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
