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Post by swank23 on Oct 10, 2009 0:25:11 GMT -4
My friend found this article put out by NASA. It is talking about the radiation exposure an astronaut would receive going to the moon or to mars. This is the article. science.nasa.gov/headlines/y2005/24jun_electrostatics.html I have always lambasted anyone who tries to talk about the Van Allen Belt, NASA clearly states that the astronauts received minimal exposure due to the one hour time frame, but this article seems to directly contradict what NASA has said. I can normally shut most people up about the moon landings, but I really do not know how to argue with this point. Please answer these questions so that I can shut my friend up. 1)Why would NASA be worried about any of this. We obviously had the technology in the 60's to take care of the problem. I would think that by now we would have technology that far surpasses what we had then. You will have to forgive my lack of knowledge concerning the eccentricities of space travel. 2)These are the quotes that he keeps throwing in my face. "Space beyond low-Earth orbit is awash with intense radiation from the Sun and from deep galactic sources such as supernovas. Astronauts en route to the Moon and Mars are going to be exposed to this radiation, increasing their risk of getting cancer and other maladies. Finding a good shield is important." I thought that the Van Allen Belt was only an hours worth of exposure time? This definitely makes it sound like all of space past low earth orbit is "awash" with radiation. "Portable designs might even be mounted onto "moon buggy" lunar rovers to offer protection for astronauts as they explore the surface, Buhler imagines." Once again my friend keeps pointing to the fact that we already supposedly took care of this. "The most common way to deal with radiation is simply to physically block it, as the thick concrete around a nuclear reactor does. But making spaceships from concrete is not an option." I am really confused and I hate being wrong. Please help me debate my friend into little pieces. I am really starting to question myself.
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Post by Nowhere Man on Oct 10, 2009 0:31:35 GMT -4
Not having read the article (it's past my bedtime), I would bet that it's talking about long-term exposure to space radiation. The Apollo missions lasted a week or so each, an acceptable risk at the time. The future moon missions, as well as a trip to Mars, would entail several months of exposure, which can have bad effects.
Fred
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Post by swank23 on Oct 10, 2009 0:41:44 GMT -4
I have asked several people about this and I honestly cannot get a straight answer. I know that the question becomes what is long term exposure, but the article makes it sound like a trip to the moon would be dangerous exposure, especially when the astronauts get to the face of the moon. From what I can gather from research, exposure of one day would be enough to cause cancerous growths. NASA states that the exposure to radiation for the astronauts going to the moon in the Apollo missions was about an hour and coming back was about an hour. Two hours was acceptable, but this article makes it sound very, very different. When I look at pictures of the lunar landing module, I cannot see how it could have withstood the radiation. (this is the quote that makes me question the capabilities of the lunar lander) "The most common way to deal with radiation is simply to physically block it, as the thick concrete around a nuclear reactor does. But making spaceships from concrete is not an option"
I hate to say it, but this just doesn't add up.
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Post by BertL on Oct 10, 2009 0:48:54 GMT -4
Your link leads me to a 404.
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Post by Czero 101 on Oct 10, 2009 0:50:04 GMT -4
Welsome to the board, Swank.
The link to the article you are referencing comes up with a "page cannot be found" error.
That said, what Nowhere Man has said above is correct in that it sounds like the article is discussing longer duration missions. The longest Apollo mission was Apollo 17, clocking in at just over 12 1/2 days. On average, the other Lunar missions were roughly 9 days each. When passing through the Van Allen Belts, the trajectories used ensured that the spacecraft only passed through the weaker edges of the belts, limiting the astronaut's exposure to roughly an hour each way. Radiation exposure cannot be eliminated completely, but for Apollo, the spacecraft design and mission plan limited exposure to acceptable levels. In practice, the astronauts were generally exposed to less radiation than the designers had expected; a testament to the robustness of the spacecraft and spacesuit designs.
For longer missions, such as a Mars mission, radiation exposure will be a much bigger concern and therefore the Apollo design will not afford the astronauts sufficient protection. This is why NASA is conducting studies into radiation levels and new shielding designs. The conspiracy crowd look at this as a sign that, since Orion takes many design cues from Apollo, the earlier Apollo designs must not have provided the levels of protection that NASA claims they designed into them, but they seemingly ignore the fact that the Orion / Altair missions call for much longer stays than Apollo was ever designed for.
Cz
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Post by swank23 on Oct 10, 2009 0:53:55 GMT -4
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Post by swank23 on Oct 10, 2009 0:58:17 GMT -4
I have had people tell me that the radiation is uneven, but the article states that space beyond low earth orbit is "awash" with radiation. Awash means to overflow with. Maybe it was a bad word choice, but I have read that the reason the Russians, nor any other industrialized nation, have not gone to the moon was because they could not solve the radiation issue.
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Post by Obviousman on Oct 10, 2009 0:59:26 GMT -4
Space beyond low-Earth orbit is awash with intense radiation from the Sun and from deep galactic sources such as supernovas. Astronauts en route to the Moon and Mars are going to be exposed to this radiation, increasing their risk of getting cancer and other maladies. Finding a good shield is important. It's correct. There IS a radiation hazard and a good shield IS important. It was important for Apollo, which was looking for up to 14 days exposure, and it will be even more important for future missions lasting from a few weeks to many months. It is certainly not proof of fakery. Portable designs might even be mounted onto 'moon buggy'; lunar rovers to offer protection for astronauts as they explore the surface, Buhler imagines. Correct. The Apollo missions went for a maximum of three EVAs over three days. The next missions are talking about a week or more - much more for the latter lunar missions. Radiation exposure is cumulative, so you want to reduce radiation exposure to the absolute minimum, not just a 'safe' level. The most common way to deal with radiation is simply to physically block it, as the thick concrete around a nuclear reactor does. But making spaceships from concrete is not an option. Once more, correct. There are various shielding strategies, but one of the key aspects is weight; the lighter the better. If weight (to get us out of the gravity well) were not an issue, the the shielding problem would be easy!
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Post by swank23 on Oct 10, 2009 1:05:38 GMT -4
I understand what you are saying, but it seems that the problem should be solved. When I look at the lunar landing module, I can not seem to understand exactly what was used to shield the men from the radiation. What I am basing this on is the official word from NASA. They stated that the astronauts received only a cumulative of 2 hours of radiation exposure and this article paints quite a different picture.
What exactly was used to shield the astronauts from exposure on the lunar landing module, on the lunar rover, and in the space suits?
Why not use the same equipment? Why a force field or a concrete dome made of moondust? I would think that 40 years of research would produce something more than capable of replicating the Apollo missions.
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Post by swank23 on Oct 10, 2009 1:09:26 GMT -4
Once more, correct. There are various shielding strategies, but one of the key aspects is weight; the lighter the better. If weight (to get us out of the gravity well) were not an issue, the the shielding problem would be easy![/quote]
So what was used to shield the astronauts during the Apollo missions? Clearly they were exposed to more than two hours worth of radiation.
I can not understand why NASA is worried about this? If I could know what they used for radiation protection in the first trip then I think that would help me understand.
Thanks to everyone for their input.
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Post by seemoe on Oct 10, 2009 4:38:58 GMT -4
aluminium i think
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Post by AstroSmurf on Oct 10, 2009 7:09:08 GMT -4
This is an apples and oranges comparison. The two hours of exposure refers to the passage through the Van Allen belts, which would be much the same duration and intensity no matter what the total mission duration - in reality, about 20 minutes each way through the densest parts. The strategy picked for Apollo was to reduce the intensity through choosing a trajectory through the thinnest part of the belts, and limited shielding in the Command Module; mainly aluminium and polyethane (?), total thickness a few inches.
The new studies refer to what happens after the passage. Conspiracy theorists like to claim that space is "awash" with radiation, but the levels are much lower than in the Van Allen belts. The general level is higher than on Earth, true, and there's the added danger of solar flares which increases the longer your mission duration is. It is for this reason that NASA now requires better shielding than the Apollo missions had. As far as I can tell, neither the Lunar Module nor the space suits had much in the way of radiation protection, since the mission was short enough that the astronauts could cope with the total exposure. For a longer-term mission, the damage will add up over time, so they need to have a strategy to reduce the average exposure, as well as plan for what to do in the event of a solar flare.
As an aside, neither concrete nor lead are the best types of shielding for particle radiation. Lighter atoms are the best for that, so most plastics, hydrocarbons and water perform well compared to their weight. Gamma radiation (which is what you'd need lead or concrete for) is typically much lower in intensity, though for a permanent lunar base, burying it in the regolith is a viable strategy.
Since water does fairly well as a particle absorber, maybe they can simply keep the water supplies in tanks surrounding their sleeping quarters. That would reduce the daily exposure, as well as provide a convenient shelter during flares. No doubt NASA are pursuing all the options.
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Post by swank23 on Oct 10, 2009 11:18:06 GMT -4
Astrosmurf, you say this: "Conspiracy theorists like to claim that space is "awash" with radiation, but the levels are much lower than in the Van Allen belts. The general level is higher than on Earth, true, and there's the added danger of solar flares which increases the longer your mission duration is. It is for this reason that NASA now requires better shielding than the Apollo missions had. As far as I can tell, neither the Lunar Module nor the space suits had much in the way of radiation protection, since the mission was short enough that the astronauts could cope with the total exposure. For a longer-term mission, the damage will add up over time, so they need to have a strategy to reduce the average exposure, as well as plan for what to do in the event of a solar flare." I am beginning to think that not a single person is reading the article that I posted, so I posted it below. Please read it. The article in question does not contain one comment concerning solar flares. As a matter of fact, I am not quoting conspiracy theorists who say that space past beyond earth orbit is "awash" with radiation, but... I am quoting an article put out by NASA which states this: "Space beyond low-Earth orbit is AWASH with intense radiation from the Sun and from deep galactic sources such as supernovas. Astronauts en route to the Moon and Mars are going to be exposed to this radiation, increasing their risk of getting cancer and other maladies. Finding a good shield is important." This statement, in no uncertain terms, makes it clear to me that ALL of space beyond low earth orbit is AWASH with INTENSE radiation. Once again. If the Astronauts made it to the moon then why not use the same, or over 40 years improved, technology? I am delighted with the many replies, but I have yet to receive an adequate response. Most of what people have said are the same tired quotes about the Van Allen belt that debunkers post on the many ill-informed hoax websites. In fact, every single response has been a logical fallacy. An ad hoc hypothesis. You guys are beginning to sound like all the lunatics on the hoax websites. I came on this forum honestly expecting to have someone clear this up, but I do not think that that will happen. I never thought that I would begin to question the landings, but I am currently changing my belief status from "not a hoax" to "I am not sure". Am I reading the same article that you guys are reading? science.nasa.gov/headlines/y2005/24jun_electrostatics.htmI fully expect the normal argument ad hominem (tin-foil hat, lunatic, nutbag, etc...) but please, if someone can respond and it makes sense then I want to buy that story. So far, I cannot buy what I am being sold.
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Oct 10, 2009 11:26:48 GMT -4
What exactly was used to shield the astronauts from exposure on the lunar landing module, on the lunar rover, and in the space suits? No special shielding was required, the lunar module and the spacesuits themselves provided considerable attenuation of radiation. Nonetheless, some radiation did get through; however, the duration of the missions were short enough that this radiation did not accumulate to a dangerous level. For long duration missions to the moon or missions to Mars, astronauts won't to be able to stand the rate of radiation exposure that they received on Apollo because it will build up over time and cause harm. For long duration missions, something more is needed than was provided during Apollo.
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Oct 10, 2009 11:38:54 GMT -4
I am beginning to think that not a single person is reading the article that I posted, so I posted it below. Please read it. The article is talking about future long duration missions. As we've been trying to tell you, duration makes all the difference. Apollo resulted in a low dose of radiation because the missions were of short duration. No special shielding was required for Apollo, but that is not adequate for future long-duration missions. It is simply apples and oranges. What worked for Apollo won't work for long duration missions, and what is required for future long duration missions wasn't necessary for Apollo. They are two completely separate engineering problems, yet you keep insisting on treating them as if they're the same.
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