Bad Astronomy: Misconceptions and Misuses Revealed, from ...

162 ARTIFICIAL INTELLIGENCE
radiation in the belts. To minimize the risk, they put the Apollo
spacecraft along a trajectory that only nicked the very inside of the
inner belt, exposing the astronauts to as little dangerous radiation
as possible. They spent more time in the outer belts, but there the
radiation level isn’t as high. The metal walls of the spacecraft protected
the astronauts from the worst of it. Also, contrary to popular
belief, you don’t need lead shielding to protect yourself from
radiation. There are different kinds of radiation; alpha particles,
for example, are really just fast-moving helium nuclei that can be
stopped by normal window glass.
Once outside the van Allen belts—contrary to the claims of the
hoax-believers—radiation levels drop, so the astronauts were able to
survive the rest of the way to the Moon. From the belts on out they
were in a slightly elevated but perfectly safe radiation environment.
There was risk, though. Under normal circumstances, the solar
wind is a gentle stream of particles from the Sun. However, there
was a very real danger from solar flares. When the Sun’s surface
flares, there can be a dramatic increase in the amount of radiation
the sun emits. A good-sized flare could indeed kill an astronaut,
very nastily and gruesomely. In that sense, the astronauts were
truly risking their lives to go to the Moon because solar flares are
not predictable. Had there been a good flare, they might have died,
farther from home than anyone else in history. Luckily, the Sun’s
activity was low during the missions and the astronauts were safe.
In the end, over the course of their trip to the Moon and back,
the astronauts got, on average, less than 1 rem of radiation, which
is about the same amount of radiation a person living at sea level
accumulates in three years. Over a very long time that level of exposure
might indeed be dangerous, but the round-trip to the Moon
was only a few days long. Since there weren’t any flares from the
Sun, the astronauts’ exposure to radiation was actually within reasonable
limits.
Conspiracy theorists also argue that the radiation should have
fogged the film used on the lunar missions. However, the film was
kept in metal canisters, which again protected it from radiation.
Ironically, modern digital cameras no longer use film; they use