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Comment Re:This study is garbage (Score 1) 186

I think you are confusing the very rare very energetic cosmic rays with the constant background of low energy cosmic rays you have in space. Nobody cares about the first kind, because they are so rare, the second is what worries people planning manned missions. Both are very tough to shield against, anyway.

And their radiation source is not similar to either kind. They just used some very radioactive isotopes to expose the rats to a nice bath of gamma rays and alpha particles for a few seconds. This is much less energetic than the cosmic rays of the first kind, but much more energetic than the cosmic rays of the second kind.

Comment Re:radiation is the big stumbling block (Score 2) 186

I said that The Real Dr John specifically was overestimating the danger. He said "until they figure out how to fully shield the spacecraft, this is not practical for humans". And I really don't agree that "~5% increase in death rate" equals "not practical for humans". You have to put things in perspective: just the launch itself has a ~5% probability of killing the astronauts, so while a further 5% increase in the death rate is certainly not welcome, it is one additional danger of an already quite dangerous task. I think you'll find very few astronauts that refuse to take this risk.

That said, of course we need to reduce the radiation exposure as much as we can, because having astronauts who are dead, or with cancer, or with cataracts, or stupid, or with lung problems, or with heart disease is clearly not desirable. Going for extra shielding, as The Real Dr John suggested, is a terrible idea. You need a crazy amount of shielding, on the order of 100 g/cm, to significantly reduce the exposure, so waiting for that to happen is to wait forever. So I think the only plausible solution in the near term is to go fast.

In this respect I find Musk's proposal quite reasonable. He intends to do the trip in 90 days, and rotate the spacecraft to use to fuel tank as a shield during solar flares. NASA calculates that 5% from the 330 mSv in the trip would come from solar flares, so cutting that out and using the shorter trip time already reduces your pessimistic 1070 mSv to 650 mSv, so about 325 mSv per year, already well below the recommended level you quote.

Comment Re:This study is garbage (Score 1) 186

I'm not going to look for their bios, the onus of proof is on you. I have checked the affiliations listed in the paper, and they are oncologists from the University of California. But this doesn't matter at all, as the radiation dose used in the paper is not anything like the radiation from interplanetary space. This is a simple fact, that does not depend on whether the study was made by random potheads, oncologists, NASA scientists, or the second coming of Feynman himself. And you would know this if you would look at the paper itself, where they don't even claim that radiation is similar to what you would experience on a trip to Mars, but instead that they just subjected the rats to a short intense burst.

If you want me to speculate on why they studied the wrong kind of radiation, I can think of two reasons:
1 - It is hard to build a source of low-intensity radiation with similar characteristics to galactic cosmic rays and keep the rats exposed to it for six months.
2 - A given amount of radiation is much more damaging when delivered in a quick burst than when delivered slowly over a period of months. Therefore if they had done the study properly the effects would be much less dramatic, and the news wouldn't make it to the first page of Slashdot.

Comment Re:radiation is the big stumbling block (Score 1) 186

According to the comic I linked, the allowed dosis for radiation workers in 50 mSv, making the trip to Mars about 7 times it. But this dosis is set to a level that is certainly safe, it doesn't mean that higher than it is certainly unsafe, just that we go into a gray zone where we can't guarantee it's safe, but we do not know whether it is actually dangerous either.

According to this table you need to be subjected to 1000 mSv in a short burst to have a 5% chance of developing a fatal cancer, which would make the 330 mSv over six months seem rather safe. I would be happy, however, if you could find a better source with more detailed information.

Comment Re:This study is garbage (Score 1) 186

You are writing an ad hominen attack in response to a comment where I complain that Required Snark was not making any substantive criticism. Isn't the absurdity of this situation too much for you? How about you make, hummm, some... substantive criticism?

But to not leave you completely without response, what makes you think that the researchers who did this study are "NASA people" who "have been in space"? And if I were to take their study seriously, being in space leads to cognitive impairment, so people who have been to space would be more likely to get the key concept in their study wrong.

Comment This study is garbage (Score 5, Interesting) 186

They didn't expose the rats to anything similar to the radiation an astronaut would be subjected to in their travel to Mars: they fried the rats with a short, intense radiation dose, while the astronauts would be exposed to a low dose long term. In fact, in the study they don't even claim that this radiation is anything similar to what one would find in space, they just say it is "space relevant". So what they found out is only that if you fry rats with radiation it impairs their cognition, and this impairment is long-lasting.

Also, TFS says that Scientific Reports is a Nature journal. This is true, Nature the company (or more precisely Holtzbrinck Publishing Group) does own this journal, but it has nothing to do with the Nature journal, editorially or scientifically. This is just a lame attempt to bestow Nature's reputation on Scientific Reports, which is in fact a pretty crappy journal, that does not even try to select papers based on quality, but claims to check only for correctness.

Comment Re:Amazing the influence Tesla has had (Score 1) 296

I also live in the EU. And when I walk on the streets the electric cars I see are the Nissan Leaf, the Tesla Model S, and the BMW i3. In this order of popularity.

Clearly the Model S has been important and popular, but let's not pretend there are no other companies producing serious electric cars that people actually want to buy. Or that it was even the first model to become mainstream. That honour clearly belongs to the Nissan Leaf.

Comment Re:Selective breeding (Score 1) 290

Stop anthropomorphizing Nature. She hates it. But seriously, there is no intention in evolution, even if it were advantageous to the species as a whole to die young (which I doubt), it doesn't imply that humans would evolve this "mortality" trait. You need a clear mechanism, that works through inheritance and mutation.

I find it much more plausible that some particular mutations are advantageous before breeding age but deleterious after breeding age, like for example some improvement in memory that leads to brain damage in the long term. Any such mutation would be selected for, with a small counter-effect from older people looking after children and thus improving the chances their genes remain in the gene pool.

I'm interested in the fruit fly experiment, though. Could you please provide a citation? Maybe instead of doing selective breeding on humans we could just find out which gene makes them live longer and then hack it into our DNA =)

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