Preparations have begun to repair and upgrade the famous crawlerway at the Kennedy Space Center (KSC) as part of the continuing modifications taking place at the world famous spaceport. The work will stretch from the East Park Site near the Vehicle Assembly Building (VAB) all the way up to Pad 39B.
Originally designed to support the weight of a Saturn V and payload – plus its Launch Umbilical Tower (LUT) and Mobile Launch Platform (MLP) – the crawlerway consists of a seven-foot bed of stones that lies beneath a layer of asphalt and a surface made of Alabama river rocks.
Construction of the crawlerway connected Merritt Island with the mainland, forming a peninsula. The main vehicle access road to and from the launch pads, the Saturn Causeway, runs alongside the crawlerway.
The iconic crawlerway is a 100-foot wide double pathway that runs between the VAB and the two launch pads at Launch Complex 39 – stretching 3.5 miles to 39A to 4.2 miles as the the path forks off to Pad 39B.
The beginnings of a second fork en route to Pad 39B can still be seen via Google Earth, showing what would have been a path to a Pad 39C launch complex.
One historical document (via L2) from 1967 shows Pad 39C on design plans, and even a road to Pad 39D.
This related to NASA’s Moon mission plans, which called for two Saturn launches per lunar expedition, requiring more pads in order to keep pace with the flight rate. NASA soon adopted the Lunar Orbit Rendezvous (LOR) mission profile for Apollo, which only required one Saturn V per mission.
Later, the notional Pads 39C and 39D were allocated to the never-built nuclear Saturn vehicle that would have supported the Mars expedition missions as a follow-on to the Apollo program.
However, that highly ambitious and costly program was cancelled, as NASA opted to transition to the Space Shuttle Program.
Earlier plans in 1963 showed the potential for five pads, with 39A becoming 39C, 39B remaining where it is today, followed up the coastline by newly allocated 39A – which then formed the bottom right corner of an equidistant triangle made up of 39D and 39E.
Despite these various options for a network of pads never coming to fruition, the two pads – 39A and 39B – served the space program admirably for decades, as launch vehicles on various missions were transported up the crawlerway via the tag team of the two Crawler Transporters (CTs).
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With 39A mothballed following the end of the Space Shuttle Program and Pad 39B now demolished and repurposed as a “clean pad”, the transition toward KSC’s ambitions of becoming a multi-user spaceport and in full swing.
Although KSC bosses hope to see commercial vehicles riding down the crawlerway to their launch pads, the only confirmed tenant for Complex 39 is the Space Launch System (SLS).
SLS will be a weighty challenge for the crawlerway, with the added weight of the Mobile Launcher (ML) and the vehicle’s fully loaded Solid Rocket Boosters (SRBs) requiring a lift from the VAB.
However, following initial rumors in the media that the Heavy Lift Launch Vehicle (HLV) would cause the complete reconstruction of the crawlerway, testing of various crawlerway rock surfaces – to better understand the feasibility of operating a tracked transporter for a heavy-lift program, similar to testing conducted in the mid-1960s in support of the Apollo Program – showed the historic pathway will be able to cope.
Via the use of a strange looking contraption, the testing simulated the impact of over 25 million pounds on the rock surface of the track.
“This compatibility testing was conducted on the crawlerway just outside of LC-39B and was performed at the equivalent rollout weight of 25,200,000 pounds versus the Shuttle/Apollo rollout weight of 18,000,000 pounds,” noted a presentation (L2) in 2010.
“Testing results provide degradation characteristics, rate of deterioration, expected lifecycle of various materials, coefficients of friction and reaction forces exerted upon a crawler-transporter shoe.
“Several surfaces were tested and included rock expected to be optimal for a tracked transporter, rock anticipated to be optimal for a dual-use crawlerway (supporting both a tracked and wheeled transporter), and resilient surfaces targeted to reduce excessive loading of a crawler shoe as it crosses roadways and VAB transitions.”
The findings of the testing – which was conducted by NASA, the United Space Alliance (USA), Architect and Engineering firm Jones Edmunds and Associates (JEA) and a couple of additional contractors – were also backed up by additional tests conducted during Discovery’s first rollout for her STS-133 mission.
Additional modifications to prepare the crawlerway for SLS have now begun, with borehole work already started at the East Park Site area near the VAB.
Soon, a large amount of work will take place on the surface of the crawlerway and associated roadways and drainage – the latter having begun modification work last year.
“The scope of this project is to improve water drainage at and around the Crawlerway and replace gravel that has reached the end of its service life,” noted a KSC construction update (via L2).
“The work entails excavating existing deteriorated gravel, scarifying the existing limerock surface, adding limerock base material, and installing new river gravel along the Crawlerway. In addition, various Crawlerway roadway crossings will be modified to reduce stresses on the crawler-transporter shoes, and Saturn Causeway Road will be widened from Ordnance Road to the pad B turn.
“The Ordnance Road utility tunnel will receive structural upgrades to ensure its ability to support future heavy-lift launch vehicles, as well as repairs to areas of spalling concrete.”
The initial work on “the crawlerway to Pad B surface” is expected to take 107 days, per additional KSC status information (L2).
This includes the list of work scheduled, such as the “removal of existing aggregate, timber materials delivery, limerock materials delivery and renovations, aggregate materials delivery and placement of new aggregate, asphalt paving materials and equipment delivery.”
Once the work is complete, it is expected that second trip of the new ML will take place with the “Super Crawler” – CT-2, which is being beefed up with SLS-level modifications – following up on the debut ML rollout last year.
The first SLS Core will be a flight ready vehicle that will be used for testing at the Stennis Space Center, prior to a barge trip to KSC for fit checks at Pad 39B. It will then be rolled back, prepared for launch, and finally sent back to the pad for the pre-launch flow ahead of Exploration Mission -1 (EM-1) in late 2017.
(Images: Via NASA and L2 content from L2′s SLS specific L2 section, which includes, presentations, videos, graphics and internal – interactive with actual SLS engineers – updates on the SLS and HLV, available on no other site.)
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