SLC-4: The Comeback Kid

By: Nicole Willett

Space Launch Complex 4 (SLC-4) at Vandenberg Air Force Base in California has a storied history that spans decades of American space exploration. From its origins as a Cold War era launch pad to its modern incarnation as a key launch site for polar orbit missions, SLC-4 has proven itself to be a resilient and adaptable piece of space infrastructure — a true comeback kid.

A Brief History

SLC-4 was originally built in the late 1950s to support the Atlas missile program. Over the decades, it has been modified and upgraded to accommodate a succession of launch vehicles, including the Atlas, Titan, and ultimately SpaceX’s Falcon 9 rocket.

The complex consists of two pads: SLC-4 East (SLC-4E) and SLC-4 West (SLC-4W). SLC-4W supported Titan launches from the 1960s through the 2000s, while SLC-4E was leased by SpaceX in 2011 and converted for Falcon 9 operations.

The InSight Connection

SLC-4E gained particular significance for the Mars exploration community when it served as the launch site for NASA’s InSight Mars lander in May 2018. This was notable because it marked the first time an interplanetary mission had launched from Vandenberg Air Force Base and the West Coast of the United States. Previously, all interplanetary missions had launched from Cape Canaveral in Florida.

The decision to launch InSight from Vandenberg was driven by the availability of the Atlas V rocket and the mission’s trajectory requirements, which could be met from a polar launch site. This opened up a new chapter in the history of SLC-4, connecting this venerable launch complex to the exploration of Mars.

Modern Operations

Today, SLC-4E is one of SpaceX’s primary West Coast launch facilities, supporting Falcon 9 missions for both government and commercial customers. The pad has been equipped with a landing zone nearby, allowing Falcon 9 first stages to return for recovery after launch.

The transformation of SLC-4 from a Cold War missile facility to a modern commercial launch site that has also supported Mars missions is a testament to the adaptability and enduring importance of America’s launch infrastructure. Like the rockets that depart from its pads, SLC-4 continues to reach for new heights.