Happy Birthday Crawler-Transporters!
Published on Jan 26, 2006 at 7:34 pm.
3 Comments.
Filed under NASA, space exploration.
Forty years ago, the Crawler-Transporters at Kennedy Space Center entered service. Originally designed for the Apollo missions to the Moon, they remain in service today, having had very minor modifications in all that time.
The Saturn V, the rocket that launched the Apollo missions to the Moon, was the largest operational rocket ever constructed. Earlier missions, such as Mercury and Gemini, had rockets that were assembled at the launch site. Small rockets can be assembled horizontally and then raised into position. Larger rockets, such as the Titan rockets for Gemini were assembled at the pad in launch position. However, the Saturn V was huge. Standing nearly as tall as a 40 story building and weighing millions of pounds, it was much too big to assemble horizontally and raise into position. Furthermore, there were no cranes that could lift the upper components onto the top of the rocket. And if that weren’t enough, it was so complicated that it took a long time to build. There was real danger of severe weather happening during construction. Such a large rocket could not be protected sitting at the launch pad. So, a decision was made to assemble the rocket inside a building, the Vehicle Assembly Building, and then transport the rocket to the launch site. The Vehicle Assembly Building, when constructed, was the largest building on Earth (by volume, not height). To protect the building form the exhaust of the rocket, it had to be situated away from the actual launch pad. Furthermore, the Saturn V, carried so much fuel that a catastrophic failure (as had happened on several unmanned flights for smaller rockets) would result in an explosion about as powerful as an atomic bomb.
Thus, the Vehicle Assembly Building and the firing rooms for Launch Control were built miles away from the actual launch pads. Somehow, this monstrous rocket had to be carried from the Vehicle Assembly Building to either Launch Complex 39A or Launch Complex 39B (the two heavy launch pads at Kennedy Space Center). This is where the Crawler-Transporters came in. The Saturn V was assembled in the Vehicle Assembly Building sitting on a Mobile Launcher Platform. The crawler would then move under the platform, raise itself up a few inches,and then carried the gigantic rocket the several miles to the launch pad. The crawlers moved along at about 1 mph. The trip typically took about 10 hours. Once at the pad, the crawler would gently lower the Mobile Launcher Platform, and then it would go pick up a service gantry building and carry this back to the launch pad. This lightly constructed shelter, over 40 stories tall, provided platforms and access for final launch preparations. Shortly before launch, the crawler carried the service gantry away, leaving only the launch gantry standing beside the rocket. After launch (and the platform had cooled down!), the crawler carried the Mobile Launcher Platform back to the Vehicle Assembly Building to be refurbished and readied for the next launch.
After the end of the Apollo program, the Vehicle Assembly Building, the Mobile Launcher Platforms, and Launch Complexes 39A and 39B were modified to handle the Space Shuttle. The two Crawler-Transporters, though, required almost no changes. They have continued in operation, carrying Space Shuttles to the launch pads, and returning with the Mobile Launcher Platforms. All told, they have crawled far enough to make it to the Moon and back several times. They are truly remarkable machines.
Happy Birthday, Crawler-Transporters!
-Astroprof
Astroprof’s Page » A shuttle hanger? on March 6, 2007 at 5:12 pm: 1
[…] On the news yesterday, I heard a reporter say that the Space Shuttle Atlantis was being rolled back to a hanger for repairs. That is a bit inexact. The Atlantis had been sitting at launch pad 39A last week in preparation for the STS-117 mission. A severe thunderstorm hit the Kennedy Space Center, with high winds and blowing hail. The hail damaged the foam on the Space Shuttle’s external tank, the ice ramps, and some of the shuttle’s heat shield tiles. The damage was more extensive than could be repaired at the launch pad, and some of the areas damaged could not easily be reached from the gantry at the pad. So, a Crawler Transporter picked up the shuttle’s Mobile Launch Platform, with the Space Shuttle sitting on it, and carried over three miles back to the Vehicle Assembly Building (VAB), where repairs will be made. “Rolling back to a hanger” does little justice to this operation. First of all, the Atlantis isn’t rolling anywhere (I know that the NASA term for this is “rollback”), rather it is being carried. Secondly, calling the Vehicle Assembly Building a hanger is just about as much an understatement as calling the White House simply a federal building with living space. […]
Astroprof’s Page » Apollo 6 on April 4, 2008 at 12:01 pm: 2
[…] Apollo 6 was the first mission to use High Bay 3 in the Vehicle Assembly Building (VAB). It was also the first to use Mobile Launcher 2. Each Saturn V was assembled in the VAB onto a mobile launch platform. Then a Crawler Transporter picked up the entire assembly (Saturn V, launch platform, and gantry) and carried it to the actual launch pad. The Launch Control Center at the Kennedy Space Center has three Firing Rooms that can be used to control the launch vehicle (and a fourth fully functional firing room used to checkout hardware and software). Apollo 6 was the first to use Firing Room 2. Incidentally, Firing Rooms 1 and 4 have been extensively modified in anticipation for the different needs of the upcoming Constellation Program. […]
Strings on October 18, 2008 at 6:22 pm: 3
That’s hangAr, not hangEr…