without being fried by the Van Allen Belts? Every study I have says that they would have to have alot of sheilding and that would be too much weight.
From Wikipedia:
The Apollo missions marked the first event where humans traveled through the Van Allen belts, which was one of several radiation hazards known by mission planners. The astronauts had low exposure in the Van Allen belts due to the short period of time spent flying through them. Apollo flight trajectories bypassed the inner belts completely to send spacecraft through only the thinner areas of the outer belts. Astronauts' overall exposure was actually dominated by solar particles once outside Earth's magnetic field. The total radiation received by the astronauts varied from mission to mission but was measured to be between 0.16 and 1.14 rads (1.6 and 11.4 mGy), much less than the standard of 5 rem (50 mSv) per year set by the United States Atomic Energy Commission for people who work with radioactivity.
Astronauts' overall exposure was actually dominated by solar particles once outside Earth's magnetic field. The total radiation received by the astronauts varied from mission to mission but was measured to be between 0.16 and 1.14 rads (1.6 and 11.4 mGy), much less than the standard of 5 rem (50 mSv) per year set by the United States Atomic Energy Commission for people who work with radioactivity.
The cardinal rules on radiation exposure are time, distance, and shielding. By limiting the time they spend within the Van Allen Belts and providing weight-conscious shielding, their exposure is minimal.
You're probably in more danger mowing your lawn on a sunny day...
Larry Resident Microferroequinologist (at least at my house) Everyone goes home; Safety begins with you My Opinion. Standard Disclaimers Apply. No Expiration Date Come ride the rails with me! There's one thing about humility - the moment you think you've got it, you've lost it...
Just a little bit of nitpicking with the Wikipedia article, RAD's an REM are not the same unit (REM = RAD x Quality_Factor), which also holds for Gy (100 RAD) and Sv (100 REM). Wackypedia is correct in that the exposure time was limited, and should have mentioned that the dose rate through the Van Allen belts had been mapped before Apollo 8.
We probably should steer this to the proposed atomic locomotive to keep this OT for this forum.
- Erik
CandOforprogress2without being fried by the Van Allen Belts?
Very simple way to look at the Van Allen belts: they're the result of the charged particles of the solar wind being pushed into a more concentrated volume by the action of the earth's magnetic field. While you can't use 'that volume of space' for long-term orbiting or human activities, you can certainly optimize things like transfer orbits to minimize time there -- that being one component of 'exposure' -- and so we did for the years of the moon program. If you get to Huntsville, I will tell you how to sneak over the fence to get into the Space and Rocket Center, and then you can go over to the displays in the Davidson Center that will tell you all about the subject (and the specific means the Apollo moon missions used to minimize the problems).
Erikem, do you have the equations for the acceleration of the different species of charged particle (and hence gain in energy over that of typical particles in the solar wind) due to interaction with the Earth's magnetic field?
My experience with ionizing radiation has traditionally been with neutral "particles", i.e. photons and neutrons, so my comments would be a slightly educated guess. Also my past interest in the interaction between the solar wind and the earth's magnetoshpere was concerned with HF propagation (e.g. is 10 meters open?).
First reaction is that that the Van Allen belt is more likely to slow down charged particles than to accelerate them, though the particles interact with the geomagnetic field to produce field changes measureable from the earth's surface. The main effect is that the particles get trapped in the Van Allen belt, with some particles leaking off to the magnetic poles and particles at inner edge of the belt being captured by the remnants of the atmosphere.
Second reaction is that a few simple equations won't even begin to describe what's going on in the Van Allen belts - though to be fair, the equations describing basic interactions between charged particles and electromagnetic fileds are relatively simple, the coupling makes it pretty hairy. A railroad analog would be that the equations of motion for a single car are pretty simple, but describing how a long freight train respsonds to dynamic conditions (e.g., derailment) can get hideously complex when details such as slack action are taken into account.
I started thinking about the bremsstrahlung EM coming off the interaction between the Earth's magnetic field and the high-speed solar wind, and promptly came across this reference that not only addresses the issue but slams the door on some of the conspiracy theory
Braeunig mentions that the trajectories of the moon missions were carefully calculated and flown to avoid most of the significant VARB volume. While he does not calculate bremsstrahlung for the interactions in the belts, he notes the contribution at the spacecraft would be negligible, as is bremsstrahlung from particle absorption in the structure.
The TL;DR for the original poster, who is probably not a physicist:
OvermodPSK-31 digital on 28.120?
Guess I'm gonna have to get a SignaLink for my IC746, too...
The Braenig article looks reasonable, pretty well matches up with what I've seen on dose rates from high energy electrons. The fact that the electron energy peters out at 7 MeV rules out any of the electrons making it through the command module hull. Two other good aspects of the 7 MeV max energy is that bremsstrahlung efficiency is pretty low for low-Z materials and that there would be essentially zero neutron production. The latter is pretty significant when electron energies go north of 15 MeV into high-Z materials such as lead.
FWIW, the flux of cosmic ray induced high energy electrons is non-zero at sea level, not to mention the cosmic ray induced muons and neutrons. The flux of all three are significantly higher at typical airliner crusing altitudes.
(Back on forum topic) One reason that the "atomic locomotive" never got past the drawing board stage is that it would be extremely difficult to get adequate neutron shielding in a typical RR loading gauge. Another is dealing the mess if the lcomoive got into a serious derailment - mainly how to maintain cooling to take care of the decay heat (e.g. what happened at Fukushima).
N.B. My favorite mode on 10m was SSB, also had a bit of fun talking to ZL's on 6m during the early 1980's solar max.
How did we get to the moon?
With 3&1/2 cups of sugar.
Ricky W.
HO scale Proto-freelancer.
My Railroad rules:
1: It's my railroad, my rules.
2: It's for having fun and enjoyment.
3: Any objections, consult above rules.
Our community is FREE to join. To participate you must either login or register for an account.