Total Members Voted: 178
Quote from: Robotbeat on 12/13/2014 01:23 amRadiation isn't THAT bad for you, anyway. Between launch from Earth, entry to Mars, launch from Mars and reentry at Earth, you're more likely to die at those points than from cancer (near the end of your natural life) from GCR radiation on the transit. I think this is way overstated. Smokers have a far greater cancer risk.Exactly. And consider early exploration on Earth with exposure to new tropical diseases etc... this is significantly safer.Quote from: gbaikie on 12/13/2014 01:30 amQuote from: Robotbeat on 12/13/2014 01:23 amRadiation isn't THAT bad for you, anyway. Between launch from Earth, entry to Mars, launch from Mars and reentry at Earth, you're more likely to die at those points than from cancer (near the end of your natural life) from GCR radiation on the transit. I think this is way overstated. Smokers have a far greater cancer risk.In engineering one builds in safety margins. And I don't think NASA should require that the crew smoke cigarettes.And it's matter of crew morale. And of course, most importantly, it's a political and PR matter.I strongly doubt that it's an issue of crew morale, or if it is, then there is something wrong with the crew selection process. The risk is just not that big -- and there are plenty of people who would be willing to accept much bigger risks to get to Mars.
Radiation isn't THAT bad for you, anyway. Between launch from Earth, entry to Mars, launch from Mars and reentry at Earth, you're more likely to die at those points than from cancer (near the end of your natural life) from GCR radiation on the transit. I think this is way overstated. Smokers have a far greater cancer risk.
Quote from: Robotbeat on 12/13/2014 01:23 amRadiation isn't THAT bad for you, anyway. Between launch from Earth, entry to Mars, launch from Mars and reentry at Earth, you're more likely to die at those points than from cancer (near the end of your natural life) from GCR radiation on the transit. I think this is way overstated. Smokers have a far greater cancer risk.In engineering one builds in safety margins. And I don't think NASA should require that the crew smoke cigarettes.And it's matter of crew morale. And of course, most importantly, it's a political and PR matter.
The number 700 mSievert/year comes from observations of populations in Ramsar, Iran, and has been proposed as a safe dose limit for continuous exposure. http://www.ncbi.nlm.nih.gov/pubmed/11769138/
I am still not convinced that any special GCR mitigation is needed. The risks do not seem to me out of line with what is traditionally accepted for exploration. If we had regular business travel to Mars, sure, but for the early expeditions there will be much bigger things to worry about.
A decade-long experiment using a human-like mannequin to assess radiation absorption inside and outside the international space station has concluded that the human body is much better at protecting astronaut internal organs than previously thought.The experiments, which used U.S. technology monitored by U.S., Russian, Japanese and European teams, conclude that previous radiation-intake measures, mainly dosimeters worn by astronauts in their pockets or on their chests, overstate the radiation exposure to internal organs.For an astronaut working inside the space station, the overestimate was about 15 percent — a fairly close correlation given that the station’s exterior shell provides much of the protection needed.But for astronauts working outside the station, the radiation absorption measured was substantially less than what had been registered by the personal dosimeters worn by astronauts.“Measurements of a personal dosimeter dramatically overstate the exposure of an astronaut, in the worst case by a factor of three,” according to a summary of the results by a Euro-Russian team. “(I)n an outside exposure the self-shielding of the human body is very effective. … (T)he effective dose equivalent is less than 30 percent higher than in an inside exposure.”
one would think that its would be best to send some mice to Mars and see if they make the trip. We can only measure what we know is out there beyond the earth moon system .
Of course the mice will survive the GCR. Heck, lab rats are so riddled with cancer, it might help them!
Being this risk-averse prevents any progress from being made.
Would you go to Mars if the figure was a 99% chance of being diagnosed with some type of cancer, between 5 years and 15 years after the conclusion of your mission?Now - Do you think in 300 million people we could find a substantial fraction who would answer 'yes' ?It's an often treatable illness that usually kills slowly, which we could easily direct inordinate amounts of money towards detecting and treating, for the money saved reducing mission cost.The numbers on water shielding are *horrible* for small missions - last time I ran the figures extrapolated from a shielding paper, I ended up at IIRC 800kg/m^2 water shielding (80cm thickness) to cut radiation by ~99%. Being this risk-averse prevents any progress from being made. It's only for larger habitats, and in particular Aldrin cyclers, that tons of shielding makes sense. If you're shipping hundreds of humans to Mars per habitat, you get to spend very reasonable amounts of mass per passenger making radiation go away: A hypothetical Bigelow BA-50,000 only costs 6000 tons of water at this standard, while a BA-330 need a little under 1 ton of water per cubic meter of volume.Using propellant as shielding works out fairly well for the first half of the mission, if you configure it right and spend some resources on thermal subsystems.
The supplemental healthcare checkups associated with being an astronaut will improve these peoples' health relative to the general population - it more than makes up for the slight change in lifetime cancer risk.
Quote from: Burninate on 12/15/2014 07:35 pmThe supplemental healthcare checkups associated with being an astronaut will improve these peoples' health relative to the general population - it more than makes up for the slight change in lifetime cancer risk.I don't think NASA wants to risk getting sued or ruining its P.R. Secondly, the researchers behind life sciences want their money as does every other department and company, which is the real reason why we haven't had a Mars mission...Regarding any radiation, I believe Mars (or even the Moon) is worth the risk, and might be easier to mitigate than expected.
Quote from: redliox on 12/15/2014 07:51 pmQuote from: Burninate on 12/15/2014 07:35 pmThe supplemental healthcare checkups associated with being an astronaut will improve these peoples' health relative to the general population - it more than makes up for the slight change in lifetime cancer risk.I don't think NASA wants to risk getting sued or ruining its P.R. Secondly, the researchers behind life sciences want their money as does every other department and company, which is the real reason why we haven't had a Mars mission...Regarding any radiation, I believe Mars (or even the Moon) is worth the risk, and might be easier to mitigate than expected.Why does NASA, which is a public agency (with sovereign immunity) charged with doing things that are canonically difficult, dangerous, pioneering things, using volunteers extremely well-informed about those risks, fear a lawsuit and PR more than a private airline, for several orders of magnitude less risk?Things like 3rd-order and 4th-order backup systems for every last device earn more risk_diminished : mass ratio points to design into a small spacecraft than craft-wide radiation shielding.
Quote from: redliox on 12/15/2014 07:51 pmQuote from: Burninate on 12/15/2014 07:35 pmThe supplemental healthcare checkups associated with being an astronaut will improve these peoples' health relative to the general population - it more than makes up for the slight change in lifetime cancer risk.I don't think NASA wants to risk getting sued or ruining its P.R. Secondly, the researchers behind life sciences want their money as does every other department and company, which is the real reason why we haven't had a Mars mission...Regarding any radiation, I believe Mars (or even the Moon) is worth the risk, and might be easier to mitigate than expected.Why does NASA, which is a public agency (with sovereign immunity) charged with doing things that are canonically difficult, dangerous, pioneering things, using volunteers extremely well-informed about those risks, fear a lawsuit and PR more than a private airline, for several orders of magnitude less risk?...
Quote from: Burninate on 12/15/2014 08:17 pmQuote from: redliox on 12/15/2014 07:51 pmQuote from: Burninate on 12/15/2014 07:35 pmThe supplemental healthcare checkups associated with being an astronaut will improve these peoples' health relative to the general population - it more than makes up for the slight change in lifetime cancer risk.I don't think NASA wants to risk getting sued or ruining its P.R. Secondly, the researchers behind life sciences want their money as does every other department and company, which is the real reason why we haven't had a Mars mission...Regarding any radiation, I believe Mars (or even the Moon) is worth the risk, and might be easier to mitigate than expected.Why does NASA, which is a public agency (with sovereign immunity) charged with doing things that are canonically difficult, dangerous, pioneering things, using volunteers extremely well-informed about those risks, fear a lawsuit and PR more than a private airline, for several orders of magnitude less risk?Things like 3rd-order and 4th-order backup systems for every last device earn more risk_diminished : mass ratio points to design into a small spacecraft than craft-wide radiation shielding.I would say it is because there is no precedent.They are doing everything they can to prevent a lawsuit that may never come...
Article today on http://spaceweather.com about cosmic rays and the movie The Martian. It references calculations by Ron Turner http://www.anser.org/docs/The_Radiation_Threat_to_the_Martian.pdf about potential radiation exposures to the characters in the movie.