[thelambentonion]

I would say that the leaders of the most powerful nations on Earth are a little more grounded in reality than Musk in this regard. Glass domes and underground Martian tunnels make for some very interesting science fiction, but I'm concerned about the engineering challenges that he seems to be ignoring in favor of his grand statements of intent.

To pick a specific example, he seems to have very little concern for radiation shielding both during the trip to Mars or on the Martian surface. Both of these present incredibly harsh radiation environments for humans, and we need to develop solutions before we even consider sending explorers, let alone colonists.

[Obi_Juan_Kenobi]

The glass domes would be for growing crops.

Most habitation would be underground (hence the mining drones) to reduce radiation exposure.

Overall radiation exposure would be higher, and life expectancy would take a hit, accordingly. This is a trade-off, not a non-starter. I too would like to see a bit more discussion of specifics, but I also don't see this as the Achilles' heel that many would make it.

[Gustomaximus]

> he seems to have very little concern for radiation shielding both during the trip to Mars or on the Martian surface.

I find it hard to believe his team have not considered something so obvious. This seems like one of those statements that assumed the experts are a bit stupid. Just because he hasn't specifically mentioned it doesn't mean it is not considered. And sure somethings are probably not considered, but something as obvious as this...

[thelambentonion]

> "The radiation thing is often brought up, but I think it’s not too big of a deal"

AFAIK no one else within the community would think of saying that.

I'm sure that there are people within SpaceX studying this and taking it into consideration, but my concern is mostly with Musk's cavalier attitude towards individual safety.

[1457389]

I don't think you have looked very hard then. Here's Zubrin on the topic:

>However, we already have data that shows that the accumulation of slow rates of cosmic ray radiation received during long duration spaceflight is not a showstopper for human Mars exploration. GCR dose rates in low Earth orbit are about half those in interplanetary space. Thus, there is a growing number of cosmonauts and astronauts who have already received Mars mission equivalent GCR doses during extended space missions without any radiological casualties.

~http://www.thespacereview.com/article/2749/1

He mentions in a recent speech that the most deleterious effect of time spent in space is related to zero gravity, not radiation - and that can be fixed with resistance training.

[wott]

You talk about a Mars exploration mission, hence a relatively short time duration, not about settling and living one's whole life on Mars.

[nickik]

How about one problem at the time. If we can actually go there with lots of stuff, stay for a long period and come back we will already have made more progress then most people thought possible.

We know most of the physics needed to deal with the situation, if we can get equipment to mars. Radiation is a problem, but its not Problem Nr. 1.

[greglindahl]

Let me get this straight:

1) You imagine what's going on in Elon's head 2) You complain about it on HN 3) You expect other people to care about your fantasy 4) ... 5) ???

There are multiple hard-to-solve problems involved in sending humans to Mars. Complaining that Elon didn't give sufficient weight to your favorite problem in his executive summary is not that interesting.

[elihu]

That's a good point, but it is relevant that Elon Musk isn't just a "scientist" or "expert" but a businessman positioning himself to sell a product.

I'm willing to give him the benefit of the doubt on this one and wait for more details, but at the same time I concede that it's not unreasonable to be wary of claims that the radiation problem "isn't a big deal" from someone planning to sell tickets to Mars. Not everyone has the same notion of what an acceptable risk is.

[elihu]

I'm not very knowledgeable of radiation hazards in space, but from some casual wikipedia browsing, it appears that the primary hazard is from protons (and various charged particles) being spewed out from the sun.

How practical is it to use an electrically charged or magnetic object between the sun and the spacecraft to deflect particles? Presumably, the farther away it is the less deflection would be necessary, but at some point it would be too far away to effectively mask the whole disk of the sun.

Similarly, you could just use a physical screen. Apparently, things like aluminum don't work very well as shielding because the undesirable particles react with the aluminum and produce more undesirable particles. However, if it were far enough away from the ship, it wouldn't need to block the radiation, it would only need to deflect most of it in a slightly different direction. (Whether the "screen" is on a long tether or whether it's a separate drone-spaceship would be an implementation detail that's not particularly important.)

I assume there's some reason this is impractical, otherwise it would be a solved problem already...

(As for shielding on Mars itself, I'm okay with the idea that humans will spend most of their time underground.)

[jfoutz]

Well, glass dome, water, glass dome is a really old idea that would work, if water is readily accessible.

something like 50 feet of water would also work for the trip, but water is heavy and you need a lot of it. maybe they can catch a comet, or pull it from the moon. I think there are answers, they're all really expensive answers though.

[nickik]

Thats not the reason. The reason is that the leaders of Earth have political constraints that does not allow them to do or change much. It has little to do with technical details.

Musk talks about it because he does not have those constraints.

As for radiation shielding, this has been a topic since the 60s. We know more or less what the risks are, we know the fundamental way to deal with the different type of radiation. The question is how to integrate it in your mission architecture.

He does not spend much talking about this because its not the fundamentally hardest problem that is to solve. The Core Problem to solve is the Transportation Problem. From what he has said about it, he proposed fundamentally the same basic ideas that people have been discussing for many years, and those should work.

[icebraining]

Yeah, the Mars One project talks about burying their habitat five meters underground to get the same protection as the Earth's atmosphere; glass domes seem downright reckless in comparison.

[ceejayoz]

You'd still need places to grow plants. The easiest way to do that is still glass domes, as you don't really care as much if plants get cancer.

[whatshisface]

All of our cereal crops are planted and harvested every year. They won't have time to accumulate the damage that we need to shield humans from. Also, plants seem to handle radiation very well - see the growth around Chernobyl[1].

(Note: The danger of eating Chernobyl's foliage is not that it has been irradiated, but that it has ingested radioactive material. That shouldn't happen with cosmic rays.)

[1]https://www.acs.org/content/acs/en/pressroom/presspacs/2010/...

[JumpCrisscross]

> The easiest way to do that is still glass domes

The prettiest way to do that are glass domes. The easiest is underground with glass cylinders piping down sunlight.

[icebraining]

Yes, but Elon Musk mentioned them as living spaces.

[ceejayoz]

Everyone's going to appreciate the opportunity to wander a green garden in a t-shirt. Do it at night and you're getting a lot less radiation, and I'll wager it'll be a hell of a sky too.

[Symmetry]

My impression was that once you're down on the surface of Mars the radiation that isn't blocked by the atmosphere is mostly cosmic rays which don't depend on day or night.

[Neeek]

Plants are living?

[icebraining]

So you're saying that beyond everything else Musk is also making contributions to the marketing of greenhouses? Because "living space" is always related to humans, as far as I can tell.

[Neeek]

Yes, thank you, my reply was tongue in cheek.

Though some other comments I think mentioned that it probably wouldn't be too dangerous to allow the occasional stroll through the greenery. Doesn't sound too far fetched if you consider I can choose to hang out at the park without a hat in exchange for an extra dose of UV radiation for the day. Not saying UV is on the same level as cosmic radiation, it's just something to think about :)

[annerajb]

I believe I recall talking about using water in the wall lining of the crewed area as shielding for radiation.

Also the radiation exposure during flight which would be the worse is equivalent to smoking for two years and dropping it. (I personally thought it was gonna be higher)

[thelambentonion]

> ...the radiation exposure during flight which would be the worse is equivalent to smoking for two years and dropping it...

Please provide a citation for this. As far as I'm aware, we simply have no idea the kinds of effects that radiation encountered during the flight would have on humans.

The sample size for human exposure to space-based radiation is incredibly small (limited to just the astronauts on the ISS, and even then that is protected by much of the Earth's magnetosphere).

[nickik]

Radiation has been studied since the 60s. Multiple Mars mission had the equipment on board to do the measurements. Nothing to surprising was measured, the same results on Curiosity and Viking.

We know a lot about both type of radiation, cosmic and solar. Why know the basic physics, and we know how to prevent it. Both types of radiation have different properties and have different levels of danger, thus need different solutions.

This had been known for a while and solutions are possible. Thus, its not the most important problem in Humans to Mars architecture, as we know much less about reusable rockets and carbon cryo tanks.