My short bio:

UPDATE: 5:20 p.m. EDT: That's all the time we have for today; got to get back to flying this spacecraft. We'll check back as time permits to answer other questions. Till then, please follow the mission online at and

We're team members working on NASA's Juno mission to Jupiter. After an almost five-year journey through space, we received confirmation that Juno successfully entered Jupiter's orbit during a 35-minute engine burn. Confirmation that the burn had completed was received on Earth last night at 8:53 pm. PDT (11:53 p.m. EDT) Monday, July 4. Today, July 5 from 4-5 p.m. ET, we're taking your questions. Ask us anything!

Rick Nybakken, Juno project manager
Steve Levin, Juno project scientist
Jared Espley, Juno program scientist
Candy Hansen, JunoCam co-investigator
Elsa Jensen, JunoCam operations engineer
Leslie Lipkaman, JunoCam uplink operations
Glen Orton, NASA-JPL senior research scientist 
Stephanie L. Smith, NASA-JPL social media lead
Jason Townsend, NASA social media team

Juno's main goal is to understand the origin and evolution of Jupiter. With its suite of nine science instruments, Juno will investigate the existence of a solid planetary core, map Jupiter's intense magnetic field, measure the amount of water and ammonia in the deep atmosphere, and observe the planet's auroras. More info at

My Proof:

Comments: 1806 • Responses: 57  • Date: 

abraksis7471402 karma

Have you seen any large black objects with the proportions of 1 by 4 by 9??

NASAJPL1033 karma

No monoliths spotted on Jupiter or any of its moons, but I did see one in the possession of Bob Pappalardo, Europa Mission Project Scientist.

-- SLS

SkywayCheerios907 karma

Something I've always wondered about controlling probes like Juno in deep space... Are the commands that control the engine burn sent to the spacecraft from Earth and executed as they're received, or was the precise start time of the burn programmed in Juno's computer ahead of time and executed pretty much autonomously?

NASAJPL1056 karma

We normally queue up the commands to the spacecraft well in advance. Occasionally, there are instances when commands are sent in "real time", but definitely not for something as critical as JOI. -Steve Levin

LordLimes457 karma

If you had to send a command in "real time" how long would it take 1byte of data to reach Juno?

NASAJPL878 karma

Right now, it would take a bit more than 45 minutes for a command to reach Juno. That's how long it takes for radio waves (or light) to reach Jupiter from Earth. Earth and Jupiter both move, of course, so the "one way light time" will change.

WiglyWorm448 karma

Follow up: Do your antennas have to account for this relative motion when sending or receiving data? Is the frequency shift significant?

NASAJPL893 karma

Yes. The big radio antennas from NASA's Deep Space Network have to take into account both the motions of Jupiter, Earth, and the spacecraft in order to point in the right direction and track at the right frequency. -Steve Levin

NASAJPL250 karma

It is a mix. In general, some of our commands are "real-time" and others are put into a sequence. Sequences contain a mixture of serial commands mixed with "absolute timed" commands. Everything last night was in an automated sequence since it needed to happen in a perfect sequence at just the precise time. Especially important when it takes 48 minutes for any commands to reach the spacecraft from Earth....


MattBaster781 karma

What specific theories about Jupiter are you most looking forward to confirming whether they were accurate or not?

NASAJPL1905 karma

I'm most interested in finding out what lurks beneath Jupiter's clouds. It's mind-blowing to think that we don't yet know what the interior is of the largest planet in the solar system. Is it rocky? Is it metallic? We just don't know. But that's exciting, and it's why we explore.

-- SLS

NASAJPL527 karma

I'm really excited about measuring the global water abundance! The amount of water in Jupiter should tell us a lot about how and where the planet formed. The leading theory right now involves large chunks of ice initially, possibly with the planet drifting inward after initially forming much farther from the Sun. The water abundance should teach us a lot about those formation theories. -Steve Levin

Pu1pFiction621 karma

Do you think NASA should make visible-light cameras a permanent feature of all future craft, both from a public engagement & scientific standpoint?

When will the first images from JUNO be released?

What are your opinions on the NASA budget, which is less than that of a single Saturn V launch in the 60's? Should we put more pressure on congress to address and raise the amount?

Thank you for the AMA, amazing work!

NASAJPL657 karma

Not necessarily; it will depend on the objectives of the mission. The first images have been released! Here's the link to the approach movie on YouTube:

Thanks for your interest. -Glenn Orton

Gravity-Lens142 karma

Over what kind of time period was the video taken?

NASAJPL303 karma

17 days


Loovian521 karma

Thanks to Kerbal Space Program I'm able to appreciate the maneuvers undertaken to get into orbit. Have you considered doing anything with the KSP guys to celebrate Juno?

NASAJPL806 karma

Lots of employees do play KSP on their own time and NASA has collaborated with KSP on other missions, such as the upcoming OSIRIS-REx mission. Learn more here: - JT

Rainmaker1973413 karma

Contratulations, team. Epic success. Question: do you plan to release the raw images taken with JunoCam to the public soon? Will there be an approach similar to the release of Cassini or Curiosity raw?

NASAJPL560 karma

The approach movie images (see will be released soon. Images from Orbit 1 will not be released immediately, because we'll be doing lots of testing of the camera operations then, but from Orbit 2 and onward, our policy will be to release all images in a format that can be read immediately as soon as we get them and this initial processing step is done. -Glenn Orton

_AlphaZulu_351 karma

Hey guys/gal, hearing about this is super exciting. My question may seem stupid/silly, but seriously, how much time/planning goes into a mission such as this? Especially from Launch in Florida, the gravitational slingshot, up until it enter Orbit.

Seeing this just blows my mind. How many backup plans do you have for a mission such as this if it doesn't go according to plan?

NASAJPL659 karma

A huge amount of time and planning goes into a mission like this! I personally started thinking about the ideas that eventually became Juno in about the year 2000, after a conversation with Scott Bolton, who had already begun to contemplate the measurements we can do. Our first proposal to NASA was in 2004, and we began designing real hardware in 2006.

As far as backup plans are concerned, we always try to keep a range of possible contingencies in mind. For some of them, we make fairly detailed plans, and for some of the less likely scenarios we might just talk it over for a while and make a few notes about "what if". -Steve Levin

NASAJPL245 karma

5+ years of development and building. 5 years of flying through interplanetary space from Earth to Jupiter (with a gravity slingshot along the way). -- JRE

Froguy1126322 karma

Congratulations on a successful voyage! I've been following Juno for months and I watched the live stream when it arrived. Awesome job guys.

I've always found it fascinating that Jupiter is just a giant ball of gas with no surface and a crazy metallic hydrogen core. But how can we be sure that Jupiter does have no surface? How would you be able to tell the difference between a ball of gas and just a planet with a super dense atmosphere?

Thanks for doing this AMA and good luck with the science to come!

NASAJPL369 karma

We'll use a combination of gravity and magnetic data to disentangle all the different combinations of material that could make up the core (or not). Our web of orbits crossing the planet at different longitudes will be important to build up these interior maps. -- JRE

darkchucky194 karma

Rick Nybakken - as PM what project management method did you use? With which program did you track it, MS Project? Would you mind share the WBS or just part of it? Congratulations on your success!

NASAJPL291 karma

A combination of techniques. Our project schedulers used MS Project pre-launch and we also used Earned Value Measurement techniques to assess money spent vs. work completed. At the top level, the WBS pre-launch (working from memory) was something like: - 1.0 Project Mangement - 2.0 Project system Engineering - 3.0 Mission Assurance (speciality engineering e.g. radiation testing/analysis, etc.) - 4.0 Engineering insight/oversight - 5.0 Instrument Development - 6.0 Spacecraft development (and instrument integration) - 7.0 Mission Operations

Other tools that we use extensively at the PM level are email, file sharing, and Powerpoint. There are also extensive requirements tracking tools, waivers (with risk assessments) and anomaly reports/risk assessments (with significant processes behind each of them). And all of our subcontractors have their management and engineering development processes as well...


yisas0929164 karma

You mentioned at the press conference that the video taken by Juno before insertion is the first real time capture of the harmonious motion of the moons around Jupiter. Is this not accomplished by satellites from Earth? How is it different besides the obvious advantages of proximity?

NASAJPL326 karma

From the Earth, we only have 8 or so hours to capture the motion of the satellites, unless you're at an unusual place like the south pole while Jupiter is in the southern hemisphere. But it's not, and there are no arctic observatories. This is the first time we've seen the motion of the satellites without interruption for weeks at a time. -Glenn Orton

NewlyListed109 karma

Have you and your team been working on other projects in the last five years while it's been on its journey, or has it required constant monitoring and action over the time?

NASAJPL176 karma

For myself, I've definitely been working on other projects. My formal time, averaged through the year, is 30% of my total professional time. I'm also a co-investigator on Cassini, as well as the Outer Planet Atmospheric Legacy (OPAL) program imaging the outer solar system annually with Hubble Space Telescope, and my own ground-based programs for infrared spectroscopy and imaging of Saturn (for Cassini support) and Jupiter (for Juno support). -Glenn Orton

NASAJPL147 karma

Many of us work on more than one project. I (JRE) have been working on the MAVEN mission for example. --JRE

NASAJPL108 karma

I spend most of my time on Juno, but I also help out with the Goldstone Apple Valley Radio Telescope project ( for a few hours each week. -Steve Levin

pdxpoker86 karma

Can you talk more about the reason Juno has to be intentionally destroyed?

Also, from the pre orbit press release there was a question about the possibility of sending an image back from under the clouds before it disintegrates. How likely could this really be?

So many more questions.. Potentially additional orbits? Any Europa science? More images of the moons?

NASAJPL237 karma

Re: deorbit: We think Jupiter's icy moon Europa has a subsurface ocean of liquid water; and because everywhere on Earth that we've found water, we've also found life, this is a good place for us to search. However, we don't want to go looking for life in the universe only to find that we brought it with us from Earth. We have to abide by something called Planetary Protection. (It's like the Prime Directive, but real.)

So, to keep Juno from ever running the risk of crashing into Europa and contaminating it, we will deorbit the spacecraft into Jupiter.

Re: pictures? Images from under the clouds would be amazing. Whether or not the spacecraft could still transmit them is another matter. We might not have the right attitude during deorbit to do that.

While the main goal of the mission is to study the planet's origin and structure, we will take as many images of the moons as we can.


Riendew81 karma

I've read that Jupiter can shed a lot of light on the creation of our solar system. I understand that we think Jupiter was among the first planets to form, could you elaborate on what we could learn about Earth with new information we may obtain?
Thanks so much for doing this AMA.

NASAJPL107 karma

Our understanding of how solar systems form is in some chaos (pun intended) due to all the exoplanets we're finding. Understanding when and where Jupiter formed (e.g. by looking at the water abundances) will help us understand when and where Earth formed with respect to our Sun. -- JRE

elakdawalla72 karma

During the broadcast last night, you only had "tones," no detailed telemetry. What have you learned since last night about how the spacecraft performed? Fuel used? Orbit achieved? And do you have any devices to monitor the "radiation health" of the spacecraft or do you just depend on the science instruments for that?

NASAJPL95 karma

We haven't used any fuel reserves (either last night or previously). Our previous TCM was canceled because we were so on target. The orbit achieved 53.5 days (no one at the table had more decimal places). For radiation monitoring we'll use the data from many of the science instruments (e.g. effects on JunoCam, SRUs, ASC images and extrapolation from JEDI energy spectra). --JRE

jeebusfish69 karma

What's the next major milestone for Juno? When will the first significant results be available?

frozencrazytuna81 karma

I believe the first scientific analysis of Jupiter will be at the end of August, the 27th if I remember correctly, after Juno finishes its first 53(?) day orbit of Jupiter. Yesterday to get into orbit all of the science equipment was turned off so the end of August is when we should see the first results of this mission.

NASAJPL109 karma

Correct! One minor clarification we've already taken some data and images during approach and will take data as soon as instruments turn. The first close-in images/data will be after Aug. 27th. -- JRE

wazooman267 karma

Congrats guys! What would be the most groundbreaking thing that Juno could find now that it's reached Jupiter?

NASAJPL158 karma

The standard answer would be the structure and composition of the interior of the planet. But in reality it would be something utterly unexpected. - Glenn Orton

TheOnlyPorcupine58 karma

What is the plan for Juno after the ship has completed its 'mission'?

NASAJPL132 karma

Default plan is to purposefully crash into Jupiter about when we expect the electronics to start failing. We'll do this to avoid possibly accidentally contaminating Europa which might have liquid water (and life??). There are plans under consideration, pending operations results, that would allow Juno to stay in an orbit that would eventually crash "naturally" into the planet after potentially more orbits. --JRE

hatsugan48 karma

Hey! Amazing work, congratulations! I know Juno will be deorbitted when it's done its mission bc of planetary protection, but if it were to be left in its science orbit, how long would it take to decay? Also, I am curious, how long did it take to develop the Juno mission?

NASAJPL58 karma

It's literally unknown how long the orbit decay might take given the uncertainties we have about atmospheric densities. Could be years. Likely the radiation would kill most things well before that. Development time = 5+ years. --JRE

nutellahotchocolate47 karma

What's the most exciting discovery Juno can make in its proximity to Jupiter?

NASAJPL105 karma

The most exciting discovery would be a surprise that we haven't thought of yet! We're exploring new territory, so we may find something brand new. We come to Jupiter looking for clues to its origin and interior, such as the water abundance and the size of it's inner core and ocean of metallic hydrogen. We hope to learn about it's giant magnetosphere and the enormous aurora in the north and south. All of those are fascinating and exciting possibilities, but it would be even more exciting if Jupiter surprises with something completely new. -Steve Levin

loki7444 karma

Why were solar panels used instead of nuclear power for Juno?

NASAJPL92 karma

We did not have a viable nuclear power option available to us at the time we were preparing the Juno proposal. So the focus shifted to how to make solar work at Jupiter. Way back in 2004, the team completed some LILT (low intensity, low temperature) and radiation testing on the commercial solar cells to confirm that they would provide enough power for Juno to operate on at Jupiter, where we see only 1/25 of the sunlight that we see at Earth. Rick

_CitationX40 karma

Hey, mad congratulations to you guys! Just wondering, what kind of fuel is used on the craft and if applicable, how much is carried? Thanks guys, and good luck for the future!

NASAJPL48 karma

Thanks! Here's the nitty gritty on fuel. You can find out more facts like this in the interactive press kit.

At the beginning of the Jupiter Orbit Insertion burn, Juno carries about 1,232 kilograms of fuel (810 kilograms of hydrazine and 422 kilograms of oxidizer). At the end of a nominal 35 minutes Jupiter Orbit Insertion burn, Juno will have burned about 447 kilograms of fuel (241 kilograms of hydrazine and 206 kilograms of oxidizer).

-- SLS

MikeCian34 karma

Does Jupiter's massive gravitational pull make it more difficult to keep a probe in orbit?

NASAJPL111 karma

Actually, Jupiters massive gravitational pull helps to keep our probe in orbit. When we fired our main engine last night, we were moving at 54.1 km/sec. After firing our main engine, we were moving away from Jupiter at 53.7 km/sec. That's still really fast! But that really small decrease in orbital speed was enough to put us into a 53 day orbit (instead of a Jupiter flyby). Jupiter's pull is so strong, it would be very challenging now to get out of orbit. This wasn't what I initially expected when the navigators explained to me but it does help demonstrate how different things are when you are around such a massive planet. Rick

floppy_penguin31 karma

Is there any plan to add live streaming, 360 degree cameras to future probes?

NASAJPL43 karma

Live streaming isn't technically possible, given the amount of time it takes for a data signal to travel back to Earth. As for 360's, we have panorama cameras that can take images to be stitched into 360's already in action on Mars. (Check out one of them: and learn more here: As for future missions, the cameras on board would depend on the mission requirements. - JT

Ye_Olde_Stone31 karma

I've heard that Earth's core and its magnetic field is what deflects radiation and makes it a hospitable environment. Is this true, and if so, is life impossible on planets that don't have magnetic fields?

NASAJPL61 karma

Planetary magnetic fields (like Earth and Jupiter have) definitely do deflect some of the radiation would otherwise impact planetary surfaces. However, there is a very active debate about the overall effect of having (or not) a magnetic field on how life would develop (or not) on a planet. --JRE

elgigantesr29 karma

First of all, congratulations! Quick dumb question, Why the name Juno? Any significance or story behind it, or was it basically assigned/ just sounded cool. Again, you guys rock, congratulations!

NASAJPL36 karma

If you feel like watching instead of reading, we also have a video that explains the significance of Juno's name. (Hint: It's not an acronym.)

-- SLS

FaxMachineMode27 karma

Will Juno be able to study the compositions of any of Jupiters moons?

NASAJPL47 karma

The focus of Juno is the interior of Jupiter. JunoCam, the education/public outreach camera, will image the satellites during the course of the mission, but at lower resolution than Voyager, Galileo, or New Horizons. That said, the composition of Jupiter will be an important consideration for future missions, such as the future Europa mission to unravel the complete story about Jupiter's formation. -Glenn Orton

Froguy112627 karma

Not a question about the mission as much as it is about the scientists here:

What kind of education did you guys receive, how many years of schooling? What majors? Etc.

Thanks for this AMA, I'm enjoying it immensely. I'm super interested in astronomy but I'm only in high school right now. Investing in an Orion XT8 to start my amateur astronomy hobby and I'm interested in what it takes to be one of the big guys at NASA. Seriously you guys are my idols :)

Thanks again for the responses!

NASAJPL45 karma

I went to U.C. Berkeley and majored in physics, then went there for grad school as well and got a PhD in physics.

Math is the language of science, so you should definitely study math if you're interested in any kind of science. Other than that, I suggest you follow your passion, and learn as much as you can about whatever interests you. There is a place at NASA for virtually every type of job you can imagine, so just find something you love and try to be the absolute best at it. -Steve Levin

NASAJPL32 karma

I have a Ph.D. in Planetary Physics - lots of years. My advice is take lots of math classes! CJH

WiglyWorm25 karma

From the Juno mission page:

For Juno, like NASA’s earlier Pioneer spacecraft, spinning makes the spacecraft's pointing extremely stable and easy to control

This makes me wonder why NASA has categorically refused to create a spinning manned craft for deep space missions? It seems like it would solve so many of the problems confronting manned space exploration.

NASAJPL48 karma

The difference between a spin-stabilized and a 3-axis stabilized spacecraft will depend on the objectives and the cost limitations. For detailed imaging, a 3-axis stabilized spacecraft is more stable, but more costly. For particle and field experiments, a spinning spacecraft is preferred because it can sense all directions in space. Adding humans, as a next step, would be immensely expensive, far more so than depicted in -say- "2001: A Space Odyssey" - Glenn Orton

alexrocks9723 karma

congrats! Just want to ask what is the most nerve wracking part of a mission like this?

NASAJPL55 karma

For me, launch was the most nerve-wracking part of Juno so far. The Juno spacecraft is the culmination of years of hard work by hundreds of people, and we put it on top of a giant tower of explosive to hurtle it into space. That was just a little scary. After that, JOI was the next most nerve-wracking time, because of the all the unknowns about entering a new environment and performing a critical maneuver at the same time. -Steve Levin

GatoAmarillo23 karma

After the mission is completed will we know for certain whether or not Jupiter has a solid core?

Also, are there any plans for Juno to retrieve information from any of the moons?

NASAJPL40 karma

We expect that we will know whether the center of Jupiter has a core, if you define that as a concentration of heavy elements, not necessarily "rocks". There will be images of the satellites, but none will be at better resolution than Voyager or Galileo images. -Glenn Orton

4n4yhack23 karma

How does titanium protect from radiation? How heavy is Juno?

NASAJPL57 karma

Titanium is a much denser metal than what we usually use (aluminum) and it offers a protection factor of 800:1 inside the titanium vault. So, we can place our critical electronics inside the vault and they see the same environment we would see at Mars (25 rad at Mars instead of 20 Mrad at Jupiter). Many of our electronics were actually used on some previous Mars missions.

As far as weight goes, Juno weighed 3625 kgs at launch - roughly half of that is was propellant (fuel and oxidizer). We used roughly 60% of that fuel to date (with one more main engine burn to go.....3 down, one to go).


Froguy112616 karma

What kind of radiation protection do the electronics on Juno have? Essentially, what is that electronics vault made of that stops the radiation? How effective is it?

NASAJPL41 karma

The predominant protection is the titanium vault that houses our critical electronics - the "brains" of the spacecraft. This vault has walls up to 1/2 inch thick and weighs approx. 400 lbs empty. The vault reduces the radiation these electronics are exposed to over the life of the mission from 20,000,000 rad to 25,000 rad and allows us to survive the full 16 months of our science mission. External sensors are outside the vault and have a side wall of tantalum or tungsten to provide them sufficient shielding to operate for our 16 month science mission. Rick

Froguy112626 karma

If it stops radiation from getting in, how does it communicate with earth using EM radiation (radio)?

NASAJPL74 karma

The antennas that we use for communications are outside the vault. But the radios themselves are inside the vault. So, the radios are protected and the antennas are not (but passive antennas built with graphite epoxy and aluminum honeycomb are fairly impervious to radiation (unlike electronic parts). Rick

jyu65016 karma


My questions is: How long will it take for the information from Juno to be sent back?

NASAJPL35 karma

A minimum of 48 minutes since that is how long it takes for the data sent from Juno to travel to Earth into our large ground based antennas and receivers. When we slow communications down significantly like we did last night, the amount of data accumulated on the spacecraft builds up and it can then takes hours for all of the data to be transmitted to the team on Earth. We are re-establishing "high rate" communications via our large "high gain" antenna today and expect to have all of our data from orbit insertion downlinked and reviewed by tomorrow. Rick

guniu15 karma

So how long will it take for Juno to make a full orbit? I'm really curious about that.

NASAJPL31 karma

We'll start in a 53-day orbit and after we check things out we'll be lowering the orbit to a 14-day orbit which will be our main science orbit. -JRE

mja201414 karma

Geology major here, what do you expect Jupiter's core composition to be? Mainly layers of metal and rock (iron)? Also how are the job prospects looking for a geologist at NASA?

NASAJPL40 karma

Central core of "heavy" stuff (not helium and hydrogen)? Then layer of liquid metallic hydrogen? Then thick layers of increasingly denser hydrogen? Then the clouds we can see. NASA definitely does hire geologists. -- JRE

spicymanatee8 karma

What was the scariest/most nail-biting moment that the team encountered during this mission?

NASAJPL21 karma

Orbit insertion. We had tried to plan for everything but we were literally going into an unknown environment (super-close to Jupiter in radiation belt). -JRE

breadman0178 karma

How soon will we get to see photos?

NASAJPL19 karma

The approach movie is already available: -Glenn Orton

cnickya2 karma

Student from ERAU here. Just how long is the mission going to last, and when it's over, what will happen to Juno?

NASAJPL3 karma

The prime mission is slated for 20 months -- July 2016 to February 2018. At its end, Juno will be deorbited into Jupiter to avoid potential future contamination of Europa. Check out for why that's important. -- SLS

MrMcSpanky942 karma

Hey guys! Great job!! When are the first photos of Jupiter going to be Available??

NASAJPL5 karma

First photos are out including an awesome movie! We'll have even more available later especially as we make the next closest approach on Aug. 27th. -- JRE

toigz1 karma

Where will I be able to see the newest photos and videos of Jupiter taken by Juno?

NASAJPL3 karma

There are a few places:

And to suggest/discuss/vote on where JunoCam should image on each orbit, sign up and join in! - LJL

undefdev1 karma

Will there be aerobots deployed?

Edit: If not, will some sensor/machine enter the athmosphere?

NASAJPL1 karma

No sensors entering the atmosphere (except for the whole thing at the mission end). --JRE

CleverStoic1 karma

There are several documented instances of large objects colliding with Jupiter's atmosphere, as with meteorites on earth or innumerable other celestial bodies. Is there any specific contingency to study an impact if one should happen during Juno's mission? What is the "wildest" contingency plan that you have in your playbook?

NASAJPL2 karma

A large contingent of amateur astronomers are observing Jupiter continuously (their pictures are posted on the JunoCam part of the Juno website), and if they observe a collision they will alert us. We will look at upcoming opportunities (the longitudes available to us at perijove) and definitely take pictures if the locations of the impact are visible. CJH

Nicolad011 karma

Massive congratulations team! I'm so proud of what you have achieved on behalf of all of us here on earth. It's so incredible how far we have come. How often will we the public be able to see imagery from Juno? Thanks for all your hard work seeing the moon orbit was surreal

NASAJPL2 karma

Once we get into the nominal operations mission (November of this year), images will be taken each and every time we come close to Jupiter (1 time every 14 days). Those images will be downloaded throughout the following days and be available online to the public shortly afterwords. - LJL