Geek Trivia: Five for (Saturn) five

How many Saturn V rockets have reached the surface of the moon, despite the facts that the Saturn V was the largest rocket ever constructed and that it was built specifically so that NASA <em>wouldn't</em> have to send Apollo launch vehicles to the moon?

How many Saturn V rockets have reached the surface of the moon, despite the facts that the Saturn V was the largest rocket ever constructed and that it was built specifically so that NASA wouldn't have to send Apollo launch vehicles to the moon?

Five is our key number here, as five Saturn V rockets have reached the lunar surface. More specifically, five upper stages of Saturn V rockets have been intentionally crashed into the surface of the moon by NASA, each of them following one of the last five Apollo missions.

The third stage of the Saturn V rocket was called the S-IVB (pronounced S-4-B), and it was the topmost conventional stage of the rocket. The S-IVB was separated from the payload section only by an instrument ring that let the lower two stages know when to cut off and separate. Unlike those lower stages, the S-IVB had a job beyond getting the Apollo capsule into Earth orbit -- it was responsible for powering the Apollo craft's trans-lunar injection. Put simply, the S-IVB was the part of the Saturn V responsible for getting the Apollo module from the Earth to the moon.

The problem with this heady trans-lunar injection role is that it put the S-IVB in a rather precarious proximity to the rest of the Apollo craft, such that it could become a hazard during the rest of the mission. Thus, once the TLI was accomplished and the Apollo module was clear, NASA controllers used the S-IVB's remaining fuel to boost it out of harm's way. For the early Apollo missions, this entailed placing the S-IVB into a solar orbit by slingshotting it around the moon. After Apollo 12, NASA scientists realized this was a waste of perfectly good guided ordnance.

Instead of directing the S-IVBs into eternal voyages around the sun, NASA decided to slam them into the moon, where seismometers left behind by Apollo missions could record the impacts. The resulting seismic data was used to map the interior of the moon. Thus, all five S-IVBs from Apollos 13 through 17 met their fate as high-impact moonlanders, fulfilling in some measure the dreams of rocket scientists who originally aspired to land a giant rocket on the lunar surface.

That's not just some seismically serendipitous space science, but a thematically satisfying slice of Geek Trivia.

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By Jay Garmon

Jay Garmon has a vast and terrifying knowledge of all things obscure, obtuse, and irrelevant. One day, he hopes to write science fiction, but for now he'll settle for something stranger -- amusing and abusing IT pros. Read his full profile. You can a...