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Post by scooter on Dec 31, 2006 14:29:04 GMT -4
Turbonium, et al, You are aware that there were contingincies planned for solar events during Apollo, correct? Do you know what they were?
The Apollo missions were short out-and-back sorties. These contingincies were planned for the unlikely (statistically speaking) event of a solar eruption of some sort. The CM was not specifically designed to withstand a major event without these contingincies, maybe not even with employing them. The "relatively long duration" missions of the future need to plan for these events, as it is quite certain they will have to deal with them over the very long term of many months or years, unlike a couple of weeks for Apollo. For Apollo, the heavy exposure was unlikely, for the next missions, it's pretty well a done deal...so they need to build for it. It's called mission design.
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Post by Obviousman on Jan 1, 2007 22:00:48 GMT -4
I contacted some of the people who were responsible for producing the report Radiation Hazards to Crews of Interplanetary Missions to see if we can lay this to rest once and for all. They specifically referred me to SPACE RADIATION CANCER RISK PROJECTIONS FOR EXPLORATION MISSIONS: UNCERTAINTY REDUCTION AND MITIGATION (JAN 2001, JSC -29295). spaceflight.nasa.gov/shuttle/support/researching/radiation/marsrisk.pdf)Within that report, Figure 3 on Page 18 is Historical radiation doses as recorded on the personal dosimeter badges and estimates of the effective doses for astronauts from all NASA Missions (through December 1999). I can't reproduce that graph here (I'll see about making a image of it later) but it shows that the lowest doses were received by the Mercury / Gemini astronauts, middle doses were received by Shuttle / Apollo astronauts, and the highest doses received by the Skylab / Mir astronauts. Then there is Table 6 on Page 19, Average dose (D) or dose-rate recorded by dosimetry badge and estimates of the dose equivalent (H) to the BFO received by crews in NASA programs through 1999.MISSION...........INCLINATION (degrees)......ALTITUDE (km)........ DOSE (mSv/d) Mercury................... - .................................... - ........................ 0.55 Gemini ................... - ..................................... - ........................ 0.87 Apollo ..................... - ..................................... - ........................ 1.2 Skylab .................. 50 .................................. 430 .................... 1.4 ASTP ..................... 50 ................................. 220 .................... 0.26 STS ...................... 28.5 ................................ >400 .................... 2.1 STS ...................... 28.5 ................................ <400 .................... 0.18 STS .................... 39 - 40 ............................. ~ 400 ..................... 0.21 STS ........................ >50 ................................ >400 ..................... 1.1 STS ....................... >50 .................................. <400 .................... 0.45 NASA/MIR ............... 51.6 ................................ ~390 ..................... 0.84 Table 11 gives the fatal cancer risk projection for 40 year old males, assuming a 4g/cm^3 aluminium shielding. From that table: Lunar Base mission, 20 days duration (14 on lunar surface) 0.08% So on a 20 day lunar mission there is less than 0.1% of a 40 year old male developing a fatal cancer. If you wish to dispute these figures, I suggest you take it up with the authors... stating, of course, your qualifications.
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Post by turbonium on Jan 3, 2007 5:04:29 GMT -4
Turbonium, et al, You are aware that there were contingincies planned for solar events during Apollo, correct? Do you know what they were? The Apollo missions were short out-and-back sorties. These contingincies were planned for the unlikely (statistically speaking) event of a solar eruption of some sort. The CM was not specifically designed to withstand a major event without these contingincies, maybe not even with employing them. The "relatively long duration" missions of the future need to plan for these events, as it is quite certain they will have to deal with them over the very long term of many months or years, unlike a couple of weeks for Apollo. For Apollo, the heavy exposure was unlikely, for the next missions, it's pretty well a done deal...so they need to build for it. Yes, I've read about SPAN - Solar Particle Alert Network, among other things. The notion that the astronauts could have somehow "dodged" large solar flares through this so-called "warning system" is patently ridiculous. But the issue of radiation hazards to man goes well beyond this. Virtually everything about deep space radiation for manned missions is largely unknown in several aspects. And again, there is a complete lack of reference to any Apollo data, or even details about (what should be considered) extremely valuable and unique events - the only times humans have ever experienced deep space radiation first-hand. Even if future manned missions were only going to be much longer in duration than Apollo (which they aren't, at first), the data and experiences from them should still be considered invaluable. They don't even merit more than a single passing mention. That's very puzzling to me, and to simply dismiss it out of hand isn't treating the issue with the consideration it deserves.
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Post by Jason Thompson on Jan 3, 2007 5:40:44 GMT -4
The notion that the astronauts could have somehow "dodged" large solar flares through this so-called "warning system" is patently ridiculous.
It would be if that were ever the stated aim. They were contingencies to reduce the damage done by a major solar event in the event one happened during an Apollo mission. They were not guarantees of safety or a way of 'dodging' solar flares.
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Post by AstroSmurf on Jan 3, 2007 5:48:02 GMT -4
Let's face it, if there had been a major solar flare, they would have been lucky to survive long enough to get home. In all likelyhood, they would be dead from direct exposure and failing that develop cancer soon afterwards. Good thing this never happened, but the odds were on their side.
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Post by Obviousman on Jan 3, 2007 6:00:20 GMT -4
Part of the reply I got from one of the report panel members:
The Committee considered all sources of radations in Space. We concluded that Solar Particle Events (SPE) would be the major source of radiation exposures supplemented by the cosmic ray background composed of many types of particles including heavy nuclei. To the best of my knowledge, all space missions carry devices to measure the radiation doses. Astronauts should not be outside of a space craft if there were an SPE. They should be shielded inside the space craft. Hence, radiation exposures for Apollo missions would be very small. Hence, I believe that radiation exposures from Apollo missions were very small, unless astronauts stayed outside during an SPE about which they would have been informed.
So, once again, all evidence supports the Apollo missions being conducted as reported.
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Post by sts60 on Jan 3, 2007 10:40:55 GMT -4
Yes, I've read about SPAN - Solar Particle Alert Network, among other things. The notion that the astronauts could have somehow "dodged" large solar flares through this so-called "warning system" is patently ridiculous.
Not dodging in the sense of "getting out of the way". But there were contingency plans to abort EVAs, shelter in spacecraft, orient the CSM stack for maximum protection, etc. I think there was some idea of even adjusting the orbit to linger in the shadow of the Moon, but I'd have to check on that. The threat of a significant SPE was recognized and planned for.
But the issue of radiation hazards to man goes well beyond this. Virtually everything about deep space radiation for manned missions is largely unknown in several aspects.
I don't know about "largely". But there is a lot to be learned in order to adequately plan for long-duration missions, as well as to maximize safety for short-duration Apollo-style missions.
And again, there is a complete lack of reference to any Apollo data, or even details about (what should be considered) extremely valuable and unique events - the only times humans have ever experienced deep space radiation first-hand.
Even if future manned missions were only going to be much longer in duration than Apollo (which they aren't, at first), the data and experiences from them should still be considered invaluable.
They don't even merit more than a single passing mention. That's very puzzling to me, and to simply dismiss it out of hand isn't treating the issue with the consideration it deserves.
I am working, slowly, on a non-out-of-hand answer to that. You've already indicated you'll wait, so I don't have anything to add right now.
But, just to clarify: are you saying that this is evidence that Apollo was a hoax? Or are you just saying it's puzzling?
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Post by Obviousman on Jan 3, 2007 18:16:42 GMT -4
And again, there is a complete lack of reference to any Apollo data, or even details about (what should be considered) extremely valuable and unique events - the only times humans have ever experienced deep space radiation first-hand. This is incorrect. A reference which is mentioned time & time again is NCRP report No98 Guidance on Radiation Received in Space Activity. That is the Mercury, Gemini, Apollo, and Skylab data. It is continually referenced.
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Post by turbonium on Jan 4, 2007 2:35:35 GMT -4
And again, there is a complete lack of reference to any Apollo data, or even details about (what should be considered) extremely valuable and unique events - the only times humans have ever experienced deep space radiation first-hand. This is incorrect. A reference which is mentioned time & time again is NCRP report No98 Guidance on Radiation Received in Space Activity. That is the Mercury, Gemini, Apollo, and Skylab data. It is continually referenced. I can't find it online, except for sites that charge for it. Is there a link? I'd like to see the actual report for myself before making any comments.
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Post by turbonium on Jan 4, 2007 3:30:01 GMT -4
Part of the reply I got from one of the report panel members: The Committee considered all sources of radations in Space. We concluded that Solar Particle Events (SPE) would be the major source of radiation exposures supplemented by the cosmic ray background composed of many types of particles including heavy nuclei. To the best of my knowledge, all space missions carry devices to measure the radiation doses. Astronauts should not be outside of a space craft if there were an SPE. They should be shielded inside the space craft. Hence, radiation exposures for Apollo missions would be very small. Hence, I believe that radiation exposures from Apollo missions were very small, unless astronauts stayed outside during an SPE about which they would have been informed.So, once again, all evidence supports the Apollo missions being conducted as reported. I don't see how this is evidence supporting the Apollo missions. It's more like a bunch of inane comments slapped together, if anything. "Astronauts should not be outside of a space craft if there were an SPE. They should be shielded inside the space craft." - can't argue over that valuable bit of advice.... Of course, that's like saying "People should not be outside during drive-by shootings. They should be shielded inside buildings." Saying something that hardly needs saying, about something that nobody can predict in order to avoid it in the first place! "Hence, radiation exposures for Apollo missions would be very small." - ?? Where do they come up with that idea all of a sudden?? Hence, I believe that radiation exposures from Apollo missions were very small, unless astronauts stayed outside during an SPE about which they would have been informed. - Beginning a sentence with "hence" doesn't magically create logic out of nonsense. The author seems to be saying that any SPE's would be known in advance, with enough time to allow wandering astronauts to get back in the shielded spacecraft, and "hence" be safe from radiation. Of course, they have no way of predicting such events with the accuracy required to warn the astronauts to quickly get back in their inadequately shielded spacecraft before getting fried to death.
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Post by Mr Gorsky on Jan 4, 2007 4:06:59 GMT -4
Of course, they have no way of predicting such events with the accuracy required to warn the astronauts to quickly get back in their inadequately shielded spacecraft before getting fried to death. But solar eruptions don't instantly travel the distance between the sun and the moon (some 8 light minutes), so even if they can't be predicted with accuracy there is time between detection of the eruption and its arrival at the moon for NASA to inform the astronauts of the event and suggest they get to a better shielded environment. All of which ignores the fact that a big part of Apollo's solar eruption planning was that the trips were short in duration and the probability of a flare happening during a mission was felt to be small enough for it to be worth taking the risk. A principle borne out by the fact that there was was no solar flare during an Apollo mission. The fundamental difference between Apollo and the proposed new moon missions is that the new missions are planned to be of much longer duration, which massively increases that probability to the point where it becomes almost inevitable that an event will happen while the astronauts are out there, therefore they need to ensure that the astronauts are properly protected. By way of a cheap analogy ... Being in the UK, I have not bothered with the expense of of a set of snow chains for my car's tyres because the probably of the weather being bad enough for me to need them amounts to around one day in every 10 years. When that day arrives, I can choose to stay at home, or if I am in the wrong place I may get stranded, but I know that is the risk. Conversely, a friend of mine used to work in Winnipeg, and carried a set of chains in his boot all Winter every Winter because he knew that at some point they would inevitably be needed. You weigh up the risks and make provision accordingly.
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Post by Jason Thompson on Jan 4, 2007 5:15:36 GMT -4
The author seems to be saying that any SPE's would be known in advance, with enough time to allow wandering astronauts to get back in the shielded spacecraft, and "hence" be safe from radiation.
Of course, they have no way of predicting such events with the accuracy required to warn the astronauts to quickly get back in their inadequately shielded spacecraft before getting fried to death.
The dangerous part of a solar particle event is, as the name suggests, the energetic particles emitted by flares or CMEs. These particles travel at speeds significantly lower than the speed of EM radiation. You don't necessarily have to predict an event to avoid the worst of it, and more than you need to predict that a car is going to go along a road at a particular time to avoid being hit by it. As with the car, you see the flare (usually in the form of an X-ray outburst) before the particles arrive, so you have time to take protective measures.
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Post by gwiz on Jan 4, 2007 5:35:27 GMT -4
Turbonium, you are implying that NASA was reckless with astronaut lives. However, if you research the subject, you find that the command module would have protected the crew from a fatal dose even if a solar flare equal to the maximum ever previously observed had occurred, and even within the LM the protection was close to adequate for this situation. The SPAN system and the detailed procedures to be followed in the event of a flare alert were designed to give the crew time to get to the CM if in the LM and to the LM if on an EVA before the worst of the particle radiation arrived.
Furthermore, none of the solar flares that occurred in 1969 - 1972 was large enough to give a fatal dose even if the crew had been on an EVA and unable to get back to the LM in time, though the Aug 1972 one came close.
In the event, as no flare occurred during a mission, no astronaut got as much as 1% of the maximum exposure allowed for in the pre-mission planning.
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Post by Obviousman on Jan 4, 2007 17:22:18 GMT -4
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Post by greigdempsey on Jan 5, 2007 11:19:50 GMT -4
This is from someone who actually knows what he's talking about.He's in charge of the NASA funded study linked below. He thinks NASA got lucky on Apollo and he's not sure how ! Not careful, but lucky !!. www.space.com/businesstechnology/lunarshield_techwed_050112.htmlLunar Shields: Radiation Protection for Moon-Based Astronauts But in Apollo, it was a very short mission and a lot of it was basically luck. I'm not sure how they managed to be so lucky, but I don't think you can count on luck on short missions for the future or trips to the planets
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