8.2 How come the Van Allen radiation belts didn’t kill the astronauts?

IN A NUTSHELL: Because these belts are not as deadly as they’re often made out to be and also because they’re belts, so you can fly around them. Russian spaceflights flew animals through them without problems. NASA also conducted sensor-laden uncrewed test flights to measure the effectiveness of the shielding of the Apollo command module. The trajectories of all the moonshots were calculated to fly around the core of these donut-shaped belts and pass rapidly through their less intense outer portions.

THE DETAILS: Many Moon hoax proponents claim that any crewed lunar mission would be impossible due to the lethal barrier of the Van Allen belts, two regions of radiation that wrap around the Earth at distances that can vary according to solar activity but are roughly located between 100 and 10,000 kilometers (62 to 6,200 miles) for the more intense inner belt and between 18,000 and 60,000 kilometers (11,100 to 37,000 miles) for the weaker outer belt (Figure 8-2).

Figure 8-2. A graphical representation of the Van Allen belts.


Vintage technical literature on the subject (for example the papers listed in the References chapter of this book) shows that the potential danger posed by the Van Allen belts was well-known when the lunar missions flew (the belts had been discovered in 1958) and was considered perfectly manageable.

In 1968, the Soviet space probe Zond 5 flew through the Van Allen belts to carry around the Moon several living creatures, which returned unharmed from their voyage. For the Apollo missions, exposure during the crossing of the Van Allen belts was calculated and measured by means of uncrewed test flights: specifically, Apollo 6 (April 1968) carried into Earth orbit an empty Apollo capsule equipped with instruments for measuring the capability of the spacecraft to block the radiation from the belts. It was found that the exposure was comparable to the effects of a few medical X-rays and therefore was quite tolerable.

The very first human beings to fly beyond the Van Allen belts were the astronauts of Apollo 8. According to NASA’s Biomedical Results of Apollo report (1975), over the course of the entire flight Lovell, Borman and Anders accumulated a radiation dose of 1.6 millisieverts. This is the equivalent of about twenty chest X-rays and is therefore far from being immediately lethal as some conspiracy theorists argue.

Moreover, the Apollo 11 Mission Report notes that the total radiation dose measured by the dosimeters and received by the astronauts during the trip was between 2.5 and 2.8 millisieverts. The Van Allen-specific dosimeter detected doses of 1.1 millisieverts for the skin and 0.8 millisieverts for the depth reading, well below medically significant values.

For comparison, according to the US National Council on Radiation Protection and Measurement the annual average radiation dose per person in the United States is 6.2 millisieverts; 52% of this is of natural origin.

We don’t have to take NASA’s word about the Van Allen belts. There is clear consensus in the science community on the matter, as shown for example by the article The Van Allen Belts and Travel to the Moon by Bill Wheaton, specialist in gamma ray astronomy at the Jet Propulsion Laboratory (JPL).

Wheaton provides objective data regarding radiation in space and specifically in the most dangerous region of the Van Allen belts. It turns out that the data published by NASA on this subject must be true, otherwise today’s automatic satellites would be fried, since they fly through the belts and their equipment, if not shielded adequately against radiation, will malfunction.

James Van Allen, from whom the belts get their name, had already stressed, as early as 1960 in the article On the Radiation Hazards of Space Flight, that these belts don’t encase the entire planet from pole to pole, but form a sort of donut that fades in intensity from approximately 30° above and below the Earth’s equator. Therefore, to fly around them or pass through their weaker regions it is sufficient to use an adequately inclined trajectory, which is what all the Apollo spacecraft did, both on the way to the Moon and on the way home (Figure 8-3).

Figure 8-3. The outbound trajectory of Apollo 11. The return path was even more inclined. Source: Rocket & Space Technology.


Records show that Apollo 11’s transit through the Van Allen belts lasted a total of 90 minutes, flying around the region of maximum intensity in about ten minutes.