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Before every launch, there's a crawl.

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Special thanks to Robert Sieck, fmr NASA-Kennedy Space Center Launch Director

[♪ INTRO].

This July marks the 52nd anniversary of Apollo 11, when Neil Armstrong became the  first person to walk on the Moon. It was one of the most historic walks ever,  but it actually started… with a crawl!

Because at the Kennedy Space Center in Florida, the iconic rockets that take astronauts  into space aren’t built on the launchpad. They ride in on a specially designed  vehicle known as a crawler-transporter. The crawler’s one and only job is  to transport launch vehicles and their mobile launch platforms between  the assembly building and the launchpad.

In other words, across nearly six-and-a-half  kilometers of alligator-infested swamp. Amazingly, the same two crawlers  have been doing this thankless task since the very beginning of the  Apollo program in the 1960s, and now, they’re getting ready  to crawl us to the Moon again. Back when they were first built, the  $14 million crawler-transporters were the largest self-powered vehicles in the world.

And they had to be to transport  vehicles like the Saturn V rocket, which was about 36 stories tall. They’re essentially giant tanks, moved by  four massive pairs of caterpillar tracks. The flat deck on top is big enough  to fit an entire baseball diamond.

On their own, the crawlers weigh a  whopping three million kilograms. But they’re able to carry more than twice  their own weight in launch hardware. So… it’s not exactly surprising that it takes some serious engine power to get them moving.

They use diesel electric engines  about five times as powerful as the ones on an 18-wheeler and consume more than 13,000 liters of fuel in one round trip. All that is just enough to get them up to a roaring speed of… 3.2 kilometers per hour! But fortunately, when you’re transporting  humankind’s million-dollar hopes and dreams for space exploration,  speed isn’t anyone’s biggest concern.

When it’s time to prepare  for launch, engineers in the. Vehicle Assembly Building  stand the rocket vertically on top of the mobile launch platform. The whole thing is supported by  four pedestals so that the crawler can scoot underneath, pick it up  using hydraulics, and drive away.

Weirdly enough, the rockets and hardware  aren’t actually secured to the crawler. Their massive weight alone is  enough to hold them in place. But even then, the tall  structures still sway a tiny bit!

So crawler drivers have to  train for more than a year to learn how to control the vehicles  and their teetering payload. Once it’s left the assembly building, the crawler’s next challenge  is to cross the swamp. Kennedy Space Center sits on more  than 550 square kilometers of land that’s never more than about  three meters above sea level.

The ground is soft, swampy, and filled with protected populations of  alligators, among other wildlife. So to even get the crawler across it,  Apollo-era engineers also had to design and build a so-called crawlerway across the swamp. It’s as wide as an eight-lane  highway, but it’s no ordinary road.

Because transporting something  the size of a crawler comes with some… special requirements. Like, the road not only needs to be able  to withstand the weight of the crawler; it also needs to prevent the  ground from liquefying beneath it. Which is an actual thing that could happen:.

The vehicle’s vibrations could essentially  turn the waterlogged ground into soup that would swallow the crawler whole. So, to make the road, workers  dredged the swamp and filled it with at least a meter of compressed sand,  followed by a meter of limestone. Then they finished it off with more  than 115,000 tonnes of river rock brought in from out of state.

On this road, the six-kilometer trip  across the swamp takes about 7 hours. The fully loaded crawler inches along at  about one-and-a-half kilometers an hour. It’s accompanied by a crew of at least 20 people, who walk alongside it and ride  on the deck checking for issues.

Oh, and this whole journey  usually happens at night, in an attempt to avoid a lightning  strike from an afternoon storm. So, lightning, swamps and  alligators. What could go wrong?

When it reaches the launchpad, the  crawler has to climb a five-degree slope. Here, it uses its hydraulics again  to jack up the back of the deck to keep the launch platform and rocket vertical. Then, once it gets to the  pad, it uses laser guidance to align the mobile launch platform just right.

After that, it lowers its hydraulics  and scoots back down the crawlerway, this time at its full speed  of 3.2 kilometers per hour! This is how it’s been done at the  Kennedy Space Center since 1967, including for the entirety of the Shuttle program. Over their lifetime, the two  crawler-transporters have traveled a combined 8000 kilometers along the  same 6-kilometer stretch of road.

In fact, they've barely changed  over the last half-century, even as we've gone through multiple  generations of launch vehicles. But now, as we get ready to return to  the Moon by 2024 on the Artemis missions, the Crawler-Transporter 2 is  in the midst of a major refit. It’s getting its tracks and  bearings upgraded to help it carry the new Space Launch System and Orion spacecraft, which could be up to 12 million kilograms.

And it’s getting a new digital interface to  bring it up to speed with the 21st Century. The crawlerway is getting a touch-up too. To brace it for the extra  weight, technicians are driving huge concrete blocks along it  to compact it even further.

And, amazingly, with these  upgrades, these old crawlers from the beginning of the Space Age  will lead us, slowly but surely, into a new age of space exploration. It’s the start of a new month, and we’re talking about a tangible thing  from the history of space exploration. By now, you probably know what  that means: a new Pin of the Month!

All July, we’ll take preorders  for a tiny crawler-transporter that you can attach to your bag,  lapel, or fabric surface of choice. And look, this is a really great one. It’s a charming piece of space history  that not a lot of people hear about!

If you’d like to get your crawl on,  check out the link in the description before the end of July to place your order. And keep an eye out for the  next one this time next month!