Crawling before launch: NASA evaluates new GPS-guided crawlerway graders

NASA puts its new GPS Laser Guided Motor Grader through its paces as it levels the crawlerway before the crawler-transporter moves the Space Launch System rocket to Launch Complex 39B. Credit: Theresa Cross / Spaceflight Insider

Before NASA’s crawler-transporter can move the Space Launch System to the launch pad, the “crawlerway” road it travels on needs to be properly prepared.

On July 25, 2022, Spaceflight Insider had an opportunity to meet and speak with several people involved in testing out a new GPS Laser Guided Motor Grader built by Caterpillar. As its name suggests, this vehicle makes sure the two-pathway, 130-foot (40-meter) wide crawlerway is level and equal when the Space Launch System is carried by the crawler-transporter back and forth from the Vehicle Assembly Building and Launch Complex 39B — a journey of about 4 miles (6.5 kilometers).

Credit: Theresa Cross / Spaceflight Insider

Sam Dove hails from West Virginia, spent his youth there growing up on a farm and went on to serve four years in the U.S. Air Force, went off to college and then landed a job at Kennedy Space Center in 1987.

Dove spent his first 10 years in design engineering and the last 25 as a crawler-transporter engineer and driver of one of the world’s largest tracked vehicles.

On July 25, Dove said the GPS Laser Guided Motor Grader was being put through its paces as engineers received first instruction on the modern equipment.

Jerry Burke with Sitech of North Central Florida went on to outline some of the more significant and robust features of the newly arrived grader.

The motor grader is equipped with GPS 3D technology with GPS correction satellites that work on a 3D surface, built to the design of the project.

Once the 3D files are loaded into the motor grader, Burke said, corrections from satellite signals are sent to the GPS receivers where the operator can push a button inside the cab putting it in 3D auto mode.

The 3D auto mode puts the blade down on the design elevation of the 3D surface, allowing the operator to cut the grade.

Credit: Theresa Cross / Spaceflight Insider

A 3D robot instrument is also used when the motor graders get too close to buildings, where it can compete with other projects for GPS signals, and use an alternate target instead of GPS, which helps guide the grader more accurately in 3D for those situations.

The vendor of the new Laser Guided GPS Motor Grader was on site to train engineers and technicians on how to use the GPS tracking capabilities, now driven with 2 joysticks — no more steering wheel.

Credit: Theresa Cross / Spaceflight Insider

The motor grader has been leased for 3 months with an eye toward the future as the Artemis program moves well beyond the capabilities of the original graders.

The completion of further testing and evaluation of the new motor grader as a possible permanent fixture delivering a consistent, trackable transport product for the crawlerway is underway, explained Dove.

Dove went on to say, the primary graders currently require operators to physically and visually perform tasks that can now be completed electronically.

The gravel has different thicknesses on top of a lime rock base and must be level and equal throughout the crawlerway. The rock also helps to assist with steering the crawler-transporter and provides cushion for the rocket’s ride to and from the launch pad, Dove explained.

The equalization of the smooth, round stone on the crawlerway will also decrease the amount of friction on the crawler-transporter’s shoes making it much easier for the vehicle to move, as it does not have a suspension system while transporting a tremendous weight of 18 million pounds.

As of publication, the launch of the first Space Launch System rocket for the Artemis 1 mission is slated for no earlier than Aug. 29, 2022. To make that date, the crawler-transporter will need to roll the rocket and the Mobile Launcher down the crawlerway by about Aug. 18.

The SLS rocket at the top of Launch Complex 39B. Credit: Theresa Cross / Spaceflight Insider

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