Jupiter has a very intense radiation field, and thus spacecraft going to study it need heavy radiation shielding, such as Juno's radiation vault. This protects the delicate instruments and electronics. However, Juno needs the shielding because it passes by Jupiter very closely, and is exposed to the full brunt of the radiation. Would a lander on Europa need similar protection, or is Europa sufficiently far away and/or have a thick enough atmosphere that it would not need as much shielding?

EDIT: This question has drawn some conflicting answers. The fact that a lander would have shielding from the moon and that it is always in the intense radiation environment made me feel unsure of which was more important. If someone could make a more detailed answer including both facts, perhaps mathematically, I would appreciate it.

Also, wouldn't Europa's magnetic field help deflect some of the radiation? After all, most of the radiation present in the belts is just charged particles.


A Europa lander would need much more shielding, and/or more radiation tolerant components. Juno's orbit avoids the main radiation belt, but Europa is right in the middle of it.

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    $\begingroup$ Are you able to comment at all on how much radiation is blocked by Europa's atmosphere? $\endgroup$ – Phiteros Sep 15 '16 at 16:36
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    $\begingroup$ Zero. The Europa "atmosphere" is what we would call a very high grade vacuum on Earth. However Europa itself blocks about half the radiation if you're on the surface. Even if you dug in on the surface, you'd still have to deal with getting to Europa, which will be a fair bit of time in the belts. $\endgroup$ – Mark Adler Sep 15 '16 at 16:56
  • $\begingroup$ Also, what about Europa's magnetic field? $\endgroup$ – Phiteros Sep 16 '16 at 4:23
  • $\begingroup$ It's not enough to shield anything. See @ventsyv's answer for references on shielding by Europa itself. $\endgroup$ – Mark Adler Sep 16 '16 at 6:00
  • $\begingroup$ Sidenote, I heard someone in the mission staff say in an interview, that Juno will receive the equivalent of a hundred million times what one receives during a medical x-ray today. But they've shielded 99.9% so now it will be "only" one hundred thousand doses (ten an hour for a year, as far as x-ray is comparable with the mostly electron(?) radiation at Jupiter). $\endgroup$ – LocalFluff Sep 16 '16 at 9:47

That depends on where the spacecraft lands. The radiation belts rotate faster than the moon so the trailing side of Europa gets a lot of radiation while the leading side gets relatively little. It also depends if the lander will be a separate spacecraft or a part of the orbiter. If it has to go multiple times through the radiation belt with the orbiter, then it will have to be shielded. On the other hand, if the lander stays in a safe orbit until the planet is surveyed and then is commanded to land it might not need shielding. The final variable is the duration of the mission. I've seen 10 days being mentioned which will probably not need shielding.

There is very little info on the lander, so it's mostly a speculation but from what I've read it appears it will probably not be shielded.




No, a Europa (or Io) lander would need much less radiation shielding than Juno.

A lander halves its radiation exposure by simply sitting on a body which shields half of its horizon. And by melting its sensitive electronics a few meters into the surface, the radiation problem is pretty much eliminated. And getting down under the surface is pretty much the science goal of a Europa lander anyway. It's not like anyone imagines a Curiosity roving around on Europa's surface.

  • $\begingroup$ Even if Europa blocks out half of the sky, wouldn't the other half still be rather significant? Especially because the lander would remain in the radiation environment for its entire mission, not ducking in and out like Juno is? $\endgroup$ – Phiteros Sep 15 '16 at 23:35
  • $\begingroup$ @Phiteros Actually, Juno avoids most of Jupiter's radiation by staying out of the radiation belts, as mentioned in Mark's answer. When it is in close, it is nearer than the radiation belt, then it passes under them as it goes out to its apogee, and over them as it comes in again. It never passes through them. nasa.gov/image-feature/goddard/2016/… $\endgroup$ – kim holder Sep 15 '16 at 23:46
  • $\begingroup$ I meant that it is still only spending part of its time in the radiation environment. It's not always in there, like a lander would have to be. $\endgroup$ – Phiteros Sep 16 '16 at 0:08
  • $\begingroup$ It first has to get to Europa, resulting in time spent deep in the radiation belt. Also there is no plan, and no way, to melt the lander into the ice. $\endgroup$ – Mark Adler Sep 16 '16 at 3:45
  • $\begingroup$ @Mark Adler Drilling/melting is required anyway for science to motivate a landing. Why not put sensitive electronics into a drill hole? $\endgroup$ – LocalFluff Sep 16 '16 at 9:30

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