Van Allan Belt and Astronaut Concerns

john mccarthy · Feb 6, 2005

If the Van Allan Belt is filled with such a great amount of radiation, how did the astronauts survive travelling through the Belt without adequate protection from the radiation? It has been written that up to five inches of steel would be required to prevent humans from being burned to death by the radiation in the Belt. John McCarthy http://www.verpa.org

zavvy · Feb 7, 2005

This link might help explain...

CalliArcale · Feb 7, 2005

<blockquote>In reply to:<hr />If the Van Allan Belt is filled with such a great amount of radiation, how did the astronauts survive travelling through the Belt without adequate protection from the radiation? It has been written that up to five inches of steel would be required to prevent humans from being burned to death by the radiation in the Belt. <hr /></blockquote> Zavvy's got a great link there, to one of my favorite websites, but in case you don't want to follow the link, here's a quick explanation: The Van Allen Belts (there are more than one) are regions where the magnetic field of the Earth traps radioactive particles from the Sun and from the cosmos at large. They are indeed dangerous, and they grow and shrink over time, mostly in response to the interactions between the magnetosphere and the solar wind. Extra belts have even appeared at times, including a shortlived one very close to the Earth's stratosphere created as a result of high-altitude nuclear testing. (Scary thought, eh?) These belts are centered roughly around the plane of the Earth's equator. They do shift, and any trip past them needs to be planned carefully. Even unmanned spacecraft need to be careful; radiation can induce currents in their delicate wiring, causing spurious signals, corrupting data, or even overloading a circuit. There are several ways to avoid the dangers of the ionizing radiation found in the belts. The least practical is shielding. Shielding is very heavy, and the mass penalties can cost you your entire mission, really. An Apollo spacecraft built to keep everybody totally safe in the Belts for an indefinite period of time would have been way too massive for a Saturn V to launch, and there would've been no Apollo. A better strategy is to minimize exposure. You don't have to go through the thickest part of the belts. They are around the plane of the equator, so if you plan a trajectory that goes ab <div class="Discussion_UserSignature"> "People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff." -- The Tenth Doctor, "Blink" </div>

vogon13 · Feb 7, 2005

Believe solar cells on Rock and Roll (the XM satellites) are degrading much faster than expected, due in part to Van Allen effects. Even today radiation belts not fully understood and creating problems for spacecraft designers. <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

john mccarthy · Feb 7, 2005

So, conceivably, those sats that originally orbited 300-400 miles up and were called "weather' Sat's and then suddenly went stealth (missing) and positioned themselves 20-30K miles up, are at some greater risk from Van Allan radiation re degrading of their instrumentation? IF these Sat's had EMP lasers with nuclear capability (one time shots) their life span might be effected and unrepairable rendering them expendable assets, sorta like us? John McCarthy http://www.verpa.org

CalliArcale · Feb 7, 2005

Yes, spacecraft that pass through or near the Van Allen Belts repeatedly are at risk, although there are things that engineers can do to increase the spacecraft's chances of survival. SOHO, for instance, is quite tough -- it orbits outside of the Earth's magnetosphere and is thus completely unprotected from the Sun's radiation, especially during coronal mass ejections. (It's amazing to see the pictures from SOHO when a CME hits it; the CCDs get overwhelmed with protons from the Sun, and you get all this snow across the picture.) If you hear of "radiation hardening", that's what's done to spacecraft computers. It's a collection of techniques done to make them less susceptible to damage from the currents induced by radiation. Another thing that is done is to make them slower than your desktop PC. To make a CPU faster, you have to make its circuits smaller, so you can fit more of them on the CPU. (Access within the CPU is much faster than access between the CPU and other devices out on the motherboard.) This means the wires are physically smaller, which means it takes less current to melt them. A Pentium can be damaged or even destroyed by a static electric discharge too small for you to feel! (Normally, they are set into your computer in such a way as to protect them from this happening; the main risk of overload from static discharge is in the plant where the motherboard is assembled.) So many satellites have CPUs equivalent to a 386. The Galileo spacecraft had only an 8-bit message word. (Most PCs have 32-bit architecture, which allows them to be much more efficient since they can move more data around in a single word. Some have 64-bit architecture.) And even with its extreme radiation hardening and major error checking on that 8-bit word, it still would go funny on many of its close approaches to Jupiter. (Jupiter's Van Allen belts are far more dangerous than Earth's. You can survive a one-hour trip through the thinnest part of our belts, <div class="Discussion_UserSignature"> "People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff." -- The Tenth Doctor, "Blink" </div>

Leovinus · Feb 7, 2005

Jack Swigert died of cancer. Coincidence? <div class="Discussion_UserSignature"> </div>

heyscottie · Feb 7, 2005

PROBABLY a cooincidence -- one would expect at least a couple of cancer deaths even among a population as small as that of the Apollo astronauts. If memory serves, Swiggert died somewhat young -- he was about 50 or so, which is somewhat more unusual, but I think I'd have to see more than one or two of deaths in that way to assume that anything having to do with spaceflight caused it.

john mccarthy · Feb 8, 2005

Thank you for the explanation of hardening the circuits, etc. Did this technology exist in 1969 for the moon shots? If not, why didn't their computers, such as they were, malfunction to the max re solar radiation? These are most important issues to me and I hope you can address them. John

CalliArcale · Feb 8, 2005

<blockquote>In reply to:<hr />Thank you for the explanation of hardening the circuits, etc. Did this technology exist in 1969 for the moon shots? If not, why didn't their computers, such as they were, malfunction to the max re solar radiation? <hr /></blockquote> First off, for a little background -- I work for a company that makes computers, mainly embedded systems. One of the projects I'm supporting is a computer for a satellite. We make a bunch of these things, heavily customized to the particular spacecraft, but our most famous is probably Chandra's command & control subsystem. So that's where my knowledge comes from. One caveat: I work in software, so I pick this up mostly by association with the electrical engineers and systems engineers. <img src="/images/icons/wink.gif" /> Apollo computers were rad-hardened, I believe. However, it wasn't anywhere near the problem it is today. You can get a space-qualified CPU today equivalent to a PowerPC 604. (Actually, by now I bet you can find one equivalent to the 750, or even better. I confess I don't follow it as closely as I ought.) RISC processors are popular in this business; all operations are completed in a single cycle, which gives less opportunity for data corruption. But they are very miniaturized. The wires cannot be seen without a microscope. Even a circuit diagram three feet across is amazingly dense and difficult to read. So it takes very little energy to overwhelm it. The Apollo computers, by contrast, are clunky behemoths. They were amazingly small, light, and fast for their time, but by modern standards they're pretty clunky. One of the upsides of this sort of a system is that its sheer size makes it less susceptible to radiation. It's not anywhere near as sensitive. That helped them enormously. Systems in general were not so susceptible. In 1989, a CME caused a geomagnetic storm so intense it actually *melted* transformers on <div class="Discussion_UserSignature"> "People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff." -- The Tenth Doctor, "Blink" </div>

john mccarthy · Feb 8, 2005

Thanks, again! Great information and perfectly logical to an interested, yet uninformed, laymen on this subject. My interest was spiked ten years ago when I met a retired fellow who worked for TRW and a few other Sat builders. His job was to hook up the black boxes in the Sat Bay. He explained that some were in series, some parallel. He, with all his knowledge and experience in the field, had no idea of the function of these 'black boxes'. He, like you, rubbed shoulders with many scientists and others who were very much involved with the design and manufacturing of the 'black boxes' and therefore, had some inside knowledge by association. When I asked him over many years of discussing this matter he told me that his best conclusion re the function of the 'black boxes' was stealth related. This was based on Sat's that were described as "weather" functioning. They later went missing from their 300 mile altitude orbit. I was a CW radio operator in my early military years. So was my friend, in WWII. We both were involved with cryptology and the fascinating methods once used. His experience was Navy based, with lots of power and back-up systems. Mine was OSS related, used during the fifties thru the seventies. Our little 'black boxes' were low powered/high frequency crystal controlled beauties that put out 15 Watts and allowed us to communicate from Norway to Germany, and Pakistan to Germany using the ionosphere to skip our waves at various times of day and night. Those 'heady' days of association with literally every country in the mid-east, save Israel, has come back to bite us big time. Some of the tactics we taught in those days, at the behest of the CIA and without the knowledge of the Pentagon, has backfired BIG time. Our "opposition" (USSR and NSA) attempted, with limited success, to disrupt our commo with various noise techniques, which were mostly unsuccessful because of field expedien

pizzaguy · Feb 8, 2005

I was a CW radio operator in my early military years You can probably count on your hand the number of people here who understood that remark. didit .. didah dadah .. dadadah dahdit dit <div class="Discussion_UserSignature"> Note to Dr. Henry: The testosterone shots are working! </div>

john mccarthy · Feb 8, 2005

.... --- .-.. -.. - .... . .- -. -.-. .... --- ...- .. . ... Have a good one .--. .. --.. --.. .- --. ..- -.-- .- .-. -...- Had a call sign in Greece that was fun UU22 Bests, John

alokmohan · Mar 2, 2005

Somewhat preliminary question.If we dont have a van allen belt ,can we survive?I mean here on earth.

Saiph · Mar 2, 2005

well, that would mean one of two things, as I see it. 1) We wouldn't have a magnetosphere. Which isn't healthy, as the particles would come down and irradiate the earth. Absolutely lethal? Not necessarily. Highly unhealthy to us as we are now? Yes. 2) There's no radiation to be in the belt. This is, of course, good and healthy. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

nexium · Mar 2, 2005

At present, radiation levels are too high for permanent colonies in the Van Allen belts, but a few hours exposure is a minor risk, except following solar flares which eject ions toward Earth. These are sometimes called CME = solar mass ejections. My guess is 10% of Earth's humans will die of cancer instead of something else, if we loose our magnetic field or it decreases by more than 20 times. Birth rates will increase, so the population will decrease little or none, but the average age of humans could decrease by 20 years. Most however will survive to age 40 or more. Perhaps 10% will have birth defects of significance. The magnetic fields will likely return in less than a century. It will have little effect on space travel beyond the location of the present Van Allen Belt, but shielding will become more important in low Earth orbit. Neil

alokmohan · Mar 3, 2005

I understand we wont die in absence but not very niely,cancer will be more frequent.

alpha_taur1 · Mar 3, 2005

"You can probably count on your hand the number of people here who understood that remark." dah dah..dit ..............dah..dahdahdah..dahdahdah (ex GM4 ex La ex 5Z4 ex VK6 ex VK4 ex VK5) Used to send and receive at 35wpm by ear using the auroral curtain at 144 and 432.

newtonian · Mar 3, 2005

alokmohan - The Van Allen radiation belt is one of the many fine tuned details of planet earth which make human life comfortable. I sure am thankful it is up there protecting us. Increased radiation also has an adverse effect on genetic reproduction. It introduces truly random mutations which are almost entirely harmful - in contrast to beneficial mutations which have inheritied informational direction involved in the variation. [NOTE: the definition of mutation has changed in recent decades to include virtually all genetic changes, not just the random mutations like Dobzhansky extensively researched - see, for example, his fruit fly (drosophila) experimental observations of radiation induced mutations]

Saiph · Mar 3, 2005

I wouldn't call it fine tuned newtonian. It's a direct consequency of having a magnetic field, which could be a variety of strengths and still harbor life. <div class="Discussion_UserSignature"> --------------------SaiphMOD@gmail.com -------------------"This is my Timey Wimey Detector. Goes "bing" when there's stuff. It also fries eggs at 30 paces, wether you want it to or not actually. I've learned to stay away from hens: It's not pretty when they blow" -- The Tenth Doctor, "Blink" </div>

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