Hello, and welcome to the Physics World weekly
podcast.
This episode features Scott Bolton,
who is principal investigator
on NASA's
Juno mission to Jupiter.
Launched in 2011,
the mission has delivered important insights into the
nature of the gas giant planet.
And in this conversation
with Physics World's Margaret Harris,
Bolton explains how Juno continues to change our
understanding
of Jupiter and the gas giants.
Although the Juno mission was expected to last
only a few years, the spacecraft is still
going strong
despite operating in Jupiter's
intense
radiation belts.
As I'm speaking though, its future is uncertain.
Despite its great success, the mission is currently
scheduled to end at the September,
which is something that Bolton
also addresses
in the interview.
Here's that conversation.
My guest today is Scott Bolton, a space
physicist who's an associate vice president the Southwest
Research Institute in The US and the principal
investigator of NASA's Juno mission.
Hello, Scott. Welcome to the podcast.
Hi. Thanks for having me.
Juno, the mission you lead, that spacecraft was
launched in 2011, and it's been orbiting the
planet Jupiter since 2016.
What would you say have been its most
significant discoveries so far? You know, its greatest
hits if you like.
Well, that's actually quite a long list because
we kind of
revolutionized our idea of how Jupiter and giant
planets in general work when we got there.
So one of the the first discoveries that
we got was that the top of Jupiter
over both poles
rest
giant polar cyclones,
and there are sets of them that we
call them circumpolar cyclones because there's a whole
bunch of them around the poles
that's surrounding one true polar one, and they
seem to be stable the whole time. I
mean, if we've been there, they've sort of
moved around a little bit, looked like they
were gonna increase, but they turned out not
to.
So that's a very stable configuration. So that
was kind of a major discovery that, you
know, the way we look at Jupiter from
the Earth and every other spacecraft that we've
had has always looked near the Equator and
sort of saw the side view.
Juno went over the poles, and for the
first time, we saw what the poles look
like.
And so from the side, you see these
stripes, zones and belts, if you wish.
When we went over the poles, we saw
that they were full of giant polar cyclones,
like a whole bunch of great red spots,
if you will.
Not quite as big,
but still sizable, you know, near the size
of the Earth, thousands of kilometers across. So
that was kind of our first discovery was
just going over and looking at that and
saying, wow.
What's that? You know, because we had seen
the pole of Saturn with Cassini, and it
didn't look anything like that.
And so we really realized that
giant planets in general could have these kinds
of things. The next kind of discovery was
looking at the interior structure of Jupiter. So
we set out with the goal of of
learning
whether Jupiter had a core
of heavy elements at that center, a compact
core,
or none at all. And, these were things
that were gonna give us clues as to
how Jupiter formed.
Did it start with a core and then
build on it,
or did it just collapse like we think
the sun did?
And to our surprise,
it turned out neither was true, so we
weren't even asking the right questions,
which is sort of the edge of what
you hope for in discovery is that, you
know, you really do uncover brand new ideas.
And so what Jupyter has
is a large dilute core with gradients. I
mean, it's, you know, a significant
size of Jupyter is the core, and it's
still fluid. It's, not not all heavy elements,
but it has gradients of density in it.
And, you know, we're still trying to figure
out, I think scientists are, now that we've
uncovered that, how do you build a planet
like that? So, you know, we were set
out to help figure out how Jupiter and
other giant planets form. And instead,
we've learned so much that we took a
step a little bit backwards
in understanding, and and people are still trying
to develop the models of how do you
form a planet like we see
in Jupiter right now.
And we've since learned after going back and
looking at some of the Cassini data at
Saturn,
that Saturn also may have this large dilute
core. And so, you know, this may be
a a common thing in giant planets.
Next up would be trying to figure out
how the ice giants work, Uranus and Neptune.
Another piece that was really surprising
was that the deep atmosphere
of Jupiter was not well mixed.
So the assumptions had been
for for many decades that
Jupiter had layers of hydrogen, helium, and not
layers, but a mixture of hydrogen and helium
was what Jupiter is made out of mostly.
And as you drop down, Jupiter is getting
warmer, but you're also getting clouds of ammonia,
clouds of water, clouds of different things that
are forming.
And if you drop below
where it's warmer,
then that liquid can exist and turns into
vapor. So if I drop below the water
cloud, it's warmer, and so all the rain
should turn into water vapor.
The assumption was that would then become well
mixed.
And right away, we saw that when we
looked deep into Jupiter, then in fact, there
was a lot of variability,
and it was not well mixed. And so
we had to come up with theories on
how
that might actually work, how could you not
have it well mixed.
And, of course,
in hindsight, I think maybe we were naive
to believe it was well mixed. That was
a very simple model. The Earth's not well
mixed, then we employed something similar to what
we see on the Earth, which is hail.
So if you see hail sometimes come down,
it's way too warm, and yet this ice
ball lands on the ground.
And you would think, well, that should all
be melted in vapor already because it's too
warm, but it doesn't. It comes down out
of, kind of equilibrium.
And so we saw hints that maybe something
like that was happening at Jupiter, and so
we call them mush balls. But there's this
idea
that in fact you have updrafts, and
ammonia and water are mixing,
and in fact we've theorized that what we're
seeing is clouds of ammonia water mixture, that
there's a liquid
where the ammonia is almost acting like antifreeze,
and taking the water ice
and melting it into a liquid. And we've
seen lightning coming from this region that is
too
high in elevation, too high altitude
for liquid water to exist. And so we
think that this means that there's liquid
ammonia water mixed together,
and that's where it's coming from. So that
was a discovery
that's changed our views of of Jupiter.
We've also learned about the magnetosphere
and the aurora and how that works comparing
it to Earth, and it's very different.
And the acceleration of particles is happening very,
very close to Jupiter.
And we've even started to discover now that
the shape of Jupiter's magnetosphere
is flatter
than was theorized, and we're just starting to
see that because our orbit has sort of
evolved to the point where parts of it
are poking out in out of the magnetosphere
into the solar wind. And so we're seeing
how the boundaries are shaped,
and they're not as as, we've
theoretically
expected.
From a space science point of view, I
guess one other big surprise and additionally scientific
surprises about the the sort of physics of
Jupiter's atmosphere and the chemistry going on there,
another big surprise is that this mission, this
hardware, is actually still going.
I don't know about you, but my impression
is the spacecraft lifetimes are a little bit
like dog years, with a few honorable exceptions
like the the Voyager missions.
Most of them don't get to celebrate their
fourteenth birthdays in space like Juno recently has.
You know, what goes into that?
Well, it's true.
And Juno was probably even less likely to
celebrate that
because
where we were going
was really the harshest region
in our entire solar system that we know
of. It was by far the most challenging
mission
that we've probably ever launched in the sense
that it was going into
a region that we call Jupiter's radiation belts.
So Earth has radiation belts surrounding it. We
call them the Vale Island radiation belts.
Jupiter has ones that are sort
of extreme.
Almost everything about Jupiter is extreme. It's like
a planet on steroids.
You know, it's 10 times
larger than Earth, so a a thousand Earths
fit inside Jupiter.
Everything is extreme. The gravity field, the atmosphere,
and the radiation as well. And so
in order to do what we wanted to
do, which was go very close and go
over the poles,
we had to kind of prepare for this
high energy high energy particles. That's what the
radiation is, is high energy
electrons and protons and ions that are slamming
into
spacecraft, and they basically eat electronics. Right? So
this is one of the big challenges of
even Earth orbiters is getting satellites that can
survive
our own radiation.
At Jupiter,
we designed something that's pretty much an armored
tank.
We've we've got a a giant radiation vault
in the center of the spacecraft that's 200
kilos of walls of titanium,
and we pack the sensitive electronics
inside of that
in order to try to survive Jupiter.
So we set out, we hope to last
34
orbits,
and that was in order to map Jupiter.
We were gonna use 32 orbits to map
it, and then we had two spares in
case we had problems.
And so
that was,
originally
designed to be finished in 02/2018,
and you you accumulate the radiation each orbit.
Juno's orbit is very elliptical
and we come really close to Jupiter, just
screaming over the cloud tops about 5,000 kilometers,
takes about two hours to go from one
pole to the next. So we're just screaming
by
really fast, really close, dipping underneath
these radiation belts. And then,
the rest of the planet, we go out
far, way past Callisto or way past, you
know, Ganymede originally.
And so the whole orbit
at this point takes thirty days, but most
of the time, it took about fifty three
days.
And so two hours of it was close
to Jupiter in this hectic region. And so
we accumulated this radiation, and what was amazing
was
that we were surviving. You know, we designed
it like an armored tank, and that worked.
And, and so we got through all of
our what we call our prime mission,
which was the 34 orbits, And that was
in the 2021.
We finished that.
And then to our surprise,
we're still going.
Everything's still working.
We will complete our seventy fifth orbit
around Jupiter. So more than double,
what we were originally planned. And the radiation
is many times more than double because it
increases over each orbit because our orbit gets
twisted around by Jupiter's gravity field that's so
massive, and it forces us to go through
harsher parts of the radiation
every orbit.
So to last more than 30 four is
amazing, you know, the next
ten or fifteen, we probably doubled our radiation.
At this point, we're way past what we
were originally designed to last.
Now that doesn't happen without some consequences. We've
seen
various systems degrade
due to the radiation,
but
so far, everything's still working.
Now what do you mean by degradation? What
does that degradation
look like?
So the the damage due to these high
energy particles can take multiple
aspects of how they put in damage to
your your,
instrument.
So in in the simplest
thing, it can just be noise
in the camera itself. So in other words,
when we take a picture,
there's a whole bunch of spots that are
not really showing up, and so it looks
like a noisy picture.
Instead of a nice clear picture where every
pixel
is resolved and understood and is part of
your image, you have some pixels that seem
to be blank or missing because of radiation
noise. So that can hit the CCD,
and that could be on any camera. Right?
So we have some shielding, of course.
But the more we can also get other
kinds of damage,
to the electronics.
You could have a voltage regulator or any
kind of chip or a circuit board
go bad, and all of a sudden it
doesn't work because you've got some radiation coming
in depositing
charge
across some path that it it zips right
through your instrument, right, right through the electronics,
and all of a sudden the circuit boards
don't work the way they were originally designed
to do
because they've been disrupted.
I can also
have bit errors where
I have
software
bits that are stored inside memory
that can then
get interfered with. And so I could end
up with a a piece of software that
all of a sudden
doesn't work anymore
because,
the path that, you know, the software might
point
something to to some part of a memory
and the memory is gone.
You know, there's an error in that memory
now.
So you can have a lot of different
kinds of damage.
I could have damage to the solar cells
as well. The radiation glass could get
cloudy, and and all of a sudden, I
can't produce as much electricity.
So there's a wide range of damage that
comes from radiation
on spacecraft.
And over,
I would say, the entire space program since
we first launched the satellite, we've been struggling
trying to decide and figure out how to
deal with that. In fact, the very first
NASA mission was coral explorer one in 1958,
and it discovered
the radiation belts around Earth.
And ever since then,
people have been trying to figure out how
to avoid those places.
I wanna talk a little bit specifically about
one of the instruments on Juno, which is
this JunoCam.
What's its role in the mission?
So JunoCam was was put on in order
for us to take pictures of Jupiter close-up.
We were really going close, and we were
going to this unique perspective
over the poles. Right?
So we wanted to have a camera so
that we could see what the poles of
Jupiter look like.
So it was put on really in order
to engage the public and provide
humanity.
What does Jupiter look like? We put the
data
on the website immediately, and actually the public
makes the pictures for us.
However, while that was maybe the main purpose
and why we put it on, and it
didn't really carry science requirements,
that instrument has has provided
incredible amounts of science discoveries to us, right?
Everything associated with atmospheric dynamics, discovering it, it
was able to see lightning, it was able
to see aurora, we flew by the satellites,
we discovered all kinds of things associated with
Europa and Io
and Ganymede.
It's it's full of incredible
discoveries,
but it was primarily
really just to give us great pictures
of a planet close-up. And of course, it
has a very special kind of framing, a
little bit like your smartphone.
And so it it takes pictures that are
unlike most cameras that are on
spacecraft
in the sense that it's not a telescope.
And so it gets a wide field of
view, so you see these incredibly beautiful pictures
of Jupiter showing, you know, almost Van Gogh
like features in its clouds. And that's because,
they're almost it it's really designed like a
vacation camera.
What effect did that high radiation environment have
on this vacation camera on orbiting Jupiter?
Yeah. A few years ago, we saw some
hints. First, it was having trouble turning on
and getting working again, and we weren't sure
why. When we when it would turn off
and turn back on, it was taking longer
and longer to actually start working again. And
we were getting a little bit nervous that
things were gonna go go bad on it.
It wouldn't one day, it just wouldn't turn
on.
And we think that was associated with the
radiation coming into some of its circuit boards.
Then,
it also was seeing noisy
images. We were getting a lot of noise
to the point where they almost couldn't be
used.
In, sort of 2023,
right before we were gonna fly by the
moon Io, which is the most volcanic body
in the solar system,
the images
became almost unusable.
And, of course, getting close-up images of Io,
this incredibly beautiful moon with volcanoes all over
it, was really a high priority to us.
And so we were, we were a little
bit panicked at the last second to realize,
oh my god, the camera's not working. What
do we do?
So we did sign of a hail Mary.
We had
seen that there was a a theory out
there called annealing, which has been used since
the middle ages. You anneal something, you you
change its property. So, you know, people that
were making
doing metallurgy were would heat up the metal
and pound it, right, and it would change
things. And so you could change the properties
of of how the metals bonded. And there
were some experiments
on spacecraft where they were annealing different things
like solar rays, and people were thinking, but
nobody had really figured out how this works.
And so we thought, well, let's just try
that and see what happens.
And so we started heating up the instrument
as best we could because we had heaters
and different ways that we could try to
heat it up. And we started heating it
up and testing it and heating it up,
and we were getting a little bit of
help, but it really wasn't doing much. And
we were getting closer to the point where
we were gonna fly by IO. And so
we just said, let's just go all out,
and we started heating it up even longer
and higher temperatures.
And,
miraculously,
right before we flew by IO, all of
a sudden,
it started working perfectly again.
And so you can see the images on
our website or in various news articles
that we got incredible pictures. And, and then
ever since then,
we've had a program to keep doing that
annealing
and try to maintain it. And sometimes it
goes a little bit south and starts
giving bad behavior or noisy images, and then
we brought it back to life again.
And right now, it's in one of those
states where the last orbit it it kinda
went south again because we're getting through more
and more radiation. And so we're in the
process of heating it up right now, and
we we're waiting to see
whether it works perfectly.
But even if it doesn't, we'll just keep
heating it up and by maybe the next
orbit it will because it it depends on
how long it heats up for. But we've
also learned how to do this to other
systems throughout the mission
on the spacecraft, engineering subsystems,
UV cameras, other kinds of
star cameras. I mean, just we've probably fixed
quite a few things now. In fact, I
would say that we're we're learning how to
deal with this,
and we're really the first mission that's really
learning this. And what we're learning
is a technique that can be used not
only for deep space missions, but actually to
design and and operate spacecraft right here on
Earth even better.
That seems a little bit strange just to
heat something up. I I don't think I
want to try that on my laptop if
it was going bad. Do you know why
it worked?
I would not recommend it. It's kind of,
an art that's not really totally understood.
I mean, you're changing the properties, but how
it works on silicon chips or CCDs is
not so clear. We're kind of still figuring
that out. And it's not as simple as
just heating it. That you there's a whole
trick to it, if you will, and a
and a method that we are still exploring.
But how you heat it up, how you
cool it down,
what that cycling is, what temperatures you go
to,
all of these things are built into it.
It's a very complicated
process that is still
sort of on the drawing boards, if you
will.
But I guess you could say you didn't
have anything to lose because it's out there.
It's not working or it wasn't working, and
there's no question of of sending an astronaut
to go fix it or swapping out spare
parts or anything like that, is there? Yeah.
You can't get up there with a wrench.
There's no question about that. But it well,
there was a risk. I mean, it's possible
that there was some other process that could
cure it, and we would
do more damage. So we were being very
careful. In other words, you don't wanna heat
it up like you said. You know, you
wouldn't wanna heat up your laptop
beyond what it was designed to operate at.
We had tested
every electronic system on Juno in order to
see how hot can it go, how cold
can it go. And so we didn't wanna
go beyond those limits. We didn't even wanna
approach those limits because we might break it.
Right? And so you have to be very
careful
while you're doing this, and you have to
build in what you've learned
on the ground, and then you have some
engineering system that you can test it here.
So it's a very complicated, and you have
to be very careful. If you will, you're
you're kind of tiptoeing
through, you know, you're you're walking very very
lightly,
taking small baby steps.
And then as you get closer,
maybe you take more risk and you take
a couple of big jumps, which is what
we did. There was some risk, and it
was not, something that people did casually.
I was very nervous as we were doing
this whether because I didn't wanna break it
completely,
right, which could happen.
So when it worked for the first time,
was there were there shouts of joy in
the control room? What was it like? Absolutely.
Everybody started everybody
went crazy. We couldn't believe that the image
came down, and it was as good as
when we launched it. We were like, oh
my god. This is amazing.
So we, you know, took all the pictures
and took advantage, and then we've been trying
to learn how to do that
on as many subsystems as possible.
Juno offers
kind of a unique experiment in the sense
that because Jupiter is so much more intense
in radiation than the Earth, we can watch
degradation of various systems
and experiment and learn how to undo that
in in, you know, with Juno in a
way that we could never do even with
satellites on the Earth because the time frames
and the time scales of of what you're
gonna see on Jupiter
are so are accelerated. So you can you're
really learning. It's like the perfect laboratory for
this. And it was not, you know, part
of our mission
plan
to go learn this, But, you know,
it's just this incredible benefit
that we kind of stumbled into and can
now take advantage of.
And what are the plans for taking advantage
of it apart from keeping Juno going as
long as is humanly possible?
Well, I mean, we want to apply the
engineering and learn this, and then, of course,
we'll document everything and and keep learning it.
But apply it to,
future designs,
satellites that are in around Earth that are
suffering.
Because all the communication
satellites, the civil satellites,
this is really the greatest challenge we have
of satellites on the Earth.
Every kind, even even defense department satellites. This
is gonna help every aspect of space exploration.
Even our ideas of going to the moon
and Mars can be informed by the what
we're learning with Juno.
What does the future look like for the
Juno mission?
Do you have an end date, or is
it just gonna carry on until it breaks?
What's happening?
Well, the end date is is defined by
budget at the moment. And so
we had, been approved with our current budget
to go through the September.
That was our first extended mission that went
from 2021 to 2025.
And then last year, NASA asked us to
put in another three year extension, so we
proposed and showed that we were gonna go
into another really even more interesting region, more
radiation, but into the rings and little moons
and all of the science that could be
done. And so that was reviewed and came
back with, you know, very high recommendations
to continue the mission.
We are also fortunate that originally when we
were launched for something called planetary protection to
make sure Juno didn't crash into Europa, which
might be habitable,
where you had normally to have to dispose
of the spacecraft, send it into Jupiter
to crash and burn.
But once we passed Europa, we couldn't get
back to it.
We were relieved of that requirement. So whenever
Juno ends, we'll just keep going around Jupiter
until it slowly crashes into Jupiter by itself,
but might take decades.
So the trick here is is we can
keep,
doing science as long as the instruments and
the spacecraft are working. Right?
And and we're able to,
and the other is to stay funded so
that we can
continue paying the engineers and the scientists to
produce the data and send it down.
So at the moment, it's a little iffy
because the,
admin US administration's
budgets
are not settled yet for NASA, and so
nobody knows if there's enough money to keep
Juno going
past September or not. And, of course, there's
a you quickly delve into and jump into
politics
where
the congress
has to agree with the president
on the budget
for lots of things, including,
Juno,
and that process is still playing out.
And so in the meantime, we'll just keep
going until either somebody says shut off or
don't shut off.
Juno's gonna keep orbiting regardless of what we
do.
This budget process always happens this way, but
this year has been particularly,
rough, I guess you could say, because there's
been a lot of turnover at NASA, people
taking buyouts,
leaving ahead of proposed budget cuts.
How has that been affecting your work? You
know, what impact does that have on a
science missions like Juno where you're really
reliant on
continuity of expertise because you've been running for
years and you've accumulated a lot of knowledge
about how to do things.
Yeah. I mean, there's, this it's unsettling because
the uncertainty
is driving some people to maybe take early
retirement or to find another job.
And so you lose expertise as you point
out that is unique.
Judo has been spared this. We've had a
couple of people that have gone on, but
it's nothing too disastrous. But, you know, some
missions are more
directly impacted by such a thing. I think
the biggest impact to us is the uncertainty
of what's going to happen,
you know, and we're marching
toward
the September.
What, of course, October 1, in theory, the
budgets would be
agreed to.
And there's a lot of arguments of why
to keep Juno going. Right? Part of it
is
it has all these, positive effects of learning
about radiation, but there's also great science. And
it's in at this point in its life,
it's very efficient. Right? To replace Juno would
be billions of dollars. To keep running it
is tens of millions.
And so it's really,
advantageous to keep going.
But as you go toward this process,
if Congress
and the administration
don't
agree,
then maybe you go into a continuing resolution
or or even worse, you could have the
government shutdown.
We've experienced shutdowns before. Normally, NASA missions are
exempt from a government shutdown because it's an
asset that you don't wanna lose,
and so you just keep going. You don't
get more money, but you don't get less.
You hope that the government's budget will will
get figured out and sorted out, which has
always happened eventually
in the past.
So,
you know, the trick for us is is
to
try to maintain as much of the expertise
as possible because
if you if people leave,
it's it becomes very hard to
regain that expertise.
But we're also pretty deep, so, you know,
we don't there's there's usually not one person
that's so critical like that
because, you know, people also can get sicker
or pass away. Right? So you constantly have
to struggle with that on a long mission
is there is personnel turnover.
And supposing that
both factors line up, you know, both the
radiation damage isn't too bad and the budget
process gets sorted out,
what is your your hope for whatever is
remaining of June? What next project are you
really excited about?
So, it's really exciting because at this point
we're moving into a region that's virtually unexplored.
So what happens is is Jupiter's is not
perfectly spherical.
It's fatter in the middle than it is
at the poles. We call it oblate.
And that makes our
orbit twist.
So it was an it's an ellipse, right,
and we're the close part to Jupiter that's
really close to 5,000 kilometer over the cloud
tops, started out near the Equator, and that
part is just moving further and further north.
It's almost going over the North Pole.
And so that means that as you come
into
to as Juno is approaches Jupiter, it's moving
in closer and closer
in closer to Jupiter
because the orbit is twisting around, and that's
causing us to go into through more radiation
that we originally were trying to avoid. But
it's also going into a region where Jupiter's
rings
and a collection of inner moons exist
that are virtually unexplored,
and they coexist with the radiation, the rings,
and these inner moons are all together.
Nobody really knows much about these inner moons.
They may be tied to, like, asteroids where
they were captured. They might be formed there.
We don't know how much ice versus rock
they are. So Juno offers the first real
exploration of that system.
In addition to
I mentioned that we're going out now poking
out into the beyond the magnetosphere into what's
called the solar wind.
We will be doing that even more. So
we will get the shape of Jupiter's three
d magnetosphere,
which has never really been understood or and
there's really no other spacecraft that can do
this. We also will go over the poles
closer and closer. We may be able to
study those polar cyclones
and understand how much mass or even how
deep they go.
We will learn about
something called tidal forces, which is,
so there's there's these moons of the of
the giant planets we call ocean worlds, where
there's an ocean underneath the ice crust. Those
are very interesting because maybe they're habitable. So
Europa and Ganymede are two examples of those.
And but nobody really understands exactly
how tidal forces work. We know it squeezes
the planet or the moon and produces heat,
but it's not clear exactly how it works.
It also produces
the volcanoes on Io. But by studying,
these little inner moons and how they're orbiting
really close and getting some images of those,
we will learn about those tidal forces for
the first time. And this is another unique
experiment, and that will tell us about how
Jupiter's inner interior works and how it affects
other satellites, which
must be happening throughout
our solar system in the universe in all
of these exoplanetary systems as well.
So there's a lot of incredible science that
can be done, as well as learning about
the polar cyclones,
about the temperature profile. So at this point
now, Jupiter
has moved around the sun, so,
Juno goes behind Jupiter, and we do something
we call occultations,
where we actually normally a solar, you know,
solar powered spacecraft, you wanna stay in the
sunlight. We go into Jupiter's shadow, but we
pass our radio beam through the atmosphere as
we go in and out of shadow, and
we learn about the atmosphere.
And you learn about the temperature profile, the
density of charged particles.
And so what we're learning
is maybe how the equatorial
atmosphere is different than the polar. So how
does the aurora,
which is depositing energy,
get translated
and moved and transported around to the rest
of Jupiter? So there's an immense amount of
science that can be done in this in
this next phase.
And and that's why when we wrote it
up, it was, you know, incredibly highly recommended
to continue because it's brand new. A lot
of extended missions are sort of more of
the same. You follow-up on discoveries.
This is like a completely new mission. And
our first extended mission was like that too
because we the first one, you know, the
primary mission we focused on Jupiter. The first
extended mission, we flew by Ganymede, Europa, and
Io
close-up
for the first time
in, you know, decades with new kinds of
instruments. Right? So we were able to see
how deep the ice is on Europa and
Ganymede and learn about
the volcanoes and things on Io.
That's one of the most surprising things about
Juno is because of this orbit evolution.
As it goes on from one step to
the next, it's a brand new mission.
Best of luck with the next phase of
that mission. Scott Bolton, thank you very much
for being on the podcast. It's been a
pleasure.
It's been a pleasure of mine, and I
really appreciate you helping to share the excitement
of Juno with everybody.
That was Juno's principal investigator,
Scott Bolton,
in conversation with Physics World's Margaret Harris.
Thanks to both of them for a fascinating
discussion about Jupiter and the challenges
of exploring the solar system.
And a special thanks to our producer,
Fred Isles.
We'll be back again next week.
See you
then.