8.18 How could the astronauts still send TV to Earth when their directional antenna wobbled?

IN A NUTSHELL: Because the antenna had ample pointing tolerances and its signal still reached Earth even if this pointing shifted a little. Incredibly sensitive giant antennas on Earth were ready to pick up even a slightly attenuated signal.


THE DETAILS: During the Apollo moonwalks that used the Lunar Rover electric car, communications between the astronauts and the Earth and TV transmissions from the Moon were sent through the car’s transmitter. The Rover was equipped with a parabolic antenna which had to be pointed precisely toward the Earth.

Figure 8.18-1. Top center: the parabolic dish antenna of Apollo 17’s Lunar Rover. Left: the remote-controlled TV camera. Photo AS17-134-20475.

Figure 8.18-2. Right: the Rover points its antenna toward the Earth while an astronaut works close to the Lunar Module (left) during Apollo 17. Detail of photo AS17-134-20435.

According to some Italian conspiracy theorists (Luogocomune.net; Giuseppenardoianni.it), this configuration should have caused interruptions of the signal when the parked car wobbled because it was touched by the astronauts and therefore was no longer exactly pointed at the Earth. However, they say, the recordings of the TV broadcasts don’t show any such signal breaks.


Actually, the NASA manuals referenced by these theorists include a key technical detail which they somehow failed to mention: the antenna could be off-center up to 10° without causing excessive attenuation of the signal.

For example, the Crew Training Manual - Lunar Communications Relay Unit, on page 21, describes the parabolic antenna (known as High Gain Antenna or HGA) by noting that it has a diameter of approximately 92 centimeters (three feet) and a gain (in this context, a indicator of signal strength) equal to 24 dB when centered on Earth, 23.5 dB within 5° and 20.5 dB within 10°. Specifically:

The antenna gain is nominally 24 db on boresight, 23.5 db over a 5° cone and 20.5 db over a 10° cone.

Accordingly, any oscillation of the Rover of up to 10° would have caused an attenuation of the signal but would not have make it miss the Earth completely. The weaker signal would still have been picked up by the giant 64-meter (210-ft) dish antennas on Earth.

Moreover, it’s not true that there are no breaks in the TV transmissions. Researcher Diego Trystero published a video (Figure 8.18-3) which assembles some of the many conspicuous interruptions that occurred during live transmissions from the Moon, often in relation to oscillations of the vehicle.

Figure 8.18-3. A collection of TV signal loss episodes during Apollo 15, 16 and 17.

NEXT: Chapter 9. Other alleged anomalies

8.17 How come the pressurized spacesuits don’t look like they’re inflated?

IN A NUTSHELL: Because they had an inner pressure containment layer, just like present-day spacesuits, and the outer layer wasn’t pressurized.


THE DETAILS: Some Moon hoax proponents wonder how astronauts could flex their fingers inside the bulky gloves of their spacesuits and more generally how they could move at all, since the suits, if pressurized as NASA claims, would have inflated like balloons in the vacuum of space and would have become impossibly rigid. Yet Apollo photographs show astronauts on the Moon moving around quite comfortably, with suits that show no sign of ballooning and are actually flexible and surprisingly creased and saggy.

This objection can be dismissed simply by considering that the American, Russian and Chinese spacesuits currently worn today by astronauts during spacewalks on the International Space Station and in Chinese spaceflights are quite obviously flexible and don’t balloon, and neither did the suits used in Skylab or Shuttle flights or by cosmonauts aboard Soyuz spacecraft or the Mir space station, so there must be a way to solve these allegedly unsurmountable problems. That way is essentially the same one introduced by Russian and American spacesuits of the 1960s.

The issue is probably based on limited knowledge of the actual structure of Apollo spacesuits. Each suit was in fact composed of two suits, worn one inside the other: a pressurized inner suit (shown in blue in Figure 8.17-1), rarely seen on its own, and an unpressurized outer one (shown in white in the same figure), which is the one visible in all the Apollo moonwalk photos.

Figure 8.17-1. Artist’s illustration of a cutout of a complete spacesuit (pressurized inner suit and unpressurized outer suit). Credit: Paul Calle.

The inner suit, known as Pressure Garment, was the airtight part of the suit that enclosed the astronaut’s body. It was pressurized to approximately one third of sea-level pressure; this helped to reduce the suit’s tendency to balloon and stiffen. It was mostly made of neoprene in which a non-elastic containment layer of mesh was embedded.

In other words, the inner suit could only expand until this mesh was taut. If you can imagine a balloon placed inside a bag of netting, or if you look at a garden hose, you have a good example of a pressure containment layer.

The fingers, shoulders, knees and elbows of the suit had accordion-like joints that allowed flexing without ballooning (Figures 8.17-2 to 8.17-5).

Figure 8.17-2. Gene Cernan checks the fit of the airtight inner layer of the Apollo spacesuit, known as Pressure Garment. Note the accordion-like joints at the elbows and fingers. NASA photo AP17-72-H-253.

Figure 8.17-3. Charlie Duke (Apollo 16) tests the flexing of his Pressure Garment.

Figure 8.17-4. A color photograph of the Apollo Pressure Garment.

Figure 8.17-5. Apollo 17 astronaut Harrison Schmitt tests the Pressure Garment.

The outer layer, shown in Figure 8.17-6, was made of fireproof, abrasion-resistant materials and was designed to provide thermal insulation and protection against micrometeoroids, microscopic specks of dust that travel through space at enormous speeds and strike the astronauts on the lunar surface like minute bullets, which are stopped by the multiple layers of the outer suit.

Figure 8.17-6. Ron Evans (Apollo 17) checks the maximum upward reach of his arm while wearing both the inner Pressure Garment and the white outer protective suit.

In summary, the Apollo spacesuits don’t look like they’re pressurized simply because what we normally see is their outer layer, which indeed wasn’t pressurized.

NEXT: 8.18 How could the astronauts still send TV to Earth when their directional antenna wobbled?

8.16 Wasn’t the lunar module hatch too narrow?

IN A NUTSHELL: No, it wasn’t. People who claim that the spacesuit was too wide to pass through the hatch are referring to the width of the suit when spread flat and with the arms at its sides, but the suit is much narrower when worn. Also, the moonwalkers crawled through the hatch on all fours and therefore with the arms tucked under their bodies, not at their sides. All this greatly reduced the actual suit width, allowing it to pass easily through the hatch. Besides, if the whole thing had been faked, it would have been trivial to fake a comfortably bigger LM hatch.


THE DETAILS: James Collier, author of the book and DVD Was It Only a Paper Moon?, reported that he went to the National Air and Space Museum in Washington and the Johnson Space Center in Houston, where he

video taped an actual LM. Here research indicated that the crew compartment and hatches were too small for the astronauts to actually enter and exit. After taking the video footage I challenged NASA to prove that two six-foot astronauts, in ballooned-out pressure suits (4-psi in a vacuum) could either get in or get out of a LM.

Mary Bennett and David Percy, in their book Dark Moon (pages 340-341), argue that

...the aperture of the LM is only 32 1/4 inches wide [...]. Surely, it would be very difficult for a pressurised, spacesuited astronaut, fully loaded with his PLSS and measuring over 31 inches in width to exit through such a small and awkward aperture.

The width of the LM hatch quoted by Bennett and Percy is essentially correct, as confirmed by NASA’s Apollo 11 Press Kit and Lunar Module Operations Handbook.

However, their measurement of the width of a suited astronaut is definitely wrong, because it refers to the spacesuit laid flat and with its sleeves at the sides of the flattened torso of the suit (as shown in the photograph on page 341 of Dark Moon). Any garment measured in this way will appear to be much wider than when it is being worn, because it’s not wrapped around the wearer’s body. Try this for yourself: your sweater, when spread flat, is much wider than your body. Basically, Bennett and Percy are confusing girth and width.

The PLSS backpack was approximately 51 centimeters (20 inches) wide and therefore posed no problems in terms of hatch width.

This mistake is compounded by the fact that the Apollo astronauts crawled out through the hatch on their hands and knees and therefore held their arms tucked in under their bodies, not at their sides as shown in Dark Moon. This reduces further the actual width of the spacesuited astronaut.

Besides, Apollo photographs such as AS11-40-5862 (Figure 8.16-1), which shows Buzz Aldrin as he exits the lunar module through the hatch, clearly demonstrate that the hatch was wide enough. Astronauts reported that exit certainly wasn’t easy, but it was feasible.

Figure 8.16-1. Buzz Aldrin exits from the Lunar Module to walk on the Moon. NASA photo AS11-40-5862 (cropped), taken by Neil Armstrong.

There’s a very simple way to check all this. The hatch width reported by Bennett and Percy, 32 1/4 inches (82 centimeters), is the width of an average interior house door. The widest part of a suited astronaut’s body is at the shoulders, so try standing in a doorway and notice how much clearance you have on either side. Even if you take into account a bulky Apollo spacesuit, there’s still room enough to walk through easily.

If you really want to be thorough, buy or rent a replica Apollo spacesuit (available from specialist dealers), put it on and compare its actual width with the hatch of an original LM, such as the ones on display at the National Air and Space Museum in Washington, DC, at the Kennedy Space Center in Florida or at the Johnson Space Center in Houston, Texas.

While it may seem impossible to access priceless museum artifacts like the Lunar Modules to measure them, today’s technology actually allows this without even getting too close. A 2018 article on Metabunk.org describes how the LM on display at the Kennedy Space Center, which is an unflown original vehicle, was measured remotely using a home-made portable LIDAR scanner. The same technique was then used on an Apollo spacesuit worn by a manikin and displayed at the KSC. This method allowed not only to measure the various widths but also to create a digital model of the interaction between the suit and the LM. The result is that the suit fits through the hatch. All the data are publicly available.

Figure 8.16-2. LIDAR acquisition of the dimensions of the hatch and of the spacesuit.

The Metabunk article notes that some conspiracy theorists even claim that the astronaut manikins placed next to the Lunar Module at the Smithsonian are smaller than real people to hide the fact that the hatch is (allegedly) too small.

There’s another logical rebuttal to any claim of an impossibly narrow hatch or cramped LM interior: if the whole Apollo project was faked, there would have been no point in skimping on the size of the spacecraft. Why not simply fake a slightly bigger LM with a wider hatch and avoid any questions about hatch size?

NEXT: 8.17 How come the pressurized spacesuits don’t look like they’re inflated?

8.15 How can the astronauts’ footprints be so sharp?

IN A NUTSHELL: They’re as sharp as they should be in dry, jagged, electrostatically charged moondust in a low-gravity vacuum, which behaves quite differently than weathered sand in Earth’s atmosphere and gravity.


THE DETAILS: In NASA Mooned America!, Ralph Rene claims that “clear tracks in deep dust require moisture; otherwise they form only indistinct depressions [...] There can be no moisture on the Moon [...] And yet, every picture allegedly taken on the Moon shows clear footprints” (page 7). In other words, sharply outlined bootprints such as the famous one shown in Figure 8.15-1 are said to be impossible on the Moon.

Figure 8.15-1. A bootprint left on the Moon by Buzz Aldrin (Apollo 11). Detail of photo AS11-40-5877.

Figure 8.15-2. Aldrin leaves another bootprint in the very fine lunar dust during Apollo 11. Detail of photo AS11-40-5880.

Proponents of this claim, however, fail to consider that sand on Earth is exposed to very different conditions than dust on the Moon.

First of all, on Earth, the wind, the flow of water and other natural phenomena constantly move and churn the grains of sand against each other, smoothing their surfaces and reducing their friction. On the Moon this smoothing doesn’t occur, and therefore the grains of lunar “sand” (termed regolith in geological jargon) are sharp-edged and uneven. Accordingly, they tend to lock together and stick to each other far more than Earth sand, much like a stack of smooth river stones will collapse easily while a similar pile of jagged rocks will keep its shape. This leads to higher cohesion and sharper footprints.

Then there’s gravity, which is one sixth of the Earth’s. Stacked moondust particles are pulled down by weaker forces than on our planet and therefore the edges of footprints, for example, hold their shape more easily.

Finally, there’s electrostatic attraction. Lunar regolith has a considerable electrostatic charge and therefore its grains tend to cling to each other more than ordinary Earth sand, in the same way that dust clings to an electrostatically charged glass surface, such as an old-style (CRT) television screen.*

* Effects of gravity on cohesive behavior of fine powders: implications for processing Lunar regolith, Otis R. Walton, C. Pamela De Moor and Karam S. Gill, in Granular Matter, vol. 9 no. 6 (2007).

These differences, therefore, allow lunar regolith to form far sharper prints than sand on Earth. This is confirmed independently by the images of lunar soil sent by the Soviet Lunokhod rovers, which show finely detailed wheel tracks (Figure 8.15-3).

Figure 8.15-3. Sharp-edged wheel tracks left on the Moon by Soviet Lunokhod 1 in 1970.

As further confirmation, in 2008, the Mythbusters TV show placed a sample of powdery material, geologically equivalent to lunar regolith, in a vacuum chamber and then pressed a footprint into it, using a replica of an Apollo Moon boot. The result closely resembled the sharp-edged footprints seen in Apollo photographs, despite the six times stronger gravity and the lack of any significant electrostatic charge (Figure 8.15-4).

Figure 8.15-4. The bootprint produced in vacuum in synthetic regolith by Mythbusters.

NEXT: 8.16 Wasn’t the lunar module hatch too narrow?

8.14 How can there be no dust at all on Apollo 11’s LM footpads?

IN A NUTSHELL: It was blasted away. Dust moved by a rocket exhaust in an airless environment such as the Moon doesn’ billow up around the spacecraft and then settle on it: it travels in straight lines away from the vehicle, unhindered by any air resistance, and therefore is unlikely to end up on the vehicle’s footpads.


THE DETAILS: Photographs of Apollo 11’s lunar module footpads on the Moon show them to be completely dust-free (Figure 8.14-1). To some this seems suspicious. Shouldn’t the engine blast have blown at least some dust onto the footpads? Says Bill Kaysing in the 2001 documentary Did We Land on the Moon?:

“If they had truly landed on the Moon, this dust would have then descended on the lunar lander, on the footpads, and we find not a trace of dust on the footpads.”

Figure 8.14-1. A spotless Apollo 11 footpad. NASA photo AS11-40-5920 (cropped).

However, the lack of dust on the footpads doesn’t prove that the spacecraft was actually a mockup delicately placed on a movie set and that the hoax perpetrators incredibly forgot to spread some dust on the footpads to make the scene more realistic. There’s a simpler, entirely non-conspiratorial explanation: on the Moon, dust doesn’t “descend” as Kaysing suggests, simply because it doesn’t rise and float in the first place.

The Moon is airless, so there’s no atmosphere to carry the dust and allow it to form billowing clouds that then settle. The dust simply gets blown sideways and outward, racing roughly parallel to the ground and away from the landing spot, and then falls down at the end of its essentially rectilinear trajectory, without floating around. This effect is clearly visible in the footage of the Apollo lunar landings and liftoffs.

Moreover, in a vacuum only the dust that is struck directly by the exhaust gets moved, and the exhaust expands very rapidly and just as rapidly weakens, so the displacement is very localized (on Earth, such a displacement has a broader action because the exhaust displaces the surrounding air, which in turn displaces dust, spreading out the effect). Indeed, the Apollo 11 photographs show pebbles and dust a short distance out from the footpads, as evidenced in Figure 8-14 by the footprints behind the LM’s landing gear.

The dust that is moved, however, can travel quite a distance at high speeds, since there’s no air resistance to slow it down and the low gravity drags it down more gradually than on Earth. On Apollo 12, dust displaced by the LM exhaust reached the Surveyor probe, roughly 200 meters (650 feet) from the LM, as evidenced by the sandblasting detected on the side of Surveyor that faced the LM.*

* Watch Out for Flying Moondust, by Trudy Bell and Dr. Tony Phillips (2007), Nasa.gov.

NEXT: 8.15 How can the astronauts’ footprints be so sharp?

8.13 Why are Apollo 11‘s footpads clean while later missions have dusty ones?

IN A NUTSHELL: Different terrains and different landing styles. Some missions  landed in flat regions of the Moon and others landed in hilly areas, with different dust covers. Some pilots landed less gently than Apollo 11; some dragged their footpads on the ground, scooping up dust. The astronauts also occasionally kicked dust into the footpads as they walked close to the LM landing gear.


THE DETAILS: While Apollo 11’s Lunar Module landing gear is immaculately dust-free, the footpads of other lunar modules are very dusty. Compare, for example, Figure 8-13.1 (Apollo 11) with Figure 8-13.2 (Apollo 16).

Figure 8.13-1. A very clean Apollo 11 LM footpad. NASA photo AS11-40-5920 (cropped).

Figure 8.13-2. A dusty Apollo 16 LM footpad. NASA photo AS16-107-17442 (cropped).

So what, you might say. But according to some doubters, this is important. Such a conspicuous difference allegedly proves that Apollo 11 was faked badly (forgetting to sprinkle dust on the footpads) but later missions were staged more accurately, correcting this omission.

Once again, a conspiracy theory is based on the assumption of bungling perpetrators: for some bizarre reason, the most important fakery of the century was assigned to a bunch of sloppy amateurs who made all sorts of mistakes and left evidence in the photographs, and somehow their bosses didn’t notice the mistakes before releasing the pictures to the public.

Moreover, this kind of theory is also a typical example of how conspiracy theorists focus on absolutely trivial and insignificant detail and present it as some kind of devastating evidence of fakery, instead of considering the most obvious and simple answer: the dust is different because the various spacecraft landed in geologically different places.

They did so in order to acquire the broadest possible variety of samples: Apollo 11 and 12 landed on very flat terrain; Apollo 14 touched down in a broad, shallow valley; and Apollo 15, 16 and 17 landed in the highlands of the Moon.

It doesn’t take a degree in geology to realize that the Moon isn’t the same all over. It’s not some sort of giant, uniformly dusty billiard ball. Even with the naked eye it is possible to distinguish darker regions, which are the lunar plains, and brighter mountainous areas, with different colors and made of different rock. Some regions will have more surface dust than others.

Compare, for example, the Apollo 11 site (Figure 8.13-3) with the Apollo 17 site (Figures 8.13-4 and 8.13-5).

Figure 8.13-3. Composite panorama of the Apollo 11 landing site (photos AS11-40-5930/31/32/33/34/39/40). Credit: NASA/Moonpans.com.

Figure 8.13-4. Composite panorama of the Apollo 17 landing site. Credit: NASA/Moonpans.com.

Figure 8.13-5. Another composite panorama of the Apollo 17 landing site. Credit: NASA/Moonpans.com.

It seems reasonable to assume that vastly different locations might have different dust coverings. Indeed, Pete Conrad (Apollo 12) and Dave Scott (Apollo 15) reported that they had to fly on instruments for the final 30 meters (100 feet) of their landing because the dust kicked up by their engine’s exhaust obscured their view of the surface, while other LM pilots didn’t have the same problem.

Moreover, some landings were quite rough. Apollo 11 landed very smoothly after hovering and blowing away most of the local dust, but Apollo 14, for example, dragged its landing gear sideways after touchdown. This caused the footpads to scoop up moondust, as shown for example in NASA photo AS14-66-9234 (Figure 8.13-6).

Figure 8.13-6. An Apollo 14 footpad shows considerable dust displacement. NASA photo AS14-66-9234.

Apollo 15 landed with one footpad in a 1.5-meter (5-ft) deep crater, damaged its engine exhaust bell and came to rest at a steep angle. Its footpads dug quite deeply into the ground and got very dusty.

Finally, dust could also accumulate on the footpads after landing, for example if the astronauts worked close to the LM’s landing gear (as in Figure 8.13-2). As they walked around, they kicked up dust which, in a vacuum and in low gravity, could travel quite far and end up on the footpads.

NEXT: 8.14 How can there be no dust at all on Apollo 11’s LM footpads?

8.12 How could the timing of the lunar liftoff footage be so perfect despite the signal delay?

IN A NUTSHELL: Because it was calculated in advance. Liftoff time was known to the second and the rate of ascent was known precisely, so the camera operator compensated the delay by tilting the camera up 1.3 seconds early with a predetermined rate of motion.


THE DETAILS: In his Wagging the Moondoggie website, conspiracy theorist David McGowan considers with suspicion the spectacular TV footage of the liftoff of Apollo 15, 16 and 17 from the Moon. This footage was shot with the Rover’s TV camera, which was controlled by radio signals from Earth.

Considering that the radio commands to move the camera took about 1.3 seconds to travel from the Earth to the Moon and the resulting TV picture took just as long to be received on Earth, how could the camera operator track the ascending Lunar Module? “There apparently either wasn’t any delay in the signal or NASA had the foresight to hire a remote camera operator who was able to see a few seconds into the future”, argues McGowan.

Actually, the remote camera operator (Ed Fendell) could see more than a few seconds into the future, in a way, because the liftoff time of the Lunar Module was known very precisely in advance. Exact timing was critical, otherwise the LM would not be in the right place at the right time to rendezvous with the Command Module once in orbit around the Moon. The delay caused by the Earth-Moon distance was also known very precisely. So Fendell knew exactly when to send the commands: about 1.3 seconds ahead of the scheduled liftoff time.

The rate of climb of the LM was also known very precisely and therefore the rate at which the camera had to tilt up in order to keep the LM in frame could be calculated in advance and commanded in advance accordingly. The tilt rate depended on the distance of the camera from the LM and had to be calculated carefully.

The hard part wasn’t calculating the exact timing of the commands, but their direction and speed, so as to take into account the distance of the Rover from the Lunar Module, as explained by Fendell himself in the video of Figure 8.12-1.

Figure 8.12-1. Ed Fendell, lunar TV camera operator, explains the techniques and challenges of obtaining video of the liftoffs from the Moon.

The first attempt at this remarkable shot (during the Apollo 15 liftoff) failed because the tilting mechanism malfunctioned and the camera didn’t tilt up. The second attempt (Apollo 16) went better, but the Rover was parked closer than expected to the LM and this threw off the calculations, so the camera lost track of the LM quite early. The third attempt worked out perfectly, and Apollo 17’s lunar liftoff was tracked until the LM became a tiny bright speck on the TV screen.

NEXT: 8.13 Why are Apollo 11‘s footpads clean while later missions have dusty ones?

8.11 How come there’s no blast crater under the LM’s engine?

IN A NUTSHELL: Because there’s not supposed to be one. The idea that the lunar module’s engine should have formed a crater upon landing was suggested by some artist’s illustrations published by NASA ahead of the Moon landings. But the crater is merely an artistic license: the engineers already knew that no crater would form because the Surveyor uncrewed probes had already landed and sent back pictures of their landing sites, which showed no crater under their engines.


THE DETAILS: Conspiracy theorist Bill Kaysing argues that the Lunar Module mysteriously failed to blast a crater in the surface of the Moon with its powerful rocket engine.

NO CRATERS! [...] In all pictures of the LEM on the “moon”, there is absolutely no evidence of a crater underneath the engine. If indeed the module had landed on the moon, the engine would have blasted out a substantial hole in the dustlike surface of the moon.

– We Never Went to the Moon, page 75.

Kaysing repeats the claim in the FOX TV documentary Did We Land on the Moon? (2001):

“The fact that there is no blast crater under the LM is one of the most conclusive pieces of evidence that I find supporting the hoax.”

But if a blast crater was expected, why would the alleged fakers be so clumsy as to forget to sculpt one into their lunar movie set?

Actually, the expectation of a blast crater under the LM was fostered by many artistic depictions of the Moon landing that were circulated by NASA and by the press ahead of the event, as witnessed for example by Figures 8.11-1 and 8.11-2.

Figure 8.11-1. The Moon landing as depicted by Norman Rockwell (1966). Credit: Eric Long, National Air and Space Museum, Smithsonian Institution.

Figure 8-11-2. The Moon landing as depicted by NASA in 1966. Detail from S66-10989.

But mission planners didn’t really expect the LM engine to gouge a crater in the Moon: that detail, like many others in artists’ illustrations, was dramatic license.

Artistic depictions are, well, artistic: they’re not intended to portray an event with absolute fidelity, but to bring the event to life, explain it and communicate its significance, drama and excitement. If accuracy gets in the way of the message, it is often set aside.

For example, Figures 8.11-1 and 8.11-2 include stars, despite the fact that stars are normally not visible from the Moon when the lunar surface is in daylight, and the LM is shown without its characteristic protective “tin foil” (thermal blankets and micrometeoroid shielding), which in 1966 hadn’t yet been added to the vehicle’s design.

The crescent Earth in Figure 8.11-1 is likewise impossible, since the planet could only be lit in this way when the Sun is below the lunar horizon and therefore the moonscape should be in darkness; yet in Rockwell’s exciting depiction the shadows suggest that the Sun is above the horizon and to the left. 

In other words, the presence of a crater under the LM in illustrations doesn’t prove that the landings were faked: it proves the talent of the artist who found a way to suggest the dynamic action of the engine’s exhaust in a static image. Essentially, Kaysing was mistaking artwork for hard science.

Actually, not all NASA illustrations show a crater under the Lunar Module. Figure 8.11-3 is an artist’s concept created for Grumman (the company that designed and built the LM), in which there’s no blast crater and the LM is depicted far more realistically than in the previous figures (note, for example, the MESA equipment rack and the exhaust deflectors under the attitude control thruster quads). However, the stars are still shown in order to give depth to the artwork and the Earth is too low on the horizon for any Apollo landing site.

Figure 8.11-3. An artist’s concept of the LM created for Grumman before the first Moon landing. NASA image S69-38662.

Leaving artistic license and conspiracy theories aside, why didn’t the rocket blast of the LM form a crater or visibly disturb the surface? After all, the Lunar Module was a 15-ton spacecraft, so it needed a powerful engine to counter that weight and make it hover. Instinctively, we expect that kind of force to do some damage to the landing site.

But first of all, lunar gravity is one sixth of the Earth’s, so the LM’s weight on the Moon isn’t 15 tons; it’s 2.5. Moreover, these figures refer to the initial weight of the spacecraft, which decreased dramatically as its rocket fuel was used up. For example, for Apollo 12, which had an initial LM mass of 15,115 kilograms (33,325 lb), telemetry data reported the use of approximately 7,810 kilograms (17,200 lb) of propellant mass,* leaving a landing mass of approximately 7,305 kilograms (16,104 lb). The spacecraft essentially halved its initial mass by burning propellant, and in lunar gravity that residual landing mass is equivalent to a weight of just 1,217 kilograms (2,700 lb). In other words, keeping a LM in a hover above the landing spot entailed countering a weight of just 1,200 kilograms (2,700 lb), not 15,000 (33,000 lb); far less than assumed initially.

* Apollo 12 - The Nasa Mission Reports, Apogee Books, 1999, p. 44 and p. 137.

Secondly, since the surface of the Moon consists of hard rock covered by a layer of dust, this rather modest rocket thrust would merely blow away the dust and expose the underlying rock. That’s exactly what we see in the Apollo photographs (Figure 8.11-4).

Figure 8.11-4. Apollo 11’s LM descent engine bell on the Moon. Note the dust-free, smooth, rocky surface in the foreground and the radial pattern formed on the surface by the engine exhaust. NASA photo AS11-40-5921.

The LM rocket exhaust might be expected to melt the lunar rocks at the landing spot, but the estimated temperature of the exhaust was approximately 1,500 °C (2,800 °F)* and decreased very rapidly because the hot plume expanded into a vacuum and therefore cooled down, like any other expanding gas.

* The Blast Crater, Clavius.org.

Moreover, it takes several minutes of intense heat to melt the kind of rocks that form the surface of the Moon, whereas the LM’s exhaust struck the same surface spot only for a few seconds. There simply wasn’t enough heat or time to cause significant melting or cratering. What we do see in the Apollo photographs is a slight discoloration, possibly due to charring or to a chemical reaction of the propellant with the rock, and traces of fluid erosion.

No crater was expected by mission planners due to direct previous experience: seven automatic Surveyor probes had landed on the Moon between 1966 and 1968, sending back TV pictures of the landing site and chemical and physical tests of the lunar surface, which showed no cratering and indicated a compact rocky nature that allowed safe touchdown. The Apollo astronauts didn’t fly into the absolute unknown; they had a fairly good idea of what to expect.

NEXT: 8.12 How could the timing of the lunar liftoff footage be so perfect despite the signal delay?

8.10 Isn’t it impossible to cool an astronaut in a vacuum?

IN A NUTSHELL: No, it isn’t: if it were, then present-day spacewalks would be impossible too. You just have to transfer the astronaut’s heat to the water reserve in their backpack and then discard the heated water. Exposing the water to the vacuum of space freezes it, removing even more heat from the astronaut’s suit.


THE DETAILS: People who are not familiar with spacesuit technology are sometimes puzzled by the idea of maintaining a comfortable temperature inside a thick, bulky insulating suit that is in the vacuum of space and goes from being exposed to full sunlight to being in total shadow, with consequent extreme temperature variations. A vacuum would seem to be an almost perfect insulation into which it might appear impossible to dump excess heat. It obviously rules out the use of a compressor like those used in air-conditioning units.

Yet Russian and American astronauts have been performing spacewalks since the 1960s and have since been joined by astronauts of many other countries, so clearly there must be a technology that allows to keep an astronaut cool in a vacuum, otherwise one would have to claim that every spacewalk ever made was faked (and still is, since spacewalks are routine events on the International Space Station).

Many of these spacewalks didn’t rely on umbilicals (long hoses that supplied air, power and temperature control to the suit) but used self-contained equipment located in the spacesuit backpack, so they were (and still are) very similar to the Apollo moonwalks.

If cooling an astronaut in a vacuum were really impossible, then this famous photograph would be impossible too (Figure 8.10-1). It shows US astronaut Bruce McCandless in space, completely untethered and disconnected from any cable or umbilical.

Figure 8.10-1. Bruce McCandless performs the first fully untethered spacewalk while orbiting around the Earth in 1984 during Shuttle mission STS-41-B (NASA).

The photo shown in Figure 8.10-2 would likewise be impossible: it shows Italian astronaut Luca Parmitano outside the International Space Station, retained only by a bracket that secures him by his feet to the Station’s robot arm.

Figure 8.10-2. Luca Parmitano during his first EVA, in July 2013 (ESA/NASA).

Any doubters can simply read the technical literature (for example the book US Spacesuits by Kenneth S. Thomas and Harold J. McMann and Russian Spacesuits by Isaak P. Abramov and A. Ingemar Skoog) and realize that the necessary technology does indeed exist and was already available at the time of the Apollo flights, as described in the section entitled PLSS (Portable Life Support System) of the Apollo Lunar Surface Journal.

During lunar excursions, the heat generated by the astronaut’s body was captured by a tight-fitting undergarment, known as Liquid Cooling Garment, in which water was circulated inside a web of fine tubing. This method is still used today for modern spacesuits and in some suits for racing car drivers and mechanics.*

* This kind of undergarment was first used commercially in 1964 by NASCAR driver Paul Goldsmith. It enabled him to stay cool despite track temperatures of 54° C (130°F), as reported by U. S. Spacesuits, by Kenneth S. Thomas and Harold J. McMann on page 122.

The heated water then entered a heat exchanger, located inside the suit’s backpack (Figure 8.10-3), where it released its heat to a water reserve of approximately four liters (8.5 pounds), which was increased to 5.2 liters (11.5 pounds) in later moonwalks.

Figure 8.10-3. The inside of an Apollo spacesuit backpack or PLSS, seen from the rear. Credit: Ulli Lotzmann/NASM.

Figure 8.10-4. A schematic rear view of a backpack of an Apollo spacesuit, from the book Exploring Space by Kenneth Gatland (1983). 1) Oxygen purification system 2) High-pressure emergency oxygen reserve 3) Low-pressure oxygen 4) Radio 5) Electric junction box 6) Water circuit for thermal control 7) Ventilation circuit 8) Cooling liquid circuit 9) Primary oxygen subsystem 10) Water supply and dump valves.

This water then reached a sublimator, where it was slowly and gradually exposed to the vacuum of space. The consequent pressure drop, in accordance with the laws of physics, made its temperature fall: the water would freeze on the outer surface of the sublimator and turn directly from ice to water vapor, which was discharged through an appropriately provided duct.

This system allowed to dissipate up to 2,000 BTU/hour (approximately 580 W): enough to air-condition a small room and therefore more than adequate for cooling the inside of an astronaut’s suit, so much that John Young, for example, remarked that even the intermediate setting made him feel freezing cold if he wasn’t exerting himself.

NEXT: 8.11 How come there’s no blast crater under the LM’s engine?

8.9 How could the astronauts have changed film magazines outside on the Moon?

IN A NUTSHELL: Their cameras had light-tight magazines, designed to allow film changes even in direct sunlight and while wearing the spacesuit’s bulky gloves, as shown in the TV transmissions from the Moon. This wasn’t an exceptional technological innovation: the same feature was part of any professional photographer’s equipment in the 1960s.


THE DETAILS: Some Moon hoax theorists argue that astronauts on the Moon couldn’t change the film of their cameras while wearing the clumsy, bulky gloves of their spacesuit and while they were in full sunlight, yet the mission records don’t report that they ever went back into the lunar modules to reload their cameras. So how were they able to take thousands of photographs?

The answer is quite simple but clever: the films used for the Hasselblad cameras taken to the Moon were prepackaged in light-tight magazines that snapped onto the camera body (Figure 8.9-1) and were designed to be changed even in full sunlight. The same method was used by professional photographers of the time to change films even halfway through a roll.

Figure 8.9-1. Snap-on mounting of a film magazine on a Hasselblad EL/M camera, similar to those used on the Moon. Lunar magazines were larger than the one shown. Credit: PA.

Not all missions, moreover, changed films during their excursions outside the spacecraft. For example, the Apollo 11 moonwalk made do with a single magazine, so the problem didn’t occur at all.

Handling the film magazines while wearing the thick gloves of a lunar spacesuit wasn’t a problem because the magazines were cubic objects about 10 centimeters (4 inches) wide on each face (Figures 8.9-2 and 8.9-3).

Figure 8.9-2. Charlie Duke is holding a film magazine and is about to change it outside on the Moon. Frame from the Apollo 16 TV transmission.

Figure 8.9-3. Duke changes film magazine outside on the Moon during the Apollo 16 TV broadcast. Note that he reports that he tried to blow the dust off.

Moreover, the magazines used on the Moon had been modified to have larger grip rings, so as to allow easy removal of the so-called darkslide (a removable metal lamina designed to protect the film) even with gloves. This removal can be seen in the video of Figure 8.9-3.

Figures 8.9-4 and 8.9-5 show the darkslide ring of a commercial Hasselblad magazine and of a lunar magazine: the larger size of the ring to allow gripping it with spacesuit gloves is clearly visible.

Figure 8.9-4. A standard Hasselblad magazine with its partially extracted darkslide. Credit: Ulli Lotzmann.

Figure 8.9-5. Magazine R of Apollo 11, currently displayed at the National Air and Space Museum in Washington, D.C. Note the larger ring used to pull out the darkslide while wearing spacesuit gloves. Credit: NASM.

In other words, changing films outside on the Moon was perfectly feasible and had been designed into the Hasselblad lunar cameras.

Charlie Duke’s strange gesture

In the video shown in Figure 8.9-3, astronaut Charlie Duke removes the darkslide before mounting the magazine on the camera. This often perplexes Hasselblad camera experts, since the darkslide is usually removed only after the magazine has been installed, so that the film is not exposed to light. Removing it before mounting exposes the film to light, spoiling it. But Duke isn’t wrong.

In the 1960s, darkslides were normally used in Hasselblads and other cameras that used a film magazine to protect the film from light. This allowed to change film mid-roll, without exposing any frames to unwanted light.

Magazine changes were performed for example to install a Polaroid instant film magazine, take a test photograph with the camera already in position and set up, check the result and then mount a standard high-quality film magazine to take the final photograph.

At the time, cameras didn’t have a video screen that could show the result of the photograph straight away and therefore a Polaroid was the only way to have a preview of the final photo and make sure that the camera was set up correctly.

But Charlie Duke’s actions are correct, because lunar Hasselblads didn’t use the darkslide for protection against light. They used it to prevent Moondust from contaminating the reseau plate, i.e., the glass plate that carried the cross-shaped markings that are visible in most Apollo photographs taken on the Moon.

This different use entailed that the portion of film that was visible during a magazine change would catch the light and become unusable. However, this wasn’t a problem in the particular case of the lunar astronauts, who usually didn’t need to change magazine mid-roll.

The astronauts, moreover, usually took three or four blank shots when they started and ended a magazine, so as to make the film advance and be sure to use a part of the film that had not been exposed to light inadvertently.

NEXT: 8.10 Isn’t it impossible to cool an astronaut in a vacuum?

8.8 How come meteoroid showers didn’t kill the astronauts?

IN A NUTSHELL: Because big enough meteoroids are actually incredibly rare. The spacesuits and spacecraft had protective layers designed to absorb the impact of the minute specks that constitute the vast majority of meteoroids. There is no protection against larger meteoroids other than the very low probability of being struck, but this is an acceptable risk, as demonstrated by the fact that satellites, space probes, crewed spacecraft and the International Space Station don’t get riddled by meteoroids.


THE DETAILS: The Moon is pock-marked with craters produced by the constant crashing of meteoroids: rocky or metallic masses of all sizes that travel through space at speeds up to 80,000 kilometers per hour (about 50,000 mph).

Although the terms meteor and meteorite are often used, strictly speaking a space rock is a meteoroid when it travels through space: it becomes a meteor only if it punches into the atmosphere of a planet or moon and forms an incandescent trail and then becomes a meteorite if it reaches the surface of the planet or moon instead of disintegrating completely.

Looking at the Moon, it’s understandable that someone might wonder how the moonwalkers could have possibly coped with this constant lethal danger. The answer is actually quite simple: they relied on probability.

Meteoroid showers aren’t as frequent and dense as often depicted in Hollywood sci-fi productions. If they were, our fleets of satellites that provide us with weather data, TV programs and telephone calls would be destroyed all the time and the International Space Station would be Swiss cheese after over a decade in space. Several automatic probes have been traveling through deep space for three decades or more and have survived essentially unscathed.

Figure 8.8-1 shows a hole, produced by a meteoroid or by spacecraft debris, in the large solar panels of the Space Station. It’s one of the very few impact holes detected in this orbiting outpost, despite the fact that when the picture was taken, in 2013, it had been in space for 14 years: according to NASA estimates, the hole measures about 6 millimeters (a quarter of an inch) in diameter and is probably due to a high-speed impact with an object measuring 1 to 2 mm (.04 to .08 inches) in diameter. Objects of this size are expected to hit somewhere in the large surface area of the Station roughly once every six months. Impacts with larger objects are even rarer.

Moreover, the Station orbits in a region of space close to Earth where there is artificial debris generated by many decades of satellite launches in addition to natural meteoroids. In deep space and around the Moon there is no such debris.

Figure 8.8-1. The tiny white dot is a rare impact hole in the large solar panels of the International Space Station. Credit: Chris Hadfield, 2013.

In addition, most meteoroids are literally microscopic in size. They have an enormous speed, but an almost negligible mass, so if a micrometeoroid strikes an astronaut it is stopped by the spacesuit’s outer layers, which are designed for this purpose. The space suits used by the Apollo moonwalkers and the ones used today for work in space have essentially the same type of multilayer protection against micrometeoroids. That’s one of the reasons why they’re so bulky.

Non-microscopic meteoroids are quite rare. While the Moon’s cratered surface might appear to suggest otherwise, one must bear in mind that those craters are the result of millions of years of exposure.

Accordingly, Apollo astronauts and all lunar spacecraft (including the Russian Lunokhod rovers) had a vanishingly small chance of being struck by a significant space pebble. The same applies to the more recent Chinese Chang’e and Yutu vehicles.

NEXT: 8.9 How could the astronauts have changed film magazines outside on the Moon?

8.7 Wouldn’t sunlight outside on the Moon have burned or boiled the astronauts’ faces?

IN A NUTSHELL: No. It doesn’t affect the faces of astronauts who routinely perform spacewalks outside the International Space Station, where sunlight is essentially as strong as on the Moon. The clear part of the helmet shields their face against the ultraviolet light that causes sunburns.


THE DETAILS: Some Moon hoax proponents argue that the fiercely strong sunlight on the Moon, unfiltered by the Earth’s protective atmosphere, should have caused intense sunburns or overheating, yet we see photographs and footage of the moonwalkers walking around in full sunlight, sometimes even with their protective visor up (Figure 8.7-1), which would have been impossible or extremely hazardous, as claimed for example by Mary Bennett and David Percy in their book Dark Moon.

* Dark Moon: Apollo and the Whistle-Blowers (2001), page 102.

Figure 8.7-1. Harrison Schmitt’s reflective visor is up and his face is in full sunlight in this frame from the Apollo 17 moonwalk TV broadcast.

Figure 8.7-2. The live TV broadcast from which Figure 8.7-1 is excerpted.

Figure 8.7-3. A detail of a frame from the 16 mm film footage of the Apollo 11 moonwalk: Buzz Aldrin’s face is in direct sunlight. Note the “Snoopy cap”, the black and white cap that held the headset and microphones of the suit’s radio.

This claim is contradicted by the simple fact that even the astronauts who work outside the International Space Station are exposed to full sunlight without the shielding of the Earth’s atmosphere, just like their former colleagues on the Moon, yet they don’t get sunburned or overheated, even when they lift their reflective visors, as shown for example in Figures 8.7-4 to 8.7-8. The same applies to the astronauts who performed spacewalks outside Skylab, Shuttle and Mir.

Figure 8.7-4. Jerry L. Ross working outside the Shuttle Atlantis (1991). NASA photo STS037-18-032.

Figure 8.7-5. Mike Good spacewalking outside the Shuttle Atlantis, in full sunlight. NASA photo ISS023E047863.

Figure 8.7-6. Akihiko Hoshide working outside the International Space Station, 5 September 2012, with his face in direct sunlight. Source: NASA/Space.com.

Figure 8.7-7. Alexander Gerst outside the International Space Station, with his reflective visor raised. Fonte: ESA/Instagram.

Figure 8.7-8. Jessica Meir photographs her reflection outside the International Space Station, with her reflective visor up. Source: NASA/Twitter, January 2020.

The Apollo technical manuals explain that during Moonwalks and space walks, lunar astronauts wore a pressurized helmet (the inner goldfish-bowl transparent enclosure) inside an outer helmet. The inner helmet was made of Lexan, which is very tough and, most importantly, highly opaque to ultraviolet rays, which cause sunburns.

The outer helmet in turn had an inner visor, which further filtered ultraviolet and infrared radiation, and an outer visor (the gold mirror-like surface visible in many photographs) that filtered visible light (like mirror shades) to prevent dazzling and provided a further barrier to ultraviolet and infrared rays.*

* Biomedical Results of Apollo, Section 6, Chapter 6, Pressure Helmet Assembly.

Perhaps not unsurprisingly, these issues had been anticipated and solved during mission planning and suit design and had been tested during spacewalks in the early Apollo flights in Earth orbit, where sunlight is essentially as intense as on the Moon.

Basically, moonwalkers didn’t get sunburned for the same reason why you don’t get sunburned if you drive around in your car with the windows up: the transparent material allows visible light to get through but blocks the ultraviolet light that causes sunburns.

Astronauts, both on the Moon and in Earth orbit, often raise their golden visor when they are in shadow and sometimes don’t bother to lower it when they move back into sunlight, but in any case the multiple helmet layers still protect them against sunburn. The worst that can happen to them is that they are dazzled by the bright sunlight.

NEXT: 8.8 How come meteoroid showers didn’t kill the astronauts?

8.6 Wouldn’t the camera films have melted or frozen on the Moon?

IN A NUTSHELL: No. Temperature extremes refer to the lunar surface, from which the films were insulated by vacuum. In any case they were not reached during the Apollo missions, which landed on the Moon shortly after the beginning of the two-week-long lunar day at the landing sites, when ground temperatures were far lower. The films were also a heat-resistant type used for high-altitude reconnaissance and the cameras were treated to reflect the heat from direct exposure to the Sun, which is comparable with the heat from sunlight on a mountaintop on Earth.


THE DETAILS: Gerhard Wisnewski is one of the many hoax theorists who claim that the extreme temperatures of the lunar surface would have damaged the camera films irreparably and therefore the photographs must be fake. In his book One Small Step, Wisnewski argues thus:

There was no other protection against temperature extremes of over 100°C plus and under 100°C minus [...] It was to be expected that the sensitivity of the chemical films would be affected by the extreme temperatures – if indeed not rendered useless by temperatures of over 100°C.

However, a little fact-checking shows that Wisnewski’s premise is incorrect due to a common misconception about temperatures in space.

It’s true that there are great temperature variations on the Moon. Data from recent lunar probes, such as the Lunar Reconnaissance Orbiter (2009) or Chang’e-4 (2019), show maximum temperatures of 110°C (230°F) and minimum temperatures of -180°C (-292 °F) at the lunar equator, and even -190°C on the far side; in some polar regions, which are perennially in shadow, the temperature plunges to -238°C (-397°F). But all these values refer to the temperature of the lunar surface.

This is a crucial detail, since on the Moon there’s no significant atmosphere that can be heated by the ground and therefore there is no way to transfer heat from the ground to the films. Vacuum is a very good heat insulator, as thermos flasks demonstrate. In a vacuum there is no heat transfer by conduction or convection, which are the main heating and cooling processes on Earth. There’s no air to warm or chill objects by contact.

On the Moon and in space, heat is transferred between objects that are not in mutual contact only by radiation: the same principle by which we are warmed when standing next to a fire. Clearly the heating produced by radiation is nowhere as intense as heating by direct contact: there’s a significant difference between warming your hands in front of a fire and putting your hands in the fire.

Consequently, on the Moon the temperature of the ground is essentially irrelevant as regards film temperatures and claiming that ground temperatures would overheat or freeze the films is a misleading and amateurish scientific error.

Wisnewski also doesn’t consider that the reported ground temperature extremes are reached only far into the lunar day (which entails fourteen Earth days of uninterrupted exposure to the Sun) and just before local sunrise (after fourteen days of continuous darkness). But all the Moon landings took place shortly after local sunrise, when the temperatures were far from these extremes.

The maximum elevation of the Sun above the horizon during the Apollo moonwalks was 48.7°, at the end of the third excursion of the Apollo 16 crew. This mission recorded ground temperatures of 57°C (135°F) in sunlight and -100°C (-140°F) in shadow.

The only heat to which the Apollo films were exposed was therefore produced by solar radiation. An object exposed to the Sun on the Moon receives essentially the same amount of heat that it receives on Earth on a mountain top on a clear day, since heat transfer by radiation depends on the distance from the heat source and the Earth and the Moon are essentially at the same distance from the Sun. There’s nothing magically incendiary about the sunlight that strikes the Moon: in terms of heat, it’s roughly the same that we receive here on Earth.

In other words, a film exposed to sunlight on the Moon is affected by the same level of thermal stresses that wouldaffect it on Earth on a bright sunlit day on a high mountain. As we all know, before digital cameras were introduced, tourists were quite able to take photographs in the mountains and even in the heat of tropical forests or deserts without their films melting or spoiling their colors.

One might object that on the Moon the sunlit side of the camera is heated intensely while the shadow side cools just as dramatically. However, these processes are not instantaneous, because once again there’s no air to carry the heat from the camera body to the film or away from the film into space. The camera is in vacuum and therefore the film is like in a thermos flask. Heat transfer between the film and the camera occurs only at their few points of mutual contact. In any case, the cameras used on the Moon were being moved all the time by the astronauts and therefore were never left for long with the same side exposed to the Sun.

Besides, if someone argues that it would have been impossible for film to withstand the vacuum and the temperatures on the Moon, then he or she is implying that all the photographs ever taken on film in space during Russian, European and American spacewalks are fake, because there are no differences, in terms of temperature, vacuum and exposure to sunlight, between the conditions on the Moon and those in Earth orbit.

For example, Figure 8.6-1 shows US astronaut Ed White during his spacewalk outside the Gemini 4 spacecraft in 1965. He is carrying an ordinary camera and his picture was taken with another camera, which also was outside in space. Neither of the films in these cameras melted or was spoiled.

Figure 8.6-1. Ed White used an ordinary camera (which can be seen here in front of the astronaut’s chest), with no thermal protection, during his spacewalk in 1965. NASA photograph S65-30431.

Moreover, the Apollo lunar cameras had been treated specifically to have reflective surfaces instead of the traditional black finish, as shown in Figure 8.6-2. This treatment reflected most of the heat received from the Sun.

Figure 8.6-2. A Hasselblad 500 EL lunar camera.

In addition, lunar photography didn’t use ordinary film, but a special 70 mm Kodak film engineered specifically for high-altitude reconnaissance applications, in which it had to deal with air temperatures as low as -40°C (104°F). This film had a custom-made thin polyester base (Estar), with a melting point of 254°C (490°F), and used an Ektachrome emulsion capable of providing adequate results over a wide temperature range.

Sometimes it is objected that chemical films have a narrow temperature range, so much that professional photographers are very careful to keep their films warm or cool as needed. But this is an optimum range, which yields the best possible colors: it doesn’t imply that the film will break or melt outside of this interval.

NEXT: 8.7 Wouldn’t sunlight outside on the Moon have burned or boiled the astronauts’ faces?

8.5 Shouldn’t X-ray radiation in space have fogged the films?

IN A NUTSHELL: No. The X-ray doses received in space by films during a Moon trip would not have been strong enough. The tests performed by conspiracy theorists use flawed methods and vastly exaggerated doses compared with those to which films might be exposed during a journey to the Moon and back.


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.

NEXT: 8.6 Wouldn’t the camera films have melted or frozen on the Moon?

8.4 How come deep space radiation didn’t kill the astronauts?

IN A NUTSHELL: Because it’s not as deadly as some people claim. The radiation normally present in space at lunar distances from Earth is comparable to the radiation affecting the astronauts on the International Space Station, who stay in space up to one year at a time and don’t come back dead. A round trip to the Moon lasted no more than twelve days.


THE DETAILS: It is often claimed that the lethal radiation of deep space would have killed any Apollo astronauts who tried to get to the Moon, venturing outside of the safety of Earth’s protective magnetic field, which provides a shield against this radiation.

However, the claim’s premise is factually incorrect: on Earth we’re protected against deep space radiation mainly by the atmosphere, not by the planet’s magnetic field, which has a small role in shielding us.

The dose of cosmic radiation (ions traveling at nearly the speed of light) that reaches anyone who lives at sea level is approximately 0.3 millisieverts/year, which is the equivalent of a couple of chest X-rays. This rises to 0.8-1.2 millisieverts/year for people living at high altitudes, for example on a 3,000-meter (10,000-ft) mountain range. At 12,000 meters (40,000 feet), the usual altitude of airline flights, cosmic radiation rises further to 28 millisieverts/year: nearly a hundred times more than at sea level, even though the aircraft’s occupants are still well within the Earth’s magnetic field.

Once you leave the atmosphere, this radiation increases considerably right away. In low earth orbit, such as on the International Space Station, it averages 100 millisieverts/year. At this altitude, the protective effect of the Earth’s magnetic field becomes significant, but only for astronauts who follow equatorial orbits; the ISS has a highly inclined orbit.

In interplanetary space the dose is 130-250 millisieverts/year and by some estimates may be as high as 800 millisieverts/year on a trip to Mars; on the surface of the Moon it drops to 70-120 millisieverts/year.*

* Shielding Space Travelers, Eugene N. Parker, emeritus physics professor at the University of Chicago and member of the National Academy of Sciences, in Scientific American, March 2006.

In other words, the doses of deep space radiation to which the Apollo vehicles and the astronauts were exposed during missions to the Moon are comparable with those that affect the International Space Station, yet the occupants of the ISS stay in space for up to one year without dying of radiation exposure, compared to a maximum of twelve days for the lunar astronauts during Apollo 17.

NEXT: 8.5 Shouldn’t X-ray radiation in space have fogged the films?