3304: Jupiter Icy Moons Explorer

Jupiter Icy Moons Explorer

|< < Prev #3304 (September 28, 2026) Next > >|

Title text: "I did briefly visit Venus in August 2025, but I figured out the mistake on my own because it didn't have any moons."

|< < Prev Random explanation Next > >|

Explanation

The Jupiter Icy Moons Explorer (JUICE) is a scientific space exploration spacecraft created by the European Space Agency (ESA). Its planned voyage began in 2023 and includes flybys of the Earth–Moon system (2024), Venus (2025), Earth (2026, on the day of this comic), and Earth (2029), before orbiting Jupiter (2031) and finally using additional flybys of Jupiter's moons to settle into an orbit around the moon Ganymede in 2034. The many flybys it will make provide gravity assists (25 in total) to help it reach its final destination. The gravity assists work by using the celestial bodies' orbital and gravitational energy (instead of rocket fuel) to accelerate JUICE high enough up through the Sun's gravity well to settle into Jupiter's gravity well, thereby reducing the amount of rocket fuel, and hence mission costs, needed to reach its destination. Each such flyby transfers momentum from the celestial body to the probe, allowing it to accelerate outwards in the solar system using less propellant than if it were to simply use some form of Newtonian propulsion. Momentum is conserved; the celestial bodies lose exactly the same amount of momentum as the probe gains. However, the probe is so much less massive than the celestial bodies that the effect on those bodies is negligible.

This comic shows supposed interactions between JUICE and (presumably) ESA Mission Control each time JUICE is near Earth. These suggest that, rather than the gravity assist explanation, the reason for all the flybys is that the probe is inattentive or forgetful, and has to keep returning to Earth to check its instructions. It appears that the person communicating with it was unclear why so many flybys were planned, but the mission planners were expecting this behavior from the probe and deliberately built them in as contingency.

The title text extends the joke, making reference to JUICE's visit to Venus. The probe indicates that it knew Venus wasn't Jupiter, but only because of the lack of moons, rather than the extreme size and appearance differences. JUICE thinks its visit to Venus was a “mistake,” when in fact its flyby of Venus was carefully planned in advance. Jupiter is over ten times the diameter of Venus, and (among other things) currently has a storm system larger than Venus. Even Ganymede is half the diameter of Venus. In JUICE's defense, distances in space are hard to judge, so the probe might have had difficulty assessing the size of Venus without additional reference data. Venus is also much closer to the Sun than Jupiter, so solar proximity should have been a giveaway that it was the wrong planet.

Trivia

Jupiter isn't actually that 'near' Saturn. The distance between their orbits averages more than four times the Earth-Sun distance, and the planets themselves are almost always much farther apart than that because they're at different points in their orbits.

Also Jupiter does in fact have rings, though not the large prominent ones that Saturn (currently) has.

Transcript

[Panel labeled "April 2023". Earth is shown, and the JUICE space probe is flying away from it, with dotted lines showing its path since liftoff.]

Mission Control: We have liftoff!

Mission Control: JUICE is en route to explore the icy moons of Jupiter!

JUICE: Wheee!

[Panel labeled "August 2024". Two images of JUICE are shown, with dotted lines showing its path through space. One is to the left of Earth, the other to the right, and the path goes below Earth. The path curves, indicating the effect of Earth's gravity.]

JUICE: ...So which planet was I visiting again? I got distracted.

MC: Jupiter!

JUICE: Right, OK.

[Panel labeled "September 2026". Two images of JUICE again on its path, with the path going above Earth this time. Again the path curves.]

JUICE: Is Jupiter the one with all the rings? Or...

MC: No, the big one near it.

JUICE: Got it!

[Panel labeled "January 2029". JUICE is approaching Earth from the left.]

JUICE: And which moons am I looking at?

Mission Control 1: Oh my God.

Mission Control 2: Now I get why we budgeted for so many Earth flybys.

  Add comment 

Discussion

Juice is such a worser name than like juno TheTrainsKid (talk) 04:11, 29 September 2026 (UTC)

Could have been worse: MOIST = Moon Orbiter In Search of Trapped water. Barmar (talk) 04:33, 29 September 2026 (UTC)

Who comes up with these names? Titintheword (talk) 01:03, 1 October 2026 (UTC)

I think it's the responsibility of the International Normalisation Institute To Inculcate Apposite Letters In Situational Mnemonics. 92.23.3.72 21:16, 1 October 2026 (UTC)

I feel like the personality of the JuIcE rover may be a reference to 17776 but I may be mistaken. 2607:FB92:2681:8304:293A:9C3D:680A:1979 04:30, 29 September 2026 (UTC)GC

Honestly my first thought as well, but it's also a very xkcd personality so could go either way. Bpendragon (talk) 08:29, 29 September 2026 (UTC)

(The notes after some terms show as just whitespace on my screen, although they are valid links. Am I doing something wrong?) 2601:19B:4103:97F0:548E:6B90:6F59:B8C4 14:06, 29 September 2026 (UTC)

It's not just you. Something seems to have happened to the new Wikipedia link styling. Barmar (talk) 14:18, 29 September 2026 (UTC)

Greetings; are you missing the text of the links or just the graphic icon next to the text? The graphic is a "Wikipedia puzzle piece" and it is being fetched by CSS here: https://upload.wikimedia.org/wikipedia/commons/0/02/WikiPuzzle.svg see if your browser can access that graphic normally. The "padlock icon" is a GIFhttps://upload.wikimedia.org/wikipedia/commons/0/00/Lock_icon_blue.gif I believe that this CSS is generated by the MediaWiki interface configuration, rather than a template that can be changed by editors or administrators. If you cannot access that SVG image on the Wikimedia site, check your firewalls, ad blockers, DNS and so forth in the usual way. If you are able to get it, try those pages again (Shift + Ctrl + R) to refresh and bust your cache, and perhaps they will begin loading for you. If you are having trouble with SVG filetype, and the GIF comes through OK, then perhaps your browser is not completely capable of rendering those? Elizium23 (talk) 05:04, 1 October 2026 (UTC)

JUICE isn't so bad when you consider that the next mission on the docket is the "Rocket Exploration Consortium's Tracking of Unidentified Meteors" project. These Are Not The Comments You Are Looking For (talk) 00:29, 5 October 2026 (UTC)

"Near" is, in fact, referring to "Saturn's orbital distance is more than that of Jupiter, and there is no planet between the two". 2001:4C4E:1C02:5700:4DA0:2883:EE61:4B63 20:14, 7 October 2026 (UTC)
        Add comment