NASA's Curious Universe - The Crawlers

Episode Date: November 16, 2020

A pair of behemoth machines called crawler-trans­porters have carried the load of taking rockets and spacecraft to the launchpad for more than 50 years at NASA’s Kennedy Space Center in Florida.

It dominates whatever is around it. You can feel as it comes by, you know, shakes the ground a little bit. It would just amaze you at the size and the complexity of it. Think of something that's moving very slow, about 0.8 or 0.9 miles an hour, moving this big rocket down the road. It's fun to get up every day and come out and work on the crawler. Our Universe is a wild and wonderful place. I'm Patty Boyd, and in this show, NASA is your tour guide.

Rockets are what launched some of our heaviest and most far-reaching instruments into space. But what gets these rockets to their last destination on the ground? The launch pad. In this episode, we're exploring some of NASA's most powerful ground machinery, the crawlers. These one-of-a-kind, six million-pound behemoths are what transport rockets and their mobile launch platforms so that they can make their ascent into space. And the crawlers have a long history.

You almost have to go all the way back to the beginnings of NASA here at Kennedy Space Center. That's where they built the launch vehicles. That's the crawler's senior project manager, John Giles. The launch vehicles he's referring to are the rockets that would help NASA send humans to the moon for the first time. In the early 60s, NASA built the Saturn 5 rocket to carry out the Apollo missions. Saturn 5 was built upright and was a staggering 363 feet tall

with the Apollo spacecraft on top. That's taller than the Statue of Liberty. And somehow, the rocket had to travel from the vehicle assembly building to the launch pad four miles away. Engineers at NASA scratched their heads. Well, how do you get it there? Something 300 feet long is a little tough to put on some kind of a flatbed truck and roll. You can't really put it on a barge or float it there.

So there were many studies done over the years, and they came up with the best way to get it there was to build this machine, this crawler-type machine. NASA needed a vehicle that could pick up millions of pounds, of pounds and transport it for four miles, all while keeping it level. But NASA couldn't just call up any company to make a machine of this scale. They looked to an industry making some of the most powerful machinery out there, the coal mining industry.

When you watch on TV and you see those giant dump trucks and those giant cranes that scoop up all the rock and stuff, the company that builds that type of equipment built this crawler. I think it's one of the most phenomenal pieces of engineering equipment ever designed. The Marion Power Shovel Company worked with NASA to make two of the most specialized pieces of equipment on the planet, Crawler 1 and Crawler 2. They both live at Kennedy Space Center in Florida, but crawler 1 mostly hangs out in storage, while Crawler 2 gets to do the heavy lifting. And here to give you a tour of that crawler are two of its operators. There's Breanne Roloff who just graduated with her bachelor's in aerospace engineering. Brianne, she's a blast to be

around because she's young and to her this is just so exciting and so neat. This is my first job out of college. And then there's Sam Dove. Sam's on the complete other spectrum. Sam is a senior driver, ice water runs through his veins, nothing phases him. I grew up in West Virginia as a farm boy, right? Did four years in the Air Force. I went to college. And then I was fortunate enough to get a job in a space program down here. I spent the first 10 years in design engineering.

And then I became a crawler driver. So it wasn't just something I stepped off the street and did. Brianne and Sam both maintain and drive the crawlers. It's a truly unique job. And Brienne still vividly remembers the first time she saw a crawler. I just remember looking at it and being like, this is massive. It really reminded me of when you kind of take off in an airplane. You start to gain altitude and you see all of these things that you normally think of as being big as buildings and houses and cars

and they kind of just shrink. And that's kind of what I remember thinking, wow, people in cars look small compared to it. It's really not something comparable to what a lot of folks see. It's kind of like you took a steel one-story building and sheared off the top of it, so it's completely flat. A steel box, basically. A steel box that's bigger than a baseball field. The crawler's platform, which needs to be big enough to accommodate a launcher and rocket. Inside the steel box, below where the cargo would sit, is a whole host of important things to keep the crawler going

and to keep it level. Cables, fans, motors, pumps. And the crawlers don't move on wheels. But on tracks, like a tank, there are eight total tracks. If you think of a giant bulldozer, there'll be one on each corner. These tracks are heavy duty. The tracks are made up a little segments. Well, the crawler segments are called shoes, and they're big.

They're six feet long and about, I think almost 18 inches wide. and they weigh 2,000 pounds per shoe. With 456 shoes on each crawler, the shoes alone weigh almost 1 million pounds. Once you add up the rest of the equipment on the crawler, the total weight comes to 6.5 million pounds, and that's without any cargo on top. That's how big the crawler is.

Once you add the rocket and the launcher, that's when things get really heavy. You know, you're looking at almost 25 million pounds. I really don't think I fully understand how heavy that is. That's a lot of weight on the ground. So you may be thinking, can a normal road withstand the pressure of a crawler? So when the crawlers were first built, they did try to roll them on roads out here. Needless to say, the asphalt roads did not fare so well.

We put some cracks on them. So it just tore it up. Once again, NASA engineers and contractors, had to get creative and designed something that could support the hefty vehicle. Just like the crawlers,

the crawler way is one of a kind. Everything's special about the crawler way. I mean, first of all, it's the size on the interstate road,

right? You have two lanes on one side, two on the other in the median. But what's most special about the crawler way

is what it's made of. It's filled with crushed and compacted limestone, hydraulic fill under that. And on top of that, about 8 to 10

inches of gravel. That gravel is actually Tennessee River Rocks. That's what the tracks make contact with. And the river rock becomes the sacrificial component because the crawler doesn't have shock absorbers

like your car does. And when you're carrying a multi-million, multi-billion-dollar launch vehicle on top, you don't want to shake it to death while you're rolling it. So the crushing of this rock attenuates the vibration. As more and more rock crushes into finer pieces, it has to be replaced to make sure it can continue to be a good shock absorber for the crawler. Rollout days, or when

the crawler actually makes a trip, are big affairs. The team, composed of about 30 engineers, gathers four hours before the roll, around 8 p.m. They go over the mission, talk safety and discuss who is in charge of each task. Then the team fires up the engines, which take 45 minutes just to heat up. The first thing that lets you know we're starting up is you use compressed air to start these large engines and it just goes... And it just gets louder and louder. And then the second the engine starts, that noise goes away and then you'll just hear this

wh-hm, and some black smoke comes out. Then the rest of the systems get going. The pumps, the lubrication system, the hydraulics, the fans, all with their unique sounds. It really has sounds all its own. You really need to be attuned to what those sounds sound like. If it's not running right, you can almost immediately tell you need to start looking at something. If everything is running properly, the crawler will pick up its freight by rolling right under the launcher. It's usually around midnight when the crawler begins its journey to the pad.

To transport a rocket to the launch pad, the team breaks out into their individual posts. There are technicians on the ground constantly checking the position of the crawler. If you're walking alongside of it, it's dusty, and there's bugs flying around, and then you just hear these shoes that just constantly just slapping on the ground, and it just never goes away. They just keep rolling. And then there are the people on board. There's probably about at least 10 people on the crawler at any time. You'll have three engineers that are actually operating something at one time,

the test conductor, the leveling system operator, and a driver. All of those people have backups, people to switch out with if they need a break. This is very important given that the journey to the pad takes eight hours. Why does it take so long to travel only four miles? while the crawler rarely goes faster than one mile per hour. The speedometer shows zero to two. Driving such an enormous vehicle is an experience few of us will ever have, but Sam tries to explain what it's like.

Driving the crawler is, it's something like driving your car, except it's very slow. You're constantly watching your speed because you can't just do a, you know, drift through a curve like a NASCAR race car can. And with your car, any inputs you make to the steering wheel, you immediately see that, right? Because you're moving into a much faster speed and it's a smaller vehicle. With the crawler, you have to think ahead. Going so slowly might seem like it would be monotonous.

Oh, no, no, no. Bortem is not something that you have on the crawler, right? You're watching where you're going, where you've been, where you're at, the speed, what you're steering, because if the crawler catches you not, I'll pay an attention, it'll remind you. Driving the crawler can be tricky as is. But the team has to be aware of other things that might obstruct rollout, like forces of nature. Florida, where the crawlers are located, is the number one hurricane and lightning capital in the U.S.

We don't like rolling, carrying very tall things during thunderstorms and lightning storms. Lightning and a rocket are not my favorite combination. So the way to get around at is we start rolling very early in the morning. That's to avoid the afternoon, when storms are most likely to strike. The weather is one thing to watch out for, but another obstacle involves things on the ground because the Kennedy Space Center rests on a wildlife refuge. You are constantly on the lookout for wild animals. You know, we see bobcats.

Turtles. Snakes. wild hogs, coyotes are starting to come in here. You kind of just sit there and you're like, oh, please don't, please don't come into the crawler way. Sometimes though, pleading doesn't work. Animals can get in the path of the crawler, and that slows the team down. There was like a 10 or 12 foot gator that was under one of the trucks. And we had to call the wildlife officer to come and pull that gator out.

And he was kind of like the crocodile hunter there, you know, like Steve Irwin was. He just reached under and grabbed that alligator by the tail, pulled him up, trust him up. and took him to another part of the space center. It was the darndest thing you ever saw, and off we went. And then there is the tale of the tortoise and the crawler, less well known than the tortoise and the hare. One time we were going up the pad slope, and I noticed a tortoise.

They dig burrows in the ground here, and this tortoise happened to come out of his hole while we were rolling. This vibration that we're making kind of got him a little uneaseless, easy, so he starts walking around. The tortoise and the crawler were both heading up the ramp, side by side. And this is a true statement, the tortoise beat us to the top of the pad. That's how slow we go sometimes. I guess slow and steady doesn't win the race after all.

The whole ride down the crawler way is leading up to the most crucial and technical moment when the crawler approaches the launch site. It has to go up a ramp. called the pad slope, and place the rocket with its launcher precisely onto its mounts. And that's when things get really exciting, but also things get very focused. By far, the most stressful part of any role is going up the pad. Everything's got to be perfect. We've got to do this right. Everybody's got to work as a team. Can't get anything wrong.

The first time I was on the crawler when we pulled up the pad slope, And I wasn't even driving. I was just observing. But seeing other engineers, the more experienced ones pull up, I felt nervous. Just being in there for them. I was like, oh my gosh. When we go up the slope, it's all hands on deck. Everybody is stationed in a certain area.

All of our engines have to be running at their peak performance. There'll be technicians standing by them watching every gauge and every fluid level on them as we're rolling. If we were to go up that ramp and then lose power for some reason, we could roll backwards. The crawler is on a five-degree slope, but the rocket needs to stay completely level, so the jacking and equalization equipment kick into high gear.

By that time, the crawler is going even slower than normal. Then once you get up close, you jack up to the proper height to go over the mounts, and then you get yourself straight, and we use a laser to do that. And then once you're all lined up left and right, and you're high enough, then you get over everything, and you get stopped, and then you set the whole thing down on the mounts, and it fits within a quarter inch. After a successful rollout, everyone on the team can breathe a sigh of relief

and take a moment to celebrate. They've just taken a rocket on its last earthbound leg of its journey before it launches into space. We have a tradition when we complete rollout. We pop open a bag of chips and somebody breaks out a jar of salsa. Gosh, everybody comes in off the pad to the crawlers to get chips and salsa. It's just something you need to experience. When NASA first conceived of the crawlers, it wasn't clear how long they would stay in use.

By now, the crawlers have long outlived the lifespan of most vehicles. And that's because the crawler operators spend most of their time maintaining and upgrading them. It's over 55 years old now, and she was not designed to last this long. So the reason it has lasted this long is because it's so well maintained. The crawlers have been there almost since the beginning of NASA, starting with the Apollo days. Now the crawler team is getting ready for another mission to bring humans back to the moon. The Artemis One mission. For this mission, the crawler will need to move some of the heaviest loads it ever has.

To prepare, the team has had to upgrade the crawler. New, more powerful generators and cooling systems, bigger bearings. There's a lot at stake, because without the crawler, there is no launch. It's a big responsibility, but it's really great because if there's something going on in the space center, you know, that's really important. And whether the crawler's usually right in the middle of it. What we're doing here is just, it's so important for the country, I believe. And you've got to have to have this machinery to be able to launch that rocket.

And it's just great to be a part of it. Engineers like Sam and John have maintained the crawlers throughout the space shuttle program and will need them again when we return to the moon and go on to Mars as part of the Artemis era. and young engineers like Brienne will keep the crawlers functioning for wherever NASA goes next. As long as there are rockets that need to get from point A to point B,

the crawlers will keep rolling. This is NASA's Curious Universe. This episode was written and produced by Margoe Wall. The Curious Universe team includes Maddie Arnold, Michaela Sosby, and Vicky Woodburn. Our executive producer is Katie Atkinson. Special thanks to Laura Aguilar, Rylent Heggy, Lorne Maythry, Daryl Nail, Madison Tuttle,

Tracy Yates, and the Kennedy Space Center. If you liked this episode, please let us know by leaving us a review, tweeting about the show at NASA, and sharing this episode with a friend. Still curious about NASA? You can send us questions about this episode, or a previous one, and we'll try to track down the answers. You can email a voice recording or send a written note to NASA-curious Universe at mail.nasa.gov.

Go to nassah.gov slash curiousuniverse for more information.