|
Post by laurel on Nov 9, 2009 19:09:59 GMT -4
|
|
|
Post by Jason Thompson on Nov 9, 2009 19:20:16 GMT -4
I find the arugment that NASA would recklessly risk the lives of their astronauts is honestly a silly argument. So do we, but we're not the ones making that argument. It is only to those who don't grasp the complexities of radiation and space travel that it seems reckless. Where are the professional physicists, engineers and space scientists who agree it was reckless to make the trip to the Moon because of the radiaiton environment? Isn't their silence rather telling? Agreed. Only you seem to think they weren't sure it was safe. But that is not the only way. Not by a long shot. It does remove several of your quotes from consideration, however. No, because this is a three-dimensional problem. You are still talking of altitude in ways that indicate you still view the van Allen belt as all-encompassing: i.e if they go 589 miles high they are always going to encounter the belts. The belts are belts, not spheres, and they are also somewhat amorphous. They do not have clearly defined boundaries where you can sit on one side safely and on the other suffer huge radiation damage. The radiaiton increases gradually into more intense regions as you move closer to the Earth's equatorial plane. The inner belt in particular can be moved through in such a way as to avoid the most intense regions because of the inclination of the orbit. You also need to take into account that the belts are compressed on the sunward side of the Earth, and this is the direction the Apollo 11 spacecraft was going (confirmed by the phase of the Moon during the flight). They therefore leave the belts more quickly than if they were going the other way, away from the Sun. No. Three-dimensional problem. Stop looking at it in a two-dimensional way.
|
|
|
Post by Jason Thompson on Nov 9, 2009 19:43:43 GMT -4
Here's a sketch I made of the type of thing I am trying to describe. Yes, it is oversimplified, but I hope it gives you an idea of what we are talking about. It's a side vide of the Earth/Moon system with the belts. The Earth is on the left, the Moon on the right. The finely dotted line represents the trajectory a spacecraft travelling to the Moon at zero inclination would follow viewed from this angle. The Apollo spacecraft were not at zero inclination: they were orbiting with an inclination of about 25 degrees or so. Firing themselves to the Moon from an orbit so inclined would follow a trajectory more like the dashed line. You can see how that line avoids the most intense regions of the belts. Again, the sketch is an oversimplification, but it conveys the key point: just because the van Allen belts extend to a certain altitude doesn't mean that any spacecraft at that altitude will be in them. They can be avoided to a degree.
|
|
|
Post by echnaton on Nov 9, 2009 22:53:16 GMT -4
Im getting a lot of corrections for info that I posted. That's fine, you can take it up with the people who posted the info and tell them to correct their websites.
So why are you making claims based on information that you cannot verify. If you bring the claims into the argument, you are responsible for the accuracy.
I find the arugment that NASA would recklessly risk the lives of their astronauts is honestly a silly argument.
More unfounded accusations and question begging. Why do you still contend that NASA was reckless if you have distanced yourself from the sources that you brought in to show that they were?
So I doubt NASA would send anyone into a sea of radiation until they were absolutely sure that it was completely safe.
When you are the NASA Chief you can make the call as too what is too dangerous. Complete safe is a entirely unreasonable standard. In the mean time, since you backed away from your sources on the level of danger, please provide some real information that this "sea of radiation" was excessively dangerous.
First what was the duration that the craft was flying through the belts? This is a basic question to ask before arriving at a conclusion. You have already com to your conclusion and are notw trying to back fill your story.
|
|
Bob B.
Bob the Excel Guru?
Posts: 3,072
|
Post by Bob B. on Nov 9, 2009 23:41:02 GMT -4
Im glad that we now know that the Apollo missions, at least Apollo 11, orbits the earth 1.5 times before making its way to the moon. Now the responses I have read do not deal with where the craft is while its making its orbit, meaning, how high is it. And how long it takes. The parking orbits were about 100 nautical miles for Apollo 8-14 and about 90 nautical miles for Apollo 15-17. The period was about 88 minutes. First what was the duration that the craft was flying through the belts? I asked this in my last post but nobody commented. So I will ask again. They really didn't fly through the belts, they just skirted the edges. You need to start thinking three dimensionally. The following might help you; the chart at the bottom of the page gives distance from Earth versus time: www.braeunig.us/space2/trajectories/free-return.htmAnd one way to do that is to send animals first, unfortunately. Yes, that's one way. Can you name another way?
|
|
|
Post by Count Zero on Nov 10, 2009 3:17:33 GMT -4
Don't forget that the Earth's magnetic axis is tilted with respect to its rotation axis, thus the Van Allen belts are inclined to the equator. This makes it even easier to pass either north or south of the areas of maximum intensity. You don't need to incline your spacecraft's orbit as much.
|
|
|
Post by JayUtah on Nov 10, 2009 3:34:56 GMT -4
I linked most of the places that I got the info.Unfortunately it is not possible to link to the source of your (mis)interpretation of that information, because that is you. And it is to you that we turn to receive a justification for the interpretation. I find the arugment that NASA would recklessly risk the lives of their astronauts is honestly a silly argument.It would be a silly argument if that's what was being made. NASA is "reckless" only because you either ignorantly or willfully exaggerate the risk. Maybe NASA (and the rest of the appropriately qualified scientific authorities) don't see the risk to be as great as you've made it out to be. So I doubt NASA would send anyone into a sea of radiation until they were absolutely sure that it was completely safe.There is middle ground between recklessness and timid caution. Crab fishing is not completely safe, yet there are people who risk their lives to do it just so you can have a tasty treat on the dinner table. Likewise there are people willing to shoulder a risk in order to expand the frontiers of knowledge, and to fly some really cool spacecraft. That does not absolve the engineers from their obligation to make it as safe as possible. But it was not nor will ever be "completely safe." When you run your own space program you can decide how much risk to take. Until then, your personal standards of risk do not apply. You cannot rationally use them to measure whether someone else achieved a certain thing or not. As for the American taxpayer, I'm pretty sure he understood the risk of space travel, and that this understanding had much to do with the ticker-tape parades and other accolades that were heaped upon the returning crews. You don't get to be a hero by waiting until you're absolutely sure it's perfectly safe. Well I thought the VAB issue was over. But I guess not, not for me at least.It is for Dr. Van Allen. He heard the hoax theories, especially the part about how the trapped radiation belts he discovered would have prevented travel to the Moon. He specifically repudiated those theories, called them "nonsense," and reiterated that nothing about the cislunar radiation environment would have prevented the Apollo missions. You seem to be one to urge others to take statements at what appears to be their face value. Dr. Van Allen cannot have stated the case any more succinctly. If you're not willing to accept what he plainly stated, then please have the courtesy to leave the subject alone. "Duration duration...." Yes I get it. But I disagree it solves the problem, it just asks for more clarification.Not to those properly qualified in health physics and space engineering. You are trying to impose protocols intended for longer missions upon short-term missions. You do not seem to understand that the risks to which you insist on handwaving are sufficiently mitigated by a shorter-term mission. The chances of lethal solar activity were miniscule. The threat from GCR was non-existent. First what was the duration that the craft was flying through the belts? I asked this in my last post but nobody commented. So I will ask again.The answer was given. It was that your question was too simplistic. You expect there to be a precisely-timed period for operation within "the belts." The trapped radiation environment is not that cut-and-dried. If you want to establish what you believe to be an acceptable lower threshold for absorbed dose, then it can be roughly determined how long the spacecraft was subjected to that level or greater. I would say that's below the Van Allen Belts. Safe area.No. I described why your formulation of the problem doesn't work. The interaction between an outbound translunar trajectory and the trapped radiation belts is a complexly three-dimensional problem. You're trying to reduce it to a mere geodetic altitude. The universe will not change its behavior simply so it can fit within your understanding of it. Now were they in the belts for a duration of 4 to 5 hours and if not, why not?Why not? Inclination. Please either take the time to learn something about orbital mechanics or stop arbitrarily deciding who is right and who is wrong.
|
|
|
Post by gillianren on Nov 10, 2009 4:03:06 GMT -4
Was, Jay. It was for Dr. Van Allen.
Note to tedious HB-types--"was" because he is dead, not because he changed his mind.
|
|
|
Post by Mr Gorsky on Nov 10, 2009 6:37:08 GMT -4
I find this "NASA wouldn't send out astronauts unless they knew it was completely safe" argument to be a little tiresome. There is very little in this world that could be classed as "completely safe". Getting into my car and driving into the office every day is a risky business - it only takes one idiot to do something stupid and you can end up in the hospital (or worse), as my parents can testify.
The astronauts in question were military test pilots, they had spent their entire careers doing jobs that were inherently risky. They didn't refuse to test aircraft if they didn't know they were "completely safe" but I can bet they would have refused to test them if they thought those asking them to had not taken sufficient action to reduce the level of risk to an acceptable level.
That is exactly what NASA did with Apollo. They assessed the risks, and put in place sufficient precautions to ensure the risks were at a level acceptable to NASA, the astronauts and congress, who were funding it with taxpayers money. Hence the outcry and enquiries over the Apollo 1 fire ... where it was felt that NASA hadn't done enough to address the level of risks involved.
|
|
Bob B.
Bob the Excel Guru?
Posts: 3,072
|
Post by Bob B. on Nov 10, 2009 10:10:43 GMT -4
Here's a sketch I made of the type of thing I am trying to describe. Yes, it is oversimplified, but I hope it gives you an idea of what we are talking about. Although you're correct about how the spacecraft skirted the edges of the radiation belts, you've got the position of the Moon wrong -- you've drawn the orbit of the Moon in the same plane as Earth's equator. In relation to the ecliptic, the Moon's orbit is inclined 5.145 o and Earth's axis is inclined 23.439 o. Due to precession of the nodes, the inclination of the Moon's orbit in relation to the Earth's equator varies between 23.439 - 5.145 = 18.294 o and 23.439 + 5.145 = 28.584 o. The nodal precession cycle is 18.6 years. The inclination was at its maximum in 1969, and was last maximum in 2006. You should revise your drawing to show the Moon about 28 1/2 degrees below the Earth's equatorial plane and straighten out the trajectory of the spacecraft. This would still be a simplification, but it would more closely represent the actual path flown.
|
|
|
Post by Jason Thompson on Nov 10, 2009 10:29:23 GMT -4
You're absolutely right Bob. It was a quick sketch done in two minutes just to illustrate. I'll revise it later.
|
|
|
Post by fm on Nov 10, 2009 11:29:07 GMT -4
Guys... Im not looking this Van Allen BELT in a 2 dimensional way, Im seeing it in 3D. Thats why Im asking the questions about the ORBIT. I have several people accusing me of not being able to "SEE" it but then sit there and give me drawings and links to computer models that are in 2D, and do not show the 1.5 orbit around the Earth. In other words, it doesn't help at all with my questions. Work with something like this at least if you want to illustrate your point upload.wikimedia.org/wikipedia/en/0/03/Tli.svgLets make it simple, do any of you dispute the information I quoted from NASA that for about 4 to 5 hours the Apollo 11 craft was within the range of the Van Allen Belts? Belts that circle our entire Earth except at the poles? I mean basically everyone here says they went through the belts, but nobody is saying how and where. It must have happened sometime during those 4 to 5 hours, right? NASA says: "Transfer energy considerations. In order to arrive in the vicinity of the moon the spacecraft was 'aimed' (targeted) at a position where the moon would be at the time of its arrival..." "Apollo astronauts, and astronauts in the upcoming visits to the Moon, will have to travel through some of these belt regions because the orbit of the Moon lies along the fastest line-of-travel from Earth." "In order to accomplish this 'rendezvous' with a minimum expenditure of propellant, the injection (TLI) must occur very close to the extension of the earth-moon line at the time of the spacecrafts lunar arrival." "This minimum energy transfer trajectory would have placed the earth parking orbit perigee at the moons antipode if the moons mass did not perturb the trans lunar trajectory. However the moon does perturb the spacecrafts trans lunar trajectory, as shown in figure 5 above, and therefore the earth parking orbit perigee must lead the moons antipode by approximately 8 degrees to compensate." history.nasa.gov/afj/launchwindow/figs/Fig%209.pngSounds like a situation where the shortest distance between point A and B is a straight line. Im just not seeing any evidence that the Apollo craft left Earth and made some big longitudinal curve to go over the belts, skimming them, and back down to the moon vrs a straight line to or maybe a latitudinal curve. Every picture shows this: Anyway, what about the return flight, did that take an hour through the belts? thats should be easier to look at since it was basically a straight path, right? NASA says in a math exercise that: Within 40,000km of Earth. That's less then another figure of 65.000km, but ok. They say if a spacecraft travels about 25,000 km/hour. It will go through the belts in 52.8 minutes. This is not going through straight through but at the edge of the VABs, as everyone has been saying. Ok so, 24 July 1969 EDT 09:00 AMT+191:28 height = 34000 mi (within 40.000 miles) or if you like: 10:20 AMT+192:48 height = 22901 mi, speed = 9338 mph (within 25.000 miles) to 12:28:59 PM T+194:56:59 height = 688 mi. Moonset. Thats more than 2 hours going through the VABs or 3 hours and 30 minutes if you want to use the 40.000 mile distance. I dont see anything here under an hour. Until someone can show me different, I count up to six possible hours in the VAB coming and going. Tell you the truth, I wouldn't be surprised if they found radiation belts around the moon as well. Let me also address the following: "The recent Fox TV show, which I saw, is an ingenious and entertaining assemblage of nonsense. The claim that radiation exposure during the Apollo missions would have been fatal to the astronauts is only one example of such nonsense." -- Dr. James Van Allen Talk about cherry picking quotes, comparing this to published... Anyway... Someone show me where he published a scientific paper or article where he reverses his previous published claims prior to Apollo. Plus, as smart as he is, where does he retract the dangers of the VABs in the quote? We know its dangerous. And for him to say that space radiation is not fatal to astronauts when every scientist says... wait... he said Apollo missions, which, if they were fake would mean they wouldn't have been exposed to any radiation exposure.... hmmm.... Anyway, I have to give this to the hoaxers 2 (published quotes) to 1 (vague remark) regarding Van Allen until we find something more to support the opposite. Sorry, for me its the end of that discussion. spacemath.gsfc.nasa.gov/weekly/3Page7.pdf
|
|
|
Post by randombloke on Nov 10, 2009 12:01:50 GMT -4
"Tell you the truth, I wouldn't be surprised if they found radiation belts around the moon as well." This alone illustrates a shocking ignorance of the nature of the VABs and how they are formed and maintained.
And this: "Sounds like a situation where the shortest distance between point A and B is a straight line" indicates to me that you didn't actually read the quotes you mined from wherever it is you got them from, since they clearly state that the minimum energy path has to aim ahead of the moon so that the lunar gravity can curve the otherwise straight trajectory towards lunar orbit.
And your picture is clearly meant to be illustrative, since it appears to have the Moon orbiting within about 3.75 Re, or somewhere inside the VABs. It also has the Saturn V at about 6000km long. Truly it was the biggest rocket ever built but that's just ridiculous. That you then go on to claim that the orbit illustrated is diagnostic of the one actually taken is equally so.
|
|
|
Post by Jason Thompson on Nov 10, 2009 12:25:57 GMT -4
I have several people accusing me of not being able to "SEE" it but then sit there and give me drawings and links to computer models that are in 2D, and do not show the 1.5 orbit around the Earth. In other words, it doesn't help at all with my questions. Simply choosing to ignore things is not helping yourself. The 1.5 orbit around the Earth is largely beside the point. What matters is what happened following the TLI burn. Yes, I do. You have totally ignored everything everyone has said about the nature of the belts: the way their intensity varies with latitude, and distance, and so on. You still cling to the notion that anything at an altitude that is given as the extent of the belts must be within the belts, regardless of inclination. No orbital transfer is ever a straight line. I have already had the error of my sketch pointed out and will update it later. No, the return was curved just like the outward trajectory. I repeat: no orbital transfer is EVER a straight line. It just isn't possible with the interaction of gravitational forces and momentum involved. Nice demonstration of ignorance there, thank you. The van Allen belts are the result of interaction of the solar wind with Earth's magnetic field. The Moon has no such magnetic field, ergo will have no radiaiton belts. He did NOT reverse his claims. He never reversed his claims. You still are taking the quotes made early on totally out of context. He did not say, anywhere, ever, that the belts were an insurmoutable obstacle. He said 'adequate shielding' was required. The hull of a spacecraft, for example. That's the difference between scientists and, well, you. I hear van Allen talking about the belts early on and hear him say more work is needed and they must be taken into account when designing spacecraft intended to pass through them, such as to the Moon. You hear 'there is a deadly sea of radiation and men can't get past it at all'.
|
|
|
Post by homobibiens on Nov 10, 2009 12:30:02 GMT -4
Was, Jay. It was for Dr. Van Allen. Note to tedious HB-types--"was" because he is dead, not because he changed his mind. Was, and remains so.
|
|