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No Need for Speed


Driving along at one mile an hour doesn't always feel as excruciatingly slow as you might think.

Close-up of Crawler-Transporter treads and cabJust ask Bob Myers of United Space Alliance at NASA's Kennedy Space Center in Florida. He's spent more than 20 years helping to drive and care for NASA's two Crawler-Transporters, which have the heavy task of moving the fully-assembled Space Shuttle and its Mobile Launcher Platform (MLP) to the launch pad for flight.

Image to left: In this photo, taken in December 2004, a Crawler-Transporter takes its first road test following the replacement of all its shoes. Credit: NASA/KSC

"When you're walking on the ground, of course, at one mile an hour you can outwalk the Crawler in a heartbeat," explains the Crawler systems engineer. "But when you have 18 million pounds and you're up in the cab and it's moving a mile an hour, it seems fairly fast."

Myers had the honor of driving Space Shuttle Discovery out of the Vehicle Assembly building when the Return to Flight vehicle made its move out to Launch Pad 39B in March.

Only a handful of engineers are certified to drive the gargantuan transporters, and with good reason. The Crawlers can extend from 20 to 26 feet tall and are 131 feet long, 113 feet wide. They weigh six million pounds without the MLP and Space Shuttle stack.

As far as Myers is concerned, driving a vehicle so huge, heavy and downright unusual is nothing like driving a car.

He laughs when he's asked how the Crawlers "handle" on a drive. "How about 'really slow?' " he replies. But he explains that there's really no better way to train for driving a Crawler than through hands-on experience. "It takes some time to learn how to get out on the Crawlerway and learn how to anticipate a turn, to keep the Crawler straight, and learn how it's going to accelerate, decelerate and stop."

"When you have 18 million pounds and you're up in the cab and it's moving a mile an hour, it seems fairly fast."
-- Bob Myers,
    United Space Alliance
Myers' job stretches beyond driving. Crawler engineers and technicians spend much of their time refurbishing and upgrading the tracked vehicles, which were built in the mid-1960s for the Apollo-era Saturn V moon rockets. The Crawlers are still hard at work today, thanks to tender loving care and ongoing maintenance.

In the last two years, the Crawlers have undergone major structural, mechanical and electrical upgrades. New motor control centers run the vehicles' electricity, and improvements to the ventilation system provide a safer environment for the people monitoring the engines and pump rooms. Both crawlers received new treadbelt shoes -- 456 on each vehicle -- and new mufflers to reduce the noise level generated by the engines.

Each Crawler's dual driver cabs were removed and replaced with new ones, complete with hurricane-safe marine windows. The original cab windows weren't up to hurricane code, so whenever a storm threatened Kennedy Space Center, the Crawler's windows were treated just like those on a building: boarded up for safety!

Inside the cab, the driver's console is remarkably simple. A small, red steering wheel occupies the center. Just behind it is the speedometer, ranging only from 0-2 miles per hour. Gauges on the right indicate height, steering angle and the status of the Crawler's Laser Docking System, used in launch pad docking operations. The vehicle's speed is controlled by a knob on the left.

Bob Myers inside Crawler-Transporter cab Image to left: Bob Myers, a crawler systems engineer with United Space Alliance, stands beside the driver's console inside a Crawler-Transporter cab. Credit: NASA/KSC

On the floor, a single pedal activates the air brake. Because standing offers the driver a wider field of view when the Crawler is in motion, the driver's chair has three settings for sitting, leaning and standing.

Myers' fondness for these extraordinary vehicles is obvious. But he says despite their size or the unusual task they're called on to perform, the Crawlers' best-kept secret is their speed -- or lack of it. A Crawler can move even the smallest distance (say, one-eighth of an inch) if it's told to. This precision is critical when it comes to delicate operations such as docking a Space Shuttle and Mobile Launcher Platform at the launch pad.

With Return to Flight on the horizon, Myers has already decided on a special launch viewing area. He'll be on the catwalk of the Crawler.

"That's where we typically watch launches from, the catwalk. And we'll all watch, I'm sure, with great anticipation and our fingers crossed. We want to see a perfect launch, a successful launch. That's what we're here for."

Anna Heiney
NASA's John F. Kennedy Space Center

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