Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Dec 24, 2009 11:25:49 GMT -4
The surface of the Earth is awash with solar radiation from sunrise to sunset every day.
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Post by Count Zero on Dec 24, 2009 13:30:38 GMT -4
Yes, I picked-up pretty bad radiation burns the first two times I went to Hawaii.
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Post by trebor on Dec 24, 2009 13:41:37 GMT -4
Yes, I picked-up pretty bad radiation burns the first two times I went to Hawaii. Hmm, this means Hawaii must be a hoax. People would be fried instantly in the harsh radiation. Obviously only the UK with its 100% cloud cover can be real!
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Post by Count Zero on Dec 24, 2009 13:42:02 GMT -4
[Launching into Earth orbit with an inclination of about 32.5 degrees was common NASA practice going all the way back to the first orbital Mercury flight. Off the top of my head, I don't recall the exact reason for this. Perhaps to widen the ground track to allow existing tracking stations further north (in the US) and south (in Australia) to follow the missions? Just a guess...
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Dec 24, 2009 14:04:28 GMT -4
Launching into Earth orbit with an inclination of about 32.5 degrees was common NASA practice going all the way back to the first orbital Mercury flight. Off the top of my head, I don't recall the exact reason for this. Perhaps to widen the ground track to allow existing tracking stations further north (in the US) and south (in Australia) to follow the missions? Just a guess... That is one of my guesses as well. The higher inclination also allows more opportunities to land in the Atlantic Ocean near Florida, which might be favorable in case of an abort within the first few orbits. With the 32.5 o inclination, Atlantic landings can take place after any of the first three orbits, after which Pacific landings are optimum. This is why Glenn's and Carpenter's flights were set at three orbits. I suspect the higher inclination was chosen for a combination of both tracking and abort reasons.
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Post by echnaton on Dec 24, 2009 14:24:42 GMT -4
This is why Glenn's and Carpenter's flights were set at three orbits.
An interesting tidbit. Thanks.
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Post by gillianren on Dec 24, 2009 15:30:34 GMT -4
Obviously only the UK with its 100% cloud cover can be real! That's a rain forest just over those hills from me; I can assure you that the Pacific Northwest of the United States can exist just fine in its avoidance of radiation!
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Post by fm on Dec 26, 2009 9:55:49 GMT -4
trebor:"awash" is a meaningless term. Please be more specific.
drewid: "The earth's surface is "awash with radiation"
tedwardI hate it when you see comments like "awash". Well, not hate it, just that it appear to be used as the old 50's radiation killer mutant mentality to get across to the uninformed that space is deadly so we could not have gone there.
Count ZeroYes, I picked-up pretty bad radiation burns the first two times I went to Hawaii.
Im sorry that many of you dont like the word "awash" for one reason or another. But dont look at me for answers, ask NASA. Thats the word they used. Like I said referring back to the O.P. quoting:
"Space beyond low-Earth orbit is awash with intense radiation from the Sun and from deep galactic sources such as supernovas. Astronauts en route to the Moon and Mars are going to be exposed to this radiation, increasing their risk of getting cancer and other maladies. Finding a good shield is important."
So I cant provide you with the "specific" answer you are looking for.
Im assuming they mean overflowing with. More than usual for our Earth standards. More than we can normally handle. More than we find here on Earth. Specifically more than low-Earth orbit.
So what point are you all trying to make when your talking about Earth and radiation? I suppose if you want to make analogies then you would say, Chernobyl is awash with radiation in comparison to my living room. Or something like that.
To me its quite simple. Space has more intense radiation than Earth. Anybody want to disagree with that?
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Post by echnaton on Dec 26, 2009 10:45:45 GMT -4
Im sorry that many of you dont like the word "awash" for one reason or another. But dont look at me for answers, ask NASA. But you are the one who we are having a discussion with. The term "awash" is hopelessly vague. Everyone agrees there is radiation in outer space and that that radiation is different than what we have on the surface of the earth. But if you just want to throw around vague terms with no attempt to discern some meaningful measure, what kind of conversation can we really have? To me its quite simple. Space has more intense radiation than Earth.So? Whats your point? Edited for my usual reasons.
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Post by tedward on Dec 26, 2009 14:37:16 GMT -4
tedward I hate it when you see comments like "awash". Well, not hate it, just that it appear to be used as the old 50's radiation killer mutant mentality to get across to the uninformed that space is deadly so we could not have gone there.To me its quite simple. Space has more intense radiation than Earth. Anybody want to disagree with that? Please excuse me edit. Righto. What radiation and what effects does it have and can it be countered?
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Post by Jason Thompson on Dec 26, 2009 18:31:12 GMT -4
To me its quite simple. Space has more intense radiation than Earth. Anybody want to disagree with that? No, but I do want to qualify it. The point everyone is making is that 'awash' is meaningless in any practical terms. Any time you want to discuss radiation in meaningful terms you must include more specific qualitative and quantitative information. Yes, space has more intense radiation of various types than you would encounter on Earth, but that does not automatically mean it is intensely dangerous or too difficult to deal with. For example, space is awash with UV radiation, unfiltered by atmosphere. No-one would dispute the dangerous effects of UV radiation. Anyone who has suffered sunburn knows full well how bad it can be. However, if you wish to send someone into the unfiltered UV environment of space then you just have to put them in a spacesuit with a UV-opaque polycarbonate faceplate and the problem is solved. As you must have gathered by this point, there are many different types of radiation and how you shield against them depends on their type, their energy and their flux density.
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Post by Jason Thompson on Dec 26, 2009 18:32:43 GMT -4
This is the problem with the use of the term 'awash'. You have to interpret it yourself. It's fine for a simple summary information page, as is the context of the OP, but not for a detailed discussion of the radiation problems of space travel.
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Bob B.
Bob the Excel Guru?
Posts: 3,072
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Post by Bob B. on Dec 28, 2009 11:28:37 GMT -4
So I cant provide you with the "specific" answer you are looking for. Then there is nothing to discuss.
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Post by ka9q on Mar 29, 2010 8:24:19 GMT -4
These videos and visuals have really clarified this whole issue for me, but this is something I'm still not clear on: why does that window start to close? I guess I was under the impression that these belts don't move. I assume you mean the closing of that gap between the denser parts of the outer belt, the one through which Apollo flew? The later part of that animation shows the VABs sliced through like an apple by the plane of the TLI orbit. An orbit plane is (pretty much) fixed in inertial space, so you're actually seeing the VABs move with respect to that fixed plane as the earth turns and drags the VABs with it. The VABs would remain stationary in space, and this change wouldn't happen, if the earth's magnetic dipole were perfectly aligned with its rotational axis. But the earth's magnetic field is significantly offset and tilted, so it does change. The launch site is also moving with respect to the orbital plane, and that's one of the main reasons for launch windows. If you could look at that diagram from different directions you'd see that Kennedy Space Center moved through the orbital plane every 12 hours. At other times it was not possible to launch into it. It's actually a little more complex than this because most Apollo missions had fairly generous launch windows made possible by changing the TLI orbital plane to include the actual launch time as well as the moon at arrival. This latter criterion is mandatory if you want to fly to the moon! What this says is that since the launch site and the VABs both move with the rotating earth, then flying the same trajectory regardless of launch time will take you on the same path relative to the VABs. This is not 100% correct as the outer belts are modified by the solar wind, but it's close enough for avoiding the worst parts. That's why all the lunar missions, except for one, looked more or less the same on the map: a launch from KSC into a parking orbit inclined on the order of 35 degrees or so, with TLI over the central Pacific. (The one exception was Apollo 17, which performed TLI over the Atlantic). In this way they all flew pretty much the same path out through the VABs, avoiding the densest parts each time. It helped that the longitude of the launch site is (very) roughly equal to the longitude of the earth's north geomagnetic pole. This put the Apollo climbout from TLI at a high geomagnetic latitude, avoiding the belts' densest concentration over the geomagnetic equator.
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raven
Jupiter
That ain't Earth, kiddies.
Posts: 509
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Post by raven on Mar 29, 2010 13:42:03 GMT -4
And if you don't believe NASA, believe their competitors. While scouring the Internet for more detailed results from the Zond 5 & 7 probes/unmanned test prototypes, I found this paper by Russian scientists in the former USSR on the results of the retrieved on-board radiation measurement experiments. cdsweb.cern.ch/record/864491/files/p484.pdf It explicitly says, "Seven day flights along the trajectories of the Zond-5 and 7 probes are safe from the radiation point of view."
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