Now here comes a little bit of math: the engine nozzle was about 54 inches across (from the Encyclopaedia Astronautica), which means it had an area of 2300 square inches. That in turn means that the thrust generated a pressure of only about 1.5 pounds per square inch! That's not a lot of pressure. Moreover, in a vacuum, the exhaust from a rocket spreads out very rapidly. On Earth, the air in our atmosphere constrains the thrust of a rocket into a narrow column, which is why you get long flames and columns of smoke from the back of a rocket. In a vacuum, no air means the exhaust spreads out even more, lowering the pressure. That's why there's no blast crater! Three thousand pounds of thrust sounds like a lot, but it was so spread out it was actually rather gentle.
[Note added December 6, 2001: Originally in this section I said that the engines also cut off early, before the moment of touchdown, to prevent dust from getting blown around and disturbing the astronauts' view of the surface. This was an incorrect assertion; it was known that dust would blow around before the missions were launched, and steps were taken to make sure the astronauts knew their height above the surface. Anyway, the incorrect section has been removed.]
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Bad: The next argument presented on the show deals with the lunar dust. As the lander descended, we clearly see dust getting blown away by the rocket. The exhaust should have blown all the dust away, yet we can clearly see the astronauts' footprints in the dust mere meters from the lander. Obviously, when NASA faked this they messed it up.
Good: Once again, the weird alien environment of the Moon comes to play. Imagine taking a bag of flour and dumping it onto your kitchen floor (kids: ask your folks first!). Now bend over the pile, take a deep breath, and blow into it as hard as you can. Poof! Flour goes everywhere. Why? Because the momentum of your breath goes into the flour, which makes it move. But note that the flour goes up, and sideways, and aloft into the air. If you blow hard enough, you might see little curlicues of air lifting the flour farther than your breath alone could have, and doing so to dust well outside of where your breath actually blew.