|dan (67) myron (1) rich (61) shiloh (4) :: Contact|
Wed, 30 Apr 2008
You wouldn't think it would be hard to drive at a top speed of one mile per hour, but when you're carrying thousands of metric tons around, it's a lot trickier than you think.
As noted in some of my earlier essays here, I have been something of an space buff for as long as I can remember, and my interest is still fairly keen after all these years. (Although I think the "routine" of more than one hundred space shuttle flights has tempered my enthusiasm a bit; it's hard to get tremendously excited about watching crews going around in circles over and over and over.) And while there are now paying space tourists who pay millions for a ride in a Russian Soyuz capsule to the International Space Station for a week of frolicking in zero gravity, baring a sudden and dramatically positive change in my financial circumstances, I will never be one of them. So I am left to experience spaceflight more or less vicariously, mostly through coverage in the media and the Internet.
But I do have a couple of inside sources that allowed me to get a tiny bit closer to space than most.
One of them was a great-uncle who worked in California for what was then North American Rockwell. North American was the prime contractor for the Apollo spacecraft and for the second stage of the Saturn V launch vehicle, and, knowing of my interest in space, he would regularly send me lots of technical "insider" information, like copies of assembly and process manuals for the Apollo spacecraft. I always looked forward to the bulky envelopes from Uncle Ralph, never knowing what would be inside.
As exciting as these things were for me, Uncle Ralph had been with North American since its World War II days, and so around the time that the Apollo program was ending and construction on the Space Shuttles was just getting underway, he retired, and I reverted back to "regular citizen" status.
Years later, my cousin Anne met and married a dashing man from eastern Florida, who, as it turned out, works for Lockheed Martin, the parent company of United Space Alliance, the company responsible for launch operations at the Kennedy Space Center. Last fall, I was down in Florida on a business trip, and planned to spend a couple of days visiting them (since I had not seen Anne in years, and to also make up a bit for the fact that I was unable to attend their wedding years before).
Anne and Greg live in Rockledge, Florida, near the Atlantic coast. After my last meeting in Tampa, I drove across the state, taking I-4 to the outskirts of Orlando, then turned further east on Route 528, the "Bee Line" Expressway, aptly named due to its nearly perfectly straight east-west orientation once you pass the Orlando airport. Travelling eastbound in the morning or westbound in the afternoon along 528 must be brutal, but fortunately, the setting sun was behind me as I made my way that afternoon.
I arrived not too late in the evening, and the three of us went out for a late supper. Anne and Greg were curious about my work, mostly wondering why I didn't get down to Florida more often (an unfortunate consequence of perennially tight corporate travel budgets). Anne had left her position as a logistics manager at a trucking company to take care of their daughter, Lauren, now nearly a year old; Greg continued to work at the space center in Spacecraft Assembly and Test, helping to mate the shuttle orbiters to the external fuel tanks and then testing verifying the connections between the two. I thought this was very, very cool, moving spaceships around inside a fifty-story tall building -- my middle management job seemed (at least to me) awfully dull by comparison. I asked Greg a lot of technical questions, which he found both amusing and a little surprising, not expecting an average person to know very much about what his work involved. But Anne had alerted him to my astronautical interests, so he was not surprised at least. In fact, as we waited for the desserts to arrive, Greg had a surprise waiting for me.
"How would you like to come to work with me tomorrow?"
"Are you kidding? That would be great! I'd love to see what you do."
"Well, I can't actually get you into where I work. There's an orbiter currently being processed, and visitors aren't allowed inside the assembly building while that's going on. But I did make a couple of phone calls to some people I work with, and I think I found something to occupy a few hours of your time in an enjoyable way."
Now I was really curious to find out more. Although I would have settled for a morning of emptying the wastebaskets, I was sure that whatever Greg had planned for me would be more interesting than that.
"How'd you like to take one of the crawlers out for a short test drive?"
A bit of explanation and some historical context is in order here. No doubt many of you have seen pictures or videos of space shuttles being moved from their assembly building out to the launch pad about four miles away. (Those of us of a somewhat older vintage will recall similar scenes of the Apollo moon rockets making the same journey to the pads.) Usually unnoticed, far down at the bottom of these pictures, was an enormous machine the size of a baseball diamond with tank-like treads, lumberingly carrying the launch platform and the spacecraft on its back -- the crawler-transporter.
In the early 1960s, when NASA was figuring out how exactly to get to the moon, one of the decisions they needed to make was how the rockets would be assembled, tested, and readied for liftoff. Historically, the rocket and missile crews at the Cape would receive booster stages and the spacecraft itself via truck or cargo plane, check them out in hangar buildings, then assemble the rocket directly on the launch pad itself. The process tied up the launch pad for months at a time, during which the rocket was exposed to the elements (including rain, winds, and the salt air); storms and hurricanes passing nearby (not uncommon in Florida) meant that the rocket had to either be disassembled and removed from the pad, or lashed down with guy wires to fend for itself in the gusts.
The sheer size of the Saturn launch vehicles proposed for the lunar missions (over 360 feet tall) made on-pad assembly impractical. In addition, some early planning documents for the moon landing program indicated that, at its peak, there could be anywhere from twenty to fifty launches per year -- impossible with only two launch pads, if it took months to assemble and launch just one flight while working out at the pad itself. Clearly, the vehicles would need to be assembled and tested at one site (preferably enclosed to provide protection from the weather and to make access easier), then moved to the pad for a relatively brief checkout and launch.
So NASA built the Vehicle Assembly Building, one of the largest enclosed spaces in the world in terms of sheer volume. More than 300 feet on each side and over 500 feet tall, it rose Kaaba-like from the palmetto scrub of the Cape, a shrine to technology visible for miles. Inside the moon rockets (and now the space shuttles) were assembled and made ready for launch.
But how to get them to the pad? Some preliminary ideas included floating the launch platform on barges down canals to the launch site (nixed because the canal system was expensive (lots of bridges!), didn't provide the necessary stability, and would have meant bringing the canals right into the assembly building itself, negating the idea of having an environment with controlled temperature and humidity) or moving the rocket and launcher on rails (unworkable because of the complexity of the switches involved in rounding curves on the path to the pad). In the end, NASA decided to construct a land-based crawler to carry the rocket on a specially-reinforced roadway from the assembly building to the pad.
The crawler-transporter's design was based on equipment used for strip-mining in the Kentucky coal fields, a design which had long before proven itself capable of moving heavy loads safely. The final configuration of the crawlers consisted of a trussed metal frame about 100 feet on a side. On each corner of the frame were mounted a pair of tank-like tread assemblies. A pair of diesel engines within the frame powered electrical generators which supplied power to the traction motors that moved the treads. A separate hydraulic system provided steering and leveling power to keep the spaceship vertical and the crawler on course as it moved between the assembly building and the pad. In its entirety, the crawler itself weighed over six million pounds.
In order to minimize stresses and loads (and due to the enormous weight they carried), the crawlers had a top speed of only about two miles per hour. Theirs was the slowest part of a journey into space, but one that was critically important.
"Are you kidding? Will they let me?"
"Yes. I checked with the team, and crawler number two has just completed a major overhaul. They start its initial drive testing tomorrow, and the supervisor said it would be okay for you to help take it out on its shakedown runs. And, before you ask, no, it isn't carrying a shuttle or anything, so you don't need to worry about trashing a billion dollar spaceship if you hit the brakes too hard or something."
I smiled at the thought of NASA letting a goofball like me take a space shuttle out for a little spin. "Yeah, like they let untrained people off the street do that all the time," I replied, grinning.
The next morning, Greg and I left early for the short drive to the Cape; the crawler tests were scheduled to start around eight AM. Greg showed his ID at the employee gate, and I showed my ID to the guard as I filled in the sign-in sheet. Then it was onto the center grounds and across a causeway to the VAB, several miles from the main gate.
Greg parked near the assembly building, handed me a NASA hard hat, and together we started walking down the roadbed to the crawler maintenance site nearby. A team of workers was already working on it, making preliminary checks in preparation for the morning's tests.
Not having grown up around giant earthmoving equipment, and despite my familiarity with what I was seeing, I was unprepared for just how big the crawler was. And how noisy: the support crew was already well into the engine startup procedures, and the rumble from the 1600 horsepower diesels sounded much more like a locomotive than a big truck. Greg introduced me to Bob, the crew chief for this test run, and my mentor for my morning spin.
"Isn't there a simulator or something I should check out on first?" I asked him. "After all, this is NASA."
Bob chuckled. "No, nothing that fancy. We always figure that the best way to learn to drive the crawler is by hands-on experience. And besides, this is just a test run, about a hundred yards -- nothing fancy, just a straight drive out and back."
Greg called, "Good luck," as Bob and I turned and headed up the stairway located amidships on the side of the crawler. The main platform of the crawler is about twenty feet in the air, and a catwalk runs around its perimeter, providing access to the engines, generators, and hydraulic systems inside. On the right "front" and left "rear" corners of the platform are the driver's cabs, looking much like the operator cabs found on large cranes -- except without the panoply of levers and handles inside that you would see on a crane. In fact, from the outside, I couldn't see anything inside the cabs at all.
We walked around to the front cab; Bob opened the door and motioned me inside. The cab was air conditioned, providing a pleasant respite from the sticky morning warmth and humidity outside. Given the six to eight hours it takes to move a shuttle from the VAB to the launch pad, I could understand the need to keep the driver comfortable.
But the controls were nothing like I expected. Again, I had thought to myself, "This is NASA," and was expecting a futuristic cockpit with computer screens and LED readouts. I was forgetting that the crawlers were designed and built in the mid-1960s -- and so the controls had about the same level of complexity as a Fischer-Price ride-on dump truck. A small red steering wheel about a foot in diameter with white degree markings on it was set alone in the center of the console. Behind it, a speedometer (range from zero to two miles per hour) sat on the top of the dashboard just behind the wheel. There were a couple of gauges on the right, and a large knob and dial on the left. No gas pedal per se, but there was a brake pedal on the floor of the cab.
"So, what have we got?" I asked Bob anxiously.
"Okay, over there in the middle is your steering," he began very straightforwardly. "On the left, that dial puts in your power, kind of like the gas pedal of your car."
"So why not a pedal?"
"Your foot tends to get tired on long drives, and this baby doesn't have cruise control," Bob answered. "Also, your foot can't give you as fine a level of control as your fingers do on that dial."
"How fine do you guys need to be?"
"When we're working inside the VAB or out at the pad, we have to be able to maneuver a fully loaded crawler in increments of one eighth of an inch. Those instruments on the right are part of our laser guidance system; they also display our height and steering angle."
"So what's the plan? What do I need to do?"
"This morning's test is a simple out-and-back run. While that's happening, the guys at the mechanical and hydraulic controls inside are going to monitor pressures and check for leaks. The ground crew will be doing the same from outside as we go. This test is called TP-21. We have a manual with several hundred different tests and procedures we follow for checking out the crawler before it's cleared to carry a shuttle out to the pad."
"So what's the first thing?"
"The first thing is to sit down."
The drivers seat was supple and comfortable. I sat down, listening to the growl of the engines in the background. Bob handed me a radio headset. "Put this on." As I settled on my head and put the earphone over my left ear, I could hear a number of jargon-filled conversations all taking place concurrently. I imagined it was, on a small scale, what a flight controller must hear in their headset in Mission Control during a flight. "You're not on VOX right now," Bob reminded me, "so you have to push this button to talk." He pointed to a small green button on the console.
"What do I say?"
"The first step is to tell the test conductor that you're on the radio so you can check that you can hear each other. Your 'name' in the test is 'CT-2'. Give them a call."
This was it, I was about to do this for real! I think I got a little tongue-tied in my nervousness and excitement.
"Test Conductor, this is TC-2 -- sorry! -- CT-2, standing by."
"Roger, CT-2, we read you five by five. On behalf of United Space Alliance, welcome aboard, and thank you for helping us this morning."
"Thank you, it's an honor and a privilege," I radioed, then I turned to Bob. "Now what?"
"You need to tell them that you're ready to begin TP-21. Ask the Test Conductor for clearance to proceed." Okay, I could handle that.
"Test Conductor, this is CT-2." At least I got the name right this time. "We're ready to begin the TP-21 test. Request permission to proceed." There was a pause, and I heard the Test Conductor polling the various teams on the crawler and on the ground around us; each reported their status as "Go".
"CT-2, Test Conductor; you are clear to proceed when ready."
I turned to Bob again. "Okay, time to go for a ride. Put your hand on the wheel, and slowly turn that dial to about...here." He pointed to a point about a third of the way around. I gulped and swallowed. Here we go. My right hand gripped the wheel even tighter, and I slowly turned the power knob. It moved smoothly, with no slack or free play, and it stayed exactly where I let go. As it turned, I could hear the diesel engines revving up a bit. But then nothing seemed to be happening. Had I somehow managed to screw it up already? I turned to Bob again.
"That's it! You're under way!"
"You're kidding!" It had been at least thirty seconds since I had turned the dial, but I had absolutely no sensation of moving.
"No, look at your speedometer," Bob gestured, and sure enough, it read "0.2". And when I did look up and ahead of us, I could see that we were moving slowly forward relative to a couple of the ground crew stationed at the side of the crawlerway.
"Okay, now watch where you're going. The crawler probably wasn't lined up quite down the middle of the road when we started, so you'll have to put in a bit of steering to the left. Turn the wheel gently to the left about five degrees."
"Just hold it there." And that was my first real learning experience with driving the crawler -- it's important to do everything slowly and gently, because everything happens so slowly. "Your instinct is to put in all the steering right away, but you learn not to do that," Bob added. "When we're making that turn to go to pad 39A, you put some steering in, start the turn, and half an hour later you're coming out of the turn, and only then you start to straighten out. Everything here happens in slow motion."
"Give her a little more gas," Bob added. "Turn the dial to...here." He pointed to a spot about two thirds of the way around. I turned the dial slowly, the engines revved louder, and the speedometer crept up to 0.9. "Okay, that's good. Now just keep it on the road."
And there I was, driving what was once the largest self-propelled vehicle on land. In my naiveté and excitement, I told Bob it seemed pretty easy. He laughed.
"Yeah, I know, it seems that way now. But put a shuttle and launcher on top, and that's another twelve million pounds to carry. In the wind, the wings of the shuttle act like sails, and you can really feel yourself being pushed around sometimes."
"So what do you do when the winds kick up?"
"If the winds are gusting too much, we don't leave the VAB. We have to have a good forecast before we start to move. And if the winds pick up when we're en route, we can just stop and wait them out."
"So how fast can this puppy go?"
"In a test like this, without any load, the top speed is about two miles per hour. Loaded, it's tough to go much faster than one. At 0.7 things are okay, at 0.8 you start to feel some vibrations, and at 0.9 things can get pretty bumpy. And every bump we feel down here is magnified tenfold at the top of the stack. So we never go too fast. That's especially hard when you're coming down the incline at the pad after leaving the shuttle there -- she wants to freewheel, but you can't do that or the engines will stall, and that's not good. So you spend a lot of time riding the brake. Like everything we do, moderation is the key."
Bob chuckled again, and looked around. "We're near the end of the test. Ask the Test Conductor for clearance to halt."
I keyed the microphone. "Test Conductor, this is CT-2. The TP-21 test is complete; request permission to halt." Another pause as the teams gave their status. "Roger, CT-2, you are clear to halt." I turned the dial all the way back to the left, and the engines slowed down to a moderate growl. "Give it a little brake -- gently," Bob advised. I pushed down gently, and could hear s slight hissss as the air brakes came on and brought us imperceptibly to a stop, the speedometer now back to reading "0.0". "Give them a call and tell them we've stopped, and we're done."
"Test Conductor, CT-2. We are stopped; TP-21 complete. Over."
"Roget, CT-2, and thank you for a fine job. Nice driving out there today."
Bob and I clamored out of the cab, and down the catwalk to where Greg was waiting for me. Bob shook my hand. "Got to go now, but you did fine. If you ever think of giving up your day job, you might consider a career as a crawler jockey." Then he turned, walked back to the other cab to begin the preparations for the trip back, and was gone.
Greg and I walked back to the VAB, and I spent the rest of the day with him visiting the firing rooms, the mission control rooms for the launch teams, and several of the other spacecraft operations and checkout buildings around the complex. I wasn't able to go into the VAB itself, but frankly, it didn't matter. I'm not terribly keen on heights anyway, and besides, I had the ride of a lifetime at a height of twenty feet and a speed of less than one mile per hour.
Posted Apr 30, 2008 at 04:53 UTC, 3750 words, [/rich] Permalink