 Welcome to the February webinar of the NASA Night Sky Network. This month we welcome Adam Sabo to our webinar who will share with us the latest from the Parker Solar Probe as it explores the Sun. Dr. Adam Sabo is the Chief of the Heliospheric Physics Laboratory at NASA's Goddard Space Flight Center. He serves as the mission scientist for the Parker Solar Probe. He is also the project scientist for the Deep Space Climate Observatory. He specializes in the study of solar wind structures like CMEs and interplanetary shocks, things like that. Lots of excitement. Space weather. So please welcome Adam Sabo. Good evening everyone and thank you for your interest for the Parker Solar Probe. Can you hear me? Yes. Excellent. So next I will start sharing my presentation. And let me know if you can see a slide. It looks perfect. Thank you Adam. Excellent. So Parker Solar Probe. Let's see if it actually advances for me. Here we go. As the name implies of course it's a mission to explore the Sun but before I plunge into the details of the mission I decided to give you guys a one-page history lesson on what it takes to get such a mission going. Back in 1958 and okay at least we didn't have to start with the creation of the world or the Big Ben. In 1958 as NASA was forming the National Academy of Sciences commissioned a committee called the Simpsons Committee that once we figured out how to launch rockets into the space the obvious question was raised that so where should we go once we get into space? And one of their top candidate targets even back then was we need to go as close to the Sun as possible definitely well within the orbit of Mercury. In 1962 starting at that time NASA started seriously to explore the how to do this. They were consecutive major we call it science and technology definition teams. These are year-long studies that both the science and the technology is assessed and an attempt is made that how can we implement such a mission. So for eight times they tried and either they came back that sorry we do not have the technology to do it or even if we might be able to do it it's way too expensive. That changed in 2008 and finally the technology that we needed namely heat shield technology, miniaturization because we needed a really small satellite and computer technology that enabled autonomous operation of the spacecraft all became a reality and at least it became an attemptable mission. It still took 10 years before we had a spacecraft which by the way do you guys see my cursor if I move it around I have it over the lower right image. Yes we can see it. Okay so this is the actual spacecraft that was built by 2018 and to demonstrate to you that indeed it did live Earth. Here is a video of the launch it was launched on a Delta 4 heavy the biggest rocket in our inventory. It was a really really tiny 600 kilo spacecraft put on the biggest rocket to get close to the Sun. It went really fast that we launched in August by October we were at Venus and by November 5th we were at the first perihelion closest approach to the Sun. We did three orbits around the Sun that we cut up again with Venus that allowed us to get a little bit closer and we just finished the fourth orbit around the Sun. We are waiting for the data coming back we know that the spacecraft is healthy but it takes a really long time to tell a meter back all that data that is collected near the Sun. So in this video the green light shows the orbit of the solar probe. We start of course from Earth and then we get to Venus and many people ask me as I talk about Parker's solar probe well why do you need such a big rocket just lift up from Earth and fall right into the Sun how hard can it be? Now most of you as astronomers you are probably well versed in Keplerian mechanics so it wouldn't be a surprise to you that it does make a difference that we start from Earth and so we already have a very hefty orbital velocity around the Sun at on 29 kilometers per second. So you know that to fall in what we do with this big rocket we step on the brakes so that is we fire in the opposite direction of the orbital motion to slow this spacecraft down so it can actually fall in and even with that huge rocket and a tiny mass on top of it we can barely get closer to the Sun than Venus. So we went to Venus and we do there an inverted gravity assist or reverse gravity assist maneuver in the sense that we in the past use for example Jupiter to go by go behind it and slingshot us out at a faster speed so we can get up to the outer heliosphere. Here we go in front of Venus in order to get slow down but even this maneuver is not enough to get us close enough to the Sun as close as we want to go which you see at the bottom of the screen that we really want to get below 10 solar radii so one grid Venus gravity assist only barely took us below 37 so to get closer we needed to come back to Venus and then get yet another Venus gravity assist and then we get a little bit closer then we come back and we have to do this seven times to get down to 10 solar radii so every time we fly by Venus is not only that we want to get closer that to the Sun that is slow down but we had to carefully target such a day that either two or three orbits later we will reacquire Venus again remember we do not carry much fuel so it's not that we go in and then we just fire our rockets to find Venus again we have only enough fuel to orient ourselves for minor corrections so it is a phenomenally difficult job to target from one encounter to the next but it has been working very well so far so on the next I zoom into that plot on what was on the upper right hand this actually shows the timeline of how far we are from the Sun versus the speed the blue line is the distance we are from the Sun the scale is on the right hand side and so what you can see is that we have 24 orbits so like those reds numbers on the top indicate the perihelion the closest approach numbered from 1 to 24 and so you can also see in the blue boxes below that what are the closest distances as we get closer and closer to the Sun so we had first just below 36 solar radii and with the current one that we are dating the data for we have now finally below 28 and it will take two more orbits before we get to 20 and so on and six years later we will get done to 10 solar radii by the way the red curves so it is the speed of the spacecraft which is really really fast so we will be approaching 200 kilometers per second which by far the fastest man-made object ever so couple of curiosity item I just if you are into these sort of tidbits at 6.1 to million kilometers Parker will be the closest ever to the Sun the doig that's of course was our objective before us the record order was a helios to it and really nice the German spacecraft between actually the helios one and two that got to 43 million kilometers that is just inside Mercury's orbit in 1976 and live to survive and talk about it and on our heat shield we expect to reach 1300 degrees centigrade and not get burned off as I said that we will get to really high speeds and it only took 16 years to get to this point so next I'm going to talk about the instrumentation that we are of course we don't just want to get there we want to make measurements so the first one that you probably care a lot about is the whisper camera we cannot take pictures directly at the Sun there's just too much heat too much light it would burn the instrumentation so what we have this telescope that there are really two of them they are looking sideways and their objective is to image the solar beam the charged particles of the expanding corona of the Sun sort of evaporating atmosphere of the Sun and we can see the scattered light from from primarily from electrons actually I did show pictures just in a moment I'm just introducing right now the instruments the next sweet is Scott fields it measures magnetic and electric fields of various frequencies it has two plugs gate magnetometers at the end of the boom and then a search coil measure the very tip they measure magnetic fields at different frequency ranges and it has a couple of antennas so for up front and a tiny little stub in the back that gives a fifth point of measurement it measures electric and magnetic field of variations that has much higher frequencies it enables us to make radio science measurements but also local plasma frequency measurements which allows us to determine for example the local electron density next instrument sweet is what we call sweep the day again it's a number of different instruments they measure the thermal component of the solar beam these are the electrons and positive ions that stream a day from the Sun they they can be of various kinds they require your measurements from both sides of the spacecraft they have detectors on both sides and then there is one at the tip which I show you next to the heat shield I will show you in a later figure and then finally but not least the east is and we we picked this name you thought we were very cute about it way before ISIS was had a different connotation we mean it after the Egyptian goddess so the pronunciation is east is to be clear and we put that sun sign in the middle it's energetic particle sweet so this mushroom looking sink measures lower energy particles each little sort of looks like cannon battles they allow particles to enter in and these happier set of tubes measure the higher energy particles so that's all we have in terms of instruments and so on this figure you can see a little bit better how they are arranged so here is the whole spacecraft again by the way here is the Faraday Cup which is part of the terminal iron measurement suite we are here which actually the problem with the ions is that they are streaming away from the Sun so if you really wanted to measure them we do have to look at look at the Sun and we had to design an instrument that can withstand that kind of heat and still make measurements so that's a pretty nifty device by itself too by the way this whole spacecraft so here is the thermal protection system there's a heat shield the actual spacecraft is only this gold blanketed portion which is about one and a half meter tall and one meter diameter so it's rather small as far as NASA birds are concerned so because we have to limit the mass in order to be able to get close to the Sun that's moving on that's the backside looks the same except they are different instruments visible so science results so you guys are allowed to ask questions about the technology but I figured that since we already had three orbits completed I will start summarizing the science accomplishments that we made so far it's early in the game we just barely learned how to calibrate our measurements and some of the measurements types of measurements are still not really calibrated but we already saw some remarkable stuff so this is the first slide image from the whisper camera so the Sun is this time to the right and we have two cameras the smaller one is looking forward so the Sun is this way this is the second camera well obviously you will recognize the galactic plane and the zillion stars and so it convinced us that a that we can see something real because the most of us recognize the picture that it's indeed correct now after a little bit of cleaning up the data here is unfortunately I flipped the directions of the sunlight this way again the two cameras taking a picture this was a unique time during the Venus and contact where we were able to look back and so this bright thingy is earth I just was just a novelty by the way it's also points out the difficulties of taking this kind of picture so those of you night astronomers this line here is what became of bitter juice in the Orion it's elongated from due to a reflection from detector masks so we had to eliminate that and then you can see a ghost image of earth appearing there which again later processing eliminated but it was sort of a neat picture now in terms of more science then my pictures so after much processing and removing the background such as stars and galaxy and so on this is sort of the pictures that we get what you see in the background so this is the solar wind streaming away the Sun is obviously to the left and the Sun is streaming away and so there are a couple of things that I want to draw your attention to one of them is as it starts out in a moment again you will see a corona mass ejection just everything like sink is such a big blowout an explosion on the on the Sun that is blowing away and what was very new for us is that if you look behind it there is lots of turbulence behind it that we didn't expect we also see lots of these tricks and I will come back to that and first we saw that well you know energetic particles on the CCD device that they they can cause things but these these actually persist for a long time so our current understanding most of these are actually dust particles going right by us but I will come back to that point in a moment so back to these smaller blobs we did see a few bigger blobs from Earth and then we have similar white light images heliospheric images and other spacecraft for example on stereo so it's not exactly a new kind of measurement but taking these pictures from bunny you we can only see relatively larger blobs floating up here we could actually track rather small ones so again here is the streamer belt a solar beam the equatorial region and so conveniently to a dry a green ellipse is drawn where we believe there is a blob and this pink dot is in the middle representing the center of it as far as we can tell so as we move in time left to right top to bottom you can see that it's not only moving out it's getting fatter so we can see a clear evolution of the aspect ratio which actually as something we were never able to observe in this detail before so in this plot what I'm showing is the time profile of the aspect ratio that it remains fairly elongated and then it becomes a rather circular later on so that has some physics there's something strange happened that that certain altitude or time in this plot but it refers to a certain distance from the Sun that different physical processes took place and it allowed the change so pressure balances were disrupted so meet first observation now this is on the left this is actually how one of our inner telescope images look like if you just download the raw data and then display this is what you will get as the Sun is here and everything is dominated by what we call the f-corona which is basically just dust while the light scattering out from dust so careful work has to be done to remove all of that to reveal the cake corona below it and of course even the stars jumping out of it now the scientific question here is we of course always knew and worried about that as we are getting closer to the Sun the dust environment expected to be more and more intense and you just heard how fast we are traveling so it's not a really good idea to get that the sort of the dust cleaned one day to remove paint for example right to throw that much dust at us at high speed and puncture holes all over so we were worried about Adam we ended up with a couple of questions here that I think relate to where you are so pardon me for interrupting yeah so kind of going back to the last one and so we're delayed just slightly here and so Jeffrey asked how fast do the island structures move away from the Sun so if you look at the time on the top so those are all within the same day so these are within a couple hours of each other so that that close to the Sun we typically expect solar wind stuff to move sort of 50 to 100 kilometers per second and then they speed up as they get further away which one is one of our objectives to understand that why is the solar wind starting out in the corona at the leisurely 100 kilometers per second and that ends up running at 400 to 800 was sometimes even 1000 kilometers per second does that answer the question I think so and so here's another question that I think is perhaps related to where you are here and so Ron asked and I'm gonna add to this a little bit he asked what's the closest we can get to the Sun with the current technology and I'm gonna kind of embellish that because it looks like that these images with the island structures in the next one that you're looking at with the dust are relatively close to the Sun and so are these things that you're able to image only when you're really close to the Sun and we be able to get better data the closer you get to the Sun yeah so there are couple questions there how much closer can we get to the Sun we also have asked this question because of course leave it to the scientists and then the engineers asked us that question so how close would you like to go to the Sun we had a couple of ideas on that topic and they didn't like the answer so we wanted to go down a minimum of four to five solar radii because that we felt that that really that's where the most exciting science is so we really went as far in we could have gone a little bit closer just with the orbital mechanics but it's the temperature that determines how close we can go so it's not these blobs is the solar wind pressure is completely irrelevant light pressure is an order of magnitude larger than anything coming from the solar wind particles it's really the heat it's the light and the heat that puts a limit on how close we can get so what I mean there was another question yeah and so we've got a we've got a couple of questions here and so when you're talking there about the temperature and so William had a question earlier and about you know the temperature changes from the interior the Sun into the corona and of course the corona is much hotter and so what happens to the temperature as you move outwards and then through the corona and what is the you know the cause of the temperature high temperature in the corner maybe that's what one of the goals of the mission is yes if I knew the answer I would be a rather famous by now it is indeed one of the top priorities and objectives of the mission to try to figure out it is if you think about it it doesn't follow that you look at the photosphere the visible surface of the Sun and you get four four and a half thousand Kelvin type of temperature and yes we have hotter and cooler portions but on that that range then you get a on solar radio 2 out and then all of a sudden you have one million degree temperature so what the body is going on and so we of course all you can tell that scientists don't know the answer is not that they are no on proposed answers but that we have at least a four or five possible explanations all mutually exclusive so that indicates that we really know not sure we have candidates here is my favorite one is if you must ask that waves electromagnetic waves as they spread out from the Sun as the density drops as the solar means spreads out in 3D space as the spherical expansion it gets into resonance with waves and that happens at that altitude and so the electromagnetic waves can transfer all of the sudden lots of energy to the particle which then turns into heating but that that's just a theory there are many others magnetic reconnection for example turbulence so long this so so back to these island structures and so you don't know what they are quite yet you're you're trying to figure out what they are you don't really they're just some denser part of the the screen coming out is that yes okay now I remember your question that so why is it that we only see them with Parker and would we see more later on then so we are seeing reflected or diffracted light so from Earth these closing structures are always sort of head on or very near the Sun so they are not bright like Corona mass ejections they are really really huge and bright so you you see them fairly well even from one EU these little dudes are just as even on these images are hard to discern so the only way we can see it is that we have to be next to them looking sideways which will never ever happen from one EU so our expectation is that as we get closer and closer we would see more and more of these structures so these structures have an implication to the origin of the solar there is a big debate going on to one of our other questions that how does the solar wind come back come about is it happening that continuously and smoothly or it happens as little jetlets shoot out this continuously the gaps between them and we just see them as more together soup when we see observe it far enough from the sun so if these little blobs are really becoming a more and more frequent as we get closer and closer to the Sun it might be implying that they are really really little explosions that throw out the solar wind at all times and so it would imply that indeed the solar wind is intermittent rather than continuous but the truth is still out just because we see a few of these that doesn't mean that everything else is that way though it might be true so last question this little series you know this crowd will keep asking question after question after question they're great questions and so sometimes we have to but I'm gonna you know ask this one because it's a really good one and so J is thinking about the geometry of where the cameras are pointing when you're looking at this imagery and he says that you can't point them directly at the Sun and so he's wondering about the structures that you're seeing the CME that you saw actually passing and so kind of where are you pointing with with the camera in relationship to where the Sun is and how far out from the Sun are you looking at these structures so as I mentioned earlier we really cannot look anywhere near the Sun because it would melt or optics so we are looking sideways and so then we started to do some hot search in that okay I can point well 360 degrees perpendicular the direction to the Sun so where should I be point and so obviously we want to point in the ecliptic because that's where the slower and denser solar wind is that's where we can see structures that then we still have two choices we can point forward or backwards the backwards direction had the speaking for it that it's safer because the front is where the dusting the dust spray happens because we are moving forward all the dust particle hit there optics doesn't really like a whole lot of dust particles hitting it so that would be much safer to look backwards but we decided to go with the forward one because this way we actually see what we will fly through typically in a few minutes or in an hour so first we immediate and then the in situ instruments measure it so we sort of like the idea is sort of like turn on your headlight in fog and then you see blobs coming at you and so you know a couple seconds ahead of time what is it what blob you hit with your car so that decided that we look forward and we just took the risk and so far it paid off okay all right perfect thank you so back to the dust to finish this up so back in 1929 it was postulated that the dust particles cannot really survive very close to the Sun because well it gets really hot there and the light pressure would even if they don't evaporate the light pressure would push them right out so that there should be a dust free zone inside 405 solar radii this could not have could not be substantiated till now so what I'm showing on the right is a curve where you take a cut through the center of this image and then you just from closest to the Sun as close as we can get and by the way that changes as we get closer to the Sun so it's not a constant distance from the Sun all the way out and just plot this so the different curves refer to different times therefore different distances so we started at 71 solar radii all the way down to 36 and so those are the different curves and this dashed line is what you would expect to see if there is just a constant increase as you would have one over our square increase of of the dust the density as you are getting closer to the Sun and what was noticed that as we are getting closer and closer to the Sun there is deviation on the inner edge it's not quite as bright as it should be still brighter than before but not as much as we expected so some interpret this that we are starting to see the end of the fog we are still in it excuse me we are still in it but we can sort of sense that it's clearing up ahead so that's an intriguing hint that indeed there might be a dust-free zone now I told you that I will come back to these tricks so this is a single image where we have quite a number of these tricks so first of all are the energetic particle hits and we know that energetic particles when they hit CCDs they show up as bright light but they show up as single dots these are tricks and so during the integration time of this image they moved but no that means they move really slowly the spacecraft is moving at this point close to 100 kilometers per second these particles move relative to the spacecraft a few centimeters a second so somehow this particle know how to match up their speed to the spacecraft how is that possible so then we notice that if you look at these lines they are not parallel they are if you take them back outside of the image they seem to have a single focus point most of them and so then the engineers looked at as well we can make a couple assumptions how far away they are and it's at a later moment that the focal point is the heat shield up front so our understanding is that as dust particles hit our carbon carbon fiber and sandwiched heat shield it sheds slow-moving particles as well slow relative to the sun and it's relative to the solar wind those are basically the explosion when a dust particle hits the heat shield and we see the debris field moving away so that terrified the engineers as I wait a moment how long do we have before we lose the whole heat shield so then you can't top these particles these are single molecules so then I think we added up that even at first case scenario we have over a hundred years before the heat shield is gone so we can afford to lose this many particles but it's sort of scary at times all right switching slightly a topic moving into the institute word if we look at the sun and I mapped out the surface of the sun here is the is like an earth map the whole surface wrapped around the sun all to all 60 degree to 60 degree in this particular case so this is a map of the surface of the sun the black and gray or darker or lighter gray areas the magnetic field orientation as we know from for example ground observations and then the colorful area is what models tell us that well this is where the solar wind is coming from now most of the sun at low latitude has closed magnetic field loops so particles that take off somewhere in the middle well they will go around on a loop and come back down on the other side they will not leave the sun they will come back down to the surface so the only way particles can come out is that in the polar regions they open up and the particles can stream out and they are a few corona holes as we call them at low latitudes that come and go now here is the projection of the orbit of Parker solar probe if we were actually sitting we were going so fast that we actually went faster than the rotational speed of the sun for a while so we were like hovering over this spot for a while and then we moved on and these well it used to be black lines it's turned into a solid surface this is what models predict that from the altitude of Parker solar probe where is the magnetic field the local magnetic field connected on the surface of the sun so they map to color corona holes or to local corona holes low latitude corona holes now if we move a little bit further out to five solar radii and this is what this cartoon is illustrating if you look at the magnetic field lines from the poles that where the particles are to streaming out the streaming solar beam stretches out everything is called the frozen in condition that plasma drags magnetic field with it and they cannot so they are blue to each other they cannot get separated so as the solar wind is flowing out it stretches out these magnetic field lines but they are being pushed each against each other so field lines going away from the sun and back they are right next to each other without touching forming a current sheet in between it's called the heliospheric current sheet is sort of the largest coherent structure in the heliosphere that nobody ever heard of so in five solar radii the models predict that this is where this baby current sheet is and this is again the projection of the solar probe orbit and that told us that during the end contact we were in the southern polar region so the the magnetic field lines were expected to largely point towards the sun so that was the prediction so let's look at what we actually measured so here are actual field and plasma measurements from the first encounter it covers the basically the full encounter region that when we are close to the sun you can see the distance in AU so we are starting here just above mercury at 0.36 AUs get down to perihelion and go back out to pretty much the same distance so on the top is the magnetic field strength this is just the scalar strength so obviously as we get closer to the sun not surprisingly the magnetic field strength goes up no surprise there they were by the day we observed two corona mass ejections which stick out like a fourth sun unfortunately we didn't see any during the closest approach which would have been really nice but these were nice anyways hopefully next time around this is the radial component of the magnetic field and as predicted we are mostly in the negative direction in the radial of course is positive away from the sun and negative back toward the sun so the predictions by and large the accurate next one is the speed of the solar wind and here we didn't expect to see any increase because once the speed when the solar wind is going well that's its speed it's not going to change as it's streaming away significantly it does if you look at it all the way to voyager but not at this distance by the way this increased hash is just an artifact of that we switched to higher time resolution so you can see more hash so that's not a real physics next is the number density of the protons and this we didn't expect to go up and indeed it did and the temperature of the same protons and there is not much change there so generally but the physics is expected as well okay so we knew this so why in earth did we go there so the interesting thing right away are these hashes if you are in that negative magnetic polarity what are these spikes doing there why is the magnetic field every now and then pointing the 180 degrees the wrong direction and by the way these correspond to hashes in the in the velocity two so we started to refer to them as switchbacks so first question of course is that are these switchbacks maybe the heliospheric current sheet is more maybe than we thought that money you'll be depicted as a ballerina skirt in the occasion are wrinkled in it but that's it maybe it's much more wrinkled up and so we just keep crossing from one side to another that would explain why the magnetic field changes a sign so to test that we have luckily super thermal electrons available to us now electrons generally match the number of protons and heavier ions so that the plasma remains neutral but there is a component of the electrons on the hotter end of things the super thermal side of things that they stream only from the sun the only source is the corona and they stream away following the magnetic field lines they don't come back so what I am plotting here on the top is the pitch angle distribution of the super thermal electrons pitch angle means that we look at their direction relative to the local magnetic field so zero means that they are streaming along the magnetic field 180 means that they are going in the opposite direction now most often you don't expect them to be in between because well the electrons better follow the highway the magnetic field line so either you go one way or the other but you cannot go perpendicular to it and indeed that seems to work out very nicely so one sign of the heaviest very current crossing is that you change the direction of the magnetic field but you also change the pitch angle at the same time so that as you when the electrons were coming out on let's say on the top following they were going along the magnetic field line if you really cross the heaviest very current shade then when you cross to a magnetic field line going back to the sun the electrons are still going away from the sun so all of the sudden they would be contrasting so we would see a switching of sign but if there is a kink in the field and it's still it was the same field line the electrons don't get confused they just follow the magnetic field line so if we have all these direction changes which is by the way these are the angles of the magnetic field is an magnitude again on the top then we would see that the electrons even if when they are the magnetic field seems to be oriented back toward the sun they are still just following the magnetic field that is we have not crossed the heliosperic current sheet we are in the same polarity so we are not seeing the crossing of the heliosperic current sheet so what are these so those hashes here are blown off in terms of time so it's now 80 minutes rather than several weeks so rather than hashes now you can see structures so let's start with panel B that I am plotting here the change in velocity that's in blue and the change in the magnetic field which is red so as there is a change so it's basically taking an average so that we can plot them on the same scale so when we see the magnetic field changing suddenly from one side to another notice that the velocity does exactly the same thing so there is a great correlation and it's there is such a correlation also of course with the tangential and normal components not just the radial component so now in top of it if you look at this red line which is the magnitude of the magnetic field you don't see anything there so that tells us that these changes are rotations the magnitude does not change but all the components change so the only way to do that if you move the vector the tip of the vector stays on a sphere you can change the components whichever way you like and the magnitude will not change so these are usually referred to as alternate fluctuations so where do they come from they last sometimes from a few seconds maybe a few minutes sometimes they have associated density with the green is density change sometimes not at all and so this became an all encompassing question because these are all over the place now we've seen similar structures at one AU but very few of them in Ulysses measurement a couple in the wind measurements these helios had a couple more historically but not this many so here is an artist's tradition of the switchbacks clothing out are they often signatures of magnetic reconnection or they are these jets flowing out from the sun so for example here is an SDO observation these are the you can see the jet flats and the each jetlet breaks into even smaller thin jetlets streams flowing away to be see signatures of one of these hotly debated topic next in the meanwhile I'm watching the time so the next interesting topic that is for me is that so we know that the sun's atmosphere corrotates with the photos. Adam could I break in here for a quick question that I think might you know I'm kind of a bellishing long time ago Barry asked about solar neutrinos whether they're being studied on this mission and and and it occurred to me that in thinking about this how the electrons that you're talking about of course will respond to the electromagnetic field the magnetic field around the sun the neutrinos of course won't but if you were looking at the flux of neutrinos coming from the sun would that give kind of a check on the electron flow to kind of check in on the solar wind that you're doing there to see you know what it is that's having the impact. Unfortunately we don't have they to measure the neutron neutrino flux so so I I cannot really use that to limit the other measurements. Okay well well no I was just kind of curious I was thinking about it and looking at what you're saying there about the electron flow and the in the switchbacks in there and I thought well gee I wonder if the neutrinos might have something to inform as kind of a control on that so but if you're not measuring them then you're not measuring them so also just a kind of a time check we're down at six minutes before the hour so just wanted to give you a time check so thanks. So the sun's a corotating atmosphere we know about it you take images of the solar corona and we can see it's corotating with the photosphere is differentially so not at the same rate at all that it is but more or less corotating. We also know that at one year the solar wind is pretty much radial so it's not corotating at all so somewhere there is a transition. So generally it was understood that there is an all-frame point which is a layer this somewhere between 10 and 20 solar radii and all of a sudden the coupling between the solar wind and the photosphere sees this to exist and therefore the as you are moving away of course you need to apply torque to a particle to keep it corotating as it's streaming away from the sun so at that point it cannot apply torque anymore so from there on angular momentum conservation jumps in and you move far enough heavy and basically the tangential component disappears and it becomes exclusively radial so what I am plopping down here is the observed velocity in the tangential component of the solar wind so before we jumped up and down of course we see the world it's not radial it's going minus 50 kilometers per second well yeah because the spacecraft is moving at 50 kilometers per second so this is just how we measure it so one perhaps to one has to remove the spacecraft speed once we've done that we get this green curve and there I would expect that we should be very close to zero and indeed when we started we are very close to zero and of course there is variation because it's it's a fairly turbulent medium so there's up and down and left and right but on average I would expect things to be zero but we notice that at closest approach there is this systematic tendency for the solar beam to go sideways but we are nowhere near the expected of a point so what does this really mean so here on this plot the different models are shown so well first of all measurements of the transverse speed the actual corrected transverse speed so for inbound first encounter the blue circles and the odd bond the purple squares and then the second encounter the red and yellow and so this curve here the orange curve is that is the simple model that hey we have rotation we know how the sun is rotating so if we if it stopped rotating the solar wind at 20 solar radii and then just allow angular momentum to take its course this is the the speed the tangential speed that the solar wind should have and so well let's see maybe 25 was so this solar radii are the are the right answer but the problem is that well these curves look very very different so not only that maybe the asking point is much further out and that's why we are excited about this current orbit because we will be done at 26 so we will be able to rule out the 30 because we will see it in a couple weeks but this falls off way too fast so this would imply that some sort of pork in the negative direction slowing the solar beam down but we haven't figured out what physical force would do that so if i can have two more minutes just a couple words on energetic particles we do measure energetic particles if you look at the spectrum of the energy of particles coming from the sun so here's the solar beam they are done there at the few kilo electron volt range there are a whole lot of them notice this is a log scale and we are moving from 12 to minus 10 so quite a bit it's sort of like an astronomy looking at luminosity so we have at the higher energy a superterm model which every now and then is bumped up by corona interaction regions impulsive events like flares or scp is generated by corona mass ejections so these are these typical curves so that's what we are after here is the first two orbits here are the first two orbits of solar probe so here's orbit one and orbit two and the energetic particle fluxes are plotted on top of the orbit so the high energy particles are plotted outward lower energy particles inward by the height and the color and coding both the intensity of the measurements so what we first noticed is that not a whole lot happened especially when we were near the sun these are really small tiny little events and even small tiny events were far in between the sun was extremely quiet for the first couple orbits so we are hoping that it will wake up now in terms of exciting the stuff here is the last slide here here is a short time period in the from the second encounter the lower energy particles here's the fluxes measured as a function of time this time and here is the high energy particles measured the same time scale so here is one event where we see a low energy particle event and nothing happening at higher energy and this is yeah we understand this because of course whatever accelerated the thermo particles get only accelerated to the lower energies and never made to the height but then we really had a headscratcher here because well we had the high energy particles but nothing below so how did they get there how did they jump across they obviously had to come from the thermo particles that even lower energy than this they got there but not here so that's a real dilemma so something we will have to look at that magnetic field line connections of course the higher energy particles travel much much faster than the lower one so maybe we had some disconnection the highway was disrupted and the the faster ones get got to us but the slower will not this is just illustrating that even with small events like these there are plenty of enigmas for us to to look at so with that I will close and uh I'm open for questions yeah I think that uh we're a little bit past time but let's do one last question and this is from Janet and I think that this is always a good one and I think you kind of alluded to it there um towards the end and she wants to know about what was most surprising and maybe even what was most exciting about what you've discovered or maybe not discovered so far around the measure well in terms of engineering we were really really worried about the the dust we had our solar panels are water cooled most people would have thought that's well the power generation shouldn't be a problem if one thing we have plenty of is sunlight and it turns out we have too much of it it's sort of like I am really thirsty here is a bio hydrant help yourself so solar panels tend to matter that kind of temperature so the only way we could make solar panels work is that we fold them back only the very tip stick out into a partial view of the sun and even then we had to water cool it and the water about how do we cool it in space is that that skirt below the heat shield that's where the bike radiator in a car we circulate the water around and it radiates away the heat and then goes back out cooling the solar panels so what is the enemy of a water cool system a punctured hole and there is no repair shop anywhere nearby so we were really really worried about the dust particles it only takes one to successfully puncture one of the pipes and then we are pretty much done so that's one thing that I did we did not see and we are very relieved that it is so for me this corruptation is very intriguing if we really find that it is indeed further out this would force us to rewrite textbooks for not just the sun but astronomy in terms of the lifetime of stars how do we de-rotate stars it's really one way to carry away angular momentum with the star is there austral wind or the stellar wind and we had a general understanding or we thought we had one that how much angular momentum and how fast can be carried away from a rotating star well if indeed the stars know a way to do it more effectively or efficiently than this sort that would really change the lifetime how long it takes for a star to de-rotate now because you asked the next question so when would the sun stop spinning we still have billions of years to go so I didn't lose sleep over it and did that answer the question I think so so that's really fantastic and so this is really great it's such an exciting mission to be able to be that close to the sun have a spacecraft that was able to be engineered to go that close to the sun I think that that it's a marvelous feat that it's returning the science that it is and we're we're discovering new stuff that we didn't know was there before so that's what's really exciting so thank you so much Adam we really appreciate your your joining us this evening thank you very much for having me