CT-2: Super Crawler taken for a test drive at KSC

by Chris Bergin

Crawler Transporter -2 (CT-2) is enjoying a spin around the Kennedy Space Center (KSC) block, as engineers test the latest upgrades ahead of its role carrying the Space Launch System (SLS) to launch pad 39B. Both of NASA’s workhorses are being upgraded to the role of “Super Crawler”, with the ability to carry 14.2 million pounds of heavy lift hardware on their shoulders.

Crawler Transporter:

The famous CT duo – nicknamed “Hans” and “Franz” – will continue their role in providing space vehicles with a lift from the Vehicle Assembly Building (VAB) to Complex 39.

Their deep history began with the fabrication of the giant machine’s parts in Ohio back in 1963. Assembly of the first crawler-transporter was completed on Merritt Island the following year.

The CT’s were built in response to the huge effort to put a US astronaut on the surface of the Moon by the end of the 1960s, with the first Saturn V rocket transported to the pad by the CT was the “Facilities Checkout Vehicle” AS-500F, ahead of the unmanned Apollo 4 mission, with the CT transporting the Saturn Vs for all of the Moon missions.

The final Saturn to be transported to Complex 39 was the Saturn IB for the ASTP mission in 1975, ahead of the transition towards the Space Shuttle Program (SSP).

After rolling out Saturn launch vehicles, complete with their service tower structures rising towards the Florida skyline, the CTs role with Shuttle saw the use of the Mobile Launch Platform (MLP) hosting the orbiter with her External Tank and Solid Rocket Boosters (SRBs).

The CT began its Shuttle career by rolling Enterprise to launch pad 39A on 1 May 1979 for testing.

During rollout, Enterprise was driven at various speeds to measure and note the various vibration strains on the fully-mated Shuttle stack. This was used to determine an optimal rollout speed for operational Space Shuttle missions.

Once at the pad, Enterprise helped validate launch pad procedures – with her biggest test and benefit to the ground processing operations coming during the full-up Wet Countdown Dress Rehearsal when she helped simulate External Tank fueling operations for launch.

With vital data already at hand from the Enterprise roll to 39A, Columbia and the STS-1 stack were rolled out to the same pad by the CT on December 29, 1980.

As mid-February 1981 arrived, teams at Pad-A began prepping the vehicle for the wet countdown dress rehearsal and Flight Readiness Firing (FRF) of her three Space Shuttle Main Engines (SSMEs).

STS-1’s launch took place in April of that year.

The CTs took it in turns to rollout all of the Shuttle stacks for their missions, an always-impressive sight, not least STS-6, as the CT rolled its superstar passenger of Shuttle Challenger out in fog bank over the crawler way at the Kennedy Space Center (KSC) in March, 1983.

Modifications were made throughout the lifetime of the CTs, including ahead of Return To Flight when replacement work was carried out on large amounts of the vehicle, including the huge shoes that make up the tracks on the Crawlers – no small feat considering the CT has eight tracks, two on each corner, with each track consisting of 57 shoes, each shoe weighing in at 1,984 pounds (900 kg).

The CTs continued their role with Shuttle, but also enjoyed what was to be their opening task with the Constellation Program (CxP), rolling the Ares I-X vehicle to Pad 39B for its October, 2009 test flight.

With the Constellation Program cancelled, CT-2 paid its first visit to the Ares Mobile Launcher (ML) in 2010, relocating the newly built structure to its parksite home.

For more SLS Articles, click here: http://www.nasaspaceflight.com/tag/sls/

At the time, the ML faced a bleak future, until lawmakers approved the replacement program for Constellation, calling for the CTs to roll vehicles more akin to the Saturn V’s they used to carry to Complex 39. That vehicle will be the Space Launch System (SLS).

With the Crawlerway tested to show it could handle the massive weight of the Heavy Lift Launch Vehicle (HLV), a test run of the CT with the former Ares ML – since designated to host SLS vehicles – was conducted in November, 2011.

The trip to 39B was taken at a very steady pace, allowing for critical measurements to be taken during the 4.2 mile journey. The CT conducted the roll of the large structure without issue, prior to returning it to near the VAB after pad testing was completed.

However, it will be a much heavier stack to carry once the SLS is integrated on the ML inside the VAB – with the heaviest SLS rollout weight, including the ML, estimated to be about 14.2 million pounds.

As such, CT-2 received approval for modifications, to modernize and beef up its capability almost immediately after completing the ML roll testing.


CT-2’s upgrades began with JEL (Jacking, Equalizing, and Leveling) valve replacement.

Z5The upgrades included the Alco E1 & E2 Engine Panel upgrades, Parking/Service Brakes improvements, Cabin replacement/modifications and the installation of two new massive 1500KW Generator sets.

Classed as a 20 year life extension effort under NASA’s Ground Systems Development and Operations Program (GSDO) effort, 45 areas were worked on – right down to new carpets in the cabins – with a test roll down the Crawlerway from the VAB conducted in 2012.

CT-2 returned to the VAB to take up residency inside the giant building’s High Bay 2 (HB-2) for the next set of modifications, focusing on the modification work on the roller bearings.

Z3It was soon joined by CT-1 in High Bay 3 (HB-3), as it too began its upgrades, opening with asbestos abatement/removal tasks ahead of the engine control room modifications.

By the start of the year, CT-1 had completed modifications in line with those already conducted on CT-2, along with being the test bed for new JEL Cylinder Prototype testing.

In late March or April of this year, CT-1 will be used as the test article for a complete generator load bank test.

Z8Meanwhile, CT-2 – now with a fresh set of bearings – was moved out of HB-2 for a short trip before returning to the VAB, allowing for lubrication checks and testing.

With everything looking good on the CT, it was the rolled out of the High Bay and taken on a test run around the VAB to a point just behind OPF 1 last week.

The test – according to L2’s dedicated update section for the Crawler Transporter modifications – helped evaluate the CT’s new rollers, bearings and shafts on the vehicle’s A and C corners, along with a new Strain and Temperature System.

Z4“These upgrades are designed to make sure the crawler will support us for another 50 years,” noted Mary Hanna, CT project manager in the Vehicle Integration and Launch Branch of GSDO. “Many of the older parts were wearing out from years of use.

“The original rollers were simply ball bearings. The roller bearing and associated assembly, including roller shafts and new sleeve bearings were redesigned and installed. The new assemblies will help the crawler carry the heavier load.

“The newer system will also be better lubricated and that should provide a longer operational life.”

Z10The CT then made another move, this time to its CT yard – a familiar port of call for the Crawlers.

On Tuesday, CT-2 rolled to the east side of the VAB through the curves and then back to the SRM Road, twice.

It then returned to the CT Yard for a refuel and some maintenance.

After what is expected to be a brief CT yard stay, CT-2 will be moved back to the VAB for continuation of Phase II modifications.

All of the modifications to CT-2 are expected to be completed by early 2016.

Z6The crawler is then expected to carry out its first operation role by picking up the Mobile Launcher (ML) – which is currently undergoing conversion work for the SLS – before carrying it inside the VAB later that year.

This will be a key part of the build up to Exploration Mission -1 (EM-1), with the first Space Launch System (SLS) expected to be stacked on the ML for a roll to Pad 39B in 2017. The first rollout is expected to test all of the systems, along with pad fit checks.

The stack will likely roll back to the protection of the VAB ahead of preparations for the first mission rollout of the Heavy Lift Launch Vehicle (HLV) with Orion, for the Exploration Mission -1 (EM-1) pad flow to launch.

(Images: Via 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. Other image via L2 Historical and NASA)

(L2 is – as it has been for the past several years – providing full exclusive SLS  and Exploration Planning coverage.  To join L2, click here: http://www.nasaspaceflight.com/l2/)

Related Articles