tag:blogger.com,1999:blog-28823501.post8245005562983521927..comments2023-06-19T23:26:32.126+10:00Comments on QuantumG's Blog: The Radiation Exposure Numbers GameQuantumGhttp://www.blogger.com/profile/17336493213317053535noreply@blogger.comBlogger4125tag:blogger.com,1999:blog-28823501.post-85187777723717567642010-11-28T11:56:56.422+10:002010-11-28T11:56:56.422+10:00Quant,
One thing that you missed on the return tri...Quant,<br />One thing that you missed on the return trip is that it is likely to take much longer than even 8 months, baring nuke engines. As such, this is one more reason why ppl need to be sent on one-way missions. It is safer to stay on mars for multiple decades than to do the return trip.windbournehttps://www.blogger.com/profile/02174518869761480529noreply@blogger.comtag:blogger.com,1999:blog-28823501.post-28767134831320836272010-05-31T23:27:04.073+10:002010-05-31T23:27:04.073+10:00Clark, there's been a whole lot of studies of ...Clark, there's been a whole lot of studies of using propellant as shielding, including some that say aerobraking is human Mars missions make no sense because the mass you save from fuel has to go into shielding.<br /><br />LupusSolus, and your evidence for this wild claim is? The established medical evidence is that, although non-solar-flare radiation levels has only a minor effect on loss of mission, the statistical cancer risk to crew is beyond the acceptable levels for astronauts - who are already 5x above the acceptable levels for other government radiation workers. This is published in the medical literature, if you want to refute it you have to be able to point to overwhelming contradictory studies.QuantumGhttps://www.blogger.com/profile/17336493213317053535noreply@blogger.comtag:blogger.com,1999:blog-28823501.post-77761406613248724502010-05-31T10:11:38.111+10:002010-05-31T10:11:38.111+10:00As for radiation, the whole thing about the radiat...As for radiation, the whole thing about the radiation exposure is way out of line. News reports in the past have misrepresented the risk, stating that it might prevent human missions to Mars. However, it could be easily managed with current technology and is within tolerable limits. An astronaut in a six-month journey to Mars, the time required with conventional propulsion, would be exposed to about 0.3 sieverts, or 0.6 on a round-trip. Eighteen months on the surface (if it takes so long to get there, you might as well stay awhile!) would bring another 0.4 sieverts, for a total exposure of 1 sievert. Limits set by NASA vary with age and gender but range from 1 to 3 sieverts.<br /><br />The danger lies in an unexpected intense solar flare but there are "good enuff" ways to add in the protection needed. One way to add more protection spacefarers aboard a Mars transport ship might be to surround them with the water they'd need for their journey or hydrogen used for fuel. The hydrogen in water, scientists have learned, is one of the best absorbers of particle radiation. And, of course, the "better" way to lower the dose received would with shielding technology such as a simple magnetic plasma bubble that NASA has been testing for years. This alone would protect the astronauts from most radiation on its trip to Mars. Add a radiation compartment completely surrounded by water or hydrogen as mention above to stop the fast and slow solar neutrons then you would have a very, very safe journey.Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-28823501.post-39968265682167844322010-05-31T04:45:26.417+10:002010-05-31T04:45:26.417+10:00As best that I can tell, most estimates of deep sp...As best that I can tell, most estimates of deep space exposure start from the assumption that the habitat module will follow the same basic structural design of an Apollo capsule or ISS module. That is, aluminum outer walls followed by layers of insulation, micrometeorite shielding, etc. It would be interesting to see how low the exposures could be made if habitats were designed with exposure minimization as the top priority from the start (within roughly the same total mass).<br /><br />For example, one would arrange water and fuel tanks, food stuff storage, and all other hydrogen rich and low atomic mass materials to surround the living quarters or areas where the most time is spent (just doing this around the sleeping quarters could reduce the exposure considerably for 1/3 of a crew-members time.) Also, using Bigelow style inflatable modules would eliminate the metal in the walls and thus reduce secondary production. I suspect that even cumulative GRC doses could be lowered significantly with such measures.<br /><br />I'll also note that in the long term, a Mars cycler type of transport, like that championed by Buzz, could have its shielding mass increased to an arbitrary level over time since it is in a stable orbit and doesn't need fuel except for occasional orbital corrections. Each vehicle that makes a rendezvous with it can leave behind some mass for shielding.Clarkhttp://www.spacetransportnews.comnoreply@blogger.com