Mars Radiation

[Yggdrasill]

I have started a YouTube channel and have made a video on Mars Radiation, and thought many here would find it interesting.



It would surprise me if I haven't made any errors, so if you spot any - let me know and I'll see if I can pin it in a comment on the video. I know there are a lot of knowledgeable people here, so hopefully no one completely destroys my video.

One issue I am aware of is that not all figures are fully consistent. The video uses estimates from a range of sources and the different sources have made different assumptions. But the big picture should be largely correct.

I decided to make the video because radiation is something I see generating a lot of uninformed discussion (not on this forum in particular), and hopefully it can over time become less uninformed.

[Slarty1080]

Interesting video - thanks. One point I would make is that there are a lot of unknowns about the effects of some types of space radiation such as heavy ions (Fe⁵⁶⁺) which although very low in numbers, appear to be very damaging. There are also some very complex interactions with some high energy particles creating secondary and tertiary particle cascades. So as things stand there are many unknowns about radiation effects on humans.

Perhaps not relevant, but another big issue is low gravity especially in terms of the longer term if and when colonisation is considered. We don't know to what extent the adverse effects of zero g will be mitigated by 0.38g and what effect it might have on pregnancy and developing children. It could be a show stopper.

[Robotbeat]

Interesting video - thanks. One point I would make is that there are a lot of unknowns about the effects of some types of space radiation such as heavy ions (Fe⁵⁶⁺) which although very low in numbers, appear to be very damaging. There are also some very complex interactions with some high energy particles creating secondary and tertiary particle cascades. So as things stand there are many unknowns about radiation effects on humans.

The idea these are unknown is inaccurate. The higher damage effects of heavy ions is already taken into account in any model of space radiation dose in use today. Same for secondary and tertiary radiation. Don’t mistake having larger error bars than we’d prefer with there being some big unknowns here (ie order of magnitude). This stuff is well-characterized, and the dosage effects assumptions are extremely conservative.

Perhaps not relevant, but another big issue is low gravity especially in terms of the longer term if and when colonisation is considered. We don't know to what extent the adverse effects of zero g will be mitigated by 0.38g and what effect it might have on pregnancy and developing children. It could be a show stopper.

No, it can’t, because we already know of methods to mitigate these problems, and future methods will necessarily be better.

[Yggdrasill]

Interesting video - thanks. One point I would make is that there are a lot of unknowns about the effects of some types of space radiation such as heavy ions (Fe⁵⁶⁺) which although very low in numbers, appear to be very damaging. There are also some very complex interactions with some high energy particles creating secondary and tertiary particle cascades. So as things stand there are many unknowns about radiation effects on humans.

The thing is that heavy ions are roughly as prevalent on the ISS as they are on Mars, so we have a pretty decent understanding of the damage they do. And the data thus far is very promising.

We don't know if the increased levels of these heavy ions during transit would be exponentially worse. The levels would be roughly twice as high. It's not impossible that it would be a problem, but at the same time, it could also be completely fine.

We should get more data about this when we start doing research on the lunar gateway. It should have mostly the same radiation environment as deep space.

Perhaps not relevant, but another big issue is low gravity especially in terms of the longer term if and when colonisation is considered. We don't know to what extent the adverse effects of zero g will be mitigated by 0.38g and what effect it might have on pregnancy and developing children. It could be a show stopper.

Yeah. Low gravity could be problematic. We have absolutely no idea what 0.38g does, so we must do more research on it before we have any idea to what extent it is an issue, or whether it is an issue at all. If it is a major issue, it's perhaps not completely a showstopper for Mars colonization, but it would make it much more difficult.

In my view, this is one of the biggest risks the first Mars crew would take. They absolutely would be guinea pigs, or maybe more accurately canaries.

[Robotbeat]

We actually do have “ideas” about what happens. People often use this idiom, and I think it’s a gross exaggeration. We’ve done lots of hypogravity simulation tests using off-loading, etc, plus interpolation hypothesis (of various curves) between zero gee and full gravity. Plus, we recently tested the long term effects of lunar gravity on mice on ISS, and the effects don’t seem to be too bad. Martian gravity would certainly be better.

[Yggdrasill]

We actually do have “ideas” about what happens. People often use this idiom, and I think it’s a gross exaggeration. We’ve done lots of hypogravity simulation tests using off-loading, etc, plus interpolation hypothesis (of various curves) between zero gee and full gravity. Plus, we recently tested the long term effects of lunar gravity on mice on ISS, and the effects don’t seem to be too bad. Martian gravity would certainly be better.

Assuming results from mice transfer to humans. And assuming results from lunar gravity transfers to martian gravity.

The logical thing is that the data is relevant, and can be extrapolated from, but without actually doing the research on the effects of the Martian environment on actual humans, we just don't know. It could be that some effects get better with lower gravity, and some effects get better with higher gravity, and exactly 0.38g is right in an area that is terrible for some reason.

We do have ideas. And it is reasonable to assume that Mars gravity should be okay for at least a short mission, to learn more about it, but there are some huge gaps in our actual knowledge.

[Slarty1080]

Perhaps not relevant, but another big issue is low gravity especially in terms of the longer term if and when colonisation is considered. We don't know to what extent the adverse effects of zero g will be mitigated by 0.38g and what effect it might have on pregnancy and developing children. It could be a show stopper.

No, it can’t, because we already know of methods to mitigate these problems, and future methods will necessarily be better.

Do you have any references to this research?

[Twark_Main]

It could be that some effects get better with lower gravity, and some effects get better with higher gravity, and exactly 0.38g is right in an area that is terrible for some reason.

While we're invoking bizarre special pleading arguments, it's also possible that there are alien ghosts on Mars who will be angered by our presence, and will pick us off one by one like in certain Hollywood movies. 

Perhaps not relevant, but another big issue is low gravity especially in terms of the longer term if and when colonisation is considered. We don't know to what extent the adverse effects of zero g will be mitigated by 0.38g and what effect it might have on pregnancy and developing children. It could be a show stopper.

No, it can’t, because we already know of methods to mitigate these problems, and future methods will necessarily be better.

Do you have any references to this research?

So just so we're clear, you're asking if we have any references to the fact that people will prefer any superior method that may come along, instead of preferring inferior methods? 

[Twark_Main]

At ~22 minutes in the video, you say that lava tubes suffer from stability issues, so one compromise is to put the colony at the base of the cliff.

The problem is that Mars cliffs also collapse, producing landslides... 

https://www.syfy.com/syfy-wire/heres-why-you-shouldnt-stand-at-the-base-of-a-martian-cliff-in-spring

https://skyandtelescope.org/astronomy-news/four-martian-landslides-caught-in-the-act/

[whitelancer64]

It could be that some effects get better with lower gravity, and some effects get better with higher gravity, and exactly 0.38g is right in an area that is terrible for some reason.

While we're invoking bizarre special pleading arguments, it's also possible that there are alien ghosts on Mars who will be angered by our presence, and will pick us off one by one like in certain Hollywood movies. 

That's not special pleading. We really don't know what level of gravity will mitigate the negative effects of zero g that we have spent the past few decades observing and researching. It could be that Mars gravity (0.37 g) will be sufficient to ameliorate these effects, or it might not. Maybe 0.5 g is the sweet spot. We don't know and we won't know for sure until we either build a rotating space station to study the long term effects of partial g, or we just go there.

Perhaps not relevant, but another big issue is low gravity especially in terms of the longer term if and when colonisation is considered. We don't know to what extent the adverse effects of zero g will be mitigated by 0.38g and what effect it might have on pregnancy and developing children. It could be a show stopper.

No, it can’t, because we already know of methods to mitigate these problems, and future methods will necessarily be better.

Do you have any references to this research?

So just so we're clear, you're asking if we have any references to the fact that people will prefer any superior method that may come along, instead of preferring inferior methods? 

It's obvious that Slarty is asking about the research implied in the statement "we already know of methods to mitigate these problems," which is partly true, we know that vigorous daily exercise and some medications do reduce some of the negative effects of zero g. But we are not able to mitigate all of them. We know nothing about how partial g might affect human pregnancy and childhood development. There have been some studies of mice in partial g (using the rodent habitat in a centrifuge on the ISS) that are promising, however, sometimes research in mice does not pan out when its applied to other animal or human studies.

[Yggdrasill]

At ~22 minutes in the video, you say that lava tubes suffer from stability issues, so one compromise is to put the colony at the base of the cliff.

The problem is that Mars cliffs also collapse, producing landslides... 

That did occur to me.

However, not all cliffs are prone to collapse, just like not all cliffs on earth are prone to collapse. In areas like Valles Marineris, there are a *lot* of cliffs to choose between, so being able to find a good spot with stable cliffs seems likely. And if all the cliffs are unstable, you can just ensure that the habitat is set up outside the expected landslide path, for a bit lower shielding effect, but still some shielding, if the cliffs are within view.

For lava tubes, you are much more at mercy of circumstance. With far fewer options, you may just have to settle for whatever option happens to be remotely close to the area you want to be.

[Yggdrasill]

I found this map of observed caves. https://www.mdpi.com/2072-4292/12/12/1970



As you can see, if you have a specific location in mind for a base, the nearest cave (that we are aware of) could be thousands of kilometers away.

And most of the caves on the map aren't ideal, as they are at a high altitude, making landings more costly (or reducing payload), providing less shielding, and making ISRU more complicated. Water ice is also thought to be most prevalent at lower altitude.

[Robotbeat]

It could be that some effects get better with lower gravity, and some effects get better with higher gravity, and exactly 0.38g is right in an area that is terrible for some reason.

While we're invoking bizarre special pleading arguments, it's also possible that there are alien ghosts on Mars who will be angered by our presence, and will pick us off one by one like in certain Hollywood movies. 

That's not special pleading. We really don't know what level of gravity will mitigate the negative effects of zero g that we have spent the past few decades observing and researching. It could be that Mars gravity (0.37 g) will be sufficient to ameliorate these effects, or it might not. Maybe 0.5 g is the sweet spot. We don't know and we won't know for sure until we either build a rotating space station to study the long term effects of partial g, or we just go there.

Perhaps not relevant, but another big issue is low gravity especially in terms of the longer term if and when colonisation is considered. We don't know to what extent the adverse effects of zero g will be mitigated by 0.38g and what effect it might have on pregnancy and developing children. It could be a show stopper.

No, it can’t, because we already know of methods to mitigate these problems, and future methods will necessarily be better.

Do you have any references to this research?

So just so we're clear, you're asking if we have any references to the fact that people will prefer any superior method that may come along, instead of preferring inferior methods? 

It's obvious that Slarty is asking about the research implied in the statement "we already know of methods to mitigate these problems," which is partly true, we know that vigorous daily exercise and some medications do reduce some of the negative effects of zero g. But we are not able to mitigate all of them. We know nothing about how partial g might affect human pregnancy and childhood development. There have been some studies of mice in partial g (using the rodent habitat in a centrifuge on the ISS) that are promising, however, sometimes research in mice does not pan out when its applied to other animal or human studies.

No. Rotating the whole building like a merry go round would totally mitigate any problems. That’s what tells us for certain this is not a showstopper. It’s probably not the best way, it would suck if this was necessary for kids or whatever but it would for sure work and wouldn’t even be that hard.

It’s extremely unlikely this would the the only possible mitigation. Complex life on Earth developed in the ocean, went to land, then in some cases went back to the land. Life is adaptable to large changes in effective gravity. (Buoyancy and other off-loading methods is not a PERFECT analogue to changes in gravity or zero-gravity, but we’re also not talking about zero gravity but just reduced gravity. Off-loading is considered a close enough analogue to publish peer reviewed studies, so it should not be completely dismissed.) Life, uh, finds a way. Humans, with the benefit of technology, most certainly will.

[Robotbeat]

I think that’s good enough to put the hypogravity temporarily to rest, we should focus on the actual topic of this thread, space radiation.

[whitelancer64]

It could be that some effects get better with lower gravity, and some effects get better with higher gravity, and exactly 0.38g is right in an area that is terrible for some reason.

While we're invoking bizarre special pleading arguments, it's also possible that there are alien ghosts on Mars who will be angered by our presence, and will pick us off one by one like in certain Hollywood movies. 

That's not special pleading. We really don't know what level of gravity will mitigate the negative effects of zero g that we have spent the past few decades observing and researching. It could be that Mars gravity (0.37 g) will be sufficient to ameliorate these effects, or it might not. Maybe 0.5 g is the sweet spot. We don't know and we won't know for sure until we either build a rotating space station to study the long term effects of partial g, or we just go there.

Perhaps not relevant, but another big issue is low gravity especially in terms of the longer term if and when colonisation is considered. We don't know to what extent the adverse effects of zero g will be mitigated by 0.38g and what effect it might have on pregnancy and developing children. It could be a show stopper.

No, it can’t, because we already know of methods to mitigate these problems, and future methods will necessarily be better.

Do you have any references to this research?

So just so we're clear, you're asking if we have any references to the fact that people will prefer any superior method that may come along, instead of preferring inferior methods? 

It's obvious that Slarty is asking about the research implied in the statement "we already know of methods to mitigate these problems," which is partly true, we know that vigorous daily exercise and some medications do reduce some of the negative effects of zero g. But we are not able to mitigate all of them. We know nothing about how partial g might affect human pregnancy and childhood development. There have been some studies of mice in partial g (using the rodent habitat in a centrifuge on the ISS) that are promising, however, sometimes research in mice does not pan out when its applied to other animal or human studies.

No. Rotating the whole building like a merry go round would totally mitigate any problems. That’s what tells us for certain this is not a showstopper. It’s probably not the best way, it would suck if this was necessary for kids or whatever but it would for sure work and wouldn’t even be that hard.

It’s extremely unlikely this would the the only possible mitigation. Complex life on Earth developed in the ocean, went to land, then in some cases went back to the land. Life is adaptable to large changes in effective gravity. (Buoyancy and other off-loading methods is not a PERFECT analogue to changes in gravity or zero-gravity, but we’re also not talking about zero gravity but just reduced gravity. Off-loading is considered a close enough analogue to publish peer reviewed studies, so it should not be completely dismissed.) Life, uh, finds a way. Humans, with the benefit of technology, most certainly will.

The habitat on a circular track concept could produce 1 g, but then again that could be much easier to do in Space (no need to go into a gravity well) and surface bases on Mars or the Moon would only be part-time research stations, which isn't necessarily a bad thing except to those who want full scale colonization.

All of which is cart before horse, we still don't know if any of that is necessary or not.

[Robotbeat]

It’s not at all clear that spinning a building is much harder on the ground with all the available resources than in space. It’s certainly much easier on Earth to build a merry go round than to build a spinning merry go round in orbit. Lots of people (including chidlren) live in mobile homes or actual RVs with wheels.

This is one of those “let’s throw objections at Mars settlement to make the whole thing seem doubtful” things. And Slarty1080 succeeded, we were sidetracked successfully with concern trolling about a problem that might not even BE a problem. An ugly solution exists even to worst-case assumptions, we can doubtless do far better, let’s go back to the actual freaking topic.

[Robotbeat]

The REALLY frustrating thing about responding to off topic concern trolls is that if you don’t respond, people think their objections are valid, and if you DO respond with a solution to even their worst case assumptions, you’ve unwittingly gave the impression that such unscientific worst case assumptions are actually likely to be true, which they most certainly are not (many people struggle immensely with understanding hypotheticals). So let’s focus on radiation, and report other directions as off-topic.

[whitelancer64]

It’s not at all clear that spinning a building is much harder on the ground with all the available resources than in space. It’s certainly much easier on Earth to build a merry go round than to build a spinning merry go round in orbit. Lots of people (including chidlren) live in mobile homes or actual RVs with wheels.

This is one of those “let’s throw objections at Mars settlement to make the whole thing seem doubtful” things. And Slarty1080 succeeded, we were sidetracked successfully with concern trolling about a problem that might not even BE a problem. An ugly solution exists even to worst-case assumptions, we can doubtless do far better, let’s go back to the actual freaking topic.

I don't read that as Slarty's intention at all, it's a very reasonable concern and an area of active study.

[whitelancer64]

The REALLY frustrating thing about responding to off topic concern trolls is that if you don’t respond, people think their objections are valid, and if you DO respond with a solution to even their worst case assumptions, you’ve unwittingly gave the impression that such unscientific worst case assumptions are actually likely to be true, which they most certainly are not (many people struggle immensely with understanding hypotheticals). So let’s focus on radiation, and report other directions as off-topic.

If you responded with information rather than just handwaving the concern away, then whining about it and calling people trolls, it would be a more productive conversation.

[ccdengr]

There have been some studies of mice in partial g (using the rodent habitat in a centrifuge on the ISS) that are promising...

The most promising one I found was "Lunar gravity prevents skeletal muscle atrophy but not myofiber type shift in mice" https://www.nature.com/articles/s42003-023-04769-3 and that says "that gravity greater than 1/6 g might be required to prevent slow-to-fast myofiber type transition" but AFAIK they haven't done any testing for levels between 1/6g and 1g.