[HN Gopher] ESA - Jupiter Icy Moons Explorer: Live Launch
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ESA - Jupiter Icy Moons Explorer: Live Launch
Author : laktak
Score : 172 points
Date : 2023-04-13 06:37 UTC (16 hours ago)
(HTM) web link (www.esa.int)
(TXT) w3m dump (www.esa.int)
| teh_klev wrote:
| Scott Manley did quite a good video explaining the mission and
| the space craft's journey:
|
| https://www.youtube.com/watch?v=-mEehdFt9Yw
| [deleted]
| robin_reala wrote:
| Launch scrubbed due to lightning risk. Next launch date is is
| same time tomorrow (to be specific, one minute earlier for some
| reason).
| sunflower_01 wrote:
| > one minute earlier for some reason
|
| I might be wrong but my thoughts were that they altered the
| minute to launch at 14:14:14 (at least in my timezone)
|
| This might also be completely wrong but today they would've
| launched the 13th at 14:15 (13 14 15).
| stronglikedan wrote:
| I like this theory better than mine. My jaded view of
| bureaucracy has me thinking that there are additional fees
| for delaying the launch 24 hours or more.
| [deleted]
| goodcanadian wrote:
| This is almost certainly due to the fact that a full rotation
| of the Earth is shorter than a day. As the Earth moves around
| the sun, it has to turn slightly further than a full rotation
| to bring the sun back to the same position in the sky.
| Additionally, Earth's position relative to Jupiter will have
| changed slightly.
| dabluecaboose wrote:
| Off the top of my head I'd have to say the planetary
| ephemerides are more of a factor than the earth's rotation.
| That much we have pretty down pat, otherwise they'd just
| announce it's at (Day+23.6h)
| [deleted]
| throw_a_grenade wrote:
| Did not launch today for the risk of lightning.
| lostgame wrote:
| If 2001 taught us anything, it's that this mission is doomed.
| fbn79 wrote:
| Save the date. If all goes right, expected arrival _2031_.
| speps wrote:
| "Alexa, set a reminder for juice in July 2031"
| retSava wrote:
| "I'm sorry, I didn't understand that. Here are some shopping
| results for furniture and sexual performance enhancer pills."
| WeylandYutani wrote:
| ALL THESE WORLDS ARE YOURS, EXCEPT EUROPA. ATTEMPT NO
| LANDING THERE. USE THEM TOGETHER. USE THEM IN PEACE.
| Sharlin wrote:
| The last two sentences are not in the book, mind. They were
| added to the film version.
| burkaman wrote:
| You could argue that the last two sentences were removed in
| the book version, since the book and film were written
| simultaneously and the book came out later.
| Sharlin wrote:
| No, the message is from _2010_ ; the book was published in
| 1982 and the film, adapted from the book, in 1984.
| groos wrote:
| You're thinking of _2001: A Space Odyssey_, which even
| though it was written simultaneously with the movie, had
| quite some deviations from it.
| belter wrote:
| Now that you mention that...The mission will conclude with a
| crash on Ganymede. I guess from then on a bunch of Tardigrades
| will be the new population. Surprised they went with this
| decision.
| pklausler wrote:
| If tardigrades can survive launch, deep space, Jovian orbital
| conditions for years, and a crash on Ganymede, and then be
| able to reproduce, maybe they deserve to be there.
| belter wrote:
| That is no problem for tardigrades.
|
| "Tiny animals survive exposure to space" - https://www.esa.
| int/Science_Exploration/Human_and_Robotic_Ex...
| stolen_biscuit wrote:
| Why would there be a bunch of tardigrades sitting on the
| probe? Unless they walk out to their nearest moss pile and
| smear it all over I think the chances are remarkably,
| incredibly slim.
|
| You know they go to every length to sterilize the probe
| before launch?
| Laaas wrote:
| Why do they sterilise it? Seems counter-intuitive.
| sph wrote:
| Remarkably slim is not impossible.
|
| Let me remind you of when we sent a probe to Earth,
| thinking it was sterile, and a few billions of years later
| our RNA-based lifeforms had spread everywhere.
| standardUser wrote:
| That is a bizarre decision. Have we learned nothing from the
| hundreds or thousands of examples of humans inadvertently
| messing with ecosystems by introducing new organisms?
| BubbleRings wrote:
| What, are you saying that it is expected that the probe will
| actually be inadvertently carrying Tardigrades that might
| actually survive to the surface? Hidden in little corners of
| the probe? Why didn't we sterilize it?
| calcifer wrote:
| > Surprised they went with this decision.
|
| ESA explains it like this [1]:
|
| > Category II missions are flyby or orbiter missions that
| venture to worlds where there may be some possibility of
| life, but the chances of contamination are slim. Then there's
| category III, where the chances of contamination are deemed
| greater.
|
| > The planetary protection classification for Ganymede is
| driven by the likelihood that living organisms from Earth,
| brought to Ganymede by the spacecraft, can make their way
| down to the ice-ocean interface [...] In turn, this
| likelihood is deemed so low for Ganymede that it justifies a
| category II protection level, allowing for the spacecraft to
| be disposed on Ganymede's surface.
|
| [1] https://www.space.com/europe-juice-jupiter-mission-
| planetary...
| recursinging wrote:
| We designed and built the RIME antenna for this craft. It deploys
| to 16 meters long and weighs only 1.5 kg! See [1] for some more
| info.
|
| If you are already in, or are willing to relocate to southern
| Germany, I'm looking for flexible, multi-domain software
| engineers to build out our small team here at SpaceTech. Check my
| profile if you are interested.
|
| Looking forward to a successful launch tomorrow!
|
| [1] https://spacetech-i.com/news/news-details/spacetech-
| antenna-...
| forgotthepasswd wrote:
| Nice video on the link!
|
| I like how those "1-G challenges" were solved.
| recursinging wrote:
| Indeed, the length of this antenna required some creativity.
| We have some really cool, high-tech solutions [1] for these
| "1-G challenges" as well.
|
| [1] https://carbospacetech.com/innovations/zero-g-robot/
| codethief wrote:
| I had a brief look at the open positions listed on your
| website. The only (pure) SWE role that doesn't require a degree
| in electrical or aerospace engineering seems to be this one:
|
| https://spacetech-i.com/career/open-positions/jobs/software-...
|
| ?
| recursinging wrote:
| Yes, that's the role I'm looking to fill at the moment, but
| it's a small company, and the horizontal coupling is tight. A
| SWE here will be confronted with many hands-on EE and ME
| challenges as well (hence the on-site requirement). People
| who thrive in such environments are a good fit.
| exitb wrote:
| That mission features a complex trajectory that will use a lot of
| gravity assist to get to Jupiter. It will actually take eight
| years to get there, while Juno needed five and the Voyagers only
| two. Why do recent missions choose to do that? Is that a cost
| saving measure?
| detuur wrote:
| The Voyager missions were able to use a rare and convenient
| alignment of the planets that would slingshot them into deep
| space. Juno is orbiting Jupiter itself, which is not a hard
| thing to do in our solar system. JUICE is attempting flybys of
| several of Jupiter moons, to end up orbiting around Ganymede.
| This is a much more delicate orbital insertion and has much
| stricter requirements for the gravity assists on its way there.
| [deleted]
| vikingerik wrote:
| It's cost saving, but the cost saved is really weight (mass) of
| the fuel. Using the gravity assists means you can save on fuel
| and use that mass for the spacecraft and its instruments
| instead. JUICE masses 2400 kg, where Juno is 1600 and the
| Voyagers were 700.
| bauruine wrote:
| JUICE has a launch mass of 5,963 kg while Juno had 3,625 kg and
| Voyager only 721.9 kg. I guess it may be a limit of the launch
| vehicle and the mass the spacecrafts have.
| JanKanis wrote:
| Indeed. The same rocket will give a light probe a much higher
| velocity than a large probe. The launch vehicle for JUICE is
| the Ariane 5 ECA which can launch 16 tonnes to low earth
| orbit[1], while the Titan IIIE that launched the Voyagers had
| a capability of 15.4 tonnes to a (lower) low earth orbit[2].
| So the current launch vehicle is a bit more powerful, but not
| 8 times as much. There are some more powerful (and more
| expensive) rockets active at the time, but nothing 8 times as
| powerful as the Titan IIIE.
|
| So NASA has the choice of 1) launching a lighter/smaller
| probe with less scientific capabilities and endurance, 2)
| spend $$$ and time developing a much more powerful launch
| vehicle, or 3) have a few years of patience waiting for JUICE
| to get to Jupiter on a slower trajectory.
|
| Jupiter has already been visited by multiple probes so
| sending a small and not very capable probe would not gain us
| much scientifically. (But this option was taken with the New
| Horizons probe to Pluto some years ago.) (2) Wouldn't
| actually be faster and much much much more expensive (see how
| long the SLS rocket is taking to get done. But mr. Musk is
| taking this route too with SpaceX's Starship, so this will be
| an option in the future if all goes well). So that leaves
| option 3, which NASA has taken. They could probably have
| opted for an existing more powerful and expensive launcher to
| shave some years off the transit, but they preferred to wait
| a bit longer and not spend that money.
|
| [1]: http://www.astronautix.com/a/ariane5eca.html [2]:
| http://www.astronautix.com/t/titaniiie.html
| dividedbyzero wrote:
| > So NASA has the choice of ...
|
| > So that leaves option 3, which NASA has taken.
|
| As far as I'm aware, JUICE is an ESA probe. NASA is
| providing one of the instruments, but I believe that's it.
| usrusr wrote:
| Much higher confidence to not mess up those gravity assists?
| Control and sensors have come a long way since then
| mpweiher wrote:
| The Voyagers took advantage of a special constellation that
| doesn't happen often:
|
| "In the 1960s, mission designers at JPL noted that the next
| occurrence of a once-every-175-year alignment of the outer
| planets would happen in the late 1970s. A spacecraft could take
| advantage of this opportunity to fly by Jupiter and use its
| gravity to bend its trajectory to visit Saturn, and repeat the
| process to also visit Uranus, Neptune, and Pluto."
|
| https://www.nasa.gov/feature/45-years-ago-voyager-1-begins-i...
| [deleted]
| perihelions wrote:
| That didn't affect the Earth-Jupiter leg, which was direct.
| GravitasFailure wrote:
| If I'm reading the specs correctly the Titan IIIE was a
| significantly more powerful vehicle than the Ariane 5 while
| launching a much smaller payload. JUICE also has to be
| going slow enough to enter orbit without carrying an insane
| amount of fuel for braking while Voyager just did a flyby.
| perihelions wrote:
| - _" Titan IIIE was a significantly more powerful vehicle
| than the Ariane 5 while launching a much smaller
| payload"_
|
| Yes, with a fourth stage. (I don't think it's
| particularly that modern rockets _can 't_ integrate such
| a solid-rocket boost stage, but rather there's no payload
| that needs this).
|
| https://en.wikipedia.org/wiki/Star_(rocket_stage)
|
| - _" JUICE also has to be going slow enough to enter
| orbit without carrying an insane amount of fuel for
| braking while Voyager just did a flyby"_
|
| The flyby speeds are similar; but JUICE takes a time to
| get to that speed.
|
| It's not really that difficult to capture into Jupiter.
| Parent's link [3] says it's only 900 m/s for JUICE. Part
| of the reason is the extremely deep gravity well; and
| another is that the moons are large enough to give you
| effective gravity assists, within the orbit of Jupiter.
| GravitasFailure wrote:
| > _The flyby speeds are similar; but JUICE takes a time
| to get to that speed._
|
| Ahhh, that makes sense. Essentially Voyager did do a
| direct flight while JUICE isn't, instead building speed
| by doing slingshots off Earth and Venus.
|
| "First, it will do a fly-by of Earth and the Moon, then
| slingshot around Venus in 2025 before swinging past Earth
| again in 2029."
|
| https://phys.org/news/2023-04-europe-juice-mission-
| jupiter-i...
| raverbashing wrote:
| Yes the problem is not only getting to Jupiter, it is
| stopping once you get there
| eep_social wrote:
| Efficiency [1] in the form of reduced delta-v requirements [2].
| The "yellow book" assessment study report probably has even
| more details [3].
|
| [1] https://theconversation.com/the-much-anticipated-juice-
| missi...
|
| [2]
| https://www.lpi.usra.edu/opag/mar2012/presentations/Friday/5...
|
| [3] https://sci.esa.int/web/juice/-/49837-juice-assessment-
| study...
| perihelions wrote:
| Here's a key figure [3]:
|
| - _" The mass injected into the Earth escape trajectory would
| be 4800 kg (without launch adapter), with a hyperbolic escape
| velocity of 3.15 km/s, which increases to 9.5 km/s after the
| last Earth swing-by"_
|
| The _Voyagers_ were launched directly to hyperbolic excess of
| >10 km/s -- comparable to the speed JUICE will reach on its
| _third_ flyby, of Earth, in 2029.
|
| https://sci-hub.ru/10.1016/j.actaastro.2019.06.013 ( _" C3
| of... 105.5 km2/s2 and 102.4 km2/s2 for Voyagers 1 and 2,
| respectively [75]"_)
| mytailorisrich wrote:
| Voyager was also only weighing 773kg.
|
| The mass of JUICE is probably a big parameter here.
| belter wrote:
| [1]: "From Earth to Jupiter...JUICE trajectory is designed by
| ESOC Mission Analysis team. It is the result of an
| optimization, iterated with ESA project and Airbus teams,
| aiming at maximizing the dry mass at launch, keeping the total
| mass within the launcher capabilities and minimizing the
| transfer duration, while respecting other mission constraints,
| like total radiation dose, minimum Sun distance and maximum
| eclipse duration..."
|
| [1] - "JUICE interplanetary operations design drivers and
| challenges" - https://arc.aiaa.org/doi/pdf/10.2514/6.2018-2493
|
| This is also an interesting Thesis on optimization required for
| the flybys due to the uncertainty of the Moons positions on
| arrival :
|
| "Preliminary Navigation Analysis for the Flyby Tour of ESA's
| JUICE Mission" - An investigation on the trajectory correction
| maneuvers design
|
| https://repository.tudelft.nl/islandora/object/uuid:455ec2e9...
| euroderf wrote:
| I wonder what the predictions are like. When it finally gets to
| Jupiter, eight years from now, do we know now where the moons
| will be ? To what accuracy ?
| hermitcrab wrote:
| I believe orbits are chaotic over a timespan of many millions
| of years (due to weak interactions with multiple other
| bodies), but accurately predictable over a human lifespan.
| rbanffy wrote:
| It's always a tradeoff. For every kilogram of propellant you
| save on the trip, you get one extra kilogram for the payload.
|
| Also, you may end up bumping into payload limits of the
| launcher itself, so you can get there, but you'll need to take
| the scenic route with fewer delta-v tolls.
| shagie wrote:
| https://trajbrowser.arc.nasa.gov/traj_browser.php
|
| In particular
| https://trajbrowser.arc.nasa.gov/traj_browser.php?NEAs=on&NE...
|
| This EVEEJ route doesn't appear to be in the trajectory list,
| but it's interesting to explore and see the various windows.
| saberdancer wrote:
| Cost saving as there is no prestige or gain in coming fast or
| first. Probes are also bigger and heavier.
| Sharlin wrote:
| The Voyagers, besides their much lower mass, were flyby
| missions. They could afford to be fast because they didn't need
| to slow down for orbit insertion.
|
| NASA's Europa Clipper, due to launch in Oct 2024 on a Falcon 9,
| will take 5.5 years to get to Jupiter. The Congress directed
| NASA to investigate the option to launch it on an SLS, should
| one be available (it won't, and it would be ridiculously
| expensive) - it would have been able to send the probe on a
| direct ~1.5 year Hohmann transfer to Jupiter without gravity
| assists, but no other existing launch vehicle could do that.
| dogma1138 wrote:
| The voyagers were launched within very specific window iirc
| which is why they managed to get to the outer planets so
| quickly. Also the voyagers only did a flyby so they could
| afford to go as fast as they want as they didn't needed to
| enter orbit.
|
| The length of time to get to Jupiter is pretty much dictated by
| orbital mechanics. As well as your ability to slow down and
| actually get into orbit instead of just doing a flyby.
|
| So the longer journey is likely a combination of the launch
| vehicle, the cruise stage vehicle and how much fuel they want
| to dedicate into getting into orbit vs the mission since the
| probe is expected to visit multiple moons it's likely that they
| prioritize the fuel for in mission orbit corrections so they
| are taking a longer and slower approach.
| exitb wrote:
| Well, sure, the window was very specific to visit multiple
| planets, but Jupiter was the first stop. Similar Earth-
| Jupiter configuration happens every year.
| avar wrote:
| The ISS made a "stop" in my general vicinity earlier today
| by your definition of "stop".
| exitb wrote:
| Sorry, English it not my first language, I meant it as a
| first destination, it obviously just flew by.
| dogma1138 wrote:
| Jupiter makes an orbit around the sun once every 12 years
| there likely are years where it is closer to earth than
| others.
|
| Also there are years when it's retrograde and there are
| years when it's prograde so there is that too.
|
| With Voyager it also wasn't just Jupiter it was an
| alignment of all the planets which is far rarer.
|
| And again voyager didn't entered orbit it had a very brief
| flyby of Jupiter.
|
| Cassini also took a decade to reach Saturn because it
| needed to enter orbit around it and its moons.
| kej wrote:
| Tangentially related, but if you haven't read 17776: What
| Football Will Look Like in the Future, it's an excellent example
| of using hypermedia to tell a story (and isn't really about
| football): https://www.sbnation.com/a/17776-football
| LatticeAnimal wrote:
| That was beautifully told. Thank you for sharing
| moffkalast wrote:
| Well that's gotta be by far the most depressing utopia I've
| ever seen put into text.
| yalue wrote:
| Jon Bois is a genius, and this is the main example I return to
| when tempted to think that hypermedia is just a gimmick. It
| takes a special type of creativity to not just make it feel
| "tacked on." Perhaps the light jazz and dated look of the
| google maps visuals just meld well with the nostalgia evoked by
| the content of the story. The text alone would probably work as
| a good scifi short, but the additional material makes it so
| much more dramatic.
| temp0826 wrote:
| Has there been any word on the third part of the series? 20020
| came out then allegedly 20021 was coming out "soon", but didn't
| seem to ever materialize.
| MrRadar wrote:
| The last update on 20021 was from April 2021 when Jon
| announced it was delayed (with no specific information on
| when it would be ready): https://www.reddit.com/r/Jon_Bois/co
| mments/mwmo0i/programmin...
| uhtred wrote:
| That was about as fun to read as Blindsight by Peter Watts.
| NikolaNovak wrote:
| Hah yes, I think it evokes the feel of Peter Watts but also
| qntm / Sam Hughes even more!
|
| Mostly in the constant "what the ___ am I
| reading/watching/thinking right now"
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