You can read their paper here[0]. I agree it's very dodgy (and without even looking at that author's past). While the comet 3I/ATLAS approaches within 53 million km of Jupiter (0.3 au), all they can propose is, optimistically, to bring Juno to within half that distance–27 million km. Hardly seems worth the risks? And that'd end all of Juno's remaining Jupiter science (assuming the MAGA! FY26 budget doesn't get to it first. It's fully defunded, if anyone hadn't heard).
Referring to their figs. 3–7, that distance figure is a hard limit—there's no possibility they have of getting closer to the comet than that.
(Keep in mind this is just one random interstellar comet; there are many, many others like it—there will be infinite opportunities to study one—and Avi Loeb is a proven clown who consistently misrepresents these things for drama).
[0] https://arxiv.org/abs/2507.21402 ("Intercepting 3I/ATLAS at Closest Approach to Jupiter with the Juno spacecraft")
Tangential remark: there was a similar proposal for the end-of-life of the Cassini orbiter—it didn't happen, but, there was enough delta-v for the theoretical option, of escaping Saturn and redirecting it to a second mission at Uranus[1]. It was also a dodgy idea, since the transfer time would have been ridiculous (~20 years)—it'd have been a long-shot for Cassini to have survived that long.
[1] https://en.wikipedia.org/wiki/Cassini_retirement#End_of_miss... ("Cassini retirement#End of mission options")
> without even looking at that author's past
It is worth noting that this comes two weeks after the authors posted https://arxiv.org/abs/2507.12213 "Is the Interstellar Object 3I/ATLAS Alien Technology?"
They describe this first paper as "largely a pedagogical exercise" - clearly, if they're now providing emails to news outlets recommending this course change, their view of the target audience has certainly evolved. Orson Welles would be proud.
>Hardly seems worth the risks?
Juno's mission is at end-of-life at the proposal's starting point. So now tell me again about the risks.
It's not going to be able to see anything at the closest approach that we can't see from earth. So there are no gains to be had, so no risks are worth it.
And even the 27Mkm number requires very optimistic assumptions, including that the main engine that has had huge problems during its mission would work perfectly for one continuous burn to exhaustion. Realistically, that's not going to happen.