Effects of CME (coronal mass ejection) on astronauts, or other ways to die in space

Question

I'm writing a sci-fi story involving a lot of asteroid mining and things like that. A major character is a 'development scout' for a large company and has a backstory in which they apparently made a bad call and got a lot of people killed, but they are adamant that it's because of equipment failure on the part of the company and they were forced to take the blame. I'm trying to hammer out the details.

The scenario I was imagining for this was imagining a crew on an asteroid or the lunar surface during a CME. When they realize it's approaching, they send the other crew to the habitat modules, which are supposed to have radiation shielding, and go out in one of the rovers to try and power down a piece of key equipment to avoid damage by the storm. It's too far away to not risk exposure while going out to fix this thing, so the scout says something like 'oh, I have the best chance, I'll do it, stay in the modules'. But it turns out the company had cut costs on the habitat modules, considering a CME event of that magnitude too unlikely to prepare for, and the crew in them end up injured and/or die. The scout waits out the storm meanwhile in a rover, trapped outside, but is wearing a spacesuit and the vehicle has its own (functioning) shielding, and so manages to survive. (I was also considering including a moment where one of the engineers stripping out shielding from other vehicles and puts it into the scout's but I honestly don't know how realistic this is unless it's like, literal sheets of lead or something).

My question is:

• where in the solar system would be a reasonable possibility for this to happen? is the asteroid belt too far? would a CME cause lethal radiation exposure at that distance? this should be a freak event but not beyond the pale of possibility

• with current or near-future technology, how much shielding do you really need to prevent being irradiated from CMEs?

• what would an unshielded or poorly shielded astronaut experience through this?

• if there's an active magnetic shielding system (I'm not knowledgeable about this at all btw) - a poorly functioning one, say - would the astronauts in the habitat potentially see oxygen ionizing or anything like that?

• is there a more reasonable scenario I should use instead to achieve the same outcome? I picked this specifically because of the invisible horror of radiation and also the potential for the astronauts to be trapped together for several days, knowing they were potentially fatally irradiated, but still alive. That said I realize there's loads of other options to die horrible in space (lol) especially involving faulty equipment, so any suggestions would be great! Thank you so much

Answer 1

Your story takes place on Callisto, one of the Jovian moons.

https://en.wikipedia.org/wiki/Colonization_of_the_outer_Solar_System#Callisto

Callisto Due to its distance from Jupiter's powerful radiation belt, Callisto is subject to only 0.0001 Sv a day.[6] When NASA carried out a study called HOPE (Revolutionary Concepts for Human Outer Planet Exploration) regarding the future exploration of the Solar System, the target chosen was Callisto.[11] It might be possible to build a surface base that would produce fuel for further exploration of the Solar System.

Your storm is not a CME but a radiation storm coming from Jupiter which transiently increases radiation levels on Callisto. You can search up what that storm would be - maybe itself precipitated by a CME or other solar energy, or a volcanic conniption on Io, or some Jovian phenomenon you invent.

Your people all have on space suits but that is not enough to save them. There is something else they were supposed to do that is hard and inconvenient (go to off site undergrown shelter?) and that is how Company dodges blame.

I like the idea that your technician is saved by the piece of equipment he went out to save. Maybe he powers it up instead of down and the shielding he was augmenting saves him too.

-- Re dying of radiation - you can read up. Ugly stuff. The others will still be alive when your tech gets back. One of them can comment to him that if he had known he would not have worn the spacesuit, because then it would already be over.

I am reminded of this account by Ambroise Pare from his Apologie

Being in the Citty, I entred into a stable thinking to lodge my oivne, and my mans horse, where I found foure dead souldiers, and three which were leaning against die wall, their faces wholly disfigured, and neither saw nor heard, nor spoke; and their clothes did yet flame with the gunpowder which had burnt them. Beholding them with pitty, there happened to come an old souldier, who asked me if there were any possible meanes to cure them, I told him no: he presently approached to them, and gendy cut their throates without choler. Seeing this great cruelty, I told him he was a wicked man, he answered me that he prayed to God, that whensoever he should be in such a case, that he might finde some one that would doe as much to him, to the end he might not miserably languish.

Answer 2

is the asteroid belt too far? would a CME cause lethal radiation exposure at that distance?

I'm finding it difficult to pin down enough hard figures here, but it is certainly possible. Flares can be pretty big, after all... you might not want something Carrington-event sized, but you can handwave in one that is big enough and luckily wasn't pointing at Earth or Mars or wherever else you have habitation.

The biggest problem you have is that asteroids are small, which means that travelling to the far side of one is relatively straightforward, at which point you are exceptionally well shielded from the sun. This is a plot problem for you to solve, however.

The Moon is probably the "best" place to get zapped, because it is much closer to the Sun and has no atmosphere but is still reasonably large.

with current or near-future technology, how much shielding do you really need to prevent being irradiated from CMEs?

Have a look at this thesis that looks at shielding on Mars (127 pages, not a quick read!). There are plenty of tradeoffs to be made. 10cm of polyethelene will do a remarkably good job for a portable shield, without being either too heavy or too bulky. A fixed habitat could simply be buried... a couple of metres of regolith will keep out pretty much anything, is readily available on most moons and asteroids, and doesn't weight very much if you're not on a big planet like Earth.

what would an unshielded or poorly shielded astronaut experience through this?

"It depends".

Acute radiation poisoning can be rapidly incapacitating, but most likely the victims will be initially "fine", though they'll be well aware that they're now amongst the walking dead. Fatal radiation poisoning takes varying amounts of time to kill, with various symptoms arriving after the exposure. Headache, nausea, vomiting, diarrhoea dizziness and confusion, bleeding.

Extremely high doses incapacitate almost immediately, but I feel you'd have to be a lot closer to the sun and in the way of a really bad flare to get actually end up dead within a few hours rather than a few days or weeks.

if there's an active shielding system (I'm not knowledgeable about this at all btw) and it's say, malfunctioning or poorly functioning, would the astronauts in the habitat potentially see oxygen ionizing or anything like that?

Probably not; real life is seldom graphic like that. I'd expect people to have dosimeters though, and they'll show that something is badly wrong though in a very non-dramatic way.