L. Spiro, congratulations on making the cut. Whether the mission succeeds or fails, lifts off on schedule or is permanently grounded, there's a lot to be learned for future missions and your being involved at all in this stage is pretty cool.

I have a few questions.

What's the longest period of time where you've been confined to the office with your team in a so-called "crunch-time" scenario? Have your experiences been more like "grace under pressure" or "skin of your teeth"?. Assuming that the pressure of daily work on Mars compares to the intensity of a "crunch", and assuming that it more or less never ends, do you foresee significant long term complications with co-workers on Mars? How do you think that being unable to escape from each other might factor into the situation?

I was wondering if you've had any experience living in a small community but since you've mentioned living on a farm in Kansas, I assume that the answer is yes. Knowing how interconnected people's lives can be in small communities and how much people like to involve themselves in the lives of others (it's like they have nothing better to do or something), are you expecting a significant change in lifestyle or does your current life in Tokyo already exhibit characteristics of small community life?

Wait, you are worried about a slightly elevated risk of developing colon cancer some 20 or 30 years in the future when you're more likely to die from radiation even before you reach Mars?

You are probably aware that you are subject to roughly 1000 times the radiation dose as on Earth while in the shuttle/rocket/spaceship, assuming mother Sun isn't being premenstrual (in which case you're out of luck). And of course assuming you need not get outside in a spacesuit to do repairs, in which case the dose will be yet 3-4 times higher.

That doesn't look to you like it's more of a problem than nutrition effects on colon cancer?

You're probably also aware of the article by Zeitlin in Science last spring (also picked up by the public press some days later) which basically says that it's not that much different on Mars either. You'll have radiation doses that are hundreds of times those on Earth. Which, frankly, isn't all that much of a surprise seeing how it has no magnetosphere and an atmosphere that is at best comparable to Earth's atmosphere in an altitude of somewhat like 30km.

So basically you have a radiation comparable to 3-4 times the radiation you have in an airplane, except you don't have it for 3-4 hours twice or so per year, but all the time, day and night, every day.

Well, what I'm saying is that constant high radiation isn't precisely something to be taken lightly. Put differently, I wouldn't plan for 10-20 years on Mars. It may be the biggest adventure of your life, and the biggest, most fun trip, but it may also be much shorter than anticipated -- even if nothing serious like a crash happens.

Travelling in an airplane (which is also known for having higher radiation exposure) is no significant risk even if you do it for a living so you get 10-15 times the normal annual dose because the elevated radiation is only ever present intermittedly, for a limited time and there are rest periods in between where your body is able to repair the damaging effects. That is exactly how radio- or radio-chemotherapy works, by the way -- as long as you don't literally kill the human by poisoning him too much (or by completely suppressing leucocytes, infection, etc.), the normal tissue is able to recover from the damage during the rest period whereas the tumor isn't. At least that's how the theory goes, sometimes it doesn't work out quite so nicely -- but more often than not it does.

Permanent exposure, on the other hand, is a totally different beast. No rest period, no recovery.

Radiation is an ultra complicated topic which one can't easily assess, since there are not only many different kinds of radiation which vary greatly in what they do to machines and men, but also many effects that aren't easy to overlook and some effects that are counter-intuitive. Most of the biological effects are not well understood either (or only "understood" in a meaning of guessing).

I doubt that anyone could really give an easy, conclusive answer on that topic. The fact that NASA says it's "problematic" should be enough, though.

Is it generally possible to shield from cosmic radiation? Sure, our planet proves that it's possible, it does a mighty fine job at it. The more important question is what shielding costs and how practical it is. If you wrap a spaceship in a one-foot thick lead mantle, I'm sure there's not much going through, but the weight would be quite forbidding. An extremely strong magnetic field might do the job as well, but where would the necessary energy come from (and, what are the health effects of such a strong magnetic field)?

Also, the obvious is not always the correct thing with radiation.

For example, shielding may help against radiation, or it may create different, and more harmful radiation. As may pretty much any "solid" matter that comes in contact with some kinds of radiation. It is entirely possible that you inadvertedly kill your crew by adding the wrong kind of "shielding", and since much of our knowledge on biological effects of radiation is guesswork, you can never be certain.

This makes me remember a technical assistent back in the days when I was studying. He used to be standing next to the linac and laugh at me, the stupid guy from university who didn't know that radiation goes in a straight path and doesn't go around corners. So as long as you're not standing in the ray, there's no risk. No need to hide in the next room. And yeah, only pussies wear dosimeters anyway. Needless to say that he wouldn't bother to leave the x-ray room either, because hey, rays don't go around corners.

The day he became ill, he learned about secondary radiation. Which, of course, doesn't go around corners either, but it's going diffuse in every direction, including yours. (To be honest, I wouldn't know for sure if that's really what he learned as I never found out what "sudden grave illness" he had, but I think it's a fair guess).

To give another example of how easily one can be mislead with "radiation stuff", beta radiation and even more so alpha radiation is "entirely harmless" because it cannot even get through the callus of your skin (or is absorbed in air). However, at second look, beta radiation creates brake radiation upon hitting solid matter which will penetrate your skin, and an alpha radiator that is ingested is many times more harmful than e.g. a gamma radiator of similar dose (probably around 20 times). That's the idea behind the "equivalent dose" figure, which is more a guesstimate than a real science. Nobody knows for real how much more dangerous one is compared to the other.

Technical issues apart, another important question is how much money would an organization with limited funds who is running a TV show put into into radiation shielding? Regardless of what is feasible, and regardless of what they actually could afford.

It's not the makers of the show who are exposed to the radiation, so there is no urgent motive to make it the best possible. It's a reality TV show that goes for a decade, including training and all. As long as the candidates survive long enough to reach Mars and live for a year or so, it's all good. The reality show probably won't go for much longer anyway -- who watches a 10-year old show that is the same every day.

On the other hand, with the number of viewers decreasing over the years, a few dramatic deaths might be very beneficial. It might bring up quotes and might lend for more funding to include better protection for the second (or third) crew. Oh the poor heroes. We will never forget their sacrifice.

Seriously. You need not assume that people who have a strong financial interest necessarily have the same interests as you have. Especially if you're in a position where you can't complain. They give a fuck whether you die from radiation or not, as long as it attracts spectators.