Spaceflight Insider

United Launch Alliance celebrates Centaur’s 50th Anniversary

A Centaur upper stage is pictured being lifted onto the first stage booster of a United Launch Alliance Atlas V rocket. Photo Credit: NASA/Roy Allison.

On November 22nd, the United Launch Alliance (ULA) celebrated the 50th anniversary of the Centaur upper stage’s first successful flight. Developed during the pioneering years of spaceflight, Centaur has been and still is a workhorse of America’s space program. Originally flying on Atlas rockets in the 1960s, Centaur was the very first high-energy cryogenic upper rocket stage.

“By harnessing the power of liquid hydrogen to launch payloads to space, both near and far, the Centaur is the benchmark by which all other are measured,” said Matt Smith, ULA’s vice president of Engineering and Information Technology.

The Centaur-2A second stage of an Atlas IIA rocket is lifted onto Pad 36-A at Cape Canaveral Air Force Station. Photo Credit: NASA.

Centaur has been adapted to fly on a multitude of launch vehicles over the years, including every generation of the Atlas family, the Titan IIIE, and the Titan IV. It was even selected by NASA to launch planetary probes and geosynchronous satellites from the payload bay of the Space Shuttle. However, heightened concerns in the wake of the Challenger disaster resulted in Centaur being replaced with the simpler, solid-fueled Inertial Upper Stage.

Many of NASA’s flagship planetary exploration missions have flown on Centaur rocket stages. These include both Viking and Voyager missions, Cassini, the Mars Reconnaissance Orbiter, New Horizons, Lunar Reconnaissance Orbiter/LCROSS, the Solar Dynamics Observatory, Juno, the Mars Science Laboratory, and most recently, MAVEN.

“Centaur celebrated its 200th flight in 2012 and has sent spacecraft to nearly every planet in our solar system, as well as delivering vital commercial and national security payloads,” added Smith. “Fifty years today after its first successful launch, Centaur continues to deliver the highest mass fraction of any cryogenic upper stage, as well as meet customer requirements for reduced cost and enhanced capabilities.”

ULA has been flying the Centaur stage since its formation in 2006 when it took on the Atlas V rocket, formerly operated by Lockheed Martin. The successor to Centaur, known as the Advanced Common Evolved Stage (ACES), is currently being developed by ULA. Building on the design architecture of Centaur, ACES will reduce costs, offer more mission flexibility, and enable up to 50% payload growth.

The ACES stage is intended to fly on both the Atlas V and Delta IV launch vehicles, supplementing or replacing both the Centaur and Delta Cryogenic Second Stage.


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