United Launch Alliance (ULA) is preparing its first low Earth orbit (LEO)-optimized Centaur V, a new variant of the world’s most efficient upper stage that meets the heavy-lifting needs of the Amazon Leo satellite constellation.

As a key part of ULA’s commitment to Amazon, this new version of Centaur V was created to leverage Vulcan's powerful high-energy architecture to match the needs of Amazon to place heavy amounts of payload mass into LEO.

The upper stage has a reduced fuel load required to reach its destination and therefore can be built smaller and itself account for less overall weight than the standard high energy Centaur V. The weight savings translates into additional satellites each Vulcan mission can launch to the various orbital planes of the Amazon Leo constellation.  

At 35 feet tall, the LEO-optimized Centaur V is approximately six feet (1.8 m) shorter and carries a third less propellant than the high energy variant that successfully flew Vulcan's initial missions thus far.  
 
The stage continues the legacy of Centaur by using cryogenic liquid hydrogen and liquid oxygen to power its twin RL10 engines. The stainless-steel pressure-stabilized structure using thin-walled propellant tanks less than the thickness of a dime provides the most weight-efficient stage possible.

The stage was recently attached to its Vulcan booster stage inside the Amazon Vertical Integration Facility (VIF-A), part of purpose-built infrastructure now open for business at Cape Canaveral Space Force Station in Florida. It gives ULA a dedicated lane to launch Amazon's advanced broadband network.

Work to prepare the stage began earlier in a separate VIF-A test cell where the interstage adapter (ISA) and Centaur V were integrated and outfitted as a combined element. The facility’s overhead crane then lifted the hardware atop Vulcan.

Last month, Vulcan was hoisted aboard a new second Vulcan Launch Platform (VLP-A), which is solely dedicated to Amazon missions. These milestones give the ULA team the opportunity to test and validate hardware, systems, and launch processing procedures as we gear up for a Wet Dress Rehearsal (WDR), the next step in preparing for future Amazon Leo launch operations. 
 
The first LEO-optimized Vulcan will be transported 2.7 miles (4.3 km) northward to Space Launch complex (SLC)-41 for a partial propellant-loading test of the new Centaur V stage followed by a complete WDR to exercise the rocket, software and launch team personnel in a full-duration countdown test. 

 
Amazon is partnering with ULA to help deploy the satellite constellation designed to deliver fast, reliable internet to customers beyond the reach of existing networks. The initial Amazon constellation will include more than 3,000 satellites working together in coordinated orbits around Earth.

In addition to the two Protoflight satellites, ULA has launched 195 of the 331 Amazon Leo production satellites deployed to date across seven successful Atlas V constellation launches. Those missions used ULA’s pre-existing infrastructure at Cape Canaveral; future Vulcan missions for Amazon will utilize the newly constructed VIF-A and VLP-A facilities. SLC-41 serves as the launch pad for both integration lanes.