NASA's Jet Propulsion Laboratory
presents 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
hey good evening ladies and gentlemen
how's everyone tonight good well as
always thank you very very much for
coming out to join us junot the
solar-powered spacecraft that has been
orbiting Jupiter since July 4th 2016
flies by the giant planet every 53 days
collecting a wealth of new information
with each pass the data collected so far
have revolutionized our understanding of
Jupiter and of giant planets in general
this talk will present some of Juno's
current science results and discuss what
we might expect in the coming years
tonight's guest is the Juno project
scientist and the lead co-investigator
for Juno's microwave radiometer
instrument he has worked at the Jet
Propulsion Laboratory since 1990 during
which time his research interests have
included the light left over from the
Big Bang the search for extraterrestrial
intelligence measuring magnetic fields
in star forming regions looking for
near-earth asteroids and modeling radio
emissions from Jupiter's radiation belts
he is done radio astronomy from large
telescopes mountaintop research stations
the South Pole high-altitude balloons
and of course spacecraft additionally he
is currently the lead scientist for the
Goldstone Apple Valley radio telescope
project in which students learn about
science by doing real science he is also
an elected member of the Board of
Education in Culver City California
where he lives with his wife and three
children ladies and gentlemen please
help me welcome tonight's guest dr.
Steve Levin
hi everybody
so as you just heard I'm gonna talk to
you about Gino and what we learned at
Jupiter and I'm probably gonna try to
rush through all the slides to make sure
we have time for questions at the end
because questions are my favorite part
but if I'm going too fast let me know
and save up all your questions and ask
me a ton of questions at the end because
as I said that's the fun part okay but
first let me tell you a little bit about
what Juno is what we're trying to do so
Juno is a solar-powered spacecraft as
you just heard it's been orbiting at
Jupiter since fourth of July 2016 and
we're it's enough 53 day orbit so every
53 days we have a close flyby of Jupiter
we get a whole bunch of data for a
couple hours really say eight hours
total and most of the really good stuff
is within a couple hours of our closest
approach then we spend 53 days really
far from the planet come around again
and do it again so we get this big burst
of data every 53 days we've done dozen
or so of those so far and what we've
learned has been just absolutely amazing
our picture of what Jupiter is like and
what it's made out of and what it looks
like is completely different than it was
before we got there with the spacecraft
so before I tell you all that stuff I
need to talk a little bit about what
we're doing and it's gonna seem like I
take forever on this slide because I do
but don't worry I'll be faster on all
the others alright so there's four main
things we're trying to do at Jupiter
four main science goals we're trying to
understand the origin of Jupiter how did
the giant planet form and that's really
important because if you want to
understand how solar systems form
Jupiter is a really good place to start
if you want to know where the earth came
from where do we come from you need to
understand where Jupiter came from and
the simplest way to understand that to
picture that in your mind is to think
about our solar system and how it formed
and what we know is basically ninety
nine and a half percent
the mass in the solar system is the Sun
so almost all of it is the Sun in the
Sun form first of that remaining half a
percent or so that's left more than
two-thirds of that is Jupiter and
Jupiter form next all the other planets
and asteroids and comets and all that
stuff that we see in our solar system
are formed after Jupiter and they're in
that little bit of you know one-third
less than one-third of what's left after
you take out the Sun and Jupiter right
so you can think of it as Jupiter formed
from the leftovers of the Sun and
everything else formed from the
leftovers of Jupiter so if we want to
know how did the solar system form it's
really important to understand how to
put are formed and a couple of the
things that we didn't know before Juno
got there that'll really help us or to
understand how much water there is in
Jupiter and to understand the mass of
Jupiter's core down inside Jupiter's a
gas giant so it's made out of mostly
hydrogen and helium just like the Sun
that sort of composition and all the
heavy stuff inside Jupiter tells us
about the origin much of that will have
sunk down into the middle and made a
dense core down in the center of the
planet we needed to know how big that
core was likewise if you look at the
solar system and say what are the
elements what's the solar system made
out of the most abundant element is
hydrogen the next one is helium and the
third one is oxygen so if you think
about it hydrogen is a gas helium is a
gas the first solid you're gonna get is
going to be water h2o two hydrogen's and
an oxygen because oxygen is the third
most abundant thing so our theories of
how the planets form revolve around
water we think that Jupiter probably
formed from asteroid sized pieces of ice
colliding together and sticking until
you had enough so that it's gravity
could hold the hydrogen and helium and
make a giant planet if that's what
happened then we should find water in
Jupiter and how much water we find
should tell us whether it worked that
way whether it was smaller pieces of ice
whether Jupiter formed far from the Sun
where it's really cold or
closer to the Sun where it is now where
the the ice water still makes ice but
maybe the the other elements don't stick
to the ice the same way so the ratio of
how much water there is to how much of
the other stuff there is tells us a lot
about how Jupiter formed so those are
two big things we want to find the core
and the water and then we want to
understand the interior of Jupiter in
general right what we see from the earth
is just clouds in the top of Jupiter's
enormous atmosphere it's 300 times the
mass of the earth it's bigger volume you
could fit a thousand earths inside and
we see this amazing structure that you
see in the pig picture there with belts
and zones those those orange and white
stripes
those are jet streams moving at hundreds
of miles an hour we don't see beneath
those from the earth until Juno got
there and started doing measurements we
had very little understanding of what
the atmosphere of Jupiter was like
underneath those clouds at the very top
and the planet of course is mostly
atmosphere all right so that's a big
thing we want to understand it to
understand the interior of the planet we
need to understand about the core down
inside we need to understand how deep
those belts and zones go we need to
understand how everything moves interior
to the planet then of course it is giant
gas giant planet we want to understand
its atmosphere it has the Great Red Spot
it has a storm bigger than the entire
earth it has the jet streams that I
mentioned it has all these motions and
all these deep storms that we can learn
about to understand Jupiter and also to
understand about how weather works in
general and maybe even understand about
weather on other planets by having
Jupiter to compare with and finally
because of the orbit we're in our
spacecraft remember I said it starts out
really far away from the planet and it
comes in and it orbits over the poles so
if you watch in that little movie you
see little imaginary spacecraft flying
by what that means is that when it goes
over the pole of Jupiter it's crossing
all the magnetic field lines if you
think of Jupiter's magnetic field like
the Earth's magnetic field shown us
those white lines they're looking curly
you're these things show up yeah you can
barely see the arrow if you're looking
so if you look at those right as our
spacecraft comes in it crosses all of
those magnetic field lines and that's
important because out away from the
planet there's these giant radiation
belts high-energy particles that can fry
the electronics on a spacecraft that
generate radio waves that produce aurora
Lights in the northern and southern
whites in Jupiter's atmosphere when the
particles hit the atmosphere all of
those particles are arranged by the
magnetic field in general charged
particles spiral around the magnetic
field lines and follow them up and down
so if you measure the particles in one
place on a magnetic field line you're
learning a lot about what they do
everywhere on that same magnetic field
line and because we're coming over the
pole and because the planet is rotating
we cross all the magnetic field lines so
we can measure the particles that hit
the spacecraft and learn about almost
Jupiter's entire magnetosphere as well
by coming over the pole we get the first
good look at the north and south poles
of Jupiter and that includes the Aurora
the the lights as I said that are
generated by particles hitting the upper
atmosphere so we learn about the
magnetosphere that way we learn about
the radiation belts by taking pictures
of the Aurora at the same time as we
measure the particles that are hitting
the spacecraft that will eventually go
down and hit the planet and make the
Aurora okay so we have a great vantage
point to see the magnetosphere we have a
bunch of instruments on board to do that
and I've color-coded them with yellow to
match that yellow text and then as I
said we're trying to understand the
atmosphere we get at the atmosphere in a
number of ways but one of the key ways
that we study the atmosphere of Jupiter
is with the microwave radiometer so what
it's doing is it's using radio waves
because radio can see through the clouds
so we get really close to the planet we
look through the clouds with the radio
waves and for the first time we can see
beneath the clouds and look at you
Pater's atmosphere in the radio so
that's one way of seeing into the planet
a little bit and learn about the
atmosphere it's also how we try to
measure the water because water absorbs
microwaves so the more water there is in
the atmosphere the less we can see
inside
the less water there is the deeper we
can see so by having a bunch of channels
on the radio receiver that see different
depths and measuring how deep they
really see we can learn about how much
water there is in Jupiter's atmosphere
remember water was one of the numbers we
really care about then to understand
that interior we want to know about this
core there's a dense core way down
inside the planet so you might think
well our goal would be to drop something
in and go all the way down at the core
but the problem is that Jupiter is so
huge it's so much mass that by the time
you get a tiny fraction of the way in to
the planet the pressure from all that
mass above you the gravity is squeezing
it so much the pressure gets up to 1020
a hundred times the pressure here on the
earth by the time you get a quarter or a
third of the way in the pressure is
millions of times the pressure here on
the earth we don't know how to build
anything that can survive that and get
down at the interior so we have to
measure that core without touching it
and the way we do that is we use gravity
because gravity comes from the entire
planet including the core and we use the
magnetic field because the magnetic
field comes from deep inside the planet
it comes from an ocean of liquid
metallic hydrogen inside Jupiter so of
course you know I talked about you know
a lot and I get to say that phrase
liquid metallic hydrogen a lot and every
time I do I always want to stop and make
you think about all three words it's
liquid metallic hydrogen so if I had a
balloon full of hydrogen here in the
room it would float up into the sky it's
the lightest element there is but on
Jupiter a quarter or a third away of the
way you're so into the planet the
pressure gets up to about two million
bars two million times the pressure here
in the room that pressure is so high
that not only is hydrogen gas squeezed
down so much it becomes a liquid but in
effect the electrons are squeezed right
off the atoms it conducts electricity
it's a liquid metal
it's the swirling motion of that liquid
metal hydrogen that makes the magnetic
field so by measuring the magnetic field
we're learning about the deep interior
and as
I said gravity comes from the entire
planet Jupiter's rotating every 10 hours
300 times the mass of the earth rotating
more than twice as fast so it bulges out
at the equator right so when a
spacecraft Falls past the planet when it
goes past that bulge it speeds up as the
gravity from the Bulge part of the
planet is pulling it forward and then
when it passes over it it slows down a
little because gravity is pulling it
back in the other direction so by
measuring very accurately the speed of
the spacecraft
we're in effect measuring the gravity of
Jupiter and how it stretches when it
rotates and of course a dense core in
the center will stretch differently than
not a dense core or a larger one will
stress stretch differently than a
smaller one so by very accurately
measuring the gravity we can learn about
the interior alright so that's the basic
idea of how the spacecraft works you can
see the color coding here for all the
instruments you can see this orange
stuff that represents the radiation
belts Jupiter's surrounded by
high-energy particles trapped in its
magnetic field and they're a danger to
the spacecraft so we have to try to
that's one of the reasons we're in this
big 53 day orbit we have to try to try
to go quickly through the radiation
belts so the electronics don't get too
damaged and we go really close to the
planet both because we want to measure
things and get really close and because
there's a gap in the radiation belts
near the planet so all this stuff
trapped in the high-energy high-energy
particles trapped in the magnetic field
is dangerous to us and we want to avoid
it unfortunately it goes around Jupiter
like kind of a big donut and we can fly
over the top of it where there isn't too
much radiation get way far away from the
planet and then come back again every 53
days so that's what we do and I'm
finally off this slide okay so what you
all want to know is what have we learned
right all right so we've published about
80 papers or so so far and we have
another hundred or so in the works so at
about a minute per paper that's about
three hours which means I'm not going to
tell you everything and I
to give you the short version so here's
the short version it's a whole new
Jupiter every major area in which we
measured things for the first time every
way in which our experiments our
spacecraft was doing something new with
Jupiter and looking at it in a way that
hadn't been done before we found big
surprises all the stuff people thought
they knew about Jupiter that we went to
measure the original theories were wrong
they needed to be fixed based on the
data so as somebody who measures stuff
as an experimentalist that's really fun
making the theorists throw out all their
theories is really great and we got to
do that a lot all right so let's go
through a few of them as I said I'm not
gonna be able to tell you everything but
I'll tell you some of the highlights and
then I'll take questions at the end and
maybe we can talk about other stuff
all right so very first thing pretty
much first day we got good data which
was August 27th 2016 we went into orbit
on 4th of July 2016 but since we were
firing the main engine and going into
orbit we didn't have all the science
instruments on came around 53 days later
and that's when we took our first good
set of science data very first thing we
saw really was pictures of the north and
south pole of Jupiter and they don't
look anything like Jupiter does from the
side so on the right there is a nice
picture of Jupiter with about how you'd
see it from the earth with a really good
telescope I think that actually might be
from Cassini or something but it's it's
how Jupiter looks from the side belts
and zones orange and white stripes the
Great Red Spot all of that stuff on the
left is a picture of the South Pole and
a picture of the North Pole from our
first pass so of course you only have
it's only half lit by the Sun right you
have to go by again and get to put her
in a different rotation to see the rest
of it but already you can see from that
that it looks like you're looking at a
different planet it doesn't even look
similar so all these things that you're
seeing that will kind of like craters or
something
those are storms those are storms most
of them or many of them bigger
in the whole United States bigger than
continents here and there storms in the
north and in the south and they they
last for really long time there's a
zillion of them and we don't see the
continuation the belts and zones we
don't see the kind of pattern we saw at
Saturn basically this was a big surprise
and there were more surprises to come
just from that from looking at the North
and South Poles so what you're looking
at now is a composite image where we put
together a bunch of different views so
that we can get the whole in this case I
think that's the South Pole and we've
exaggerated the color so the colors been
stretched it's not that blue at the
South Pole but it's definitely bluer at
the South Pole than it is at the equator
at Jupiter and know we don't know why
yet but for some reason the gases were
looking at at Jupiter it's got to be
something about what what gases we're
seeing so it's different composition is
bluer up near the poles than it is down
at the equator and there's circumpolar
cyclones now those are a little hard to
see in this visible light picture
because we had to make a composite image
and it's lit from the side and you're
learning a lot we get to watch them and
see some details but we see different
details with the infrared camera so
here's the italian-made infrared camera
Jairam it's called because Jovian
infrared auroral map or because its main
job is to look at the Aurora the
northern and southern lights on Jupiter
but does a great job of looking at the
poles and what you can see is five
cyclones gathered around the South Pole
and a Pentagon with another cyclone in
the center and eight cyclones gathered
around the North Pole with another
cyclone in the center and that pattern
is pretty stable we've been we've been
watching it for almost two years now and
it hasn't changed they're slowly
drifting around a little bit but it's
basically this stable pattern of five in
the South 8 in the north we don't know
why it's 5 we don't know why it's 8
people working on a lot of theories
about why the Cyclones should be there
and they're starting to come up with
some models that maybe can and can
explain it but this was a big surprise
and then if you look carefully at this
there's another really interesting
feature of this these are all cyclones
they're not anticyclones they're all
spinning the same direction so if you
imagine this cycle and spinning around
and the one next to it spinning around
and picture what happens in between and
with this one in the center is spinning
the same direction what happens in
between it's not like gears that can
spin and match up to do that you'd have
to have some of them spinning in the
opposite direction
so in the place right in between the
Cyclones you've got wind going really
fast in this direction and right next to
it wind going really fast in the
opposite direction so something has to
be driving that so they don't all stop
or swallow each other or do something to
change that situation so this is a
really interesting puzzle for the
atmospheric folks to work on that was
probably our first big surprise that
Jupiter was seeing all these storms and
see how different the poles look but the
infrared camera you can also learn about
not just you know you can see in the
dark so you get a cleaner picture but
you're seeing the temperature in the
infrared you're seeing the the glow from
the fact that these gases are are warm
and warmer gases glow more so by
measuring how bright it is you're
measuring what its temperature is and
Jupiter is warmer on the inside than it
is on the outside the reason is that
it's still cooling off four and a half
billion years after it formed it's so
big that it's heat of formation hasn't
escaped yet but the result of that is if
you know the temperature you know
something about the depth so we were
able to make this little movie which I
think is about to start yeah
and showing 3d something like what those
cyclones look like
things are thousands of kilometres
across
all right so we could talk about just
the poles of Jupiter for an hour but
let's move on and get a couple of other
things fit in here so remember I said
we're mapping Jupiter's magnetic field
well because we're in a polar orbit we
can end in a big long one at 53 days we
can take advantage of that orbit and
adjust the timing of when we go by
Jupiter each time to get a different
stripe so what you're seeing is lines to
represent the path of the spacecraft in
the rotating field point of view of
Jupiter so if you were somehow magically
standing on top of the clouds on Jupiter
and spinning around with it that's the
path you would see this pay the
spacecraft take for each of our many
orbits which means when we're done with
all of the orbits with 32 orbits around
Jupiter we've cast a net over the planet
and if we measure the magnetic field
along the way on all of those orbits
then we've surrounded Jupiter and
measured the magnetic field completely
surrounding it so if you know a little
bit about electro magnetics then what
that tells you is if I measured the
magnetic field on a surface that I've
learned what's happening with the
currents inside that surface or to put
it another way if I measure the magnetic
field all around Jupiter then I know
what that liquid metallic hydrogen is
doing deep inside we can understand the
dynamo that generates the magnetic field
by measuring the magnetic field on a
complete surface that could encloses the
planet so that's the goal of the backing
experiment now of course we've only
completed a dozen or so orbits so far
and as you saw in that map we do them in
an order so that the first four are
evenly spaced and then the next four
fill in so that we get eight evenly
spaced around the planet and then it
takes a while you need eight more to get
sixteen filled in around the planet so
we've got eight evenly spaced orbits
around the planet so far and a few
others that will go into the next map
but the magnetometer team made a map of
the magnetic field on Jupiter based on
those on the eight good ones so
far right then we're evenly-spaced and
that was a big surprise so what's being
shown here was just superimposing on
jupiter a map of that magnetic field
where it shows you the strength of the
magnetic field that of course magnetic
fields have direction the direction of
the magnetic fields so red and blue show
you into the planet and out of the
planet and what you can see is doesn't
look like a dipole field like the
Earth's a nice smooth thing coming out
of the North Pole and going into the
South Pole it's got all kinds of
variation and all kinds of spatial
variation much on a finer scale finer
scale that we expected so more variable
on smaller patches on the planet right
and it's also got a whole lot more
variation in the north part of the
planet than in the south I'm gonna run
that little movie again just because it
goes by kind of fast so you can see
again and watch for this time as you see
all this map how this map shows up we
have all these Wiggles up in the north
the Northern Hemisphere and a blue spot
showing up in the near the equator so a
local place where the magnetic field is
stronger and somehow coming out of the
planet and kind of smooth in the south
so it's asymmetric it's got a lot more
variation in it if you think about what
that means what it tells us about the
liquid metallic hydrogen deep inside is
it says that at least part of it the
part with all those wiggles part of the
magnetic field must have been generated
closer to the surface because if it was
generated way down inside then what we
would measure from our spacecraft that
stays up above the planet would have
smoothed out by the time it got to us
all of those Wiggles are telling us that
the magnetic field is generated higher
up in Jupiter's massive atmosphere than
we expected so instead of being all of
it generated down in the liquid metallic
hydrogen it looks like maybe part of
that magnetic field is generated above
the liquid mount
hydrogen maybe in a place where the gas
is is partially ionized where it
conducts a little bit of electricity
enough to affect the magnetic field and
then of course we have to try and figure
out why it's so asymmetric why does the
northland complete completely different
from the South and people are working on
it but as you might imagine nobody
expected that and nobody really has that
wired yet for exactly what's going on so
that was the next big surprise is the
magnetic field just doesn't look like
the models matches great out far from
the planet where we had models and we
measured things before but these are the
first measurements that get really close
to the planet so you do a first kind of
measurement you get surprised alright so
let's move on to the next major
measurement we do that's different than
then anything's been done before
it's the microwave radiometer so as our
spacecraft goes by the planet it spins
and the microwave radiometer it's six
different channels looks out from the
side and observes jupiter it's not a
radar it's not transmitting anything in
the radio it's just looking at the
natural radio emission from jupiter but
we get to look at any given point along
the path at a wide range of angles as
you can see as the spacecraft moves
along each time it spins it's in a
different place and it gets to look at
jupiter from a different angle so that
means i have these six different
channels that see six different depths
and I also get to look at them at each
with each channel at every spot at a
wide range of angles so it's kind of
like doing a cat scan I can kind of
dissect what's going on inside Jupiter
and the radiometer just measures the
brightness it's not making a picture but
the spot that it sees because we get so
close to Jupiter gets pretty small so
this is an example to show you how small
the spots get when we're really close to
our closest approach when we're right in
there near the equator we can see this
tiny little spot we're really measuring
pretty precisely what we see on Jupiter
and then of course as we're further away
we're seeing a bigger part of the of the
planet so what have we learned by
looking beneath the clouds for the very
first time
well we only see a few hundred
kilometers beneath the clouds so on the
scale of Jupiter that's tiny right it
looks like the you know a thin line
there but if you think about what the
planets made out of right it's this gas
giant it's all hydrogen and helium and
other stuff it's should be all swirling
around gas so what everybody thought
before the spacecraft got to Jupiter was
as soon as you get deep enough to get
below the clouds so you get below where
water and ammonia because there's
ammonia in the planet where water and
ammonia condense and make clouds once
you get below that you should be below
the weather layer blow all the storms
and it should just be evenly mixed so
what we thought was our deepest channels
that sea is far into the planet as we
can a few hundred kilometers since
they're seeing well below all those
clouds they should have found the same
thing everywhere we looked and all the
structure should have been up above the
clouds we're up in the area where the
clouds are and higher all right well you
know the theme of this so you know what
I'm gonna say didn't look anything like
that so what we did the easiest thing to
do first so that's what I'm showing you
is to measure the opacity how much it
absorbs the microwaves and most of
that's done by ammonia so measuring the
ammonia was the simplest thing to do
first and what we found when we did that
is if you take this strip where we were
close to the planet we you spread it out
and you plot up at the top of the clouds
how much ammonia there is using color to
show the ammonia and down at the bottom
how much ammonia there is and everything
in between what we see is as deep as we
can see we're seeing structure in the
ammonia we're seeing this place north of
the Equator just north of the equator
where the ammonia seems to be uniform
with depth there maybe even getting to
be more ammonia up at the top then down
at the bottom and right next to it just
north of it there's this place where
there's a whole bunch of ammonia missing
before it gets down to the the
well-mixed part and
part all the way at the bottom we're
showing that as as the same ammonia all
the way across that's because that's the
deepest we can see we don't know how how
much ammonia there is all the way down
at the bottom beyond that so we said
well if it's well mixed how deep can we
show that it's not well mixed and it's
as deep as we can look so it could
actually have structure that goes even
deeper than that then we see if you look
carefully you're seeing more ammonia
over here and then some missing as you
go down and then more below that so this
was a complete surprise and a big
mystery as to what the heck's going on
people have been working on that for a
long time now we're starting to make
inroads we're starting to have ideas
about how this can happen and what it
says about the circulation deep within
the planet and of course one of the
things we need to do is measure the rest
of the planet
remember our orbit gets really close
here and is not as close to Jupiter up
here over the poles but as the orbit
progresses each orbit shifts a little
bit so that closest approach part the
para jove starts out down near the
equator and it moves up a degree every
orbit so by orbit 30 we'll be up here
and be getting data up in that part of
the planet anyway we have I'll show you
the first nine or ten orbits now what I
did is I took that same map and I just
spread it out so this is latitude minus
40 to plus 40 this is depth it's written
in pressure but think of that as up at
the top of the atmosphere and this is
say 350 kilometers down inside and as
you as you go around the planet and look
at it at the multiple stripes we've got
you see sure enough at some longitudes
it really is more ammonia up here than
down here but this zone of ammonia that
spreads all the way up to the top is
there at that latitude everywhere around
the planet so it's like a ring around
the plant at a latitude of a few degrees
north of the Equator
why why is it at the equator almost why
is it north and not south why is it not
matching up with the belts and zones
very well that we see at the surface
nobody really knows why is there ammonia
missing here
why is there this inversion these are
all things we're puzzles were trying to
figure out with lots of ideas but we
need a lot more data to try to figure
them out we need to spend a lot more
time basically building new theories
because we made the theorists throw out
all the theories they had which was
really lots of fun okay you can also by
looking at at that we have lots of
longitudes now you can see some other
things that are really nice to see as an
experimentalist the fact that we're
getting the same answer over and over is
really good because it means our
instruments nice and stable if there
were problems with the instrument which
were you know generating more noise than
we thought it was or if we have the gain
wrong or things like that then we
wouldn't get this nice self-consistent
picture and then we can also see some
little details as you go to different
longitudes so if you watch over here for
example you can see sometimes there's
more or less ammonia over here this
thing moves around that varies a little
bit and every once in a while we see
something at great depth and that thing
we're seeing that comes down here at
about minus 20 degrees latitude at great
depth is the great red spot
so we one of our passes we flew right
over the great red spot and what we
found was another big surprise which is
the great red spot goes as deep as we
can see so about 350 kilometers at least
the models people had theories about how
the great red spot worked and models of
predicting what it should be and all of
that and in general they expected it to
be a lot shallower than that so now we
have to explain why is the great red
spot so deep and how does it work and we
have some people working on that and
some papers that will come out before
too long
and I probably shouldn't spill the beans
on those papers until we know that
everything's right but you can tell to
look at it if you look at this picture
at the top that's the visible light
picture so you can see where the great
red spot is and then you can see from
the red here that we've got the center
of the great red spot looking cold in
the upper channel so I get down to 10 20
30 kilometers or so maybe even as deep
as 50 or 80 kilometers and the great red
spot is cold in the middle but when I
get down to 150 kilometers or 350
kilometers the great red spot is hot in
the middle we still see it still
definitely looks different from all the
other passes that didn't go over the
great red spot looks different from the
surrounding territory but something is
changing its going from hot to cold as
we go down and then there's this hot
region just to the side of it that's
changing and merging down at the bottom
so we're definitely getting a very
interesting picture of this storm and
remember it's a storm bigger than the
whole earth and a lot - a lot to chew on
so I get to tell you it's a surprise but
I don't get to tell you old and this is
what's going on and this is how it works
because we don't have that all figured
out yet okay so let's move on to the
next big thing which was the gravity
remember gravity is trying to measure
the interior and one of the first things
we got out of the gravity was the belts
and zones so remember those are the
stripes the jet streams moving up at the
top of Jupiter's atmosphere and nobody
knew how deep they went theories ranged
from all the way down to having them go
way down deep inside the planet to being
really shallow up at the top so now we
know they go about 3,000 kilometers into
Jupiter and that's what this little
animation is showing and beneath the
3,000 kilometers the rest of Jupiter
rotates kind of like a solid body
remember it's not a solid body it's a
liquid down inside there but it rotates
all together below about 3,000
kilometers
so we learned that from the gravity so
that the belts and zones go that deep is
really interesting and that the interior
rotates as a solid body is really
interesting that was a surprise and
we're starting to look at at that and
it's very interesting that it's about
three thousand kilometers because that's
about where it might be conducting
electricity enough to make a magnetic
field so it could be that the magnetic
field has something to do with holding
the inside part and why the belts and
zones only go that deep basically it
would be that they go as deep as they're
gonna get as they can until the magnetic
field interferes with them we don't
really know that yet it's speculation
the other thing that we've learned
remember we were looking for the core
dense core down inside Jupiter so what
we found is yes there's a dense core but
instead of a compact core down in the
middle where you go down and the density
is is you know the gas the liquid and
everything and then you get to the edge
of the core you get a sharp boundary and
then now we're in the dense part what we
found is something bigger than that and
fuzzier than that
like maybe it's dissolving in the liquid
or something so we found this big fuzzy
core down inside Jupiter and now we're
looking to see if there's an even denser
one inside that which will take a whole
lot more gravity measurements but again
it was a big surprise there's a reason
we're calling this the new Jupiter right
all our ideas about Jupiter of the
things that we hadn't measured yet we're
wrong and we have a new picture of
Jupiter now all right so that's the
exciting stuff some of the exciting
stuff from the gravity and I see I'd
better hurry if I want to have some time
for questions so let's talk about the
magnetosphere the Aurora so that also
was lots of big surprises
first of all they're a lot more complex
than we expected so what you're looking
at here are ultraviolet images of the
Aurora where we've taken lots and lots
of pictures and added them up to make a
composite
sort of the average northern in southern
lights how many people here have seen
the aurora on earth have been up to see
the Northern Lights or down south to see
the southern lights so a smattering of
you anyway well to give you an idea of
comparison right to something to scale
it with this auroral circle if I plot
the earth down on it the whole earth
maybe it would you know fit in there
somewhere
so these are enormous the the auroral
lights on Jupiter than the northern and
southern lights are these enormous
displays of raw power from particles
smacking into the atmosphere and there's
an auroral oval at least they call it an
oval you can see it's a little odd shape
here in the north and the south is more
I could nice clean oval there's an
auroral oval that we can see from Earth
and we've seen that glow and learned
about the aurora from Earth but there we
only see it from the side so we're only
seeing it as it comes around in our
point of view and we didn't get a really
good look now we have great pictures
with the ultraviolet spectrometer and
the infrared camera and great
measurements with the particle
experiments that measure the particles
that hit the spacecraft and we see that
the Aurora are really complex and
there's all this structure going on both
here and in the center and if you look
at it in the infrared you can see an
amazing amount of of structure so you
see this main Aurora Louisville which is
where most of the power is but there's
all kinds of stuff in the polar cap that
we didn't really realize was there
there's this tail around it it's easier
to see in the next picture there we go
in that one right so the moons of
Jupiter leave a mark in the Aurora so
that one is IO is the biggest tail is
this long tail caused by Jupiter's moon
Io and we get to see amazing amount of
structure and things going on in there
as well
so we're learning a lot about the aura
of Jupiter and some of the things we're
learning are that it's much more
complicated than we expected that we see
for example the mechanism that makes the
brightest strongest aurora on the earth
we see that acceleration mechanism the
way the particles get sped up in
Jupiter's magnetosphere we see that on
Jupiter and it makes some of the strong
Aurora but not the really strongest part
the really strongest part of the Aurora
that we see is some other mechanism that
we haven't figured out yet for how those
particles get accelerated we're looking
for acceleration regions to see where
particles are streaming down or maybe
some of them are coming up from
Jupiter's atmosphere there's a lot to
learn
we've got all kinds of surprises which
since I need to get some time for
questions I'm not gonna try to go
through right now I'm gonna move on to
one more thing that we learned which is
a new radiation belt around Jupiter
another surprise so the high energy
particle experiment that Jedi instrument
it's called Jovian I forget what the
acronym stands for a energetic detector
of ions or something like that that
detects high-energy ions found right
close to the planet there's a ring
around the planet so I'm showing you a
cross-section but imagine it coming
around in front and behind the planet as
well very close to Jupiter of ions that
we didn't expect we're seeing sulfur and
oxygen and hydrogen ions and we think
that they probably started out as atoms
that were ionized you know have their
electrons stripped off when they hit
Jupiter's atmosphere and created this
belt of ions trapped really close to the
planet that we're flying through so that
was another discovery all right get in
there
so another discovery that we made is
actually more about people than about
Jupiter which is because the the visible
light camera on Juno which is called
Juno cam we set it up basically as a
citizen science experiment so it's a
camera without a real major science team
to try to interpret all the data and all
of that stuff we basically take took the
raw data from that camera put it out on
the web and said
everybody go play so when we were
planning which images to take we got
collected input from the public about
which images to take a Jupiter when we
were trying to get context of what what
does Jupiter look like now because you
know it's a gas giant it's constantly
changing we collected images from
amateur astronomers to use this context
we let the public vote on things then we
put all the raw data out on the web and
let anybody who wanted to play with that
data and try to construct pictures out
of it you know when you take the data
from a camera out in space it's not just
like snap an image and there it is you
have to put all the pieces together and
collect you know a red green and blue
image together into a color image and
you have to work on matching up when you
take a picture here and a picture here
put them together to make a mosaic take
into account that the planet is curved
all of that stuff that is normally done
by a team of professional scientists has
been done by volunteers and they've done
an amazing job it's absolutely
spectacular what we learned is if you
let people play they'll do amazing
things so there are some I hesitate to
call them amateurs there are some
citizen scientists out there who don't
get paid to do this science but some of
them in their day jobs get paid to do
other kinds of image processing and some
of them are mathematicians and some of
them are artists and they've made
amazing images using the data from Juno
cam at Jupiter so this is just a
snapshot I went I don't know a week ago
or so to the website where all this
stuff gets posted and snapped an image
to show you and you can see if you look
through here some of these are useful
for for getting at the science and and
looking at all those cyclones and storms
and studying things and some of them are
artistic images where people have done I
think this one is somebody's taken a
picture of Jupiter and made it look like
a painting
so we found a lot of artists got
involved and we found a lot of people a
lot of amateur astronomers who know a
lot about Jupiter got involved and
there's been all kinds of things coming
out of this including a lot of science
so the message there is if you
crowdsource the science to a bunch of
citizen scientists they'll do amazing
great work okay and we also have student
scientists so one of my other hats is
the lead scientist for the cold stone
Apple Valley radio telescope project I
wasn't gonna let this opportunity go by
without telling you a little bit about
that so that's a project where students
all over the country over the Internet
run a large radio telescope that belongs
to NASA it's 34 meters across so 1/3 of
a football field and they do real
astronomy with it so they're learning
about science by doing real science one
of the things they do is measure the
radio waves from Jupiter remember
Jupiter surrounded by these radiation
belts they give off radio waves so we
have an experiment as I talked about
that looks at the radio waves from the
planet if you're trying to look at it
from Earth you have this bright radio
light shining in your eyes it's hard to
see the planet in in between if you're
where Juno goes then this bright light
is looking over your shoulder mostly you
get to see the planet but a little bit
leaks in so you have to subtract the
radio light from the radiation belts
well the students are measuring that
from the earth with the radio telescope
and that contributes to our model of the
radio at Jupiter so they're actually
contributing to the project so we have
real students doing real science and
part of the real science they're doing
is working with Juno to supply science
data that we need and that means the
Juno science team of course participates
in the classroom and so forth and in the
teacher trainings and we actually have a
few teacher trainings coming up if you
know anybody have you know any teachers
who'd like to get involved with doing
real astronomy real radio astronomy
working with the Juno team and other
professional astronomers there's those
three trainings they can find all about
it at the the website for gaved Galileo
gavotte org there's online training and
so forth as well okay so I finally got
to the part where we get to ask
questions which is my favorite part and
I put a bunch of websites up there in
case you have questions you'd rather
look up or you want to see some of the
80-something papers that I mentioned
that have already been published that I
didn't get to talk about but why don't
we open it up for any questions that you
do have to ask me yeah so I'm gonna
repeat the question because people were
watching it online or see the video
later won't be able to tell what you
asked and I'm also gonna mention which I
was supposed to do first if you have a
question there's a microphone over there
you guys can wait online to ask the
question on the microphone and then I
won't have to repeat it but his question
was whether there's a similar spacecraft
at Saturn doing similar kinds of
measurements so the Cassini spacecraft
spent a long time it's a turd measuring
all kinds of things doing amazing
science and its original mission was not
a lot like Juno's it was in the
equatorial plane so it went around the
planet sideways instead of over the top
and it was looking at the whole system
and it was looking at the moon Titan and
it had a probe that went in and did all
kinds of great science but it wasn't the
same kind of science as what we were
doing but when that minute when that
mission finished and they still had a
working spacecraft and they still had
fuel left they started working on
extended missions to do other things and
in the very last stage of that project
at the instigation of some of the Juno
scientists who were also on the Saturn
science team they said now that we're
down to the end go ahead and take a risk
why don't we and let's try and fly in a
Juno like orbit past Saturn so they did
they couldn't do all the same science
that we're doing at Jupiter because they
didn't bring instruments for that
purpose right remember they brought the
instruments they
for a completely different mission but
they were able to do some of it and they
learned some things about the interior
of Saturn which I'm sure they're not
ready to publish it because it's not
been very long since they did that but
we'll get to do a little bit of
comparison and we'll see maybe someday
in the future of Juno like mission will
be sent to Saturn to really do the job
the way we did a two Paterna soar
neptune all right who else has a
question great yeah I have two questions
the first is if you could say something
about this metallic liquid hydrogen is
it what kind of viscosity do you have is
it like lava or something and the second
question is my understanding is what
little we know about the interior of
Saturn is there might be a level of
which there's like precipitation of
helium or something is there any kind of
interesting precipitation going on
inside of Jupiter right okay so let's
start with the liquid metallic hydrogen
part and I'm gonna get to give you my
favorite answer which is nobody knows
but I can say a little bit more about
that so the way we know that there
should that hydrogen when you squeeze it
enough should make liquid metallic
hydrogen is from theories that are based
mainly on experiments where you take a
small pellet of hydrogen you zap it with
enormous really powerful lasers and for
a tiny fraction of a second before it
explodes it implodes and reaches this
really high pressure you try to measure
what's going on in that very tiny
fraction of a second so it's really hard
to do those measurements from those
measurements and from those models and
of what hydrogen should look like under
great pressure they made predictions
that it should become a metal at about
to melt to mega bar two million times
the pressure here the biggest piece of
information to validate that prediction
and make everybody say yeah liquid
metallic hydrogen is real is Jupiter has
a magnetic field and we knew that for a
long time we've known
Jupiter had a magnetic field for a long
time because even before we ever got
there because you can see the radio
waves from the radiation belts that are
trapped by the magnetic field to make a
magnetic field on a planetary scale you
need a liquid that conducts electricity
Jupiter's mostly hydrogen and helium
so you weren't gonna have molten iron
like on the earth and generate anything
near as big a magnetic field as we what
we see on Jupiter so just the fact that
it had a magnetic field confirm the
hypothesis that yes hydrogen makes
liquid metallic hydrogen but we don't
have good measurements of the viscosity
of liquid metallic hydrogen
what we have is theories about what it
ought to be like and the conditions
under which it's moving are really high
pressures you know and 10 million times
the pressure here on the earth it's hard
to even talk about things as a liquid or
a gas or a solid it's different so
that's kind of the state of knowledge
and we'll learn by measuring the
magnetic field remember we're gonna keep
mapping and get more detailed map of the
magnetic field when we finally
understand the Dynamo well that will
also be teaching us about the properties
of hydrogen what hydrogen does under
great pressure so we start out with how
does hydrogen behave let's use that to
figure out the dynamo eventually we
maybe figure out the dynamo and use that
to tell us how hydrogen behaves okay and
I forgot what was your second the
precipitation oh right now so yes so
there's probably helium rain going on a
Jupiter exactly how much and where is
something we're still working on but
should come out of our data there's
water rain no doubt on Jupiter we see
that in you know we've seen lightning at
Jupiter before we know that there's
liquid and solid water and water in the
gas state how deep that rain goes
probably well possibly has something to
do with that bizarre structure we saw in
the ammonia and how that the atmosphere
works at a few hundred kilometers below
the surface but we don't know those
answers yet I was in graduate school in
the early seventies
and they were talking about speculations
of metallic hydrogen in Jupiter then
without any bility to measure anything
thank you thank you are we beginning to
understand they're really startling
differences between Jupiter and Saturn
well we're beginning to understand the
really startling differences between two
pillars and Saturn but we've got a ways
to go still kissed all the surface stuff
then you see where you know Saturn has
these geometric shapes at the poles that
have something to do with how the jet
streams work and Jupiter has this
completely different chaotic looking
structure on a cyclones tells you that
the atmospheres behave very differently
and maybe that shouldn't be so
surprising Jupiter's a lot bigger than
then Saturn and the heat flow and out of
is different but it'll be awhile I think
before anybody is feel feels confident
saying okay now I understand Jupiter and
Saturn hi two questions first one is
I've read that Juno is the fastest
man-made object that we've ever sent out
into the cosmos but I've also read that
it's not quite that simple because I
guess it's all relative so can you talk
a little bit about that to the extent
that you can in a way that I might
understand to answer that question is
this our fastest the second question is
why did you include a giant can opener
on one of the panels okay it's not giant
can opener but it certainly does look
like one or or a bottle opener anyway
but let's start with this with the speed
record for for fastest man-made object
if I tell you I throw a baseball and say
how fast did I throw it well you can
measure how fast it went you know here
on the ground if I'm sitting on a moving
train that's going 100 miles an hour and
I throw the baseball suppose I've got a
really good arm and I can
throw it at 90 miles an hour the trains
moving in 100 maybe I threw it at 190
now because the trains 100 miles an hour
plus the 90 or if the trains going the
other direction maybe the baseball is
only going 10 miles an hour I have to
define a reference frame I have to say
how fast is it moving relative to what
okay
so if I choose the reference frame
carefully then I get to say that Junot
is the fastest thing ever built by
people and I'm not sure I'm going to
remember this exactly right but I think
the way it goes is if you take Cape
Canaveral Florida and you follow it and
you say where is where we launched from
moving in space as the earth goes around
the Sun and the Earth rotates and Juno
moves out or past the Sun and so forth
then at the time when Juno hit its
closest approach to Jupiter in its very
first time when we fired the main engine
to slow down so that we would go into
orbit before we did that before we fired
the engine when it was moving its
fastest I think if I remember right
that's the reference frame in which you
get to say it's faster than anything
anybody else has ever said so it's a
pretty you know it's kind of a cheat but
it does tell you it's moving really fast
and that's mostly because of Jupiter's
enormous gravity so another way to look
at it would be how fast is it moving
relative to Jupiter right so you ignore
the earth and the Sun and all the
motions we did to get there and you just
say what's the speed of the spacecraft
when it goes flying by Jupiter compared
to the cloud tops that it's flying by
and then it's at its fastest I think
that number was in the neighborhood of
30 kilometers a second so you've gone
all the way across the LA basin it's
pretty fast okay so the giant can opener
that's actually the magnetometer boom so
we have two magnetometers on the
spacecraft built by the same team doing
the same job but it's not just redundant
see part of it is if one of them breaks
you have another one but part of it is
one of them is closer to the spacecraft
than the other and both of them are more
or less as far from the spacecraft as we
could get them
so everybody somebody here I'm sure will
think of this immediately why do I want
my magnetometer really far from the
spacecraft right I heard at least one
person say it I want to measure the
magnetic field of Jupiter not the
magnetic field of the Juno spacecraft so
I want the magnetometer as far from the
spacecraft as I can get and I want the
spacecraft as magnetically clean as we
can get and it's really not eclis clean
the the magnetometer team the guys at
Goddard who built this magnetometer
worked really well with the spacecraft
team to help them measure the magnetic
field of parts as they were coming onto
the spacecraft and to figure out ways to
make the make the spacecraft really
magnetically clean so that every time
you have an electric current this way
right next to it you have another
electric going current the same size
going the opposite direction to cancel
out its magnetic field not using any
magnetic parts all of that stuff so the
spacecraft has a really low magnetic
field and the magnetometer is really far
away from it and that tells you why we
really want to one closer of the
spacecraft than the other because now as
the spacecraft spins around and we
measure Jupiter's magnetic field if
there's a difference between the two
magnetometers we can tell that there's a
magnetic field from the spacecraft as
opposed to from Jupiter so we can cancel
that out or subtract it out and get the
magnetic field of Jupiter but it came
out really magnetically clean so it
worked well yeah thanks for having me I
have two questions the first question is
about the is about the weather and the
circulation of gases in the atmosphere
and the magnetic field and I'm just
wondering if you can elaborate a little
bit more on that and also is there you
talked about how the movement
of gases or fluids in the quote
atmosphere of Jupiter I might be
generating might be generating magnetic
fields and I'm curious about the OP the
possibility of the opposite effect and
then my next question is about the
metallic hydrogen that you're discussing
and this the the discussion always seems
to be as if the metallic hydrogen is
pure and I'm just wondering if what
speculation has been done about the
about alloys in which other other
elements or non whatever elements are
mixed in with that and what effect that
has on on your calculations that's gonna
be a lot to talk about so all right
let's see what we can do let me take it
in reverse order because I remember the
little it is the last question best so
remember that Jupiter's composition
while not exactly the same as the Sun is
similar and we know what the composition
of the Sun and the whole solar system is
it formed from the same cloud of
material presumably and that's mostly
hydrogen and helium so by the time you
get down even to oxygen it's a few
percent or something right when you get
down to something that might conduct
electricity or mix in with the metallic
hydrogen it's a very low percentage of
the material so if and there probably
are if there are contaminants in the
liquid metallic hydrogen ocean those
contaminants probably don't play a big
role because it's such a low percentage
of the total material now you gotta you
do have to be cautious about that if I
if I said you know I made I took iron
and I put a little bit of carbon trace
elements in and it shouldn't matter much
you know I can make steel but that's a
solid with a crystalline structure
that's different from a liquid and even
there I think the percentage of carbon
is probably higher than percentage of
the law of trace elements in the
metallic hydrogen so I'm not going to
try to go beyond that because I don't
know the answers I'm sure somebody
somewhere has done that calculation
about how much we have to pay attention
to the impurities but that's the rough
sort of description of it now the
magnetic field and the atmosphere I want
to make sure that we get the picture
right so picture this liquid metallic
hydrogen under very high pressure
swirling around because there's heat
coming out of the planet and the planet
is rotating rapidly so you know the heat
wants to make things rise right you
carry the heat out you move material
around spin the planet around rapidly it
doesn't move in a nice smooth easy
pattern you get shear so you have stuff
stirred up that's generating a magnetic
field that's got to be the bulk of the
magnetic field from Jupiter but our
measurements show that the magnetic
field is more complicated than we
thought it should be based on that so
one possible answer and it's by no means
sure is that higher up just above that
metallic hydrogen layer where the
hydrogen is compressed but not enough to
make liquid metallic hydrogen that maybe
that conducts the look electricity a
little bit and we know that if you
squeeze hydrogen gas enough you can
pressure ionize it you can have those
hydrogen atoms smashing into each other
so much because of the high pressure
that every once in a while an electron
gets stripped off and so you have a
little bit of conductivity some of them
are ions instead of atoms if you do
something like that conduct electricity
there and it's all moving around that
could affect the magnetic field now the
way a dynamo works yes the magnetic
field is definitely interacting with the
motion of the liquid so it's not you
make the liquid move around and produce
a magnetic field and voila you get a
field from whatever the liquid was doing
it's you make the liquid move around it
produces a magnetic field that affects
the way the liquid is moving makes it
move in a different way that affects the
magnetic field and you get this process
that's
much more complicated but in which
actually the motion of the liquid can
generate a magnetic field that causes it
to move in that way some more and makes
a stronger magnetic field that's how a
dynamo works we think so it's it's not
simple but yeah there's definitely an
interaction between the motion of the
fluid and the magnetic field that it
generates now on top of that if I look
at the upper atmosphere if you remember
that picture with the belts and zones
the movie this one it's not playing I
can't tell if that's starting to block
there we go so if you remember that we
have this speculation and it's only
speculation at this point that the fact
that those belts and zones are 3000
kilometers deep might have something to
do with getting deep enough to where the
pressure makes a little bit of
conductivity and perhaps below that
where the the gas conducts electricity a
little better maybe the magnetic field
holds it and stops the belts and zones
from going any deeper speculation at
this point the the main thing is we can
tell from the measurement about how deep
they go and we can tell from the
measurement that below that the planet
rotates as a solid body body and then
anybody who thinks about planets can try
to figure out why it does that
and of course we have lots of people
working hard on that even as we speak
they're probably at home you know
thinking about things and working on
their computer models okay
did that cover the what you're asking
thank you very much I obviously have
other questions but I think that's
enough well you're welcome to go to the
end of the line and come back and ask
your questions thank you after the mine
is very simple I just want to know what
would you say would be a difference from
the hot Jupiter the new Jupiter would
with those all that information be
different I'm sorry say the beginning
part again the difference between hot
Jupiters oh you'd be like around other
stars
and our Jupiter so from the information
you just are discovering it right so
it's a trickier question than it sounds
and that's because in many ways what we
know about the the planets around other
stars is much more limited but of course
we have lots of them instead of just the
only one example we have here I know a
lot of people there's a bus that they're
trying to catch is why we have a bunch
of people moving at the moment so we
don't really have that comparison yet
our guess would be that the one planet
giant planet that we have Jupiter is
presumably sort of typical for what
planets that size look like but we only
have the one we don't have 50 of them to
look at and if you look at the planets
around other stars that we've discovered
there's all these biases about how you
discover them makes it easier to
discover big ones close to the star and
so forth I will say that until people
started finding exoplanets like that no
one really expected to find giant
planets that close to a star so the
model of how two stars how two solar
systems form still has a lot of work to
go on it to understand we think it has
something to do with planets forming
farther from the star and drifting
inward as they gobble up the material
that makes up the early solar system and
in fact we think perhaps that Jupiter
formed further from the Sun drifted
inward gobbling up stuff on the way and
in the process disturb the orbits of
what now our Neptune and Saturn and
kicked them out into the outer solar
system and maybe even stirred up the
things that eventually became the Earth
and Mars and all the small planets we'll
learn more about that as we finally get
the water content which is going to come
as
we understand the atmosphere better
that'll tell us a lot about whether
Jupiter moved or whether it formed where
it is now oh and then also the the Jade
I think that's what you were referring
to for the middle part of where it was
measuring I think that's what it's
called the Jovian so there's we have two
instruments on the spacecraft that
measure the particles that are hitting
the the spacecraft
there's the Jade which is Jovian auroral
distributions experiment or something
like that
and that measures the relatively low
energy charged particles and then
there's Jedi which I I will try to
remember the acronym but it oh well
you're right it was on one of my my very
first slide there you go and so Jedi is
the higher energy particles it's hard to
get through all of these slides
backwards there we go okay good so Jedi
is Jupiter energetic particle detector
of ions it must be ions because that's
the eye anyway so we have to measure a
full range of energetic particles and
then they work together right because
the particles don't know whether they're
energetic are not energetic and in terms
of distributions it's not like they come
in nice little bins so you measure that
you measure the the plasma waves that
are going through so you see magnetic
and electric fields you you measure the
the light from when those particles hit
the atmosphere so that's the ultraviolet
and the infrared cameras you measure the
radio waves given off by the particles
we can do that with the microwave
radiometer we measure the magnetic field
that organizes all of it put all that
together in a big picture and that's how
we understand the magnetosphere so it's
all of those instruments working
together as a team to really understand
the picture well that's awesome thank
you thank you all right I have a very
quick question regarding the Cyclones so
I know we previously went over that on
the same site the Cyclones next to each
other they're moving the same direction
however I was wondering if the cycling
groups on the north pole are moving the
same directions as those on the South
Pole and if so what is the popular the
most popular theories that we have come
up with or even if is speculation that
would be good too alright so let's look
at the pictures and we can actually
answer that question so here's the South
Pole so I'm looking at it from the south
and you can see the spiral goes around
that way right yes
here's the North Pole I'm looking at it
from the north and you can see the
spiral goes around the other way yeah
okay
so you know whether they're whether
that's the same direction or opposite
direction depends on you know the
viewpoint right but you can see which
directions they're they're spinning that
way and then since all of these are
doing the same thing then that's why
it's a problem if they're all spending
the same direction and rubbing on each
other somehow they have to you know so
somebody has to supply energy to keep
them rubbing on each other or something
has to give them you know a way to spin
next to each other and not destroy each
other it's also true that if you take a
rotating planet and you put a cyclone on
it and say what does it do what you
would expect actually is the cyclone
will drift up towards the North Pole or
if it's on the southern hemisphere
spending the right way to do that drift
down towards the South Pole
because if you imagine you know you're
on Jupiter you're a little bit north of
the equator and you're spinning around
well the whole planets rotating the part
that's that's closer to the equator has
further to go all the way around the
planet then the part that's north of the
Equator so if I come around in my
cyclone and I'm going north then I'm
shifting speeds if I come around the
other way then I'm shifting speeds
downward right so if you work out all
the you know add up all the speeds and
say what does the air do you wind up
with a little bit more speed heading
north and then heading south if you
cycles spinning the right direction to
be a cyclone so you expect the cyclones
to drift up to the north that of course
doesn't explain everything you have to
say well where do the Cyclones come from
in the first place and why do they last
long enough to spin up to the north and
why do they last long enough when
they're all butted up against each other
so that we see them you know for two
years so far and not much change but at
least a little piece of that puzzle is
explained by just if I make a cyclone
and I don't have anything to stop it
there's no ground for it to run into
it's gonna just gradually drift north
with northwards and pile up at the North
Pole well has anybody made any
prediction when exactly that has started
and will it ever stop or is just
constantly gonna keep going or nobody
has ever made any sort of predictions or
studies yet well it's pretty new I mean
we've been there for less than two years
and this was a big surprise to everybody
in the first place but one of the things
we're doing is watching these cyclones
really carefully to try to see how they
change so you keep coming back and you
look at those five cyclones around the
South Pole and they're always there
every pass but if you take a really good
look at the images and compare they're
shifting a little bit they're not just
rotating in place they're moving a
little bit so we're trying to start
tracking them and use that to try to
understand how long do they really last
and what do they do and how do they move
and all of that stuff do you have a
specific website that's dedicated to
this that I can sort of follow to see
they're tracking and all those status I
don't think so I think your best bet for
that is to keep on eye on NASA's website
for Juno if you look at you know
nasa.gov slash Juno or on mission Juno
dot s WRI which is a more sort of public
friendly version they're both fairly
friendly but that's that's the one
that's also got all the tune of camp
stuff I'm switching through to get to
the websites because
telling you the name is probably not
going to be easy to remember but you can
write it down or find it online probably
the place to do is follow there and of
course it will publish things in the
scientific literature but that's gonna
be a while
good question though maybe we should
think about whether there's a way to you
know take the different scientific
questions and put them out there and let
people follow the story a little better
it would be great if everybody can take
votes on like which sort of data they
want to follow and then you can open up
like a tab on a website just dedicate it
to those data and constantly updating
them every month that would be awesome I
like the idea but I'm also picturing the
people who would have to do that saying
you know we don't have anywhere near
enough people to do that right thank you
I have two questions the first is do you
think that the that there are eight
cyclones in the North Pole and five at
the South Pole does that have any
anything to do with the fact that the
magnetic fields seem to be more
turbulent in the north and my second
question is that it seems like most of
the science is coming from the flyby
period of Juno are we collecting any
data from when it's like the rest of its
orbit right okay so about the Cyclones
of the magnetic field
yeah it's striking that the planet is
asymmetric in its magnetic field and in
its atmosphere and as seen at the top
and it's gravity signature but it's hard
to picture how the magnetic field could
be influencing those cyclones because up
at the top of the atmosphere we're at
pressures similar to the pressure here
in this room the gas doesn't conduct
electricity very well so it shouldn't be
affected by the magnetic field much and
it's got huge amounts of mass moving at
pretty good velocity since these are
cyclones right think of you know the
power in a hurricane here on the earth
and now you're talking about storms that
are bigger than the biggest
hurricane you've ever imagined so nobody
has yet come up with a mechanism that
explains that that connects the northern
the the asymmetry in the magnetic field
with the asymmetry in the weather not
saying it's not possible but I haven't
heard an argument that works or anything
where the math plays out at all what was
the other thing you asked with if Juno
collects like data on the estimates date
away from pair jokes we call that part
where we get really close to Jupiter
para Jove you know near Jupiter para
Jove and the most important science data
in general is from pair Jove as you said
from within a few hours of our closest
approach but yeah we don't turn the
instruments off for 53 days when they're
out far from Jupiter and there's other
things we get to measure in particular a
lot of the fields and particles
instruments you know get to measure a
lot of interesting stuff about the
magnetosphere because to Pater's
magnetic field stretches way out there
and our orbit is big enough that we have
lively cross lots of interesting regions
quite far from Jupiter and we do those
measurements it's not a prime science we
went there for but it's lots of good
stuff and we're collecting lots of data
and the microwave radiometer that does
those atmospheric measurements the data
right up next to Jupiter are way more
valuable than any of the rest of the
data from that microwave radiometer but
it doesn't use up a lot of bandwidth to
send that to the ground we get to learn
about the radiation belts a little by
seeing them in the radio and microwave
radiometers don't like to be turned on
and off so we just leave it on let it
run and collect the data and all we do
is throttle back the data rate a little
bit when it's away from the planet so we
won't won't be wasting the communication
with the ground because you can only
send so much data at a time but we just
leave it on and I think it's about one
seventh of the data rate the whole time
just because it's safer for it to never
turn it off thanks sure
I I had a question about the consistency
of the magnetic field measurements over
multiple years given that it's being
generated by a fluid right it would seem
reasonable that maybe over the course of
multiple years that would shift and so
the map is actually changing and not
like a consistent map right so we are
looking for variation in the magnetic
field over time but you have to remember
Jupiter is so big that it's really hard
for us to picture the time scales
involved so we're gonna be a Jupiter if
everything goes well and imagine the
spacecraft lasts for a really long time
and we wind up doing an extended mission
and all that stuff suppose you know
everything goes perfectly and nASA says
sure do whatever you want we'll give you
a lots of money and all of that
maybe the spacecraft would be around for
another I don't know I'm totally making
it up but say 10 more years right it's
not going to be beyond that because the
radiation sooner or later is gonna kill
it Jupiter's been around for
four-and-a-half billion years it hasn't
even finished cooling off yet the the
motions in the interior you know suppose
that that dynamo is like shifting like
crazy on a flash of a time scale on
Jupiter's timescale that still might be
500 years so yes we are looking for
variation in the magnetic field we hope
that as we get through all our 32 orbits
and maybe you know extended mission or
something you go beyond that that we'll
be able to tell whether the magnetic
field is varying but given that of
course Jupiter is surprised us a bunch
don't expect it to be varying on
timescales of a year or two we expect to
be able to measure really small
variations of the magnetic field and say
yeah I think if you waited a thousand
years it would do this thanks sure
perhaps this hasn't been determined yet
because you get a finish the mission and
then just alluded to possible extended
mission but at some point do you
anticipate that that Juno is going to
meet the same fate as Cassini because
you have to protect Europa in particular
yes so right now we're on a plan where
we do 32 orbits
32 science orbits so it's a few more you
know with a spare or two to make sure we
get all the longitudes and do the
magnetic map and then at the end of that
we fire the thrusters so that it dives
into Jupiter's atmosphere and burns up
that's the plan
nobody's we're not even asking for an
extended mission yet you know that's
gonna be 2021 by the time that happens
but presumably if everything works great
and we're able to show NASA that we can
protect Europa without destroying the
spacecraft right away then we would
figure something out and we'd ask and
see if you know they're willing to let
us operate it longer we're in the prime
mission we're not ready to to work on
that and we have a requirement to make
sure that we don't contaminate Europa
the simplest and most straightforward
way to not contaminate Europa is to
vaporize the spacecraft in Jupiter you
can come up with more complicated things
and I'm sure you know nobody's gonna
want to destroy the spacecraft without
needing to I'm sure when the time comes
if somebody comes up with a clever plan
we'll go are you hey look your rope is
safe enough let us do this another you
know so many orbits but right now we're
on a plan and the plan has it in orbit
I think it's orbit 36 if I remember
correctly but something like that so
after 32 science orbits plus a couple of
spares plus there were one or two at the
beginning that weren't science orbits
will fire the thrusters in deorbit and
burn it up in Jupiter which is
essentially what Cassini did and as you
know Cassini did you know extended
extended extended missions until finally
they had to you know give up and say
okay we can't do this anymore we're
gonna run out of fuel and we have to
protect Enceladus
so the the thrusters are just gas we had
a we had hydrazine and an oxidizer to
fire the main engine
but we're not using the main engine
anymore the thrusters that control the
attitude and shape the orbit now are
just blow little gas out from the fact
that the tanks are pressurized and
that's the limiting factor for fuel the
limiting factor for lifetime might very
well turn out to be radiation damage
haven't seen any significant radiation
damage yet but there's a long mission to
go but that's the kind of thing that
probably limits the technical lifetime
and then of course you know we're at the
discretion of Congress and NASA to
decide whether they want to keep paying
to make this happen if we got to the
point where we weren't getting great
science or wasn't worth the money then
they might that could also be a limiting
factor looking in the two spacecraft
version and you know version was
launched in 1977 genre about three
decades or more more later and with the
limited capability especially with the
computer we had that browser now genome
is much more version just flew by and we
learned a lot about Jupiter from them
can you just briefly tell me in those
three decades what we learned we have we
had also Galileo in between I'm sure
that we learned a lot of course and that
I see the two spacecraft next to each
other well I do want to point out that
you know that's a full-scale model and
that's a 1/5 scale model but but the way
I would think of it is big picture we
explore our solar system first with
let's just get to the planet and see
what we can learn and you learn a lot
from the very first flyby and so Voyager
was about that was about getting from
one planet to the next and learning an
enormous amount of stuff because no one
never been there before and everything
was brand new Galileo was now we've
learned something about Jupiter we know
what questions to ask we know what the
spacecraft has to be able to do to
survive let's go put something in orbit
and study the Jovian system so it
studied the whole system right the moons
of Jupiter as well as Jupiter itself
learn about the magnetic field and to
make the magneto sphere and all of that
and then after Galileo and dropped it
dropped a probe into Jupiter and learned
a little bit about the atmosphere and
one of the things we learned one of the
key things we learned from the Galileo
probe was that 20 bars 20 going down to
a pressure of 20 times the pressure here
on the earth wasn't enough to get to
where the water was well mixed so people
thought they were going to measure the
water content the global water content
of Jupiter with the Galileo probe and
then what we found is we measured the
water the probe did everything it was
supposed to do but Jupiter was more
complicated than that and it found big
surprises it found the composition of
Jupiter had these heavier elements
besides hydrogen and helium and like
three or four times what they were
expected to be so it sort of matched the
proportions in the Sun if you took an
element divided how much of carbon there
was divided by how much hydrogen there
was compare that with the ratio in the
Sun everything was off by a factor of
three or four there was more of the
heavier stuff except for water were
found hardly any water so that was a big
mystery it was one of the key reasons we
sent Juno there was to respond to that
mystery and try to measure the water try
to see the greater complications and do
a more specific measurement so Juno
doesn't try to study the whole Jovian
system it doesn't try to study multiple
planets it tries to study Jupiter and
specific aspects of Jupiter that we now
know to ask questions about and get into
much greater detail so you go from a
flyby that's gonna try to study multiple
planets and learn
the big broad-brush stuff that nobody
knew yet and do raw exploration to an
orbiter that's gonna stay in the
equatorial plane and study the whole
system so not multiple planets just
Jupiter but learn all kinds of wide
variety of different things about
Jupiter - a spacecraft like Juno that's
focused on particular questions and
study particular things about Jupiter
that had never been studied before and I
hope there will be eventually a next
mission that we'll go and study perhaps
Europa which is a very interesting moon
of Jupiter and has a liquid water ice
ocean and is a place we could look for
life or any other aspect of the Jovian
system where we have more specific more
detailed questions so I see those three
spacecraft as a progression in the level
of detail we look at and the kinds of
question we answer and that happens that
all the other planets in the solar
system as well we just recently on
planetary timescales had the New
Horizons mission fly by Pluto and do
that first exploration of Pluto I hope
some time maybe in my lifetime or the
lifetime of some of the people here will
have an orbiter get to Pluto and do the
more detailed study using the
information that they learned in that
flyby so it's it's that same progression
I guess we're a couple of questions from
the web so somebody sent in why does the
Great Red Spot get colder below the
surface and how does a T about a cooling
work if warm at the top and cool in the
middle and I get to say my favorite
answer which is not only I don't know
but nobody knows but there's speculation
and if you look at scientific
conferences and at some of the papers
that are coming out people are starting
to come up with ideas for that so you
know watch this space and think about
what happens if you mix up the
atmosphere
and look at the winds and so forth and
you can come up with models for the
dynamics that might explain that I'm not
going to try to do that here tonight
both because I'm not the right guy
there's some atmospheric scientists and
really smart people working on the
project working on exactly that problem
and if I try to explain what they're
doing I'm likely to get it wrong
and because they're not ready to publish
it yet so they probably wouldn't like it
if I said well they're speculating this
and that in the other and then you know
tomorrow they find a one where they're
supposed to be a zero and have a
different answer so I'll wait till the
the people working on an announced that
that they think they understand it then
somebody else sent in our the Aurora on
the South Pole weaker because they're so
spread out I don't know the answer to
that that's not nobody knows that's just
I don't actually remember whether the
southerner or are weaker or not than the
northern Aurora so I can maybe send me
an email or send it to to JPL to our
outreach folks and I will try to get you
an answer to that whoever was watching
this from online I think we probably
know the answer to whether the northern
and southern roars are different
strength I just personally don't know
the answer off the top of my head all
right I guess we're out of time huh
thanks everybody
