How do you move a big rocket like Artemis? NASA's crawler-transporter
How do you safely move a 5.75 million-pound, 322-foot-high rocket more than 4 miles from the assembly building to the launch pad and back? Flag down the Crawler-Transporter 2, or CT-2, the slow-moving but mighty transport platform that’s been hauling rockets for NASA since 1965.
At its usual speed of 1 to 2 mph, the CT-2 began moving the Artemis II spacecraft back from Launch Pad 39B to the Vehicle Assembly Building for repair work on Feb. 25. The daylong move will postpone the historic launch of Artemis II, which will fly humans around the moon and back for the first time since 1972.
It's not surprising that public attention is focused on the spacecraft. However, while the CT-2 and its companion, CT-1, can be overlooked, they're the unsung mechanical heroes (and marvels) of the launch facility at NASA’s Kennedy Space Center in Florida.
Here's how they work:
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The two crawlers, each about 131 feet long and 114 feet wide, were constructed in the 1960s to move the giant Saturn V rockets from the Vehicle Assembly Building to the launch sites. They were first used in 1965.
After the Apollo moon mission program ended in 1972, the crawlers were used to haul space shuttles to launch pads. Shuttle missions ended in 2011.
The crawlers remain and are “envisioned as critical elements of future launch operations at Kennedy,” NASA says. CT-2, which will be used in future Artemis missions, was upgraded with new engines, hydraulic systems and brakes in late 2011. The improvements enabled it to carry the heavier SLS rockets.
An onboard crew of about 30 people is needed to operate CT-2.
How do the crawlers work?
Rocket stages are stacked together inside the Vehicle Assembly Building. The building is a single structure, 526 feet tall, with more than 129 million cubic feet of space.
The Vehicle Assembly Building has four massive spaces, called high bays, with doors 456 ft. high. Two bays are used for assembly and two for storage. High Bay 3 is used for Artemis assembly.
Inside High Bay 3 is a gigantic two-story platform called Mobile Launcher 1, which weighs about 11.5 million pounds. The SLS rocket rests on the ML-1; that's a combined total of about 17 million pounds.
CT-2 moves the platform by maneuvering beneath it and raising it off a set of pedestals. The empty platform is put inside the high bay. The CT-2 leaves and the rocket is built on the platform.
When rocket assembly is complete, the CT-2 rolls beneath the platform, lifts it and the rocket, and moves them slowly to the launch pad. The platform and the rocket are carefully kept level as CT-2 travels up a ramp with a 5% slope to the pad.
CT-2 inches along what’s called a crawlerway, a 130-foot-wide road 4.2 miles long made of rounded Alabama river rocks over an engineered base. The rocks, 3 to 4 inches in diameter, “act as ball bearings that allow the crawler to turn with minimal issues,” NASA says.
The rocks absorb energy from compaction as the crawler passes over them. That helps reduce the vibration on the surface that could damage flight hardware being transported.
When not in use, the crawler transporters are stored in the Mobile Service Structure park site near the Vehicle Assembly Building.
What is happening with Artemis II?
The spacecraft sat at Launch Pad 39B for weeks as the Artemis 2 launch date slipped once, and then again. Now, it won't be until April at the earliest that the three Americans and one Canadian will take a 10-day trip around the moon in an Orion capsule atop the rocket.
A problem with the flow of helium to the rocket's upper stage has delayed the mission by at least two months from the initial target launch date in February. Now, NASA simply hopes to preserve launch opportunities beginning April 1.
CONTRIBUTING Eric Lagatta
SOURCE USA TODAY Network reporting and research; Reuters; NASA; space.com; astronomy.com