AR 13234

[Drax Spacex]

There was also a filament eruption associated with this flare seen in 304 angstroms imagery, flung to the southwest.

[auclectic]

I'm not finding the best answer for this on the Google machine, so hoping maybe someone here might have an idea..

What kind of impact could a flare like today's X flare and filament possibly have on the ISS? I would imagine since it's on the limb the crews wouldn't be in danger, but going forward into solar maximum I'm curious if there's an increased risk of radiation sickness? (I understand it's reinforced and within Earth's orbit, just curious especially since crews arrived/departed today few hours before the x flare)

[Sam Warfel]

10 minutes ago, auclectic said:

I'm not finding the best answer for this on the Google machine, so hoping maybe someone here might have an idea..

What kind of impact could a flare like today's X flare and filament possibly have on the ISS? I would imagine since it's on the limb the crews wouldn't be in danger, but going forward into solar maximum I'm curious if there's an increased risk of radiation sickness? (I understand it's reinforced and within Earth's orbit, just curious especially since crews arrived/departed today few hours before the x flare)

The ISS orbits well within the protective shield of the Earth's magnetosphere.
That sort of thing was something the Apollo astronauts had to watch out for, and will also be a hazard for the upcoming Artemis missions, but low Earth orbit is generally unaffected.

[Jesterface23]

The events are becoming a Friday thing. The CME is Earth directed coming with a glancing blow, though unlikely to arrive.

April 1st falls on a Saturday at least.

[Danklyfrank]

Forgive me if this is off topic, but I'm curious as to why some in the community hope for the CME to be Earth directed. Wouldn't an earth directed CME have potential to cause damage to some electrical systems and potentially cause significant disruptions to global stability. So it confuses me seeing people hope for one of those, is it for research purposes, if so is it that non Earth directed CMEs are harder to study?

[Sam Warfel]

1 hour ago, Danklyfrank said:

Forgive me if this is off topic, but I'm curious as to why some in the community hope for the CME to be Earth directed. Wouldn't an earth directed CME have potential to cause damage to some electrical systems and potentially cause significant disruptions to global stability. So it confuses me seeing people hope for one of those, is it for research purposes, if so is it that non Earth directed CMEs are harder to study?

Only an extraordinarily powerful CME could damage anything. 
Many, many CMEs hit Earth and do nothing except spark auroras. For example, last Sunday two strong CMEs impacted Earth, and caused a strong G3 level storm. That caused beautiful aurora, like this pic I got, and did no damage. CMEs are an extremely common event, and we are well equipped to deal with them, protected by Earth’s magnetic field. 

[Philalethes]

6 hours ago, auclectic said:

I'm not finding the best answer for this on the Google machine, so hoping maybe someone here might have an idea..

What kind of impact could a flare like today's X flare and filament possibly have on the ISS? I would imagine since it's on the limb the crews wouldn't be in danger, but going forward into solar maximum I'm curious if there's an increased risk of radiation sickness? (I understand it's reinforced and within Earth's orbit, just curious especially since crews arrived/departed today few hours before the x flare)

As mentioned above, the magnetosphere blocks most particle-based radiation (and even sweeps away cosmic rays), so that's not an issue. The only thing that could be an issue would likely be X-radiation, as the magnetosphere doesn't block EM radiation, and due to the short warning between sudden flares and the arrival of the radiation.

The ISS orbits at ~400 km above Earth, and X-rays are absorbed throughout the thermosphere (85 to 500-1000 km above Earth) before almost of all of them being absorbed in the mesosphere (50-85 km above Earth). This means that a portion of X-radiation from flares will likely reach the ISS if it is on the right side of Earth. The exact extent of the thermosphere varies, but if for the sake of calculation we generously assume that it extends to 800-900 km and also generously assume a linear relationship between altitude and fraction of X-rays absorbed (at least I believe both of these estimates to be quite generous, if someone disagrees they can feel free to weigh in), we could assume that the ISS is exposed to 0.5 (50%) of the X-radiation that would reach someone or something in deep space.

If we further take this paper as a rough estimate of the radiation dose an astronaut in deep space would be exposed to if only having their spacesuit as protection, we can read this:

Quote

The typical areal densities of spacesuit components (∼0.5–1.5 g cm^−2) provide little protection during a large solar flare. A relatively common 10^31 erg flare would deliver over 0.2 Gy behind the current spacesuit—twice our adopted upper limit. A thicker spacesuit could reduce this dose to 0.1 Gy, but larger flares do occur, albeit less often. Bolstering spacesuits simply decreases the frequency of dangerous doses and does not eliminate the threat.

Assuming this reasonable estimate of 10^31 erg for an X-flare, which is commonly used, the radiation dose would be 0.2 Gy (gray) in deep space, so going by the assumptions above, an astronaut in only their spacesuit at the altitude of the ISS could be assumed to be exposed to 0.1 Gy. For the sake of generosity, let's say 0.05-0.1 Gy. Now, since grays are equal to sieverts for X-rays, we can take a look at some common radiation doses to see how much we'd be talking about (0.05-0.1 sieverts being 50-100 millisieverts):

As we can see, we're not talking about much, but it's worth noting that it's around the range of radiation where you start to get some statistical increases in cancer risks long-term. It should be noted that a much rarer event with e.g. 10 times as powerful would lead to 10 times the dosage, leaving you at 500-1000 millisieverts, and as you can tell that could be a lot more severe. X10 flares are very rare, though.

All of that being said, keep in mind that this assumes that the astronaut in question is outside of the ISS and directly exposed to the radiation when it reaches them; the ISS itself is well shielded, so anyone inside of it or in its shadow would be relatively unharmed. It blocks ~95% of X-radiation, so even in the event of the very rare X10 above this would mean only 25-50 milliesieverts instead, and only 2.5-5 millisieverts for the "regular" X-flare.

I don't know what ISS protocols are for maintenance and similar work outside of the station itself, but given this I suppose it could be argued that it'd be best to try avoiding transfers or maintenance work that could lead to such exposure, especially if Solar activity is high in general and/or there are highly active regions. However, in this Wikipedia article (that appears to based on a variety of NASA studies) it says:

Quote

Astronauts are exposed to approximately 50-2,000 millisieverts (mSv) while on six-month-duration missions to the International Space Station (ISS), the Moon and beyond. The risk of cancer caused by ionizing radiation is well documented at radiation doses beginning at 100 mSv and above.

In other words, astronauts are apparently already being exposed to quite a bit of radiation on average, although that doesn't specify whether missions to ISS typically only incur the lower range of that dose, which could be the case. In any case I don't believe this accounts for the possibilities of being hit by X-radiation from X-flares while outside of the ISS, so it's still something I guess would make sense to account for, and I would assume that they're already doing so.

Edited March 4, 2023 by Philalethes Bythos

[Jesterface23]

3 hours ago, Danklyfrank said:

Forgive me if this is off topic, but I'm curious as to why some in the community hope for the CME to be Earth directed. Wouldn't an earth directed CME have potential to cause damage to some electrical systems and potentially cause significant disruptions to global stability. So it confuses me seeing people hope for one of those, is it for research purposes, if so is it that non Earth directed CMEs are harder to study?

I'd happen to be in an area where I need K8 or K9 to see the aurora, so I would want a good storm (and the data would be good too). Going off the quote,

1 hour ago, Sam Warfel said:

Only an extraordinarily powerful CME could damage anything.

The highest geomagnetic storm strength limits we commonly know are K9 and Kp9. So the values can be on that limit, or rarely go far beyond the nT limit for K9 with an extreme CME. For the 2003 Halloween storms it looks like 2 main stations in Alaska and one on Colorado didn't go much over the K9 limit.

[auclectic]

5 hours ago, Philalethes Bythos said:

As mentioned above, the magnetosphere blocks most particle-based radiation (and even sweeps away cosmic rays), so that's not an issue. The only thing that could be an issue would likely be X-radiation, as the magnetosphere doesn't block EM radiation, and due to the short warning between sudden flares and the arrival of the radiation.

The ISS orbits at ~400 km above Earth, and X-rays are absorbed throughout the thermosphere (85 to 500-1000 km above Earth) before almost of all of them being absorbed in the mesosphere (50-85 km above Earth). This means that a portion of X-radiation from flares will likely reach the ISS if it is on the right side of Earth. The exact extent of the thermosphere varies, but if for the sake of calculation we generously assume that it extends to 800-900 km and also generously assume a linear relationship between altitude and fraction of X-rays absorbed (at least I believe both of these estimates to be quite generous, if someone disagrees they can feel free to weigh in), we could assume that the ISS is exposed to 0.5 (50%) of the X-radiation that would reach someone or something in deep space.

If we further take this paper as a rough estimate of the radiation dose an astronaut in deep space would be exposed to if only having their spacesuit as protection, we can read this:

Assuming this reasonable estimate of 10^31 erg for an X-flare, which is commonly used, the radiation dose would be 0.2 Gy (gray) in deep space, so going by the assumptions above, an astronaut in only their spacesuit at the altitude of the ISS could be assumed to be exposed to 0.1 Gy. For the sake of generosity, let's say 0.05-0.1 Gy. Now, since grays are equal to sieverts for X-rays, we can take a look at some common radiation doses to see how much we'd be talking about (0.05-0.1 sieverts being 50-100 millisieverts):

As we can see, we're not talking about much, but it's worth noting that it's around the range of radiation where you start to get some statistical increases in cancer risks long-term. It should be noted that a much rarer event with e.g. 10 times as powerful would lead to 10 times the dosage, leaving you at 500-1000 millisieverts, and as you can tell that could be a lot more severe. X10 flares are very rare, though.

All of that being said, keep in mind that this assumes that the astronaut in question is outside of the ISS and directly exposed to the radiation when it reaches them; the ISS itself is well shielded, so anyone inside of it or in its shadow would be relatively unharmed. It blocks ~95% of X-radiation, so even in the event of the very rare X10 above this would mean only 25-50 milliesieverts instead, and only 2.5-5 millisieverts for the "regular" X-flare.

I don't know what ISS protocols are for maintenance and similar work outside of the station itself, but given this I suppose it could be argued that it'd be best to try avoiding transfers or maintenance work that could lead to such exposure, especially if Solar activity is high in general and/or there are highly active regions. However, in this Wikipedia article (that appears to based on a variety of NASA studies) it says:

In other words, astronauts are apparently already being exposed to quite a bit of radiation on average, although that doesn't specify whether missions to ISS typically only incur the lower range of that dose, which could be the case. In any case I don't believe this accounts for the possibilities of being hit by X-radiation from X-flares while outside of the ISS, so it's still something I guess would make sense to account for, and I would assume that they're already doing so.

Thank you so much for the thoughtful response! I had read that certain areas on  the ISS will shield events up to 10 MeV but that's a per unit measurement and I couldn't find a great conversion into terms of radiation dose. This makes a lot of sense, thank you so much again! 

 

[Philalethes]

32 minutes ago, auclectic said:

Thank you so much for the thoughtful response! I had read that certain areas on  the ISS will shield events up to 10 MeV but that's a per unit measurement and I couldn't find a great conversion into terms of radiation dose. This makes a lot of sense, thank you so much again!

That's almost certainly pertaining to particles, both from Solar storms and cosmic rays. X-rays have individual energies much lower than 10 MeV, but EM radiation is much harder to shield against than non-EM cosmic rays (i.e. high-energy particles). Also, as mentioned above the magnetosphere blocks out virtually all non-EM cosmic rays originating from Solar flares, and CMEs tend to sweep away galactic cosmic rays too.

[mozy]

Another big eruption..

[Philalethes]

34 minutes ago, mozy said:

Another big eruption..

Almost looks like it could have an Earth-directed component even from the limb, heh. Doubt it, but will be interesting to see on LASCO.

[Jesterface23]

Well, there is a dull asymmetric halo from this new CME too lol. This one probably being directed to the far side though.

[arjemma]

18 hours ago, Jesterface23 said:

Well, there is a dull asymmetric halo from this new CME too lol. This one probably being directed to the far side though.

I agree. I think the halo we see is for the far side. So most likely not earth directed but we will see what happens.

Edited March 5, 2023 by arjemma