined self-importance the delusion that we have some privileged position in the universe are challenged by this point of pale light our planet is a lonely speck in the great enveloping cosmic dark in our obscurity in all this vastness there is no hint that help will come from elsewhere to save us from ourselves the earth is the only world known so far to harbor life there is nowhere else at least in the near future to which our species could migrate visit yes settle not yet like it or not for the moment the earth is where we make our stand it has been said that astronomy is a humbling and character-building experience there is perhaps no better demonstration of the folly of human conceits than this distant image to me it underscores our responsibility to deal more kindly with one another and to preserve and cherish the pale blue dot the only home we've ever known so it occurs to me that if we get the world leaders in a room and watch this video maybe they would turn to each other and say you know I think he's got a point and then world peace would break out we'd have solving climate change boys you will get the Nobel Peace Prize and that may that's probably not likely but not impossible thank you very much I think there's time for questions there's a microphone there if anyone wants to I don't know I may but maybe I could repeat it I could probably hear you there artifacts they're not real I would cynjohn khazzani here jaga Sonny was the project manager when I first was working on Voyager and he's sitting down here in the lower left hi have a hand for John stand up he made this he made this happen and that was a tremendous organizational effort to do what was done I'm telling you it was unbelievable you know someone asked me that the other day and I said oh I'm sorry I should did I have any idea that it would go 40 years plus and someone asked me that the other day and I said you know I'm not that surprised I actually thought once we got it into space and operating it would just continue to operate what could go wrong well a lot of things did go wrong and it has been several close calls it's it's nearly been a lie you know one Voyager 2 is nearly lost a couple of times so but it it's amazing the people that designed and built this and had all this redundancy and autonomy built into it where it could recover itself just save the day time and again yes um so what's the power situation like on the spacecraft how many more years do we have do the instruments have okay so I think that's at the bottom their last instrument power off is maybe up to 2030 could be a little short of that but that's the hope if the power is getting to be a problem it's we lose about 4 watts the a year and I think our instruments in jeopardy because we use about that much so they need another year they'll turn off CRS but we're studying that very carefully and trying to decide how we're going to manage the power to the end of the mission are you recycling instruments yet no okay they're all on ok yes for you what was the greatest moment during the Voyager mission the greatest moment what was the okay Wow I'll tell you the most stunning moment was the first time I saw saw aisle I wasn't joking about that that was bizarre the biggest achievement though to me I am a cosmic ray physicist and studying cosmic rays galactic cosmic rays also cosmic rays are accelerated in the heliosphere all my career so when we got to the interstellar space that was tremendous success thank you this has been just beautiful and moving on dude forgive me if I've missed this but do we yet know the shape of the heliosphere because I thought I'd heard one time here that because of when certain data had come back it seems to indicate that it's not actually a sphere there are competing theories about that going on right now and there's a person on the LACP team that thinks it's any lot of it's actually based on energetic neutral data from Cassini that is indicating to him at least that could be spherical more spherical than it is a common shape so we're still there's still things to be learned about that and maybe voyager 2 will help with that as well may I also ask did you have any interaction with Carl Sagan anyone interaction with Carl Sagan did I ever have yes yes I did Carl Sagan interviewed me interviewed me for a job and I got the job I guess he wasn't a bang job but it was a little bit bizarre he was here at Cal Tech on sabbatical in 1972 and he was house-sitting for a professor named Murray gell-mann there's a Nobel Prize winner and so but Karl needed to leave for the summer too so he couldn't house it the whole time so he needed someone to sit in so I got the job I can tell you that was some house you must not have been wearing a brown belt that's why you gave up the bathroom was 1,200 square feet I mean it was quite a quite a house thank you just wondering how many people are still on the Voyager team working today how many people are working today that's a hard question for me to answer there's somebody here would know more about the number that it takes to keep it going which I don't know it's probably under a tin I don't know remember exactly 12 about a dozen not all full-time yeah and scientists there's you know if I protein there's five instruments still operating there's all the cameras of course wouldn't wait a long time ago so the instrument team did magnetometer and the plasm wave and the energetic particles there's two of those there's no nobody's full-time either I'm not full-time either so it's it's a small group really yes how fast was Voyager going before its first planetary boost well okay that's a good question it I believe that it got about half its speed from the boosts that's my recollection of the total overall I didn't answer the question directly because I don't know the answer directly to that question but I know that the the gravitational assists were very important it couldn't be done without it and it gave it about I think as much speed as it had when it launched additional speed so after it gets the boost yeah it goes to the next place yeah gets a boost gets another boost is that a constant increase yeah the time it gets a boost yes it is and they in the video I saw last night on TV it said it was going about is it going 10 miles per second yeah it's 17 km/s yeah 10 miles per second okay that's almost as fast as your serve yes sir thank you thank you Tom since you mentioned Carl Sagan you should also mention dr. Bruce Murray here on the director at the time the Voyager was launched actually as comes second hirevue Bruce might help me oh yeah we should ask the question who is in the room here has worked on Voyager I'd like to know raise their hands John dear knowledge dr. Bruce Murray because actually everything he was responsible for right so Bruce was the director of JPL yes right yeah it was also our Caltech professor okay I'd like to know why would the two I just send outside the plane of the ecliptic because he would well let's see that happened naturally in the case of Voyager 1 which was trying to get to Titan and when to get to tighten that just gonna happen that's just the way it had to be and Voyager 2 we've done the same thing and boys are one not done a good job at Titan Voyager 2 I assume it's the same thing it was some observation that needed to be done that Neptune might have been frightened I don't remember maybe John does but hi Alan going back to something you said about the Sun it's left half of its life and then you said the earth will burn to a crisp yes not in our lifetime anyways but so I want to hear what a science a scientist like you thinks of us being able to live like a Mars you know being a spacefaring species ok I didn't quite understand that I don't think exactly but a spacefaring species do you think we can live we can live with in a similar planet you know a similar planet some other planet I'm a little skeptical personally I think it's uh it seems well I don't want to get into the negativity issues how that we're doomed in so many different ways but that's really the way I kind of feel I mean we're gonna hit by an asteroid at some point do you know that's gonna be a problem about every 60 million years something like that's probably gonna happen so anyway I I'm skeptical I think she said she knew I gave a talk to a bunch of fifth graders and they all went home and cried to their mothers and bus that guy told us eight different ways that we're not gonna live past 40 years all over them nuclear war is gonna break it I'm telling its problem hi I'd be interested in knowing if I'm assuming that these are now the the one-way light times for the signal to get back yes I would be interested in knowing what that one-way light time was when the voyagers first said I like their first encounter with five au and it's 8/3 minutes so I know it's under an hour under an hour and an hour it's a long way away yeah it's a long way is there an estimate today as to when voyager 2 will make its interstellar space and will there be enough power for like the plasma measurements you were talking about since you said it may start to run out of power in the next year or so yeah we'll keep that one going the there is no firm estimate but I can tell you our own measurements are indicating you know within a couple of years I would be fairly comfortable within two or three years that's going to happen it could happen tomorrow actually it's it's ready but what happens is that the now we know from Voyager 1 where the intensities were when it made the last little jump up to interstellar space you saw that little jump in the plateau in the flatline the nuclei the the protons and all those they're there they're there at that plateau down there ready to go but the electrons have been lagging behind and now they're they've caught up so it's just how long we're gonna sit at that plateau and go over and of course the expectation is that Voyager 2 is crossing probably totally different and we'll learn a lot then what we learned at Voyager 1 Voyager 1 went through at a particular spot towards the nose the heliosphere we're actually the solar wind had slowed down to 0 which was is still mind-boggling whereas Voyager 2 is acting more like we all thought that the solar wind would turn and go down the tail and it is turning and going down the tail so it's going off in a different place and we'll probably learn something there it's great thank you yeah I wanted to share something positive about your gold record which was it was my great honor to play many years with a guitarist named Bob Saxton and when he would come out to LA from Nashville Bob passed away just last year but every time I performed with him he would share with the audience that his recording of Stardust was on that gold record on Voyager that just gave me chills that's fantastic you know who else is on there very high what can citizens like us do to help provide more funding to NASA so we can do bigger and better space exploration contact your Congressman and being really enthusiastic about what NASA does which I think they do great things thank you if the if the solar winds slows down to zero at the edge of the heliosphere would the concept for solar sailing be limited by its ability to go further than that distance no I think all the solar sailing happens really in the energy so you're actually near the Sun you get your boost there I don't think you gonna get anything out there anyway so would you be able to go further than the heliosphere to go into interstellar space would the solar cell you know you're asking about there is a there's been a push for a long time probably 40 years for an interstellar probe a new mission but Voyager keeps going and keeps doing things and it's sort of slowing it down I think they progress but there's a new push for an interstellar probe which would go ten times faster get out there like quicker and things I have some extra instruments on it which we've been helpful but it's a ways off for sure thank you uh-oh the internet is responding oh my gosh okay first question is by our bushy ass why do you think other moons are so active compared to iris well in the case of Io it is all about titled tights in the orbit and how its perturbed just like the moon has we have tides but not enough to cause the our moon to start exploding so it's just we learned a lot about that sort of thing I don't think any of us really expected that that would be happening when we went past Jupiter that these moons would be active but it is in that case it has to do with tidal forces Moriarty asks when's the next time we could use Jupiter for a gravity assist to your to sniff teen or both you know that's something I should have mentioned that was supposed to be mentioned that happens every 176 years so we have a ways to go it did happen 176 years before you know in 1977 and Thomas Jefferson just bullet didn't do right he was in charge anyway it was a fortunate occurrence that we got the technology just at the right time and and we stretching the technology to do it even then but it was it was a fantastic coincidence and even the fact that they were in the right position that the voyagers would continue out to where he could get to interstellar space anytime soon was fortunate that was also luck could have gone down the tail if there is a tail and been going forever and never get to the eat his paws almost so anyway that was it from the internet so I think that's the end thank you very much you

Channel: DEEP SPACE TV

Views: 13,653

Rating: 4.8558559 out of 5

Keywords: nasa, science, space, universe, voyager, nasa (organization), physics, jet propulsion laboratory, astronomy, kuiper belt, jpl, exploration, planets, spacecraft, voyager 1, voyager 2, interstellar, 2017 NASA SCIENCE LECTURE, lecture, education

Id: F2PNOw7sXeo

Length: 76min 40sec (4600 seconds)

Published: Tue Aug 29 2017