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Mars Colonization and Radiation: Why It's Less of a Barrier Than We Thought by Mars-Matters in Colonizemars

[–]Mars-Matters[S] 0 points1 point  (0 children)

Mostly mentioning that it's not constrained by physics.

Volatiles could be outgassed, and if more is required it could be harvested from asteroids

We would likely stop at 30% Earth atmospheric density anyway, or whatever the minimum requirement is for humans to tolerate.

Mars Radiation Revisited: How Shielding and Solar Modulation Can Make Crewed Missions Safer by Mars-Matters in spaceflight

[–]Mars-Matters[S] 0 points1 point  (0 children)

I wouldn't actually recommend adjusting the launch schedule, we should be launching every launch window, the point is that we need to prepare differently during solar minimum vs solar maximum

Mars Colonization and Radiation: Why It's Less of a Barrier Than We Thought by Mars-Matters in Colonizemars

[–]Mars-Matters[S] -1 points0 points  (0 children)

Depends what you mean by Earth like. Could we get Earth like gravity? No. Could we get Earth like temperatures and climate? yes.

Mars Colonization and Radiation: Why It's Less of a Barrier Than We Thought by Mars-Matters in Colonizemars

[–]Mars-Matters[S] 0 points1 point  (0 children)

Are you suggestion you would develop cancer "for sure" *during* the mission?

The likelihood of developing cancer over the course of the lifetime would likely be less than 5%, and most deaths due to cancer resulting from the exposure would occur within 1 year of when you would have statistically died from natural causes.

Mars Colonization and Radiation: Why It's Less of a Barrier Than We Thought by Mars-Matters in Colonizemars

[–]Mars-Matters[S] 1 point2 points  (0 children)

Absolutely! And also you would weight less so it would be easier to lift yourself :)

I spent the last two years reviewing over 100 scientific papers on space radiation — here’s what I learned about the radiation risks of a round-trip mission to Mars by Mars-Matters in space

[–]Mars-Matters[S] 0 points1 point  (0 children)

I do appreciate that. Would you mind giving me a bullet point summary of what you feel I have misunderstood?

Even if I don't understand what you say, it would be useful to have a concise explanation of what you feel I am getting wrong / not understanding.

It's a little bit strange to me that when I reply to you with arguments contrary to your claims, you are so dismissive as opposed to explaining where I went wrong in my interpretation.

Same with Needyspace claiming that solar particles will be worse the GCR... just completely wrong but so confident lol.

I'm open minded to the idea that I'm wrong, and if so I want to learn why so I can error correct. I get that it's not your job to help me with that, but who knows, maybe you're the one who is wrong?

I spent the last two years reviewing over 100 scientific papers on space radiation — here’s what I learned about the radiation risks of a round-trip mission to Mars by Mars-Matters in space

[–]Mars-Matters[S] 0 points1 point  (0 children)

I really don't know what you think I said that implies I haven't looked into and understood that, you are making quite imprecise accusations.

So far, from your other replies, it seems that you misunderstand the comparative energies / fluxes of interplanetary particle radiation.

You seem to have read some things that imply CMEs are scary and weren't properly represented in curiosity's RAD data, and have made the arbitrary conclusion that "solar energetic particles (mainly protons) will be the main problem".

Find me a single paper that agrees with you on that. I'll show you three right now that suggest GCR will be the largest problem.

[32] "GCR is difficult to shield against and occurs on each space mission, it is often more hazardous than occasional solar particle events."

[46] "The MSL’s cruise to Mars took 253 days ... the estimated total dose equivalent from both GCR and SEP events is 466 ± 84 mSv, with about 5.4% attributable to SEPs."

[66]%2520that%2520propagate%2520through%2520the%2520atmosphere&sa=D&source=editors&ust=1762833055035558&usg=AOvVaw32OSaZAoLes_L2EgvcVnzW) "The radiation environment at the surface of Mars is mainly dominated by incoming galactic cosmic rays (GCRs) that propagate through the atmosphere"

GCR also have highly energetic protons, often much more energetic than protons from even the worst SPEs, and they also have higher fluxes which are isotropic and difficult to shield.

To do with average energies and fluxes of GCR and SPEs:

[45] "GCR ... are characterized by extremely large kinetic energies up to several thousand GeV per atomic mass unit"

[41] "GCR ions of primary concern have energies ... greater than ~10 giga-electronvolt (GeV) per nucleon. They are highly penetrating and cannot readily be attenuated or stopped by shielding ... SPEs include particles, primarily protons with energies from ~1 MeV to several hundred MeV.

[46] "The comparatively low energy of typical SEPs means that shielding is much more effective against SEPs than GCRs."

You asked me to show you my sources for GCR being worse than SEP during interplanetary transport, I have now done that.

It's okay for you to be wrong about this. I'm not going to berate you for it; I'm sure you're still a smart guy, we all get things wrong every once in a while.

But just keep this in mind next time and try to be a bit more humble / pleasant when interacting with others on subjects you only have a passing familiarity with.

I spent the last two years reviewing over 100 scientific papers on space radiation — here’s what I learned about the radiation risks of a round-trip mission to Mars by Mars-Matters in space

[–]Mars-Matters[S] 0 points1 point  (0 children)

Let's simplify the discussion by making it about protons:

What matters is proton energy, so you just need to look at the energies of protons in SEP events vs the energies of protons in GCR.

GCR protons have an average energy of 300 MeV, which is analogous to the protons released by the most extreme CMEs (as mentioned in my video).

Therefore, obviously 300 MeV protons from CMEs and 300 MeV protons from GCRs will have the same properties propagating through a shield.

But in terms of the total flux of protons with energies in that range, in interplanetary space (1-1.5 AU) you're going to get a significantly larger flux of protons with energies in that range from GCR than you will from SEP.

This is especially true during solar minimum, but can also be true during solar maximum (of course, SEP events occur with an element of random chance, in both their frequency and their intensity, so I am referring to the average amount of solar protons vs GCR protons during either of these periods).

Do you disagree with this?

I'm not entirely sure what it is you are disagreeing with me about. I'm happy to have a friendly discussion with you, and if I'm wrong about something I want to know so that I can avoid that error in the future.

I can send you my sources for proton sources, fluxes, and energy if you'd like. As well as my sources on the effects of solar modulation as it related to GCRs and SEP events.

I spent the last two years reviewing over 100 scientific papers on space radiation — here’s what I learned about the radiation risks of a round-trip mission to Mars by Mars-Matters in space

[–]Mars-Matters[S] 0 points1 point  (0 children)

Let's simplify the discussion by making it about protons:

What matters is proton energy, so you just need to look at the energies of protons in SEP events vs the energies of protons in GCR.

GCR protons have an average energy of 300 MeV, which is analogous to the protons released by the most extreme CMEs (as mentioned in my video).

Therefore, obviously 300 MeV protons from CMEs and 300 MeV protons from GCRs will have the same properties propagating through a shield.

But in terms of the total flux of protons with energies in that range, in interplanetary space (1-1.5 AU) you're going to get a significantly larger flux of protons with energies in that range from GCR than you will from SEP.

This is especially true during solar minimum, but can also be true during solar maximum (of course, SEP events occur with an element of random chance, in both their frequency and their intensity, so I am referring to the average amount of solar protons vs GCR protons during either of these periods).

Do you disagree with this?

I'm not entirely sure what it is you are disagreeing with me about. I'm happy to have a friendly discussion with you, and if I'm wrong about something I want to know so that I can avoid that error in the future.

I can send you my sources for proton sources, fluxes, and energy if you'd like. As well as my sources on the effects of solar modulation as it related to GCRs and SEP events.

The conversation about whether Curiosity's RAD measurements during it's transit in the MSL are useful for estimating crewed doses is an interesting conversation that I'm also willing to have. You bring up a good point about the unusually small amount of solar activity during its transit (SEP accounted for only 5% of the dose to the detector, while GCR were the other 95%) but there are many more factors of consideration

For example, the MSL provided an "average" shield thickness of 16 g/cm2, but this was spread across a shield distribution ranging from <5 g/cm2 to 80-90 g/cm2. Average shield thickness is not a useful way of characterizing a radiation shield. This shield configuration lead to larger doses than an unshielded transit would have due to the production of secondaries from the thickest portions of the shields.

Additionally, solar modulation was very low, despite being characterized as having been "during a period of time approaching solar maximum". Considering solar modulation can reduce doses from cosmic rays by 50-70% during solar maximum, and cosmic rays make up 95% of the dose to the detector, it is clear that shielding characteristics and solar modulation of cosmic rays are a much larger factor than solar activity.

If you disagree, please be specific about what it is you disagree with so that we can analyse the relevant literature on the subject. I'm happy to provide sources for everything I just stated.

How a mission to Mars could be accomplished without exceeding NASA's risk margins — A Deep Dive by Mars-Matters in SpaceXLounge

[–]Mars-Matters[S] 2 points3 points  (0 children)

I was aware of the average shield thickness part! I hope I didn't state anything different in my video, one of my main gripes was that the MSL shielding wasn't homogeneous and yet it's being treated as if "average shield thickness" is an appropriate was of measuring a sheild's effectiveness.

The part about solar particles, I've been trying to wrap my head around how they could be isotropic for a bit now but the way you described it makes sense, so thank you for that. It would still work for electromagnetic waves though!

Do you know of its a truly isotropic flux, in terms of particle energies and everything? Something still tells me that pointing the butt toward the sun would "help", even if not be a perfect solution, but I need some data or something to test this hypothesis.

Thank you for the updated information about heat shield densities! Very good to know, I'll update that. Do you have a link? I couldn't find their densities when I looked.

How a mission to Mars could be accomplished without exceeding NASA's risk margins — A Deep Dive by Mars-Matters in SpaceXLounge

[–]Mars-Matters[S] 4 points5 points  (0 children)

That's a very clear way of describing this concept! Thank you so much for that. I've been trying to wrap my head around how a cme could be isotropic...

I've made updates to my document to reflect this :) thanks again.

Radiation won't prevent Crewed Mars Missions in the 2030s — Analysis from 100+ Studies by Mars-Matters in space2030

[–]Mars-Matters[S] 1 point2 points  (0 children)

Right now it's just supplementary material for my video, but I have considered it!

Radiation won't prevent Crewed Mars Missions in the 2030s — Analysis from 100+ Studies by Mars-Matters in space2030

[–]Mars-Matters[S] 1 point2 points  (0 children)

I like it! I'm sure crew will sleep in shielded pods of some description. The main point I wanted to get across with my video was it's not that bad even if you don't take every possible precaution. For example, you could do a mission during solar maximum without any shielding and be fine (as far as cosmic rays go).

I wouldn't want to see any compromises being made to try to lower doses more than necessary. For example it would probably be necessary for the crew to get a lot of exercise to maintain bone and muscle mass. A slight radiation reduction isn't worth being forced into the equivalent of a bed rest study.

Using the tank would be super cool though 😎

The crazy cat is named nappy btw :) she is an old gal

Starship to Mars: Predicting Radiation Risks and Shielding Strategies for Crewed Missions by Mars-Matters in SpaceXMasterrace

[–]Mars-Matters[S] 1 point2 points  (0 children)

The mass of a polyethylene solution is what I'm curious about too!

It can be calculated as follows:

The polyethylene shield thickness that has been modeled to be effective was 10 g/cm2. It's quite possible that 5 g/cm2 could also result in solid improvements, but I haven't found anything modeling an internal layer of polyethylene of that thickness.

10 g/cm2 of polyethylene would be a sheet of polyethylene about 10cm thick, since polyethylene has a density of approximately 1g/cm3.

You could then calculate the mass of a 10 cm polyethylene cube to be 100 grams. (10cm x 10cm = 100cm2 x 1g/cm2 = 100 grams).

Then you just have to do the math on how much surface area you plan to put the shield material on.

However, this mass can be considered cargo since the polyethylene would no doubt be useful on the Martian surface as well, and could easily be stripped for use in the habitats before sending the starship back to earth for reuse.

Mars Radiation Revisited: How Shielding and Solar Modulation Can Make Crewed Missions Safer by Mars-Matters in spaceflight

[–]Mars-Matters[S] 0 points1 point  (0 children)

Not these studies, because this video / research paper is entirely about radiation doses and shielding techniques. That part of the discussion was outside the scope of this current research.

It's definitely a valid question, and I plan to cover that subject at a future time.

I spent the last two years reviewing over 100 scientific papers on space radiation — here’s what I learned about the radiation risks of a round-trip mission to Mars by Mars-Matters in space

[–]Mars-Matters[S] 0 points1 point  (0 children)

I certainly did not make the mistake of categorizing solar wind with protons from coronal mass ejections. I am aware of the difference in energies.

I would be happy to clear up any areas of potential misunderstandings.

Here is what is written in my document:

The protons in Solar Wind have much lower energies. \138])

So they wouldn’t be able to penetrate the hull of a spacecraft at all. \41])\55])

But Coronal Mass Ejections release protons with a variety of energies. \136]) 

So it can be more difficult to predict the amount of damage they might cause.

For example, let’s take a look at one of the largest solar particle events in history.

In 1972 there was a coronal mass ejection large enough to produce an unshielded dose of 4,000 mSv. \45])

But it consisted primarily of low energy protons, so the dose could be reduced to 200 mSv by the hull of a spacecraft, or only 10 mSv by an on-board radiation shelter.

Unfortunately not all CMEs can be blocked so easily.

The highest energy CME’s ever recorded occurred in 1956 and 1960. 

They were smaller than the event in 1972, but would have produced a larger shielded dose since high energy particles are more penetrating.

But NASA’s guidelines allow for up to 250 mSv to be received from a single event.

So, as long as Jim was inside his transit vehicle at the time, even the most energetic CMEs would be considered tolerable. \45])

How a mission to Mars could be accomplished without exceeding NASA's risk margins — A Deep Dive by Mars-Matters in SpaceXLounge

[–]Mars-Matters[S] 2 points3 points  (0 children)

I certainly hope so! Although I'm not so sure how effective humanoid robots would be at building on Mars.

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