THE DETAILS: In the book Dark Moon, Mary Bennett and David Percy describe tests conducted by physicist David Groves: films exposed to X-rays became fogged or their pictures were deleted. Therefore, they claim, the same should have happened to the films taken to the Moon.
However, these tests exposed the film to X-rays directly, without any protection, whereas the Apollo films were kept for almost all of the journey inside shielded canisters, which in turn were protected by the shielding provided by the Apollo spacecraft in the Command Module and in the Lunar Module. Even during the moonwalks, the films were shielded by the metal of their Hasselblad magazine.
Groves’ tests also bombarded the test films with an 8-MeV (million electron volts) beam, using a linear accelerator, while astronomers report that X-rays from space have an energy level of less than 5 keV (thousand electron volts), i.e., approximately 1,600 times weaker than the radiation that fogged films in the Groves experiment.
In other words, the tests are crucially flawed: it’s as if they compared drinking a single glass of water with drinking one thousand six hundred glasses at once (about 320 liters or 84.5 US gallons).
This difference is crucial not only in terms of numbers, which show how unfair the tests presented by Bennett and Percy are, but also in terms of the shielding required: X-rays with an energy of less than 5 keV are stopped by a few sheets of paper. Under 3 keV, just a few dozen centimeters (inches) of air are all that it takes.*
* Welcome to the World of X-ray Astronomy, Nasa.gov.
Moreover, Groves reports that he exposed the test films to 25, 50 and 100 rem of radiation, but this unit is wholly inappropriate, because it refers to radiation absorbed by human tissue. Using it for films suggests an unprofessional approach to the matter: it’s like saying that distances are measured in liters (or gallons).
However, for X-rays 1 rad is equivalent to 1 rem, so we could assume that Groves meant doses of 25 to 100 rad. Even so, as discussed in Section 8.4, 25 rad (the lowest figure claimed by Groves) are equivalent to several years in space.