h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Actually true, but only up to a point.

Apollo astronauts were exposed to radiation once outside the geomagnetic field. But the radiation levels were not lethal and in fact were minimal over the period of time that they were exposed, barely registering on the dosimeters each one of them carried. The period of highest exposure was during the transit through the Van Allen belts which took approx four hours just after trans lunar insertion.

Radiation is cumulative over time and would only be a real problem if their time in space was prolonged, say on a Mars trip lasting several months rather than days. Although the Apollo missions did take place during a period if high solar activity, no significant solar article events were encountered during any of the missions..

Radiation was a known hazard which was taken into account during the planning stages and the risks they took were calculated. Considerable protection was afforded by the spacecraft without the need for several feet of lead, which is the usual requirement of the conspiracy theorist.

None of the astronauts suffered any adverse effects from exposure to radiation.

Deke

i get wht ur sayin, u are making sense but the space craft which they were in was only made up of aluminium which is not strong enough to stop radiation, even when you got to get a xray you get a slate of lead with you to b protected.

Most of the radiation from the sun is visible light, not x-rays. The sun is not a strong x-ray source.

On the contrary, The spacecraft’s construction was quite sufficient to provide protection against the type and the level of radiation that was likely to be encountered in a mission lasting a few days.

The only reason that Conspircy Theorists cite a large thickness of lead being necessary is because it suits their argument and it is something people generally associate with ‘Radiation’. That and atom bombs and radiation sickness, y'know, the dramatic stuff. They don't tell you what sort of radiation they're talking about though. They just rely on you assuming that all 'radiation' is deadly.

Firstly, when you go for an X-Ray it's not 'you' that gets the lead block. Rather, you get the X-Rays. Right through you, otherwise they wouldn't be able to take the picture they need as they exit your body and onto the photographic plate. There would be no point in shielding you from the X-rays. It's the radiographers, that's the operators of the machine, that take shelter behind the lead. And so they should, because they are dealing with it on a daily basis, and many times a day. So you can, and do, survive X-rays.

Effectively, radiation comes in two forms. That of the electromagnetic rays (EMR) categorised in the electromagnetic spectrum, which includes everything from long radio waves, through visible light and onto short-wave X-ray and gamma rays. The other type, particle radiation, are high-energy charged particles that would be emitted by the Sun and to which we refer to as the Solar Wind. The main source of both of these is the Sun but as far as astronaut’s safety is concerned, the greater hazard comes from particle radiation.

Both types of radiation are emitted by the Sun in a more or less constant stream in all directions, but there are periodical times when the sun shows more surface activity. This has the effect of increasing both types of emission but the particle emissions increase dramatically when a solar flare erupts. But either way the hazard is dependant not only on what radiation you are talking about, but how much is occurring at any one particular time.

The spacecraft were built from alloys and were double skinned. That together with the insulation material between skins was quite effective in protecting the astronauts from the EM radiation by reducing it to levels that were acceptable for the few days that they were exposed. At least it was a calculated risk they were willing to accept.

NASA were also aware that the chances of a crew being caught out by a high emission event was slim. For a start, bursts are directional, rather like a shotgun blast, and to effect a spacecraft the burst has to head in the spacecraft's direction. EMR travels at the speed of light, but particle emissions are a whole lot slower. A certain amount of warning, reckoned in hours, could be given to crew if this occurred. In that event a spacecraft in flight could turn itself to position its heatshield and the service module towards the burst or an exposed crew on the lunar surface could take refuge in the lunar module.

You don't have to take my word for all this. It is all recognised science that is verifiable. You could also apply your own experience. 'Frinstance you will know what happens if you sunbathe too long. You get sunburned, and that's by the ultra violet radiation part of the EMR. You will also know that the only protection you need from it is a T-shirt. Also take a look at the micro-wave cooker. Look through the glass in the door and you will see an alloy mesh in the glass. that's all it takes to keep micro-wave radiation in the cooker. Visible light and radio waves are also all part of the radiation spectrum, so you will see that not all radiation is necessarily harmful if it is handled in the right way.

Another thing you could ask yourself is that if radiation is so deadly, why do communication and weather satellite circuits not fry when they are exposed to radiation?

Deke

ok then, consider gamma rays

satilites stop working all the time because of radiation. the moon mission was happening during a solar maximum and there were solar flares going off like a new year firework display, the only way to survive this is to be hidden behind the earth and in its magnetic field, e.g. being in orbit
to leave the magnetic field is just like throwing someone in the middle of the ocean and telling them to work it out for themselves even tho they cant swim.

Satellites don’t usually stop working because of radiation damage as they are shielded against all but the major occurrences, and it‘s not with meters of lead. The type of solar flare likely to cause significant damage that will render it inoperative, is a lot rarer than you suggest. Working on the solar cycle of 11 years, less than one event is likely to occur during that cycle and only three events classified as ‘serious’, on average, will occur during that same time period.

You are right in that the manned Apollo missions did occur during a high point in that cycle, but NASA still new enough to monitor the situation. There were a lot of solar flares during the years of the Apollo missions, about 1400 by one count. But not all of them presented a hazard and the vast majority were of a low level nature and none were extreme enough to present any undue threat to the crew‘s lives. The highest dosage registered during any of the missions was on Apollo 14 and it equated to about ten times the average human dosage for a year.

Deke

"A certain amount of warning, reckoned in hours, could be given to crew if this occurred" honestly deke what were you thinking,lol, so it takes hours for light to travel that distance. hmmmm, you do no that light takes 8 minutes to reach the earth, and its just a guess but i think 8 minutes is less than "hours".
so even if were using our best equiptment to monitor the sunspots we would still be seeing the light about 1 minute in the past so now its down to 7 minutes and then take another minute off for them to make the analysis and then respond corectly, so its down to 6 minutes and then the distance that the radio waves would have to travel to reach the moon lander. what were you thinking????????????????

Deke was referring to 'particle emissions' which 'are a whole lot slower'!

Well, what I was thinking was that there is more than one sort of ‘radiation‘. My apologies if my explanation was not clear enough.

I was also thinking that electro-magnetic radiation, which includes visible light, travels at the speed of light and takes approx eight minutes to reach Earth from the Sun. But particle emissions, that is those which have mass, and cannot travel at the speed of light, take rather longer.

What were you thinking?

Deke

ok if thats what you meant, but are you still trying to say that the charged particles take hours longer, even tho the smaller the matter is the closer it can get to the speed of light.

just to add on- if humans had the technology to monitor the sun so closely 40 years ago, why didnt they have any clue about the solar flare that was so strong that most of north americas power grid was wiped out, surley they would have known with there updated and more accurate technology as it was only about 10 years ago.

sorry if im being a pest im just looking for answers