@daenumen Perhaps it's because you hoaxers use all the same debating tricks and fallacies as the creationists? You know, moving the goalposts. Poisoning the well. Quote mining. Bare assertions. False dichotomies. And plenty of out-and-out false statements even when they've been repeatedly disproved.
@ApolloWasReal 'hoaxers'?.disregarding a study that did not compare lead and aluminium?. ipse dixitism?. imagining the VAB stop before 40degrees lattitude and are the only radiation containing things in space?. disproved by moving the goal posts?.
@daenumen What in hell are you babbling about? The animation in this video shows exactly how Apollo avoided the densest parts of the VAB. If you'd actually look at it you might even understand it.
@daenumen I'm in the US, where I went well beyond a high school diploma (what I believe you Brits call "sixth form"). In fact I have a graduate degree in electrical engineering. But I learned the necessary reading skills much earlier, and I'm sure you did too. So I don't understand why it's so hard for you to just read the references that talk about the differences between shielding for gamma/X-rays and for high energy particles.
and dont forget...it was a good job there wasnt any wind or atmosphere on the moon... the module designed by aeronautics company was completely non-aerodynamic...
"the module designed by aeronautics company was completely non-aerodynamic"
Wow, could the reason it was designed that way because there was no atmosphere. Amazing.
Please provide me with evidence of anyone who has ever died from one chest X-Ray. You need to back up your claim that they are deadly with something :)
@daenumen Because it's so common in spacecraft construction, aluminum is the *reference* to which other shielding materials for charged particles are compared. Lower Z materials like Al are actually more efficient, per unit mass, in stopping charged particles. Hydrogen (e.g, water, plastics, fuels) is even better. Lead's higher density will allow a thinner piece to be as effective as Al, but it will weigh more. All this has been openly published and used by spacecraft engineers for many years.
we have known of nuclear power and radiation before people even considered building a 'manned-firework' with a LRRR finale.
hydrogen stopping radiation?! dont think so...water plastics and fuels are not hydrogen...sure they contain hydrogen...deuterium? heard of it? because deuterium = you are talking out of you NASSA.
no..an equivalent mass of Pb to Al has THE SAME MASS (surprisingly) but Pb is thinner.7cm of Al wont stop most >1MeV
@daenumen You really don't know much about this, do you? It's obvious you don't realize that space and terrestrial radiation are different problems. On earth, it's mostly about stopping gamma and X-rays with lots of electrons. That means dense stuff like lead and tungsten. But water is an excellent gamma shield; consider the spent fuel pools at nuclear reactor sites.
Space radiation is all about energetic charged particles, which behave very differently from photons.
@ApolloWasReal cosmic radiation passes through the earth. YOU DONT KNOW WHAT YOU ARE ON ABOUT.
lol dont start on spent fuel pools. lol yes sure the water does stop some of the radiation, just like any matter put between you and a radioactive source will invariably stop some of the radiation.
of course water becomes radioactive.
have you heard of alphas betas neutrons neutrinos protons...not to mention muons pions kaons, etc. these are space radiation, and nuclear reactor radiation too.
@daenumen Water does not become radioactive just because it's exposed to radiation, except for neutron radiation. See the classic picture from just about any nuclear power plant showing workers standing around the spent fuel pool looking at the blue glow coming from down below. Without the water they'd be dead in minutes; with it they get less than on many airliner flights.
@ApolloWasReal those are not nuclear reactors they are spent fuel pools that are usually kept way below operational temperature like 50celcius compared to the reactor itself.
the water is also very deep and may even be heavy water. and yes that water does become radioactive. neutrons/protons/alphas are emitted in almost all nuclear reactors and especially so when we are talking about spent fuel -- a mixture of different elements many of which are unstable.
@daenumen No, those pools are filled with ordinary water, a very good radiation shield. The main difference between fuel in the pool and in an operating reactor, aside from the far lower amount of heat, is that there's little neutron activity. Boric acid is often added to pool water just to ensure that its far below critical. The fission products are contained inside the sealed Zr tubes. Unless they leak they don't get into the water. That's why people can stand around them.
@ApolloWasReal Typically 40 or more feet (12.19+ m) deep, with the bottom 14 feet (4.26 m) equipped with storage racks designed to hold fuel assemblies removed from the reactor
sure 25ft of water above non-critical spent fuel kept far below operative temperatures....
@daenumen Those spent fuel assemblies are extremely radioactive. Without water in the pool anyone nearby would receive a fatal gamma dose in a matter of seconds. With water, it's perfectly safe. You can even see how water stops electrons (fission products emit gamma + beta, and beta are electrons) within a few feet as evidenced by the Cerenkov glow. The point is that water is an excellent radiation shield despite being composed of two low-Z elements.
@ApolloWasReal what about the fuel rod casings, and the 25foot or so of water between the top of the rod pile and the top of the tank. usually a bridge above the water that people walk on in a controlled atmosphere?
i certainly wouldnt touch a spent fuel assembly even with a control rod!
@daenumen What's your point? I'm stating a fact: ordinary water, a low-Z material, is an excellent and widely used radiation shield. Are you saying it isn't? Those workers in nuclear power plants seem to think it is. There are even low power research reactors that operate in an open pool of water. We had one at college right next to the EE building. I never paid much attention to it, though I wish I'd known who to ask for a tour.
@daenumen You don't even seem to realize that heavy water would be a *worse* shield in a pool than regular water. D2O is used in reactors with natural uranium because D is more transparent to neutrons than ordinary H, and that's exactly the opposite of what you want in a shield.
Admit it, you just said "heavy water" because it sounded cool, right?
@daenumen Low Z materials like Al, C, and especially H are much more effective at stopping charged particles and minimizing bremstrahlung photons. And yes, Al is the spacecraft reference shielding. 7 cm of Al will stop protons nearly to 150 MeV, though it's pretty rare to see spacecraft walls that thick. Look it up if you don't believe me.
Maybe this is why your conclusions have all been wrong?
@ApolloWasReal no lead is better at stopping charged particles...
water is about 1/3 as effective as aluminium at radiation shielding.
Pb is some 4 times more dense than Al and it is some 100 times more shielding. as calculated at 120KeV energies. the behavior of the materials is also such that as energy increases Pb is proportionally more effective than Al at stopping radiation. this can be viewed simplistically though kinematics.
@daenumen Sorry, simply ain't true. Aluminum is substantially better than an equal mass of lead. Yes, a cm of lead is better than a cm of aluminum, but that's only because it's vastly denser.
I'm reading just fine. It's you who aren't reading the references properly. ytmoog, roamingcroat and I could all direct you to some good ones. Would that do any good?
lead is significantly better than aluminium. honestly look up attenuation coefficients al is about as good as human flesh, and human flesh is far inferior to lead at stopping radiation, except for the bones...
@daenumen You're seriously confused. q-factor has to do with the damage each type of particle does to biology. It has nothing to do with shielding. I've looked up the attenuation coefficients already, thank you, and I know what I'm talking about. When it comes to stopping charged particles, low-Z materials like water, aluminum, hydrogen and carbon are, kilogram for kilogram, more effective than high-Z materials like lead. Go look it up. Please?
@ApolloWasReal duh i know q-factor is related to biological effects of radiation.... the crew where living human beings?! the radiation protection would be for them mostly?! (also for equipment...)
"low z metals are better at stopping radiation that high z"...
you just let me know when and where you build your reactor(s) so i can move somewhere else.
30 years or 2LiE SETS has sent you bonkers /wiki/Basic_Physics_of_Nuclear_Medicine/Attenuation_of_Gamma-Rays#Effect_of_Atomic_Number
@daenumen Once again, in space the problem is NOT gamma radiation but charged particles, for which the rules are different! With sufficient mass you can use any material to shield any kind of radiation, but if you want to minimize mass in space, and you always do, you use low-Z materials, especially those with lots of hydrogen. The simple fact is that the existing CM walls could stop protons over 100 MeV. Very few had enough energy to get through.
@daenumen an equal mass of paper (carbon + hydrogen + oxygen) would probably be more effective than aluminum at stopping charged particles, yes. Assuming there are no pores or other empty spaces. But aluminum is already pretty good, certainly better than lead, and it would also help drain away any accumulated surface charge. That's also an issue in spacecraft design.
@ApolloWasReal Excellent explanations. I had some hope, after reading all that, that daenumen would realize he's misunderstanding... well, everything, but I guess he'll persist in his ignorance for a while longer.
@daenumen No, the video shows a transfer orbit inclination of about 32 degrees, just what A11 flew. It only looks higher because of the orientation, by design, of the orbital plane to the geomagnetic axis. The TLI burn was in-plane, and anything else would have been very wasteful of propellant. The VAB don't "reflect" anything. They're simply regions where charged particles from the sun have been trapped by spiraling around the earth's magnetic field.
@ApolloWasReal exactly there isnt sufficient delta-V to do anything other than the optimum path, which is not to 'avoid' the VAB....actually avoid is a bit of a misnomer as i keep pointing out the AURORA.
again dont rely on the video, those VAB are not 'real', though the path might be from the data NASA has provided, it neither shows the actual VAB distribution nor does it show lunar capture which is fundamentally necessary regardless of what you think...seriously.
@daenumen It's a model of the VAB. There's pretty much no way to get an exact representation of the VABs at any given time. Models are what you use in engineering to represent reality. Airplanes are designed in part using the Standard Atmosphere model, but even that is only true as an approximation of what's actually happening.
You say there isn't enough delta-V for this trajectory. How much delta-V do you need for this? How about for your "optimum" trajectory? You'll find they're the same.
@roamingcroat yes but it is very much an approximation that you cannot refer to as being valid.
again, you seem to be stuck around these VAB's being a proof for NASA actually going to the moon:
1. NASA CATEGORICALLY STATED: VABS POSE NO SIGNIFICANT RISK.
2. NASA CLAIMS TO HAVE AVOIDED THEM (RUSSIAN SPACE STATION EXPERIMENT CONFIRMED VAB ARE DEADLY FOR TERRESTRIAL ESCAPE (IE ARRIVING IN ORBIT AROUND ANOTHER CELESTIAL BODY) OR EVEN HEO.)
@daenumen "yes but it is very much an approximation that you cannot refer to as being valid."
Quite the opposite. It's very valid. If you're concerned about engineerd artifacts that use approximations, you'd better stop flying, driving, and living in buildings. Approximations are a way of life - there's no other way to account for the vaguaries of reality.
No one can tell me exactly how many 10 MeV particles there are this instant 6,000 miles directly above Ipswich. But there is a model...
@daenumen "sure but there is no room for approximation in such a mission. precision is fundamental."
Amusing. Everything in engineering is about approximations. That's the only way you can make things work. We don't take general relativity into account when building airplanes*. Or quantum mechanics when building skyscrapers. Apollo used a numerical technique to calculate the needed orbit. I doubt it included perturbations from Mariner 7.
@roamingcroat you make it sound like childs play to get into space...
you think that if this were the case we would not yet have a lunar base? and holidays on the moon???
if approximations were all it took???!
you know the complication of aircraft is that of the approximations, it means for any airoplane it requires repeated manufacture and remanufature by a process of trial and error do they ever complete them!!!
look at SATurn development!!! not space age technology!
@daenumen "you know the complication of aircraft is that of the approximations, it means for any airoplane it requires repeated manufacture and remanufature by a process of trial and error do they ever complete them!!!"
Do you think approximations aren't used in aircraft design? My graduate research is in compressors. If you knew how little we actually know about the details certain disasterous flows that can happen to compressors, you would never fly again.
@roamingcroat i said approximations are the complication.
you said "If you knew how little we actually know about the details certain disasterous flows that can happen to compressors, you would never fly again"
Quite the opposite. The approximations used in the design of jet engines are good enough that, even if we don't know the details, we can keep airplanes from falling out of the sky. Plane crashes are very rare indeed, so it seems that approximations can do the trick.
Likewise with Apollo. The details may not be exactly known, but they can come up with a good model of reality.
@daenumen Engineering models are used to preduct performance of an airplane. They are based on everything from experimental data and on first principles.
Likewise with the VABs. Using experimental data, a model was made to describe the belts. This is an approximation of reality. Standard atmosphere is a similar approximation of reality. That's how you turn a problem into a managable one - by making approximations consistent with the real world.
@daenumen "exactly trial and error = experimental data."
OK... and how does that preclude a manned vehicle travelling through the belts. We had experimental data, you know. Otherwise we wouldn't even know about the belts...
@roamingcroat yes we did, the russian experiments concluded from the SAA ALONE, that the belts were unpassable.
the N1 featured HUGE DELTA-V and incredible booster control with mutliple partial burn capacity on the main engine. the module also featured considerably greater radiation shielding...not just for the VAB but also COSMIC RADIATION....remember the sun spots at the time?? solar winds that knock out satellites never mind human flesh with a radiation penetrtn ~ that of Al.
@ytmoog yes it was possible to pass the belts...with heavy shielding, infact the first few probes that russia sent broke passing through the VAB as it destroyed the guidance systems.
they later refered and relied heavily on mechanical as opposed to electronic equipment, becuase of the huge amounts of radiation....
"they later refered and relied heavily on mechanical as opposed to electronic equipment"
You should pass this along to all the commercial satellite operators who have satellites in the belts (which is a lot of them) they seem to have missed this.
@daenumen "yes we did, the russian experiments concluded from the SAA ALONE, that the belts were unpassable."
If you'll be so kind as to give me the citation for that, I'd appreciate it.
"the N1 featured HUGE DELTA-V and incredible booster control..."
And it failed to ever reach orbit. I don't actually know what sort of delta-V the N-1 was capable of for a Soyuz/LK combination (and from what I understand, they used EOR). Do you?
@roamingcroat i may have already refered to it a while back in this thread...
it was a study done on the ISS aswell, as it passes through the SAA. infact the radiation is known to be so high that usually, unless an experiment is occuring on the SAA that the astronauts leave the station when it passes through the SAA because of the radiation risks.
they did some tests on materials, exposing them to SAA and seeing the damage etc.
@daenumen I'm sure the SAA is studied a lot on the ISS. If you look at NASA's orbital tracks, it's even labled. But I'm asking specifically for the journal where the Russians published their conclusion that the VABs are unpassable. I'm not looking for your interpretation here, I'm looking for the article itself. So, the citation please.
@daenumen You're claiming there is a paper that supports your position. You have to cite it. That's how it works. I'm not required to go hunting high and low for a paper in order to evaluate your position if you don't tell me where it was published. If you can't produce the citation, your position has no merit.
And you never mentioned the citation before. You've certainly made your SAA claim before, but you never backed it up.
wiki "The International Space Station, orbiting with an inclination of 51.6°, requires extra shielding to deal with this problem. The Hubble Space Telescope does not take observations while passing through the SAA. Astronauts are also affected by this region which is said to be the cause of peculiar 'shooting stars' seen in the visual field of astronauts.[8] Passing through the South Atlantic Anomaly is thought[9] to be the reason for the early failures of the Globalstar network's satellites."
"wiki "The International Space Station, orbiting with an inclination of 51.6°, requires extra shielding to deal with this problem. "
Indeed, they commonly use plastic I would also note.
Astronauts aboard the ISS generally receive larger doses than the Apollo astronauts did because they pass through the SAA quite often, and spend far longer periods in space.
@ytmoog yet the apollo crew passed through the VAB at 40degrees spent some 1hr passing through it on the way there and back, and didnt have a shielded craft specifically designed to withstand only the low VAB radiation....which of course is safe, that is why there is extra radiation shielding on the ISS.
it was a lethal dose they would have gotten. specially with 1960's 'american' trial and error space tech.
@ytmoog short duration of several days? yet exposure to the VAB for 30 mins was sufficient to reduce that time to 20 mins? and not bother about radiation shielding?>!
other than a honey comb hollow structure between two aluminium sheets, with chemical heat shields painted and fixed on...
The mean range of a 20 MeV Proton in aluminum is only 2 mm. so yes, 3 cm of Al will stop radiation.
And as for the materials, studies done by ESA show that the bast material weight for weight for reducing radiation exposure was liquid hydrogen. With Plastic superior to AL which was superior top lead.
Lead was particularly poor due to the large amounts of Bremsstrahlung produced.
In short lead is the worst material possible for shielding against particle radiation in space missions.
@ytmoog sure but stopping a 20MeV proton in aluminium produces gamma/x-rays that will effect the people within the craft.
infact there is sufficient x-ray radiation during the passing not only did all of the actuall film get destroyed even though it was in a lead box, but also enough to take whole body x-rays for 20-40mins.
Bremsstrahlung radiation it's known as. And not from Aluminium, which is another reason why it is used (along with plastic) instead of lead.
The amount of Bremsstrahlung depends on the mass of the atoms in the material. Heavy atoms such as Lead produce much more than lighter atoms such as Aluminium.
@ytmoog yes! for a given number of particles colliding with a al or pb block pb will produce more 'stoppage radiation' that is because pb pound for pound is better than al at stopping faster moving particles, becuase the nuclei are larger.
its why lead is some 100 times better pound for pound, as i detailed in calculations several days ago... and also before that in terms of attenuation...some weeks/months ago...
@ytmoog pb would reduce solid particle radiation, though may increase bremsstrahlung radiation dose.
a gamma ray is far more likely to pass through a human body than an proton or electron and certainly an alpha particle
THIS IS WHY I MENTIONED Q-FACTOR. agian i did the q-factor calculation for my radiation calculation, something you are yet to display an awareness of...
@ytmoog look at todays radiation science, the atomic agency couldnt even determine a safe reactor...they are lead by US who are the only nation to commit genocide with nukes...etc etc etc etc
@ytmoog why use lead for radiation shielding then???? even if you get a hospital or dental x-ray done, they given you a lead jacket to wear, not an aluminium one.
please check the data sheets, aluminium is as penetrative as human flesh... lead is considerably more resistant to radiation penetration:
remember the model of the atom? little nucleus lots of space? 208 to 27????
@ytmoog well i know from experiment alpha particles are more readily stopped by lead than by al, and that gamma rays are similarly more readily stopped by lead than by aluminium
again lead is far more dense than human flesh which is almost identical in behavior to aluminium.
SHOW SOME PROOF OR AGREE TO DISAGREE. ive already posted data regarding lead and aluminium that proves otherwise several days ago.
"well i know from experiment alpha particles are more readily stopped by lead than by al"
Alpha particles can be stopped by paper...
Experiments to show that are easy to do as well...
As for evidence see the paper : "Shielding of manned space stations against van allen belt protons" by the Oak Ridge National Laboratory. September 1986
@ytmoog err ISS only passes through the lower edge of the SAA, not through the VAB.
'weight for weight' pb better
Despite efforts to improve radiation shielding on the ISS compared to....such as Mir, radiation levels within the station have not been vastly reduced,...further technological advancement will be required to make long-duration human spaceflight...a possibility.....the radiation levels experienced on ISS are not excessively greater than those experienced by airline passengers.
"technological advancement will be required to make long-duration human spaceflight" ... "further into the Solar System" ... "a possibility"
You certainly seem to have the art of quote mining down to an art. Note also the words 'long duration'.
The article they reference is interesting as it talks of Mars missions, as well as the use of plastic as a radiation shield and why shielding using materials with lighter nuclei are used.
@ytmoog i have read that 2 in 8 astronauts exposed to LEO thats below VAB radiation for 80 days were found to have chromosomal mutations that may be possibly pre-cancerous.
a mission of a few days through the VAB twice and solar winds and cosmic rays etc.
@daenumen Believe it or not, the Skylab and MIR astronauts received considerably more total radiation than the Apollo lunar astronauts. That was because of their much longer missions and the high orbital inclination that took them frequently through the SAA. This is all well documented. I don't know how they compare to the ISS because I don't know how they compare in shielding.
@daenumen Even though both would be outside the earth's exosphere and subject to cosmic rays and solar proton events, a Mars mission is much harder to shield than a moon base because the trip to the moon is only 3 days and the moon base can use lunar soil for shielding. A trip to Mars takes 6 months and you must bring everything with you, including shielding. Water and liquid hydrogen fuel tanks are commonly suggested since they need those materials anyway.
@daenumen Well, that would be the problem -- when you go to the moon, you can use what's there for shielding. When you go to Mars, unless you stop at the moon or an asteroid along the way you have to take everything with you, including any radiation shielding. So the usual proposal is to reuse materials like water and fuel as shielding whenever possible. Water is hydrogen-rich, and the fuel would either be liquid hydrogen or hydrogen-rich, so it would make good shielding for particle radiation.
@daenumen Apollo didn't need any shielding beyond the structure of their spacecraft for the simple reason that the missions were too short for radiation to be a serious problem. They did gamble (and win) on there being no large solar proton events; that was just one of the several risks they faced. For longer missions, chances are good that there would eventually be a solar proton event big enough to cause illness, so building a shelter will probably be one of the first things they'll do.
@daenumen Lead is widely used for X-ray and gamma shielding simply because it's dense, and minimum volume is more important than weight. Pb packs a lot of electrons (which do the shielding, NOT the nuclei) into a small volume. Unfortunately, you can't have electrons without the much heavier protons balancing their charges. And you can't have a stable nuclei made entirely of protons so you need the heavy neutrons too.
Sometimes tungsten, tantalum and even depleted uranium are used.
@daenumen What you don't seem to understand is that most of the shielding problems on earth involve X and gamma rays, NOT the extremely energetic charged particles found in space. (Beta radiation from fission products consists of energetic electrons but they're easily stopped by anything that can stop the associated gammas). As you've already been told, LH2 is the best particle shield per unit mass. One reason is the almost complete lack of useless, heavy neutrons.
@daenumen WRONG!! Go back and study basic matter theory. Remember that atoms are made up of tiny but dense nuclei surrounded by electron "shells". They consist largely of empty space.
The incident particles -- gamma photons, electrons, ions or protons -- interact almost exclusively with the shield electrons, NOT the nuclei. The only exception are neutrons, for which you use nuclei with large neutron cross sections like B-10. Neutrons are not a problem in space unless you have a reactor.
@daenumen You asserted that the nuclei in shields do the work. That is simply incorrect except for neutron shielding, which you don't need in space unless you have a nuclear reactor. Cosmic rays are always charged particles; that's how they get accelerated to fantastic energies by interstellar magnetic fields. Also, free neutrons have a 15 minute half life.
Except for neutron shielding, the electrons in a shield do the work. The heavy nuclei just balance the charge.
@daenumen Serious about what? Reactors in space? The Americans and Russians have both flown them. The US just once, to my knowledge, the Russians many times. They had several come back down on people because they used them to power marine radars, and radars like to operate close to their targets. Reactors are probably better used for interplanetary travel, especially far from the sun where solar power is problematical.
@daenumen Oh, and thanks to the Russians' use of reactors in space, one important category of space junk consists of droplets of NaK, a sodium-potassium metal alloy liquid at room temperature and used as reactor coolant. Although liquid, it has a very low vapor pressure so unfortunately they will have long orbital lifetimes.
When Apollo started, both micrometeoroids and radiation were investigated. Today, artificial junk is the primary hazard in orbital flight.
Correction to the above -- MOST of the work in a shield for photons (X/gamma rays) and charged particles is done by the electrons through Compton scattering and the photoelectric effect. >1.02 MeV (2x electron mass) "pair production" begins: the gamma photon approaches a nucleus and is turned into an electron/positron pair. The positron soon encounters another electron and annihilates, producing more photons, which along with the electron are eventually stopped by the shield electrons.
@daenumen Once you understand that (except for neutrons) the electrons in a shield do all the work, you can begin to understand why high Z materials are worse. For one, high Z materials have proportionately more neutrons that add mass without improving shielding. But the main reason is that the inner electron shells are bound more tightly to a high-Z nucleus, and when they're excited by an incident particle they emit much harder Bremstrahlung photons.
@daenumen All this is very widely documented in many, many references. Most of them aren't even from the bogeymen at NASA that you seem to distrust so much. Just consult one and you'll quickly learn that low-Z materials are better particle shields. Why do you keep asserting the opposite?
@daenumen I keep asserting that low-Z materials are preferred for particle radiation shielding because that's exactly what all the references say. And you?
@daenumen That heat shield, made of phenolic resin, actually covered the entire command module, although it was thickest on the base. Phenolic consists primarily of hydrogen and carbon, both excellent low-Z shields for energetic charged particles. And that was on top of the double-hulled aluminum and stainless steel structure.
The Apollo CM that you denigrate so much was actually shielded quite well. The proof is in the dose figures returned from each mission.
@ytmoog no but US does use political leverage to try to stop others from getting into space/ developing nuclear technology/ increasing oil prices/ evading capital punishment (aka) capital labour / etc
@ytmoog Energetic particles (protons, etc, upwards of several hundred MeV) are now widely used in cancer therapy, so there's now a fair bit of non-NASA literature on protection against charged particle radiation, not just gamma (photon) radiation. Seems the secondary neutrons are often the limiting problem. Shielding materials include water, concrete (often with barium aggregates), earth, steel, polyethylene, etc. A variety seems best.
@daenumen What, that phenolic consists mainly of hydrogen and carbon? No, NASA didn't need to tell me this, any organic chemistry or polymer chemistry textbook tells me this.
One can see the remains of the phenolic heatshields on any of the Apollo command modules in museums. In flight it was covered with a thin aluminized Mylar layer used to reflect solar radiation that burned off quickly on re-entry. The orange/brown color is very characteristic.
@ytmoog infact you will notice that the aluminium was perhaps 7cm thick...but it was two sheets of aluminium with a honeycomb core inbetween...lots of empty space to shield lol.
did you see how much room there was for the 3 crew members in the CSM? 2 m^3 each...
@ytmoog find one person who died of a chest x-ray? im pretty sure thats illegal unless you are a doctor writing a research paper...might get a cancer named after you...
i dont think medical proffesionals could diagnose such a result from such a procedure. they wouldnt even look at such a thing, they are trained to make it feel safe for patients.
they do however limit your exposure to x-rays, ie you can only have so many in a year. people with brittle bones would know. will kill cells defo!
do you think they briefed the astronauts along these lines "right 'monkeys'... pass through the VAB pronto, we dont want you lingering around those charged particles...who knows what might happen...you might even figure out this is all a hoax! and we cant have hoaxers undermining our mission...remember apollo 1? thats because they didnt listen. now go! to the moon with you!...great apes honestly...really great apes..."
@daenumen Each astronaut had a personal radiation dosimeter that they regularly read off to Houston, chief. The astronauts were aware radiation was a concern.
@daenumen You can read the Apollo Lunar Surface Journals and the Apollo Flight Journals for that information. Keep in mind the PRDs were all initialized at different values to make sure they weren't mixed up.
The easier bet is to read some of the mission reports. Look on the NASA Technical Report Server (NTRS) for a report on radiation during the Apollo missions (maybe it's in the mission report - I'm not sure).
Sigh...128:27:11 into Apollo 14, Shepard reports on both his and Mitchell's PRD.
"and no fixed reference..."
There was a fixed reference for each PRD. However they were all offset from each other in order to ensure the readings were, in fact, for the correct astronaut.
@daenumen I'm sure the PRD results are in the mission reports. You could also look at the Apollo Flight Journals to see what the first reading was to get an estimate of what the reference point was.
@roamingcroat well ultimately apollo flight data wont shed more light than showing figures that look reasonably survivable.
if the science of the calcuations of q-factor etc etc are correct then yes apollo had a major problem without shielding, if the science is wrong then why do we not know about the corrections (..for mankind?)
@roamingcroat I recommend "Apollo Experience Report: Protection from Radiation". They give the doses through Apollo 15. The mission reports give them too.
I can't believe our friend thinks NASA was so stupid that they wouldn't record the starting point of each dosimeter. But when you already think you're always right and everybody else is wrong, such a further leap of absurdity is not hard to make.
@ApolloWasReal I was reading the requirements for the LM the other day, which included a discussion about the radiation protection requirements. If I listned to hoaxers, I'd be told there were no such requirements. The information is out there and very easy to find, if these hoaxers would just look for it. Instead, they invent convoluted explanations for rather mundane things.
@daenumen The principle is ALARA - As Low As Reasonably Achievable. In short: 1. There is NO evidence that anything less than 5-10 rem will increase your long term cancer risk even slightly. 2. Small radiation doses may actually be beneficial (radiation hormesis). 3. Medical X-rays are FAR below the levels known to cause illness. 4. But, despite all this, radiation doses are still kept as low as reasonably achievable, even when they're already far below the limits.
@daenumen The one big drawback to ALARA is that it scares the public. Because the principle is to minimize radiation exposures as much as possible even when they're far below the threshold known to cause even delayed illness, the public gets the erroneous impression that even the small exposures associated with medical X-rays are dangerous.
They're not. It's just that there's no point in also exposing the radiologist. And since it's so easy to shield him, why not do so?
1 g cm^2 when used in papers referring to shielding against radiation says that the material used to block the radiation has 1 gram of matter in each square centimeter.
What the actual width of the material happens to be is irrelevant, all that matter is the total mass.
So in the case of the CM each square cm of the walls has at least 8 grams of matter between the outside and inside.
right... 1 gram... in 1 cm^2... so do i have infinite mass in 1 cm^3?
im pretty sure density does play a part...as i discussed many days ago, and many days before that AND did a radiation calculation... well anyway... do please continue.
my reading of the CM design was 2 sheets of aluminium on either side of a hollow aluminium honey comb. its on wiki*.
@daenumen You are having obvious difficulty in understanding some really basic concepts here. And that doesn't engender a great deal of confidence in your conclusions, especially as they're contradicted by empirical data (most of the Apollo astronauts are still alive in their 80s). When they say 8 g/cm^2, that means that if you cut the wall into blocks 1x1cm by whatever the wall thickness is, it'll have a mass of 8 g.
The point is that wall mass per area, not thickness, is what counts.
@daenumen The astronauts all remarked that the CM became considerably roomier in zero gravity. It was common for one to sleep in the "tunnel", the space leading to the LM. There was also room under the couches, which were well ahead of the rear bulkhead. Apollo may be cramped by modern standards but it was considerably roomier than Gemini and Mercury.
@daenumen "you seem to be stuck between accepting NASA that the VAB are SAFE and accepting the dangers of the VAB to accept what NASA did. lol..."
I'll ignore all thats wrong before this part...
Swimming is safe. Parachuting into the middle of the Atlantic and trying to swim there is not. The VABs have the same issue. The Apollo trajectories were safe. Hanging around in the middle of the VABs for a month is not. It's not black and white - there are degrees of danger.
@ytmoog again wiki post... SAA break satellites, ISS had boosted shielding, and it wouldnt surprise me if that shielding was on a single module for weight restriction reasons, and that the crew have to spend their time in there or die.
@daenumen "...and it wouldnt surprise me if that shielding was on a single module for weight restriction reasons, and that the crew have to spend their time in there or die."
In Wikipedia, this would be marked with [Citation needed]. So... source?
i think we should leave it here, i've repeated myself more than enough.
compulsory schooling age ends at 16 in uk for a reason, not sure where you are.
daenumen 10 months ago
@daenumen
"i've repeated myself more than enough."
The problem is that you are blindly repeating things that are false.
Like your insistence that Infra-red telescopes do not require cooling, all evidence to the contrary.
You pull 'facts' from your behind like the best of creationists.
ytmoog 10 months ago
@ytmoog creationists?! why pick on creationists?
daenumen 10 months ago
@daenumen Perhaps it's because you hoaxers use all the same debating tricks and fallacies as the creationists? You know, moving the goalposts. Poisoning the well. Quote mining. Bare assertions. False dichotomies. And plenty of out-and-out false statements even when they've been repeatedly disproved.
ApolloWasReal 10 months ago
@ApolloWasReal 'hoaxers'?.disregarding a study that did not compare lead and aluminium?. ipse dixitism?. imagining the VAB stop before 40degrees lattitude and are the only radiation containing things in space?. disproved by moving the goal posts?.
daenumen 10 months ago
@daenumen What in hell are you babbling about? The animation in this video shows exactly how Apollo avoided the densest parts of the VAB. If you'd actually look at it you might even understand it.
ApolloWasReal 10 months ago
@daenumen I'm in the US, where I went well beyond a high school diploma (what I believe you Brits call "sixth form"). In fact I have a graduate degree in electrical engineering. But I learned the necessary reading skills much earlier, and I'm sure you did too. So I don't understand why it's so hard for you to just read the references that talk about the differences between shielding for gamma/X-rays and for high energy particles.
ApolloWasReal 9 months ago
and dont forget...it was a good job there wasnt any wind or atmosphere on the moon... the module designed by aeronautics company was completely non-aerodynamic...
daenumen 10 months ago
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@daenumen
"the module designed by aeronautics company was completely non-aerodynamic"
Wow, could the reason it was designed that way because there was no atmosphere. Amazing.
Please provide me with evidence of anyone who has ever died from one chest X-Ray. You need to back up your claim that they are deadly with something :)
ytmoog 10 months ago
@daenumen Because it's so common in spacecraft construction, aluminum is the *reference* to which other shielding materials for charged particles are compared. Lower Z materials like Al are actually more efficient, per unit mass, in stopping charged particles. Hydrogen (e.g, water, plastics, fuels) is even better. Lead's higher density will allow a thinner piece to be as effective as Al, but it will weigh more. All this has been openly published and used by spacecraft engineers for many years.
ApolloWasReal 10 months ago
@ApolloWasReal aluminium is not the reference at all.
we have known of nuclear power and radiation before people even considered building a 'manned-firework' with a LRRR finale.
hydrogen stopping radiation?! dont think so...water plastics and fuels are not hydrogen...sure they contain hydrogen...deuterium? heard of it? because deuterium = you are talking out of you NASSA.
no..an equivalent mass of Pb to Al has THE SAME MASS (surprisingly) but Pb is thinner.7cm of Al wont stop most >1MeV
daenumen 10 months ago
@daenumen You really don't know much about this, do you? It's obvious you don't realize that space and terrestrial radiation are different problems. On earth, it's mostly about stopping gamma and X-rays with lots of electrons. That means dense stuff like lead and tungsten. But water is an excellent gamma shield; consider the spent fuel pools at nuclear reactor sites.
Space radiation is all about energetic charged particles, which behave very differently from photons.
ApolloWasReal 10 months ago
@ApolloWasReal cosmic radiation passes through the earth. YOU DONT KNOW WHAT YOU ARE ON ABOUT.
lol dont start on spent fuel pools. lol yes sure the water does stop some of the radiation, just like any matter put between you and a radioactive source will invariably stop some of the radiation.
of course water becomes radioactive.
have you heard of alphas betas neutrons neutrinos protons...not to mention muons pions kaons, etc. these are space radiation, and nuclear reactor radiation too.
daenumen 10 months ago
@daenumen Water does not become radioactive just because it's exposed to radiation, except for neutron radiation. See the classic picture from just about any nuclear power plant showing workers standing around the spent fuel pool looking at the blue glow coming from down below. Without the water they'd be dead in minutes; with it they get less than on many airliner flights.
ApolloWasReal 10 months ago
@ApolloWasReal those are not nuclear reactors they are spent fuel pools that are usually kept way below operational temperature like 50celcius compared to the reactor itself.
the water is also very deep and may even be heavy water. and yes that water does become radioactive. neutrons/protons/alphas are emitted in almost all nuclear reactors and especially so when we are talking about spent fuel -- a mixture of different elements many of which are unstable.
daenumen 10 months ago
@daenumen No, those pools are filled with ordinary water, a very good radiation shield. The main difference between fuel in the pool and in an operating reactor, aside from the far lower amount of heat, is that there's little neutron activity. Boric acid is often added to pool water just to ensure that its far below critical. The fission products are contained inside the sealed Zr tubes. Unless they leak they don't get into the water. That's why people can stand around them.
ApolloWasReal 10 months ago
@ApolloWasReal Typically 40 or more feet (12.19+ m) deep, with the bottom 14 feet (4.26 m) equipped with storage racks designed to hold fuel assemblies removed from the reactor
sure 25ft of water above non-critical spent fuel kept far below operative temperatures....
daenumen 10 months ago
@daenumen Those spent fuel assemblies are extremely radioactive. Without water in the pool anyone nearby would receive a fatal gamma dose in a matter of seconds. With water, it's perfectly safe. You can even see how water stops electrons (fission products emit gamma + beta, and beta are electrons) within a few feet as evidenced by the Cerenkov glow. The point is that water is an excellent radiation shield despite being composed of two low-Z elements.
ApolloWasReal 10 months ago
@ApolloWasReal what about the fuel rod casings, and the 25foot or so of water between the top of the rod pile and the top of the tank. usually a bridge above the water that people walk on in a controlled atmosphere?
i certainly wouldnt touch a spent fuel assembly even with a control rod!
daenumen 10 months ago
@daenumen What's your point? I'm stating a fact: ordinary water, a low-Z material, is an excellent and widely used radiation shield. Are you saying it isn't? Those workers in nuclear power plants seem to think it is. There are even low power research reactors that operate in an open pool of water. We had one at college right next to the EE building. I never paid much attention to it, though I wish I'd known who to ask for a tour.
ApolloWasReal 10 months ago
@daenumen You don't even seem to realize that heavy water would be a *worse* shield in a pool than regular water. D2O is used in reactors with natural uranium because D is more transparent to neutrons than ordinary H, and that's exactly the opposite of what you want in a shield.
Admit it, you just said "heavy water" because it sounded cool, right?
ApolloWasReal 10 months ago
@ApolloWasReal opposites?
daenumen 10 months ago
@daenumen Low Z materials like Al, C, and especially H are much more effective at stopping charged particles and minimizing bremstrahlung photons. And yes, Al is the spacecraft reference shielding. 7 cm of Al will stop protons nearly to 150 MeV, though it's pretty rare to see spacecraft walls that thick. Look it up if you don't believe me.
Maybe this is why your conclusions have all been wrong?
ApolloWasReal 10 months ago
@ApolloWasReal no lead is better at stopping charged particles...
water is about 1/3 as effective as aluminium at radiation shielding.
Pb is some 4 times more dense than Al and it is some 100 times more shielding. as calculated at 120KeV energies. the behavior of the materials is also such that as energy increases Pb is proportionally more effective than Al at stopping radiation. this can be viewed simplistically though kinematics.
daenumen 10 months ago
@ApolloWasReal i may not be wrong, 7cm of Al may just stop a proton of energies nearly 150MeV.
regardless lead simply will stop more of those high energy protons.
eg: 1000 protons at 150MeV Al stops...1? maybe? Pb will stop considerably more, for the same thickness.
again. the space craft was built with aluminium for a light strong structure, to maximise delta-V not to protect the monkeys...i mean astronauts...
daenumen 10 months ago
@daenumen
" Pb will stop considerably more, for the same thickness."
How heavy would 7 cm of lead be compared to 7 cm of aluminum?
Weight is critical in space missions.
And weight for weight aluminum is superior to lead at shielding, and plastic is superior to aluminum.
Would you like a link to a study on the topic? You may find it illuminating.
ytmoog 10 months ago
@ytmoog no lead is still better weight for weight than al. it is some 4 times more dense, and 100 times more shielding at 120KeV.
once again you can refer to my last posts to see that you are not reading properly.
daenumen 10 months ago
@daenumen Sorry, simply ain't true. Aluminum is substantially better than an equal mass of lead. Yes, a cm of lead is better than a cm of aluminum, but that's only because it's vastly denser.
I'm reading just fine. It's you who aren't reading the references properly. ytmoog, roamingcroat and I could all direct you to some good ones. Would that do any good?
ApolloWasReal 10 months ago
@ApolloWasReal q-factor.
lead is significantly better than aluminium. honestly look up attenuation coefficients al is about as good as human flesh, and human flesh is far inferior to lead at stopping radiation, except for the bones...
daenumen 10 months ago
@daenumen You're seriously confused. q-factor has to do with the damage each type of particle does to biology. It has nothing to do with shielding. I've looked up the attenuation coefficients already, thank you, and I know what I'm talking about. When it comes to stopping charged particles, low-Z materials like water, aluminum, hydrogen and carbon are, kilogram for kilogram, more effective than high-Z materials like lead. Go look it up. Please?
ApolloWasReal 10 months ago
@ApolloWasReal duh i know q-factor is related to biological effects of radiation.... the crew where living human beings?! the radiation protection would be for them mostly?! (also for equipment...)
"low z metals are better at stopping radiation that high z"...
you just let me know when and where you build your reactor(s) so i can move somewhere else.
30 years or 2LiE SETS has sent you bonkers /wiki/Basic_Physics_of_Nuclear_Medicine/Attenuation_of_Gamma-Rays#Effect_of_Atomic_Number
daenumen 10 months ago
@daenumen Once again, in space the problem is NOT gamma radiation but charged particles, for which the rules are different! With sufficient mass you can use any material to shield any kind of radiation, but if you want to minimize mass in space, and you always do, you use low-Z materials, especially those with lots of hydrogen. The simple fact is that the existing CM walls could stop protons over 100 MeV. Very few had enough energy to get through.
ApolloWasReal 10 months ago
@ApolloWasReal ? so paper would be more effective than aluminium foil to stop an electron?
daenumen 10 months ago
@daenumen an equal mass of paper (carbon + hydrogen + oxygen) would probably be more effective than aluminum at stopping charged particles, yes. Assuming there are no pores or other empty spaces. But aluminum is already pretty good, certainly better than lead, and it would also help drain away any accumulated surface charge. That's also an issue in spacecraft design.
ApolloWasReal 10 months ago
@ApolloWasReal Excellent explanations. I had some hope, after reading all that, that daenumen would realize he's misunderstanding... well, everything, but I guess he'll persist in his ignorance for a while longer.
roamingcroat 10 months ago
@daenumen No, the video shows a transfer orbit inclination of about 32 degrees, just what A11 flew. It only looks higher because of the orientation, by design, of the orbital plane to the geomagnetic axis. The TLI burn was in-plane, and anything else would have been very wasteful of propellant. The VAB don't "reflect" anything. They're simply regions where charged particles from the sun have been trapped by spiraling around the earth's magnetic field.
ApolloWasReal 10 months ago
@ApolloWasReal exactly there isnt sufficient delta-V to do anything other than the optimum path, which is not to 'avoid' the VAB....actually avoid is a bit of a misnomer as i keep pointing out the AURORA.
again dont rely on the video, those VAB are not 'real', though the path might be from the data NASA has provided, it neither shows the actual VAB distribution nor does it show lunar capture which is fundamentally necessary regardless of what you think...seriously.
daenumen 10 months ago
@daenumen It's a model of the VAB. There's pretty much no way to get an exact representation of the VABs at any given time. Models are what you use in engineering to represent reality. Airplanes are designed in part using the Standard Atmosphere model, but even that is only true as an approximation of what's actually happening.
You say there isn't enough delta-V for this trajectory. How much delta-V do you need for this? How about for your "optimum" trajectory? You'll find they're the same.
roamingcroat 10 months ago
@roamingcroat yes but it is very much an approximation that you cannot refer to as being valid.
again, you seem to be stuck around these VAB's being a proof for NASA actually going to the moon:
1. NASA CATEGORICALLY STATED: VABS POSE NO SIGNIFICANT RISK.
2. NASA CLAIMS TO HAVE AVOIDED THEM (RUSSIAN SPACE STATION EXPERIMENT CONFIRMED VAB ARE DEADLY FOR TERRESTRIAL ESCAPE (IE ARRIVING IN ORBIT AROUND ANOTHER CELESTIAL BODY) OR EVEN HEO.)
daenumen 10 months ago
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@daenumen
"1. NASA CATEGORICALLY STATED: VABS POSE NO SIGNIFICANT RISK."
They don't.
"2. NASA CLAIMS TO HAVE AVOIDED THEM"
Because there was no reason to pass through the more intense regions of them.
"RUSSIAN SPACE STATION EXPERIMENT CONFIRMED VAB ARE DEADLY FOR TERRESTRIAL ESCAPE"
Flat out false. Russian missions such as Kosmos 110 showed exactly that for 'terrestrial escape' the VABs would not be deadly.
ytmoog 10 months ago
@daenumen "yes but it is very much an approximation that you cannot refer to as being valid."
Quite the opposite. It's very valid. If you're concerned about engineerd artifacts that use approximations, you'd better stop flying, driving, and living in buildings. Approximations are a way of life - there's no other way to account for the vaguaries of reality.
No one can tell me exactly how many 10 MeV particles there are this instant 6,000 miles directly above Ipswich. But there is a model...
roamingcroat 10 months ago
@roamingcroat sure but there is no room for approximation in such a mission. precision is fundamental.
daenumen 10 months ago
@daenumen "sure but there is no room for approximation in such a mission. precision is fundamental."
Amusing. Everything in engineering is about approximations. That's the only way you can make things work. We don't take general relativity into account when building airplanes*. Or quantum mechanics when building skyscrapers. Apollo used a numerical technique to calculate the needed orbit. I doubt it included perturbations from Mariner 7.
*Except for navigation by GPS.
roamingcroat 10 months ago
@roamingcroat you make it sound like childs play to get into space...
you think that if this were the case we would not yet have a lunar base? and holidays on the moon???
if approximations were all it took???!
you know the complication of aircraft is that of the approximations, it means for any airoplane it requires repeated manufacture and remanufature by a process of trial and error do they ever complete them!!!
look at SATurn development!!! not space age technology!
daenumen 10 months ago
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@daenumen
"you make it sound like childs play to get into space."
Hardly, but the calculations for the orbits is quite simple enough.
"you think that if this were the case we would not yet have a lunar base?"
Because chemical rockets are very expensive.
The cost of space flight is not in the calculations of the orbits, but the physical cost of the launch vehicle.
ytmoog 10 months ago
@daenumen "you know the complication of aircraft is that of the approximations, it means for any airoplane it requires repeated manufacture and remanufature by a process of trial and error do they ever complete them!!!"
Do you think approximations aren't used in aircraft design? My graduate research is in compressors. If you knew how little we actually know about the details certain disasterous flows that can happen to compressors, you would never fly again.
roamingcroat 10 months ago
@roamingcroat i said approximations are the complication.
you said "If you knew how little we actually know about the details certain disasterous flows that can happen to compressors, you would never fly again"
lol. prove my point more?
daenumen 10 months ago
@daenumen "prove my point more?"
Quite the opposite. The approximations used in the design of jet engines are good enough that, even if we don't know the details, we can keep airplanes from falling out of the sky. Plane crashes are very rare indeed, so it seems that approximations can do the trick.
Likewise with Apollo. The details may not be exactly known, but they can come up with a good model of reality.
roamingcroat 10 months ago
@roamingcroat TRIAL AND ERROR, NOT APPROXIMATIONS.
THE APPROXIMATIONS GET AN OBJECT FROM THE DESIGN STAGE TO A MODEL PROTOTYPE IN A WIND TUNNEL!!!!
airoplanes!!!
daenumen 10 months ago
@daenumen Engineering models are used to preduct performance of an airplane. They are based on everything from experimental data and on first principles.
Likewise with the VABs. Using experimental data, a model was made to describe the belts. This is an approximation of reality. Standard atmosphere is a similar approximation of reality. That's how you turn a problem into a managable one - by making approximations consistent with the real world.
roamingcroat 10 months ago
@roamingcroat exactly trial and error = experimental data.
see?
there isnt the scientific ability in the western world to justify human rights based on the behavior of gibbons let alone get a man on the moon.
grow up.
daenumen 10 months ago
@daenumen "exactly trial and error = experimental data."
OK... and how does that preclude a manned vehicle travelling through the belts. We had experimental data, you know. Otherwise we wouldn't even know about the belts...
roamingcroat 10 months ago
@roamingcroat yes we did, the russian experiments concluded from the SAA ALONE, that the belts were unpassable.
the N1 featured HUGE DELTA-V and incredible booster control with mutliple partial burn capacity on the main engine. the module also featured considerably greater radiation shielding...not just for the VAB but also COSMIC RADIATION....remember the sun spots at the time?? solar winds that knock out satellites never mind human flesh with a radiation penetrtn ~ that of Al.
daenumen 10 months ago
@daenumen
"the N1 featured HUGE DELTA-V"
Actually it had far less than the Saturn 5.
"the russian experiments concluded from the SAA ALONE, that the belts were unpassable."
False.
The Russian experiments such as Kosmos 110 show that is was perfectly possible to pass the belts.
ytmoog 10 months ago
@ytmoog yes it was possible to pass the belts...with heavy shielding, infact the first few probes that russia sent broke passing through the VAB as it destroyed the guidance systems.
they later refered and relied heavily on mechanical as opposed to electronic equipment, becuase of the huge amounts of radiation....
daenumen 10 months ago
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@daenumen
"yes it was possible to pass the belts...with heavy shielding"
Incorrect.
Kosmos 110 did not have heavy shielding yet the two dogs on board did not show the massive doses you assume.
Nor in fact do any probe, manned, dogged or otherwise which has ever passed into the belts.
ytmoog 10 months ago
@daenumen
"they later refered and relied heavily on mechanical as opposed to electronic equipment"
You should pass this along to all the commercial satellite operators who have satellites in the belts (which is a lot of them) they seem to have missed this.
ytmoog 10 months ago
@daenumen "yes we did, the russian experiments concluded from the SAA ALONE, that the belts were unpassable."
If you'll be so kind as to give me the citation for that, I'd appreciate it.
"the N1 featured HUGE DELTA-V and incredible booster control..."
And it failed to ever reach orbit. I don't actually know what sort of delta-V the N-1 was capable of for a Soyuz/LK combination (and from what I understand, they used EOR). Do you?
roamingcroat 10 months ago
@roamingcroat i may have already refered to it a while back in this thread...
it was a study done on the ISS aswell, as it passes through the SAA. infact the radiation is known to be so high that usually, unless an experiment is occuring on the SAA that the astronauts leave the station when it passes through the SAA because of the radiation risks.
they did some tests on materials, exposing them to SAA and seeing the damage etc.
daenumen 10 months ago
@daenumen I'm sure the SAA is studied a lot on the ISS. If you look at NASA's orbital tracks, it's even labled. But I'm asking specifically for the journal where the Russians published their conclusion that the VABs are unpassable. I'm not looking for your interpretation here, I'm looking for the article itself. So, the citation please.
roamingcroat 10 months ago
@roamingcroat look it up yourself, there are plenty of papers on it. im pretty sure ive posted it before on this thread.
look through all comments, only 777 of them. search SAA.
daenumen 10 months ago
@daenumen You're claiming there is a paper that supports your position. You have to cite it. That's how it works. I'm not required to go hunting high and low for a paper in order to evaluate your position if you don't tell me where it was published. If you can't produce the citation, your position has no merit.
And you never mentioned the citation before. You've certainly made your SAA claim before, but you never backed it up.
roamingcroat 10 months ago
wiki "The International Space Station, orbiting with an inclination of 51.6°, requires extra shielding to deal with this problem. The Hubble Space Telescope does not take observations while passing through the SAA. Astronauts are also affected by this region which is said to be the cause of peculiar 'shooting stars' seen in the visual field of astronauts.[8] Passing through the South Atlantic Anomaly is thought[9] to be the reason for the early failures of the Globalstar network's satellites."
daenumen 10 months ago
@daenumen
"wiki "The International Space Station, orbiting with an inclination of 51.6°, requires extra shielding to deal with this problem. "
Indeed, they commonly use plastic I would also note.
Astronauts aboard the ISS generally receive larger doses than the Apollo astronauts did because they pass through the SAA quite often, and spend far longer periods in space.
Which is why they need more shielding.
ytmoog 10 months ago
@ytmoog yet the apollo crew passed through the VAB at 40degrees spent some 1hr passing through it on the way there and back, and didnt have a shielded craft specifically designed to withstand only the low VAB radiation....which of course is safe, that is why there is extra radiation shielding on the ISS.
it was a lethal dose they would have gotten. specially with 1960's 'american' trial and error space tech.
daenumen 10 months ago
@daenumen
"and didnt have a shielded craft "
The Apollo CM was shielded.
"low VAB radiation"
The VAB's are not 'walls' they are donut shaped fields with the most intense regions above the magnetic equator.
Travel at a 40 degree angle to the magnetic equator and you never pass through the more intense regions.
See this video for a demonstration of that.
ytmoog 10 months ago
@ytmoog I wish there was just one hoaxer who would show their work. You know, actually give the calculations, and be open to criticism.
Of course, if that happened, they wouldn't be hoaxers for very long, now would they.
roamingcroat 10 months ago
@roamingcroat
That would be a change :)
ytmoog 10 months ago
@roamingcroat look back through the thread, i have done several calculations on here for radiation dosage etc.
daenumen 10 months ago
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@daenumen "look back through the thread, i have done several calculations on here for radiation dosage etc."
The hell you have. You've done a lot of "that's deadly" and not a whole lot of "here's why."
But I'd like to see your numbers for this 3x faster free return trajectory that requires less delta-V than Apollo. That would be a real treat.
roamingcroat 10 months ago
@ytmoog what shielding was present on the CM? oh yes... 'heat shield' for re-entry...
err... at 51 degrees the ISS passes through the SAA....
the video again is an approximation without SAA etc etc. and still passes through considerably radiated regions of space,
again we arent even considering cosmic radiation between earth and moon...
daenumen 10 months ago
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@daenumen
"what shielding was present on the CM?"
The walls of the CM had about 8 gcm^-2 of material.
"err... at 51 degrees the ISS passes through the SAA"
That south-Atlantic must be pretty big..
ytmoog 10 months ago
@daenumen
"again we arent even considering cosmic radiation between earth and moon..."
Which is irrelevant over the short duration of the Apollo missions.
For a year long Mars mission that would be the most significant source. But for Apollo it was not ..
ytmoog 10 months ago
@ytmoog short duration of several days? yet exposure to the VAB for 30 mins was sufficient to reduce that time to 20 mins? and not bother about radiation shielding?>!
other than a honey comb hollow structure between two aluminium sheets, with chemical heat shields painted and fixed on...
right...
daenumen 10 months ago
@daenumen
"other than a honey comb hollow structure between two aluminium sheets"
With a total mass of 8g cm^-2, easily enough to block the vast majority of the protons in the inner VAB.
ytmoog 10 months ago
@ytmoog you try getting 8g/cm^2 with aluminium sheets...
density of aluminium is 2.7g/cm^3 ie you need some 3cm thick hull. or average of 1cm of honey comb and 1cm thick aluminium...
i suppose its possible but 3cm of Al i PROMISE YOU, wont stop radiation. nearly as well 1/4 that thickness of lead. ie same total mass.
daenumen 10 months ago
@daenumen
The mean range of a 20 MeV Proton in aluminum is only 2 mm. so yes, 3 cm of Al will stop radiation.
And as for the materials, studies done by ESA show that the bast material weight for weight for reducing radiation exposure was liquid hydrogen. With Plastic superior to AL which was superior top lead.
Lead was particularly poor due to the large amounts of Bremsstrahlung produced.
In short lead is the worst material possible for shielding against particle radiation in space missions.
ytmoog 10 months ago
@ytmoog sure but stopping a 20MeV proton in aluminium produces gamma/x-rays that will effect the people within the craft.
infact there is sufficient x-ray radiation during the passing not only did all of the actuall film get destroyed even though it was in a lead box, but also enough to take whole body x-rays for 20-40mins.
daenumen 10 months ago
@daenumen
"gamma/x-rays"
Bremsstrahlung radiation it's known as. And not from Aluminium, which is another reason why it is used (along with plastic) instead of lead.
The amount of Bremsstrahlung depends on the mass of the atoms in the material. Heavy atoms such as Lead produce much more than lighter atoms such as Aluminium.
"infact"
This 'fact' is one you made up.
ytmoog 10 months ago
@ytmoog yes! for a given number of particles colliding with a al or pb block pb will produce more 'stoppage radiation' that is because pb pound for pound is better than al at stopping faster moving particles, becuase the nuclei are larger.
its why lead is some 100 times better pound for pound, as i detailed in calculations several days ago... and also before that in terms of attenuation...some weeks/months ago...
daenumen 10 months ago
@daenumen
No, a Pb shield weight for weight would result in a bigger radiation dose than Al.
And Plastic is better than Al. Which is why it is used.
ytmoog 10 months ago
@ytmoog pb would reduce solid particle radiation, though may increase bremsstrahlung radiation dose.
a gamma ray is far more likely to pass through a human body than an proton or electron and certainly an alpha particle
THIS IS WHY I MENTIONED Q-FACTOR. agian i did the q-factor calculation for my radiation calculation, something you are yet to display an awareness of...
daenumen 10 months ago
@daenumen
" though may increase bremsstrahlung radiation dose."
Which is exactly why lead is not used.
As for Gamma radiation, that is irrelevant.
ytmoog 10 months ago
@ytmoog yes exactly it increases gamma rays over particulate radiation... lead is better...
daenumen 10 months ago
@daenumen
"yes exactly it increases gamma rays over particulate radiation... lead is better..."
Lead would be better if you wanted to give your astronauts a higher dose of radiation and increase the weight of your craft.
But in reality you don't want that...
ytmoog 10 months ago
@ytmoog ok i agree to disagree, you to your views me to mine. goodbye.
daenumen 10 months ago
@daenumen
"ok i agree to disagree"
You are disagreeing with every radiation physicist from anywhere who has ever studied the problem of blocking VAB Protons.
And indeed I have a stack full of papers on the subject if you are interested.
What you have is the mistaken assumption that lead is good at stopping alpha particles... which was funny btw.
ytmoog 10 months ago
@ytmoog look at todays radiation science, the atomic agency couldnt even determine a safe reactor...they are lead by US who are the only nation to commit genocide with nukes...etc etc etc etc
daenumen 10 months ago
@daenumen Poisoning the well again, huh? Why do you engage in such obvious fallacies?
ApolloWasReal 10 months ago
@ytmoog why use lead for radiation shielding then???? even if you get a hospital or dental x-ray done, they given you a lead jacket to wear, not an aluminium one.
please check the data sheets, aluminium is as penetrative as human flesh... lead is considerably more resistant to radiation penetration:
remember the model of the atom? little nucleus lots of space? 208 to 27????
daenumen 10 months ago
@daenumen
Because X-Rays are not particle radiation and weight does not matter.
And check the data sheets, Aluminium is far better at reducing radiation dosage than Lead when protecting against high energy proton radiation.
ytmoog 10 months ago
@ytmoog well i know from experiment alpha particles are more readily stopped by lead than by al, and that gamma rays are similarly more readily stopped by lead than by aluminium
again lead is far more dense than human flesh which is almost identical in behavior to aluminium.
SHOW SOME PROOF OR AGREE TO DISAGREE. ive already posted data regarding lead and aluminium that proves otherwise several days ago.
daenumen 10 months ago
@daenumen
"well i know from experiment alpha particles are more readily stopped by lead than by al"
Alpha particles can be stopped by paper...
Experiments to show that are easy to do as well...
As for evidence see the paper : "Shielding of manned space stations against van allen belt protons" by the Oak Ridge National Laboratory. September 1986
ytmoog 10 months ago
@ytmoog the paper by oak ridge does not even consider pb.
daenumen 10 months ago
@daenumen
Because Pb would be a stupid material for shielding against VAB protons. And the engineers who designed the ISS are not stupid.
What the paper shows is that the lighter materials are better weight for weight.
ytmoog 10 months ago
@ytmoog err ISS only passes through the lower edge of the SAA, not through the VAB.
'weight for weight' pb better
Despite efforts to improve radiation shielding on the ISS compared to....such as Mir, radiation levels within the station have not been vastly reduced,...further technological advancement will be required to make long-duration human spaceflight...a possibility.....the radiation levels experienced on ISS are not excessively greater than those experienced by airline passengers.
daenumen 10 months ago
This has been flagged as spam show
@daenumen
"err ISS only passes through the lower edge of the SAA, not through the VAB."
The SAA IS part of the lower VAB.
And no, lead is far worse at protecting against high energy protons, part in thanks to the very high levels of secondary radiation it produces.
ytmoog 10 months ago
@daenumen
"technological advancement will be required to make long-duration human spaceflight" ... "further into the Solar System" ... "a possibility"
You certainly seem to have the art of quote mining down to an art. Note also the words 'long duration'.
The article they reference is interesting as it talks of Mars missions, as well as the use of plastic as a radiation shield and why shielding using materials with lighter nuclei are used.
ytmoog 10 months ago
@ytmoog mars?!
daenumen 10 months ago
@daenumen
Yes a Mars mission lasting years would require a big advance in radiation shielding to be successful.
Where as a short duration lunar mission lasting a few days would not.
ytmoog 10 months ago
@ytmoog i have read that 2 in 8 astronauts exposed to LEO thats below VAB radiation for 80 days were found to have chromosomal mutations that may be possibly pre-cancerous.
a mission of a few days through the VAB twice and solar winds and cosmic rays etc.
daenumen 10 months ago
@daenumen Believe it or not, the Skylab and MIR astronauts received considerably more total radiation than the Apollo lunar astronauts. That was because of their much longer missions and the high orbital inclination that took them frequently through the SAA. This is all well documented. I don't know how they compare to the ISS because I don't know how they compare in shielding.
ApolloWasReal 10 months ago
@daenumen
"thats below VAB "
Except of course the SAA which is part of the VAB.
"80 days"
As compared to the 10 to 14 days spent by Apollo astronauts.
Recorded radiation doses are much higher for ISS astronauts as they spentfar more time in space.
ytmoog 9 months ago
@daenumen Even though both would be outside the earth's exosphere and subject to cosmic rays and solar proton events, a Mars mission is much harder to shield than a moon base because the trip to the moon is only 3 days and the moon base can use lunar soil for shielding. A trip to Mars takes 6 months and you must bring everything with you, including shielding. Water and liquid hydrogen fuel tanks are commonly suggested since they need those materials anyway.
ApolloWasReal 10 months ago
@ApolloWasReal use lunar soil for shielding, like apollo did?.
so take the kitchen sink with you to mars?
daenumen 10 months ago
@daenumen Well, that would be the problem -- when you go to the moon, you can use what's there for shielding. When you go to Mars, unless you stop at the moon or an asteroid along the way you have to take everything with you, including any radiation shielding. So the usual proposal is to reuse materials like water and fuel as shielding whenever possible. Water is hydrogen-rich, and the fuel would either be liquid hydrogen or hydrogen-rich, so it would make good shielding for particle radiation.
ApolloWasReal 10 months ago
@daenumen
"use lunar soil for shielding, like apollo did?."
Apollo did not need to as they spent only 3 days on the surface, not months as the new plans called for.
ytmoog 9 months ago
@daenumen Apollo didn't need any shielding beyond the structure of their spacecraft for the simple reason that the missions were too short for radiation to be a serious problem. They did gamble (and win) on there being no large solar proton events; that was just one of the several risks they faced. For longer missions, chances are good that there would eventually be a solar proton event big enough to cause illness, so building a shelter will probably be one of the first things they'll do.
ApolloWasReal 9 months ago
@daenumen Lead is widely used for X-ray and gamma shielding simply because it's dense, and minimum volume is more important than weight. Pb packs a lot of electrons (which do the shielding, NOT the nuclei) into a small volume. Unfortunately, you can't have electrons without the much heavier protons balancing their charges. And you can't have a stable nuclei made entirely of protons so you need the heavy neutrons too.
Sometimes tungsten, tantalum and even depleted uranium are used.
ApolloWasReal 10 months ago
@daenumen What you don't seem to understand is that most of the shielding problems on earth involve X and gamma rays, NOT the extremely energetic charged particles found in space. (Beta radiation from fission products consists of energetic electrons but they're easily stopped by anything that can stop the associated gammas). As you've already been told, LH2 is the best particle shield per unit mass. One reason is the almost complete lack of useless, heavy neutrons.
ApolloWasReal 10 months ago
@daenumen WRONG!! Go back and study basic matter theory. Remember that atoms are made up of tiny but dense nuclei surrounded by electron "shells". They consist largely of empty space.
The incident particles -- gamma photons, electrons, ions or protons -- interact almost exclusively with the shield electrons, NOT the nuclei. The only exception are neutrons, for which you use nuclei with large neutron cross sections like B-10. Neutrons are not a problem in space unless you have a reactor.
ApolloWasReal 10 months ago
@ApolloWasReal reactors is space? neutrons?!
daenumen 10 months ago
@daenumen You asserted that the nuclei in shields do the work. That is simply incorrect except for neutron shielding, which you don't need in space unless you have a nuclear reactor. Cosmic rays are always charged particles; that's how they get accelerated to fantastic energies by interstellar magnetic fields. Also, free neutrons have a 15 minute half life.
Except for neutron shielding, the electrons in a shield do the work. The heavy nuclei just balance the charge.
ApolloWasReal 10 months ago
@ApolloWasReal are you serious?!
daenumen 10 months ago
@daenumen Serious about what? Reactors in space? The Americans and Russians have both flown them. The US just once, to my knowledge, the Russians many times. They had several come back down on people because they used them to power marine radars, and radars like to operate close to their targets. Reactors are probably better used for interplanetary travel, especially far from the sun where solar power is problematical.
ApolloWasReal 10 months ago
@daenumen Oh, and thanks to the Russians' use of reactors in space, one important category of space junk consists of droplets of NaK, a sodium-potassium metal alloy liquid at room temperature and used as reactor coolant. Although liquid, it has a very low vapor pressure so unfortunately they will have long orbital lifetimes.
When Apollo started, both micrometeoroids and radiation were investigated. Today, artificial junk is the primary hazard in orbital flight.
ApolloWasReal 10 months ago
@ApolloWasReal ok.
daenumen 9 months ago
Correction to the above -- MOST of the work in a shield for photons (X/gamma rays) and charged particles is done by the electrons through Compton scattering and the photoelectric effect. >1.02 MeV (2x electron mass) "pair production" begins: the gamma photon approaches a nucleus and is turned into an electron/positron pair. The positron soon encounters another electron and annihilates, producing more photons, which along with the electron are eventually stopped by the shield electrons.
ApolloWasReal 9 months ago
@daenumen Once you understand that (except for neutrons) the electrons in a shield do all the work, you can begin to understand why high Z materials are worse. For one, high Z materials have proportionately more neutrons that add mass without improving shielding. But the main reason is that the inner electron shells are bound more tightly to a high-Z nucleus, and when they're excited by an incident particle they emit much harder Bremstrahlung photons.
ApolloWasReal 10 months ago
@daenumen All this is very widely documented in many, many references. Most of them aren't even from the bogeymen at NASA that you seem to distrust so much. Just consult one and you'll quickly learn that low-Z materials are better particle shields. Why do you keep asserting the opposite?
ApolloWasReal 10 months ago
@ApolloWasReal "Why do you keep asserting the opposite?" i could ask you the same thing! i wont.
daenumen 10 months ago
@daenumen I keep asserting that low-Z materials are preferred for particle radiation shielding because that's exactly what all the references say. And you?
ApolloWasReal 10 months ago
@daenumen That heat shield, made of phenolic resin, actually covered the entire command module, although it was thickest on the base. Phenolic consists primarily of hydrogen and carbon, both excellent low-Z shields for energetic charged particles. And that was on top of the double-hulled aluminum and stainless steel structure.
The Apollo CM that you denigrate so much was actually shielded quite well. The proof is in the dose figures returned from each mission.
ApolloWasReal 10 months ago
@ApolloWasReal . "Phenolic consists primarily of hydrogen and carbon, both excellent low-Z shields for energetic charged particles"
NASA tell you this?
daenumen 10 months ago
@daenumen
"Phenolic consists primarily of hydrogen and carbon, both excellent low-Z shields for energetic charged particles"
Did you not read that paper?
In short any lab working with the problem of shielding against protons of energy levels found in the VAB shows this.
NASA does not have a monopoly on space, nor physics.
ytmoog 10 months ago
@ytmoog no but US does use political leverage to try to stop others from getting into space/ developing nuclear technology/ increasing oil prices/ evading capital punishment (aka) capital labour / etc
daenumen 10 months ago
@ytmoog Energetic particles (protons, etc, upwards of several hundred MeV) are now widely used in cancer therapy, so there's now a fair bit of non-NASA literature on protection against charged particle radiation, not just gamma (photon) radiation. Seems the secondary neutrons are often the limiting problem. Shielding materials include water, concrete (often with barium aggregates), earth, steel, polyethylene, etc. A variety seems best.
ApolloWasReal 10 months ago
@daenumen What, that phenolic consists mainly of hydrogen and carbon? No, NASA didn't need to tell me this, any organic chemistry or polymer chemistry textbook tells me this.
One can see the remains of the phenolic heatshields on any of the Apollo command modules in museums. In flight it was covered with a thin aluminized Mylar layer used to reflect solar radiation that burned off quickly on re-entry. The orange/brown color is very characteristic.
ApolloWasReal 10 months ago
@ytmoog infact you will notice that the aluminium was perhaps 7cm thick...but it was two sheets of aluminium with a honeycomb core inbetween...lots of empty space to shield lol.
did you see how much room there was for the 3 crew members in the CSM? 2 m^3 each...
daenumen 10 months ago
@daenumen
Check the units.
8 gcm^2, means 8 grams of material in each square cm.
And are you really claiming that one chest X-Ray would kill you?
ytmoog 10 months ago
@ytmoog i will pay you a squillion squids if you fit 1g into a cm^2...
1 chest x-ray potentially could, it only takes one match to burn a thousand trees!!!
daenumen 10 months ago
@daenumen
"i will pay you a squillion squids if you fit 1g into a cm^2..."
Go get a glass of water.
"1 chest x-ray potentially could"
Please find one person who has ever died from one chest X-Ray.
ytmoog 10 months ago
@ytmoog find one person who died of a chest x-ray? im pretty sure thats illegal unless you are a doctor writing a research paper...might get a cancer named after you...
i dont think medical proffesionals could diagnose such a result from such a procedure. they wouldnt even look at such a thing, they are trained to make it feel safe for patients.
they do however limit your exposure to x-rays, ie you can only have so many in a year. people with brittle bones would know. will kill cells defo!
daenumen 10 months ago
@daenumen
"they do however limit your exposure to x-rays" Of course, because while one would provide no risk, many of them might.
Same for the VABs, passing through them is safe... but it is wise to limit your exposure.
ytmoog 10 months ago
@ytmoog lol "wise to limit your exposure"
do you think they briefed the astronauts along these lines "right 'monkeys'... pass through the VAB pronto, we dont want you lingering around those charged particles...who knows what might happen...you might even figure out this is all a hoax! and we cant have hoaxers undermining our mission...remember apollo 1? thats because they didnt listen. now go! to the moon with you!...great apes honestly...really great apes..."
daenumen 10 months ago
@daenumen Each astronaut had a personal radiation dosimeter that they regularly read off to Houston, chief. The astronauts were aware radiation was a concern.
roamingcroat 10 months ago
@roamingcroat do you know what dose they read out to houston? or footage/data source containing that info?
daenumen 10 months ago
@daenumen You can read the Apollo Lunar Surface Journals and the Apollo Flight Journals for that information. Keep in mind the PRDs were all initialized at different values to make sure they weren't mixed up.
The easier bet is to read some of the mission reports. Look on the NASA Technical Report Server (NTRS) for a report on radiation during the Apollo missions (maybe it's in the mission report - I'm not sure).
roamingcroat 10 months ago
@roamingcroat hmmm so no 'live' evidence... and no fixed reference...
daenumen 10 months ago
This has been flagged as spam show
@daenumen " so no 'live' evidence"
Sigh...128:27:11 into Apollo 14, Shepard reports on both his and Mitchell's PRD.
"and no fixed reference..."
There was a fixed reference for each PRD. However they were all offset from each other in order to ensure the readings were, in fact, for the correct astronaut.
roamingcroat 10 months ago
@roamingcroat apollo 14...
do we have specs for PRD and initial reference? starting reference may effect efficiency.
daenumen 10 months ago
@daenumen I'm sure the PRD results are in the mission reports. You could also look at the Apollo Flight Journals to see what the first reading was to get an estimate of what the reference point was.
roamingcroat 10 months ago
@roamingcroat well ultimately apollo flight data wont shed more light than showing figures that look reasonably survivable.
if the science of the calcuations of q-factor etc etc are correct then yes apollo had a major problem without shielding, if the science is wrong then why do we not know about the corrections (..for mankind?)
daenumen 10 months ago
@roamingcroat I recommend "Apollo Experience Report: Protection from Radiation". They give the doses through Apollo 15. The mission reports give them too.
I can't believe our friend thinks NASA was so stupid that they wouldn't record the starting point of each dosimeter. But when you already think you're always right and everybody else is wrong, such a further leap of absurdity is not hard to make.
ApolloWasReal 10 months ago
@ApolloWasReal I was reading the requirements for the LM the other day, which included a discussion about the radiation protection requirements. If I listned to hoaxers, I'd be told there were no such requirements. The information is out there and very easy to find, if these hoaxers would just look for it. Instead, they invent convoluted explanations for rather mundane things.
roamingcroat 10 months ago
@roamingcroat so astronauts aware...former nasa spokesperson thinks they are safe...
fair enough, at least they tell the right people the important facts.
daenumen 10 months ago
@daenumen The principle is ALARA - As Low As Reasonably Achievable. In short: 1. There is NO evidence that anything less than 5-10 rem will increase your long term cancer risk even slightly. 2. Small radiation doses may actually be beneficial (radiation hormesis). 3. Medical X-rays are FAR below the levels known to cause illness. 4. But, despite all this, radiation doses are still kept as low as reasonably achievable, even when they're already far below the limits.
ApolloWasReal 10 months ago
@daenumen The one big drawback to ALARA is that it scares the public. Because the principle is to minimize radiation exposures as much as possible even when they're far below the threshold known to cause even delayed illness, the public gets the erroneous impression that even the small exposures associated with medical X-rays are dangerous.
They're not. It's just that there's no point in also exposing the radiologist. And since it's so easy to shield him, why not do so?
ApolloWasReal 10 months ago
@ApolloWasReal why not bother with the lead jacket for the patient? ALARA LARA laughs.
daenumen 10 months ago
@daenumen
Ok, as you are a bit slow I will expand.
1 g cm^2 when used in papers referring to shielding against radiation says that the material used to block the radiation has 1 gram of matter in each square centimeter.
What the actual width of the material happens to be is irrelevant, all that matter is the total mass.
So in the case of the CM each square cm of the walls has at least 8 grams of matter between the outside and inside.
Shall I need to expand more?
ytmoog 10 months ago
@ytmoog thanks.
right... 1 gram... in 1 cm^2... so do i have infinite mass in 1 cm^3?
im pretty sure density does play a part...as i discussed many days ago, and many days before that AND did a radiation calculation... well anyway... do please continue.
my reading of the CM design was 2 sheets of aluminium on either side of a hollow aluminium honey comb. its on wiki*.
daenumen 10 months ago
@daenumen
"so do i have infinite mass in 1 cm^3?"
Not unless you have a black hole.
Or if you meant to write in 1 cm^2 then not unless your material is infinitely thick... like you :P
ytmoog 10 months ago
@ytmoog right....
daenumen 10 months ago
@daenumen You are having obvious difficulty in understanding some really basic concepts here. And that doesn't engender a great deal of confidence in your conclusions, especially as they're contradicted by empirical data (most of the Apollo astronauts are still alive in their 80s). When they say 8 g/cm^2, that means that if you cut the wall into blocks 1x1cm by whatever the wall thickness is, it'll have a mass of 8 g.
The point is that wall mass per area, not thickness, is what counts.
ApolloWasReal 10 months ago
@ApolloWasReal the wall doesnt give 8g in all places
2 FLAT SHEETS OF AL AND A HONEY COMB STRUCTURE, HOLLOW, MADE OF AL SHEET, BETWEEN THOSE TWO FLAT SHEETS OF AL.
that was the hull. 8g/cm^2 AVERAGE.
daenumen 10 months ago
@daenumen The astronauts all remarked that the CM became considerably roomier in zero gravity. It was common for one to sleep in the "tunnel", the space leading to the LM. There was also room under the couches, which were well ahead of the rear bulkhead. Apollo may be cramped by modern standards but it was considerably roomier than Gemini and Mercury.
ApolloWasReal 10 months ago
@daenumen
"look it up yourself, there are plenty of papers on it."
There are indeed loads of papers on the VABs and radiation shielding. etc..
I have read many of them.
None of them agree with you.
And no, you have posted no source for anything as far as I can see.
ytmoog 10 months ago
@ytmoog well okay. but ISS is usually emptied when passing through SAA...
besides why else did nasa avoid the densest parts of VAB...
you seem to be stuck between accepting NASA that the VAB are SAFE and accepting the dangers of the VAB to accept what NASA did. lol...
daenumen 10 months ago
@daenumen "you seem to be stuck between accepting NASA that the VAB are SAFE and accepting the dangers of the VAB to accept what NASA did. lol..."
I'll ignore all thats wrong before this part...
Swimming is safe. Parachuting into the middle of the Atlantic and trying to swim there is not. The VABs have the same issue. The Apollo trajectories were safe. Hanging around in the middle of the VABs for a month is not. It's not black and white - there are degrees of danger.
roamingcroat 10 months ago
@roamingcroat refer to my wiki post
daenumen 10 months ago
@daenumen
"but ISS is usually emptied when passing through SAA."
No it isn't. The ISS is permanently manned and has been for a long time now. Yet is passes through the SAA regularly.
Passing briefly through the regions of the belts the Apollo missions did is perfectly safe.
Passing through the central regions would also be safe, but the increased dose 'may' increase long term chances of health issues such as cataracts.
'Safe' is a sliding scale of risk.
ytmoog 10 months ago
@ytmoog again wiki post... SAA break satellites, ISS had boosted shielding, and it wouldnt surprise me if that shielding was on a single module for weight restriction reasons, and that the crew have to spend their time in there or die.
daenumen 10 months ago
@daenumen "...and it wouldnt surprise me if that shielding was on a single module for weight restriction reasons, and that the crew have to spend their time in there or die."
In Wikipedia, this would be marked with [Citation needed]. So... source?
roamingcroat 10 months ago
@roamingcroat i dont need to cite an opinion. check wiki policy.
daenumen 10 months ago
@daenumen Wiki policy is that you can't post your opinion. You're wrong, and it would do you some good to realize that.
Can I have your orbital elements after TLI now, please?
roamingcroat 10 months ago
@roamingcroat no you can post an opinion as long as its made clear that it is an opinion.
errr.... after TLI it would be AN APPROXIMATION to use an eccentric orbit.
secondly its for orbiting satellite data not for lunar transfer!
i can give them to you, but not after we agree how much i will be paid and some contract is drawn up.
daenumen 10 months ago