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

IN A NUTSHELL: Because the other Lunar Modules landed in other regions of the Moon, which were geologically very different (e.g., more dusty), and sometimes landed less gently than Apollo 11, so their footpads dragged on the ground, scooping up dust. The astronauts also occasionally kicked dust into the footpads as they walked close to the LM landing gear. Lack or presence of dust on the footpads is not evidence of fakery.

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 8-14 (Apollo 11) with Figure 8-15 (Apollo 16). According to some doubters, this conspicuous difference proves that Apollo 11 was faked badly (forgetting to sprinkle dust on the footpads) but later missions were faked better, correcting this omission.

Figure 8-15. A dusty Apollo 16 LM footpad. NASA photo AS16-107-17442 (cropped).

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.

The difference in dust can be explained quite simply without resorting to farfetched tales of colossal incompetence. First of all, the Apollo missions landed in geologically very different sites 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. Compare, for example, the Apollo 11 site (Figure 8-16) with the Apollo 17 site (Figure 8-17).

Figure 8-16. Composite panorama of the Apollo 11 landing site (photos AS11-40-5930/31/32/33/34/39/40). Credit: NASA/Moonpans.com.

Figure 8-17. Composite panoramas 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, 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. 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 8-15). 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.