# Juno: the spacecraft that is revolutionizing our understanding of Jupiter

An episode of [Physics World Weekly Podcast](https://invisiblenetwork.ai/podcast/1400686733), 11 Sep 2025, 36 min.

Audio: https://media.blubrry.com/physicsworldweeklypodcast/content.blubrry.com/physicsworldweeklypodcast/PWWeekly11Sept2025ScottBoltonJuno.mp3

PI Scott Bolton talks about the mission’s discoveries and endurance in this podcast

## Transcript

[0:08] Hello, and welcome to the Physics World weekly
[0:10] podcast.
[0:12] This episode features Scott Bolton,
[0:14] who is principal investigator
[0:16] on NASA's
[0:17] Juno mission to Jupiter.
[0:20] Launched in 2011,
[0:22] the mission has delivered important insights into the
[0:25] nature of the gas giant planet.
[0:28] And in this conversation
[0:30] with Physics World's Margaret Harris,
[0:33] Bolton explains how Juno continues to change our
[0:37] understanding
[0:38] of Jupiter and the gas giants.
[0:41] Although the Juno mission was expected to last
[0:44] only a few years, the spacecraft is still
[0:47] going strong
[0:49] despite operating in Jupiter's
[0:51] intense
[0:52] radiation belts.
[0:54] As I'm speaking though, its future is uncertain.
[0:58] Despite its great success, the mission is currently
[1:02] scheduled to end at the September,
[1:06] which is something that Bolton
[1:08] also addresses
[1:09] in the interview.
[1:11] Here's that conversation.
[1:20] My guest today is Scott Bolton, a space
[1:22] physicist who's an associate vice president the Southwest
[1:24] Research Institute in The US and the principal
[1:27] investigator of NASA's Juno mission.
[1:30] Hello, Scott. Welcome to the podcast.
[1:33] Hi. Thanks for having me.
[1:35] Juno, the mission you lead, that spacecraft was
[1:38] launched in 2011, and it's been orbiting the
[1:40] planet Jupiter since 2016.
[1:43] What would you say have been its most
[1:45] significant discoveries so far? You know, its greatest
[1:48] hits if you like.
[1:49] Well, that's actually quite a long list because
[1:52] we kind of
[1:53] revolutionized our idea of how Jupiter and giant
[1:56] planets in general work when we got there.
[1:59] So one of the the first discoveries that
[2:02] we got was that the top of Jupiter
[2:05] over both poles
[2:06] rest
[2:07] giant polar cyclones,
[2:09] and there are sets of them that we
[2:11] call them circumpolar cyclones because there's a whole
[2:14] bunch of them around the poles
[2:16] that's surrounding one true polar one, and they
[2:20] seem to be stable the whole time. I
[2:22] mean, if we've been there, they've sort of
[2:24] moved around a little bit, looked like they
[2:26] were gonna increase, but they turned out not
[2:29] to.
[2:30] So that's a very stable configuration. So that
[2:32] was kind of a major discovery that, you
[2:34] know, the way we look at Jupiter from
[2:37] the Earth and every other spacecraft that we've
[2:39] had has always looked near the Equator and
[2:42] sort of saw the side view.
[2:44] Juno went over the poles, and for the
[2:46] first time, we saw what the poles look
[2:47] like.
[2:48] And so from the side, you see these
[2:50] stripes, zones and belts, if you wish.
[2:53] When we went over the poles, we saw
[2:54] that they were full of giant polar cyclones,
[2:57] like a whole bunch of great red spots,
[2:59] if you will.
[3:00] Not quite as big,
[3:02] but still sizable, you know, near the size
[3:05] of the Earth, thousands of kilometers across. So
[3:07] that was kind of our first discovery was
[3:09] just going over and looking at that and
[3:11] saying, wow.
[3:12] What's that? You know, because we had seen
[3:15] the pole of Saturn with Cassini, and it
[3:17] didn't look anything like that.
[3:19] And so we really realized that
[3:23] giant planets in general could have these kinds
[3:25] of things. The next kind of discovery was
[3:29] looking at the interior structure of Jupiter. So
[3:31] we set out with the goal of of
[3:33] learning
[3:35] whether Jupiter had a core
[3:37] of heavy elements at that center, a compact
[3:40] core,
[3:41] or none at all. And, these were things
[3:43] that were gonna give us clues as to
[3:45] how Jupiter formed.
[3:47] Did it start with a core and then
[3:49] build on it,
[3:50] or did it just collapse like we think
[3:52] the sun did?
[3:54] And to our surprise,
[3:55] it turned out neither was true, so we
[3:57] weren't even asking the right questions,
[4:00] which is sort of the edge of what
[4:02] you hope for in discovery is that, you
[4:04] know, you really do uncover brand new ideas.
[4:07] And so what Jupyter has
[4:09] is a large dilute core with gradients. I
[4:12] mean, it's, you know, a significant
[4:14] size of Jupyter is the core, and it's
[4:17] still fluid. It's, not not all heavy elements,
[4:21] but it has gradients of density in it.
[4:23] And, you know, we're still trying to figure
[4:26] out, I think scientists are, now that we've
[4:28] uncovered that, how do you build a planet
[4:31] like that? So, you know, we were set
[4:33] out to help figure out how Jupiter and
[4:37] other giant planets form. And instead,
[4:40] we've learned so much that we took a
[4:42] step a little bit backwards
[4:44] in understanding, and and people are still trying
[4:46] to develop the models of how do you
[4:48] form a planet like we see
[4:50] in Jupiter right now.
[4:52] And we've since learned after going back and
[4:55] looking at some of the Cassini data at
[4:57] Saturn,
[4:58] that Saturn also may have this large dilute
[5:01] core. And so, you know, this may be
[5:03] a a common thing in giant planets.
[5:06] Next up would be trying to figure out
[5:08] how the ice giants work, Uranus and Neptune.
[5:11] Another piece that was really surprising
[5:13] was that the deep atmosphere
[5:16] of Jupiter was not well mixed.
[5:18] So the assumptions had been
[5:21] for for many decades that
[5:23] Jupiter had layers of hydrogen, helium, and not
[5:26] layers, but a mixture of hydrogen and helium
[5:28] was what Jupiter is made out of mostly.
[5:31] And as you drop down, Jupiter is getting
[5:33] warmer, but you're also getting clouds of ammonia,
[5:36] clouds of water, clouds of different things that
[5:39] are forming.
[5:40] And if you drop below
[5:42] where it's warmer,
[5:44] then that liquid can exist and turns into
[5:47] vapor. So if I drop below the water
[5:49] cloud, it's warmer, and so all the rain
[5:52] should turn into water vapor.
[5:54] The assumption was that would then become well
[5:57] mixed.
[5:58] And right away, we saw that when we
[5:59] looked deep into Jupiter, then in fact, there
[6:02] was a lot of variability,
[6:04] and it was not well mixed. And so
[6:06] we had to come up with theories on
[6:08] how
[6:09] that might actually work, how could you not
[6:12] have it well mixed.
[6:14] And, of course,
[6:15] in hindsight, I think maybe we were naive
[6:18] to believe it was well mixed. That was
[6:19] a very simple model. The Earth's not well
[6:22] mixed, then we employed something similar to what
[6:24] we see on the Earth, which is hail.
[6:27] So if you see hail sometimes come down,
[6:30] it's way too warm, and yet this ice
[6:31] ball lands on the ground.
[6:33] And you would think, well, that should all
[6:35] be melted in vapor already because it's too
[6:38] warm, but it doesn't. It comes down out
[6:40] of, kind of equilibrium.
[6:43] And so we saw hints that maybe something
[6:46] like that was happening at Jupiter, and so
[6:47] we call them mush balls. But there's this
[6:50] idea
[6:51] that in fact you have updrafts, and
[6:54] ammonia and water are mixing,
[6:56] and in fact we've theorized that what we're
[6:58] seeing is clouds of ammonia water mixture, that
[7:02] there's a liquid
[7:03] where the ammonia is almost acting like antifreeze,
[7:07] and taking the water ice
[7:10] and melting it into a liquid. And we've
[7:12] seen lightning coming from this region that is
[7:16] too
[7:17] high in elevation, too high altitude
[7:20] for liquid water to exist. And so we
[7:23] think that this means that there's liquid
[7:26] ammonia water mixed together,
[7:28] and that's where it's coming from. So that
[7:30] was a discovery
[7:31] that's changed our views of of Jupiter.
[7:34] We've also learned about the magnetosphere
[7:37] and the aurora and how that works comparing
[7:39] it to Earth, and it's very different.
[7:41] And the acceleration of particles is happening very,
[7:44] very close to Jupiter.
[7:46] And we've even started to discover now that
[7:49] the shape of Jupiter's magnetosphere
[7:52] is flatter
[7:53] than was theorized, and we're just starting to
[7:56] see that because our orbit has sort of
[7:59] evolved to the point where parts of it
[8:01] are poking out in out of the magnetosphere
[8:04] into the solar wind. And so we're seeing
[8:06] how the boundaries are shaped,
[8:09] and they're not as as, we've
[8:11] theoretically
[8:12] expected.
[8:14] From a space science point of view, I
[8:15] guess one other big surprise and additionally scientific
[8:18] surprises about the the sort of physics of
[8:20] Jupiter's atmosphere and the chemistry going on there,
[8:23] another big surprise is that this mission, this
[8:26] hardware, is actually still going.
[8:28] I don't know about you, but my impression
[8:30] is the spacecraft lifetimes are a little bit
[8:32] like dog years, with a few honorable exceptions
[8:35] like the the Voyager missions.
[8:37] Most of them don't get to celebrate their
[8:39] fourteenth birthdays in space like Juno recently has.
[8:42] You know, what goes into that?
[8:44] Well, it's true.
[8:46] And Juno was probably even less likely to
[8:49] celebrate that
[8:50] because
[8:52] where we were going
[8:54] was really the harshest region
[8:56] in our entire solar system that we know
[8:58] of. It was by far the most challenging
[9:02] mission
[9:03] that we've probably ever launched in the sense
[9:06] that it was going into
[9:08] a region that we call Jupiter's radiation belts.
[9:11] So Earth has radiation belts surrounding it. We
[9:14] call them the Vale Island radiation belts.
[9:17] Jupiter has ones that are sort
[9:20] of extreme.
[9:21] Almost everything about Jupiter is extreme. It's like
[9:24] a planet on steroids.
[9:26] You know, it's 10 times
[9:28] larger than Earth, so a a thousand Earths
[9:31] fit inside Jupiter.
[9:32] Everything is extreme. The gravity field, the atmosphere,
[9:36] and the radiation as well. And so
[9:39] in order to do what we wanted to
[9:41] do, which was go very close and go
[9:42] over the poles,
[9:45] we had to kind of prepare for this
[9:47] high energy high energy particles. That's what the
[9:49] radiation is, is high energy
[9:51] electrons and protons and ions that are slamming
[9:54] into
[9:55] spacecraft, and they basically eat electronics. Right? So
[9:58] this is one of the big challenges of
[10:00] even Earth orbiters is getting satellites that can
[10:03] survive
[10:04] our own radiation.
[10:05] At Jupiter,
[10:07] we designed something that's pretty much an armored
[10:10] tank.
[10:11] We've we've got a a giant radiation vault
[10:14] in the center of the spacecraft that's 200
[10:16] kilos of walls of titanium,
[10:19] and we pack the sensitive electronics
[10:21] inside of that
[10:23] in order to try to survive Jupiter.
[10:25] So we set out, we hope to last
[10:28] 34
[10:29] orbits,
[10:30] and that was in order to map Jupiter.
[10:32] We were gonna use 32 orbits to map
[10:35] it, and then we had two spares in
[10:37] case we had problems.
[10:38] And so
[10:40] that was,
[10:41] originally
[10:42] designed to be finished in 02/2018,
[10:46] and you you accumulate the radiation each orbit.
[10:50] Juno's orbit is very elliptical
[10:53] and we come really close to Jupiter, just
[10:55] screaming over the cloud tops about 5,000 kilometers,
[10:58] takes about two hours to go from one
[11:01] pole to the next. So we're just screaming
[11:03] by
[11:04] really fast, really close, dipping underneath
[11:08] these radiation belts. And then,
[11:10] the rest of the planet, we go out
[11:12] far, way past Callisto or way past, you
[11:15] know, Ganymede originally.
[11:17] And so the whole orbit
[11:19] at this point takes thirty days, but most
[11:21] of the time, it took about fifty three
[11:23] days.
[11:24] And so two hours of it was close
[11:26] to Jupiter in this hectic region. And so
[11:29] we accumulated this radiation, and what was amazing
[11:32] was
[11:33] that we were surviving. You know, we designed
[11:35] it like an armored tank, and that worked.
[11:38] And, and so we got through all of
[11:41] our what we call our prime mission,
[11:44] which was the 34 orbits, And that was
[11:46] in the 2021.
[11:48] We finished that.
[11:50] And then to our surprise,
[11:51] we're still going.
[11:53] Everything's still working.
[11:54] We will complete our seventy fifth orbit
[11:58] around Jupiter. So more than double,
[12:01] what we were originally planned. And the radiation
[12:05] is many times more than double because it
[12:08] increases over each orbit because our orbit gets
[12:11] twisted around by Jupiter's gravity field that's so
[12:14] massive, and it forces us to go through
[12:17] harsher parts of the radiation
[12:19] every orbit.
[12:21] So to last more than 30 four is
[12:24] amazing, you know, the next
[12:25] ten or fifteen, we probably doubled our radiation.
[12:28] At this point, we're way past what we
[12:30] were originally designed to last.
[12:33] Now that doesn't happen without some consequences. We've
[12:36] seen
[12:37] various systems degrade
[12:39] due to the radiation,
[12:41] but
[12:42] so far, everything's still working.
[12:45] Now what do you mean by degradation? What
[12:47] does that degradation
[12:48] look like?
[12:49] So the the damage due to these high
[12:51] energy particles can take multiple
[12:54] aspects of how they put in damage to
[12:57] your your,
[12:58] instrument.
[12:59] So in in the simplest
[13:02] thing, it can just be noise
[13:04] in the camera itself. So in other words,
[13:07] when we take a picture,
[13:10] there's a whole bunch of spots that are
[13:12] not really showing up, and so it looks
[13:14] like a noisy picture.
[13:16] Instead of a nice clear picture where every
[13:19] pixel
[13:19] is resolved and understood and is part of
[13:22] your image, you have some pixels that seem
[13:25] to be blank or missing because of radiation
[13:29] noise. So that can hit the CCD,
[13:31] and that could be on any camera. Right?
[13:33] So we have some shielding, of course.
[13:36] But the more we can also get other
[13:38] kinds of damage,
[13:40] to the electronics.
[13:42] You could have a voltage regulator or any
[13:44] kind of chip or a circuit board
[13:46] go bad, and all of a sudden it
[13:48] doesn't work because you've got some radiation coming
[13:51] in depositing
[13:52] charge
[13:53] across some path that it it zips right
[13:56] through your instrument, right, right through the electronics,
[13:59] and all of a sudden the circuit boards
[14:01] don't work the way they were originally designed
[14:03] to do
[14:04] because they've been disrupted.
[14:07] I can also
[14:08] have bit errors where
[14:10] I have
[14:11] software
[14:13] bits that are stored inside memory
[14:16] that can then
[14:18] get interfered with. And so I could end
[14:20] up with a a piece of software that
[14:22] all of a sudden
[14:23] doesn't work anymore
[14:26] because,
[14:27] the path that, you know, the software might
[14:30] point
[14:31] something to to some part of a memory
[14:33] and the memory is gone.
[14:35] You know, there's an error in that memory
[14:37] now.
[14:37] So you can have a lot of different
[14:39] kinds of damage.
[14:41] I could have damage to the solar cells
[14:43] as well. The radiation glass could get
[14:46] cloudy, and and all of a sudden, I
[14:48] can't produce as much electricity.
[14:51] So there's a wide range of damage that
[14:53] comes from radiation
[14:55] on spacecraft.
[14:56] And over,
[14:58] I would say, the entire space program since
[15:01] we first launched the satellite, we've been struggling
[15:03] trying to decide and figure out how to
[15:06] deal with that. In fact, the very first
[15:08] NASA mission was coral explorer one in 1958,
[15:11] and it discovered
[15:13] the radiation belts around Earth.
[15:15] And ever since then,
[15:17] people have been trying to figure out how
[15:18] to avoid those places.
[15:21] I wanna talk a little bit specifically about
[15:23] one of the instruments on Juno, which is
[15:25] this JunoCam.
[15:26] What's its role in the mission?
[15:29] So JunoCam was was put on in order
[15:31] for us to take pictures of Jupiter close-up.
[15:34] We were really going close, and we were
[15:36] going to this unique perspective
[15:38] over the poles. Right?
[15:40] So we wanted to have a camera so
[15:42] that we could see what the poles of
[15:44] Jupiter look like.
[15:45] So it was put on really in order
[15:47] to engage the public and provide
[15:50] humanity.
[15:51] What does Jupiter look like? We put the
[15:53] data
[15:54] on the website immediately, and actually the public
[15:57] makes the pictures for us.
[15:59] However, while that was maybe the main purpose
[16:02] and why we put it on, and it
[16:03] didn't really carry science requirements,
[16:06] that instrument has has provided
[16:08] incredible amounts of science discoveries to us, right?
[16:11] Everything associated with atmospheric dynamics, discovering it, it
[16:15] was able to see lightning, it was able
[16:17] to see aurora, we flew by the satellites,
[16:19] we discovered all kinds of things associated with
[16:21] Europa and Io
[16:23] and Ganymede.
[16:25] It's it's full of incredible
[16:28] discoveries,
[16:29] but it was primarily
[16:31] really just to give us great pictures
[16:33] of a planet close-up. And of course, it
[16:35] has a very special kind of framing, a
[16:38] little bit like your smartphone.
[16:40] And so it it takes pictures that are
[16:42] unlike most cameras that are on
[16:45] spacecraft
[16:46] in the sense that it's not a telescope.
[16:48] And so it gets a wide field of
[16:50] view, so you see these incredibly beautiful pictures
[16:52] of Jupiter showing, you know, almost Van Gogh
[16:55] like features in its clouds. And that's because,
[16:59] they're almost it it's really designed like a
[17:01] vacation camera.
[17:04] What effect did that high radiation environment have
[17:07] on this vacation camera on orbiting Jupiter?
[17:10] Yeah. A few years ago, we saw some
[17:12] hints. First, it was having trouble turning on
[17:14] and getting working again, and we weren't sure
[17:17] why. When we when it would turn off
[17:19] and turn back on, it was taking longer
[17:21] and longer to actually start working again. And
[17:24] we were getting a little bit nervous that
[17:26] things were gonna go go bad on it.
[17:28] It wouldn't one day, it just wouldn't turn
[17:30] on.
[17:31] And we think that was associated with the
[17:33] radiation coming into some of its circuit boards.
[17:36] Then,
[17:38] it also was seeing noisy
[17:40] images. We were getting a lot of noise
[17:42] to the point where they almost couldn't be
[17:43] used.
[17:44] In, sort of 2023,
[17:46] right before we were gonna fly by the
[17:48] moon Io, which is the most volcanic body
[17:51] in the solar system,
[17:52] the images
[17:53] became almost unusable.
[17:56] And, of course, getting close-up images of Io,
[17:58] this incredibly beautiful moon with volcanoes all over
[18:01] it, was really a high priority to us.
[18:04] And so we were, we were a little
[18:06] bit panicked at the last second to realize,
[18:08] oh my god, the camera's not working. What
[18:10] do we do?
[18:12] So we did sign of a hail Mary.
[18:15] We had
[18:16] seen that there was a a theory out
[18:18] there called annealing, which has been used since
[18:21] the middle ages. You anneal something, you you
[18:24] change its property. So, you know, people that
[18:27] were making
[18:28] doing metallurgy were would heat up the metal
[18:30] and pound it, right, and it would change
[18:32] things. And so you could change the properties
[18:35] of of how the metals bonded. And there
[18:37] were some experiments
[18:39] on spacecraft where they were annealing different things
[18:41] like solar rays, and people were thinking, but
[18:43] nobody had really figured out how this works.
[18:46] And so we thought, well, let's just try
[18:48] that and see what happens.
[18:50] And so we started heating up the instrument
[18:52] as best we could because we had heaters
[18:54] and different ways that we could try to
[18:56] heat it up. And we started heating it
[18:58] up and testing it and heating it up,
[19:00] and we were getting a little bit of
[19:01] help, but it really wasn't doing much. And
[19:05] we were getting closer to the point where
[19:07] we were gonna fly by IO. And so
[19:10] we just said, let's just go all out,
[19:12] and we started heating it up even longer
[19:14] and higher temperatures.
[19:17] And,
[19:18] miraculously,
[19:19] right before we flew by IO, all of
[19:21] a sudden,
[19:22] it started working perfectly again.
[19:24] And so you can see the images on
[19:27] our website or in various news articles
[19:29] that we got incredible pictures. And, and then
[19:33] ever since then,
[19:35] we've had a program to keep doing that
[19:38] annealing
[19:39] and try to maintain it. And sometimes it
[19:41] goes a little bit south and starts
[19:44] giving bad behavior or noisy images, and then
[19:46] we brought it back to life again.
[19:48] And right now, it's in one of those
[19:50] states where the last orbit it it kinda
[19:52] went south again because we're getting through more
[19:54] and more radiation. And so we're in the
[19:56] process of heating it up right now, and
[19:58] we we're waiting to see
[20:00] whether it works perfectly.
[20:02] But even if it doesn't, we'll just keep
[20:04] heating it up and by maybe the next
[20:05] orbit it will because it it depends on
[20:07] how long it heats up for. But we've
[20:10] also learned how to do this to other
[20:13] systems throughout the mission
[20:15] on the spacecraft, engineering subsystems,
[20:18] UV cameras, other kinds of
[20:21] star cameras. I mean, just we've probably fixed
[20:24] quite a few things now. In fact, I
[20:26] would say that we're we're learning how to
[20:29] deal with this,
[20:30] and we're really the first mission that's really
[20:32] learning this. And what we're learning
[20:35] is a technique that can be used not
[20:37] only for deep space missions, but actually to
[20:40] design and and operate spacecraft right here on
[20:43] Earth even better.
[20:44] That seems a little bit strange just to
[20:46] heat something up. I I don't think I
[20:48] want to try that on my laptop if
[20:49] it was going bad. Do you know why
[20:51] it worked?
[20:52] I would not recommend it. It's kind of,
[20:55] an art that's not really totally understood.
[20:58] I mean, you're changing the properties, but how
[21:00] it works on silicon chips or CCDs is
[21:03] not so clear. We're kind of still figuring
[21:06] that out. And it's not as simple as
[21:08] just heating it. That you there's a whole
[21:11] trick to it, if you will, and a
[21:13] and a method that we are still exploring.
[21:16] But how you heat it up, how you
[21:18] cool it down,
[21:20] what that cycling is, what temperatures you go
[21:23] to,
[21:24] all of these things are built into it.
[21:26] It's a very complicated
[21:28] process that is still
[21:31] sort of on the drawing boards, if you
[21:32] will.
[21:33] But I guess you could say you didn't
[21:34] have anything to lose because it's out there.
[21:37] It's not working or it wasn't working, and
[21:39] there's no question of of sending an astronaut
[21:41] to go fix it or swapping out spare
[21:43] parts or anything like that, is there? Yeah.
[21:46] You can't get up there with a wrench.
[21:47] There's no question about that. But it well,
[21:49] there was a risk. I mean, it's possible
[21:51] that there was some other process that could
[21:53] cure it, and we would
[21:56] do more damage. So we were being very
[21:58] careful. In other words, you don't wanna heat
[22:01] it up like you said. You know, you
[22:02] wouldn't wanna heat up your laptop
[22:05] beyond what it was designed to operate at.
[22:08] We had tested
[22:09] every electronic system on Juno in order to
[22:12] see how hot can it go, how cold
[22:15] can it go. And so we didn't wanna
[22:17] go beyond those limits. We didn't even wanna
[22:19] approach those limits because we might break it.
[22:22] Right? And so you have to be very
[22:24] careful
[22:25] while you're doing this, and you have to
[22:28] build in what you've learned
[22:30] on the ground, and then you have some
[22:32] engineering system that you can test it here.
[22:34] So it's a very complicated, and you have
[22:36] to be very careful. If you will, you're
[22:38] you're kind of tiptoeing
[22:40] through, you know, you're you're walking very very
[22:43] lightly,
[22:44] taking small baby steps.
[22:46] And then as you get closer,
[22:49] maybe you take more risk and you take
[22:51] a couple of big jumps, which is what
[22:53] we did. There was some risk, and it
[22:55] was not, something that people did casually.
[22:59] I was very nervous as we were doing
[23:02] this whether because I didn't wanna break it
[23:04] completely,
[23:06] right, which could happen.
[23:08] So when it worked for the first time,
[23:10] was there were there shouts of joy in
[23:12] the control room? What was it like? Absolutely.
[23:14] Everybody started everybody
[23:16] went crazy. We couldn't believe that the image
[23:18] came down, and it was as good as
[23:20] when we launched it. We were like, oh
[23:22] my god. This is amazing.
[23:25] So we, you know, took all the pictures
[23:26] and took advantage, and then we've been trying
[23:28] to learn how to do that
[23:31] on as many subsystems as possible.
[23:33] Juno offers
[23:35] kind of a unique experiment in the sense
[23:37] that because Jupiter is so much more intense
[23:40] in radiation than the Earth, we can watch
[23:43] degradation of various systems
[23:45] and experiment and learn how to undo that
[23:49] in in, you know, with Juno in a
[23:51] way that we could never do even with
[23:53] satellites on the Earth because the time frames
[23:56] and the time scales of of what you're
[23:58] gonna see on Jupiter
[23:59] are so are accelerated. So you can you're
[24:01] really learning. It's like the perfect laboratory for
[24:04] this. And it was not, you know, part
[24:06] of our mission
[24:08] plan
[24:09] to go learn this, But, you know,
[24:11] it's just this incredible benefit
[24:14] that we kind of stumbled into and can
[24:16] now take advantage of.
[24:19] And what are the plans for taking advantage
[24:21] of it apart from keeping Juno going as
[24:23] long as is humanly possible?
[24:26] Well, I mean, we want to apply the
[24:28] engineering and learn this, and then, of course,
[24:30] we'll document everything and and keep learning it.
[24:33] But apply it to,
[24:35] future designs,
[24:37] satellites that are in around Earth that are
[24:39] suffering.
[24:40] Because all the communication
[24:41] satellites, the civil satellites,
[24:44] this is really the greatest challenge we have
[24:46] of satellites on the Earth.
[24:48] Every kind, even even defense department satellites. This
[24:52] is gonna help every aspect of space exploration.
[24:55] Even our ideas of going to the moon
[24:57] and Mars can be informed by the what
[25:00] we're learning with Juno.
[25:03] What does the future look like for the
[25:05] Juno mission?
[25:06] Do you have an end date, or is
[25:07] it just gonna carry on until it breaks?
[25:10] What's happening?
[25:11] Well, the end date is is defined by
[25:14] budget at the moment. And so
[25:16] we had, been approved with our current budget
[25:19] to go through the September.
[25:21] That was our first extended mission that went
[25:24] from 2021 to 2025.
[25:27] And then last year, NASA asked us to
[25:29] put in another three year extension, so we
[25:32] proposed and showed that we were gonna go
[25:33] into another really even more interesting region, more
[25:37] radiation, but into the rings and little moons
[25:39] and all of the science that could be
[25:40] done. And so that was reviewed and came
[25:43] back with, you know, very high recommendations
[25:45] to continue the mission.
[25:47] We are also fortunate that originally when we
[25:50] were launched for something called planetary protection to
[25:53] make sure Juno didn't crash into Europa, which
[25:55] might be habitable,
[25:57] where you had normally to have to dispose
[25:59] of the spacecraft, send it into Jupiter
[26:02] to crash and burn.
[26:04] But once we passed Europa, we couldn't get
[26:06] back to it.
[26:07] We were relieved of that requirement. So whenever
[26:10] Juno ends, we'll just keep going around Jupiter
[26:13] until it slowly crashes into Jupiter by itself,
[26:16] but might take decades.
[26:18] So the trick here is is we can
[26:20] keep,
[26:21] doing science as long as the instruments and
[26:25] the spacecraft are working. Right?
[26:27] And and we're able to,
[26:29] and the other is to stay funded so
[26:31] that we can
[26:33] continue paying the engineers and the scientists to
[26:35] produce the data and send it down.
[26:38] So at the moment, it's a little iffy
[26:40] because the,
[26:41] admin US administration's
[26:43] budgets
[26:44] are not settled yet for NASA, and so
[26:47] nobody knows if there's enough money to keep
[26:49] Juno going
[26:50] past September or not. And, of course, there's
[26:53] a you quickly delve into and jump into
[26:56] politics
[26:58] where
[26:59] the congress
[27:00] has to agree with the president
[27:03] on the budget
[27:04] for lots of things, including,
[27:06] Juno,
[27:08] and that process is still playing out.
[27:10] And so in the meantime, we'll just keep
[27:13] going until either somebody says shut off or
[27:15] don't shut off.
[27:17] Juno's gonna keep orbiting regardless of what we
[27:19] do.
[27:20] This budget process always happens this way, but
[27:23] this year has been particularly,
[27:26] rough, I guess you could say, because there's
[27:27] been a lot of turnover at NASA, people
[27:29] taking buyouts,
[27:30] leaving ahead of proposed budget cuts.
[27:33] How has that been affecting your work? You
[27:34] know, what impact does that have on a
[27:36] science missions like Juno where you're really
[27:39] reliant on
[27:40] continuity of expertise because you've been running for
[27:42] years and you've accumulated a lot of knowledge
[27:45] about how to do things.
[27:47] Yeah. I mean, there's, this it's unsettling because
[27:50] the uncertainty
[27:52] is driving some people to maybe take early
[27:55] retirement or to find another job.
[27:58] And so you lose expertise as you point
[28:00] out that is unique.
[28:02] Judo has been spared this. We've had a
[28:05] couple of people that have gone on, but
[28:06] it's nothing too disastrous. But, you know, some
[28:09] missions are more
[28:10] directly impacted by such a thing. I think
[28:13] the biggest impact to us is the uncertainty
[28:15] of what's going to happen,
[28:17] you know, and we're marching
[28:19] toward
[28:20] the September.
[28:22] What, of course, October 1, in theory, the
[28:24] budgets would be
[28:26] agreed to.
[28:28] And there's a lot of arguments of why
[28:30] to keep Juno going. Right? Part of it
[28:32] is
[28:33] it has all these, positive effects of learning
[28:35] about radiation, but there's also great science. And
[28:38] it's in at this point in its life,
[28:40] it's very efficient. Right? To replace Juno would
[28:43] be billions of dollars. To keep running it
[28:45] is tens of millions.
[28:48] And so it's really,
[28:51] advantageous to keep going.
[28:53] But as you go toward this process,
[28:56] if Congress
[28:57] and the administration
[28:59] don't
[29:00] agree,
[29:01] then maybe you go into a continuing resolution
[29:04] or or even worse, you could have the
[29:06] government shutdown.
[29:07] We've experienced shutdowns before. Normally, NASA missions are
[29:11] exempt from a government shutdown because it's an
[29:14] asset that you don't wanna lose,
[29:16] and so you just keep going. You don't
[29:18] get more money, but you don't get less.
[29:21] You hope that the government's budget will will
[29:24] get figured out and sorted out, which has
[29:26] always happened eventually
[29:28] in the past.
[29:29] So,
[29:31] you know, the trick for us is is
[29:33] to
[29:34] try to maintain as much of the expertise
[29:36] as possible because
[29:38] if you if people leave,
[29:40] it's it becomes very hard to
[29:43] regain that expertise.
[29:44] But we're also pretty deep, so, you know,
[29:46] we don't there's there's usually not one person
[29:49] that's so critical like that
[29:51] because, you know, people also can get sicker
[29:54] or pass away. Right? So you constantly have
[29:57] to struggle with that on a long mission
[29:59] is there is personnel turnover.
[30:02] And supposing that
[30:04] both factors line up, you know, both the
[30:06] radiation damage isn't too bad and the budget
[30:09] process gets sorted out,
[30:11] what is your your hope for whatever is
[30:14] remaining of June? What next project are you
[30:16] really excited about?
[30:18] So, it's really exciting because at this point
[30:20] we're moving into a region that's virtually unexplored.
[30:24] So what happens is is Jupiter's is not
[30:26] perfectly spherical.
[30:28] It's fatter in the middle than it is
[30:29] at the poles. We call it oblate.
[30:32] And that makes our
[30:34] orbit twist.
[30:35] So it was an it's an ellipse, right,
[30:38] and we're the close part to Jupiter that's
[30:40] really close to 5,000 kilometer over the cloud
[30:42] tops, started out near the Equator, and that
[30:45] part is just moving further and further north.
[30:47] It's almost going over the North Pole.
[30:49] And so that means that as you come
[30:51] into
[30:52] to as Juno is approaches Jupiter, it's moving
[30:56] in closer and closer
[30:58] in closer to Jupiter
[31:01] because the orbit is twisting around, and that's
[31:03] causing us to go into through more radiation
[31:06] that we originally were trying to avoid. But
[31:08] it's also going into a region where Jupiter's
[31:11] rings
[31:12] and a collection of inner moons exist
[31:14] that are virtually unexplored,
[31:16] and they coexist with the radiation, the rings,
[31:19] and these inner moons are all together.
[31:22] Nobody really knows much about these inner moons.
[31:24] They may be tied to, like, asteroids where
[31:26] they were captured. They might be formed there.
[31:29] We don't know how much ice versus rock
[31:31] they are. So Juno offers the first real
[31:33] exploration of that system.
[31:36] In addition to
[31:38] I mentioned that we're going out now poking
[31:40] out into the beyond the magnetosphere into what's
[31:42] called the solar wind.
[31:44] We will be doing that even more. So
[31:46] we will get the shape of Jupiter's three
[31:48] d magnetosphere,
[31:50] which has never really been understood or and
[31:52] there's really no other spacecraft that can do
[31:54] this. We also will go over the poles
[31:56] closer and closer. We may be able to
[31:58] study those polar cyclones
[32:00] and understand how much mass or even how
[32:02] deep they go.
[32:04] We will learn about
[32:06] something called tidal forces, which is,
[32:09] so there's there's these moons of the of
[32:12] the giant planets we call ocean worlds, where
[32:15] there's an ocean underneath the ice crust. Those
[32:17] are very interesting because maybe they're habitable. So
[32:19] Europa and Ganymede are two examples of those.
[32:22] And but nobody really understands exactly
[32:25] how tidal forces work. We know it squeezes
[32:28] the planet or the moon and produces heat,
[32:31] but it's not clear exactly how it works.
[32:33] It also produces
[32:35] the volcanoes on Io. But by studying,
[32:38] these little inner moons and how they're orbiting
[32:41] really close and getting some images of those,
[32:44] we will learn about those tidal forces for
[32:46] the first time. And this is another unique
[32:48] experiment, and that will tell us about how
[32:50] Jupiter's inner interior works and how it affects
[32:54] other satellites, which
[32:55] must be happening throughout
[32:57] our solar system in the universe in all
[32:59] of these exoplanetary systems as well.
[33:02] So there's a lot of incredible science that
[33:04] can be done, as well as learning about
[33:07] the polar cyclones,
[33:08] about the temperature profile. So at this point
[33:11] now, Jupiter
[33:13] has moved around the sun, so,
[33:15] Juno goes behind Jupiter, and we do something
[33:18] we call occultations,
[33:20] where we actually normally a solar, you know,
[33:23] solar powered spacecraft, you wanna stay in the
[33:25] sunlight. We go into Jupiter's shadow, but we
[33:28] pass our radio beam through the atmosphere as
[33:31] we go in and out of shadow, and
[33:32] we learn about the atmosphere.
[33:35] And you learn about the temperature profile, the
[33:37] density of charged particles.
[33:39] And so what we're learning
[33:41] is maybe how the equatorial
[33:44] atmosphere is different than the polar. So how
[33:47] does the aurora,
[33:49] which is depositing energy,
[33:51] get translated
[33:53] and moved and transported around to the rest
[33:55] of Jupiter? So there's an immense amount of
[33:57] science that can be done in this in
[33:59] this next phase.
[34:01] And and that's why when we wrote it
[34:03] up, it was, you know, incredibly highly recommended
[34:06] to continue because it's brand new. A lot
[34:08] of extended missions are sort of more of
[34:10] the same. You follow-up on discoveries.
[34:13] This is like a completely new mission. And
[34:15] our first extended mission was like that too
[34:17] because we the first one, you know, the
[34:19] primary mission we focused on Jupiter. The first
[34:22] extended mission, we flew by Ganymede, Europa, and
[34:25] Io
[34:26] close-up
[34:27] for the first time
[34:29] in, you know, decades with new kinds of
[34:31] instruments. Right? So we were able to see
[34:33] how deep the ice is on Europa and
[34:36] Ganymede and learn about
[34:39] the volcanoes and things on Io.
[34:41] That's one of the most surprising things about
[34:43] Juno is because of this orbit evolution.
[34:46] As it goes on from one step to
[34:48] the next, it's a brand new mission.
[34:51] Best of luck with the next phase of
[34:53] that mission. Scott Bolton, thank you very much
[34:55] for being on the podcast. It's been a
[34:56] pleasure.
[34:57] It's been a pleasure of mine, and I
[34:58] really appreciate you helping to share the excitement
[35:01] of Juno with everybody.
[35:11] That was Juno's principal investigator,
[35:14] Scott Bolton,
[35:15] in conversation with Physics World's Margaret Harris.
[35:19] Thanks to both of them for a fascinating
[35:21] discussion about Jupiter and the challenges
[35:24] of exploring the solar system.
[35:27] And a special thanks to our producer,
[35:29] Fred Isles.
[35:31] We'll be back again next week.
[35:33] See you
[35:41] then.

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