Monday launch from California begins countdown to Atlas 5 retirement – Spaceflight Now - Spaceflight Now

The launch of a Landsat environmental monitoring satellite Monday from California’s Central Coast will be the first liftoff of a United Launch Alliance Atlas 5 rocket since the company confirmed there will be 29 more Atlas 5 flights before the Atlas family’s retirement.

ULA is retiring its Atlas and Delta rocket lines with the debut of the company’s new Vulcan Centaur rocket, which is scheduled to blast off for the first time next year.

An Atlas 5 rocket standing on a launch pad at Vandenberg Space Force Base, set for liftoff Monday with the Landsat 9 Earth observation satellite, is one of 29 Atlas 5s remaining in ULA’s inventory.

ULA says the Vulcan Centaur will have more lift capability, additional mission flexibility, and will be cheaper to operate than the existing Atlas 5 and Delta 4 rocket families.

The expendable Atlas 5 rocket will fly in ULA’s basic “401” configuration with a four-meter (13.8-foot) diameter payload fairing, no strap-on solid rocket boosters, and a Centaur upper stage with a single hydrogen-fueled RL10 engine.

The Atlas 5-401 is the most-used variant of the Atlas 5 rocket, but just three of the remaining Atlas 5s will use that configuration, including the Landsat 9 mission Monday.

The launch of Landsat 9 will be the 16th Atlas 5 launch from Vandenberg.

One “last” that Monday’s mission will achieve is it will be the final daytime Atlas 5 launch from Vandenberg.

To round out the stats for Monday’s launch, it will mark the 300th flight of an Atlas rocket from Vandenberg, and the 2,000th total launch from the California spaceport since 1958.

The first Vulcan Centaur rockets will take off from Cape Canaveral, but ULA plans to reconfigure the SLC-3E launch pad at Vandenberg for eventual Vulcan missions.

Space Force, and the National Reconnaissance Office have taken the lion’s share of Atlas 5 and Delta 4 flights, and make up the bulk of the Vulcan Centaur’s backlog, too.

Formed in 2006 by the merger of Lockheed Martin’s Atlas 5 and Boeing’s Delta 4 rocket programs, ULA has faced increasing competition from SpaceX in the military launch market.

ULA has completed modifications to launch facilities at Cape Canaveral for the Vulcan Centaur rocket.

Vulcan flights will take off from Space Launch Complex 41 at the Cape, the same site used by Atlas 5 rockets.

The Atlas 5 launch pad at Vandenberg has a mobile gantry that allows ground crews to stack rocket segments on the launch pad.

The Atlas 5 launch set for Monday will propel the Landsat 9 satellite into an orbit more than 414 miles (666 kilometers) above the planet, positioning the spacecraft to join a nearly identical predecessor named Landsat 8 collecting daily images of land surfaces around the world.

Live coverage: Atlas 5 rocket set for launch from Vandenberg Space Force Base