United Launch Alliance announces mid-November return to flight for Vulcan rocket

ULA’s Vulcan is a launch vehicle designed to carry payloads into space. It uses a methane-fueled first stage, a hydrogen-fueled Centaur upper stage, and strap-on solid rocket boosters. Its return to flight matters because the rocket had been paused after repeated booster-nozzle failures.

The planned mission, called Vulcan Leo 1, will carry 40 Amazon Leo satellites. It will be Vulcan’s fifth flight since the rocket debuted in 2024 and its first flight with six solid rocket boosters. The satellites will separate from the Centaur upper stage over about half an hour.

ULA scheduled the launch for Friday, November 13. The rocket will fly with an improved nozzle design, while testing and analysis continue during the mission. A successful flight would provide valuable flight data and support future customer missions, including Amazon’s planned Vulcan Leo 2 launch.

Vulcan launches were grounded because Northrop Grumman’s solid rocket boosters experienced nozzle failures. A nozzle disintegrated on one booster during Vulcan’s second flight. ULA believed the problem was resolved, but a similar failure occurred on one of four boosters during the fourth flight in February 2026.

The latest incident happened less than 30 seconds into the USSF-87 mission. In both flights, the methane-fueled first stage and hydrogen-fueled upper stage compensated for reduced and uneven booster thrust. The rocket still reached its intended orbit, but the repeated failures required a formal investigation before another launch.

ULA, Northrop Grumman, and the U.S. Space Force formed an industry-government team to study the latest anomaly. The team identified potential contributors and introduced nozzle design and process improvements. Vulcan remained grounded for nine months while those changes, testing, and analysis proceeded.

Vulcan Leo 1 is planned to carry 40 satellites for Amazon’s Leo internet service. The satellites will be released from an adapter attached to the Centaur upper stage. Their deployment will happen over about half an hour, rather than all at one instant.

The mission will add to the nearly 400 Amazon Leo satellites already on orbit. Amazon is assembling these spacecraft into an internet-from-space constellation. The scale of the existing network shows why the company needs repeated launches rather than a single mission.

Amazon has booked 38 Vulcan launches for the constellation. Vulcan was intended to help accelerate deployment because it can launch more Leo satellites than any rocket other than Blue Origin’s New Glenn. Amazon’s rollout has also faced delays, including the loss of a New Glenn rocket in a May launch-pad explosion.

In rocket engineering, a solid rocket booster nozzle is the shaped outlet at the motor’s rear. It directs expanding exhaust and turns that flow into thrust. The nozzle also helps control the direction and efficiency of the booster’s push. The article identifies nozzle failures as the reason Vulcan flights were grounded.

When a nozzle disintegrates, exhaust may no longer leave in the intended direction. The booster can produce less thrust, and the remaining thrust can become asymmetric. On Vulcan’s second and fourth flights, those effects came from failures involving Northrop Grumman-built 63XL Graphite Epoxy Motors.

The failures did not destroy the missions. Vulcan’s methane-fueled first stage and hydrogen-fueled upper stage compensated for the reduced and uneven booster thrust. Still, the repeated problem required investigation and an improved nozzle design before the rocket could return to flight.

The investigation found several potential contributors to Vulcan’s solid rocket booster anomaly. ULA said those contributors were mitigated through design and process improvements to the nozzle. The upcoming mission will use the improved nozzle design, giving the team a chance to collect performance data in flight.

Northrop Grumman also performed a test firing of a 63XL motor earlier in the year. That test was part of the effort to resolve the nozzle problem. The redesigned boosters will fly with six solid rocket boosters on Vulcan Leo 1, making this the first Vulcan mission with that configuration.

Testing will not end at launch. ULA said additional testing and analysis will continue in parallel with the mission. Engineers can compare the booster’s behavior with expected results and use the flight data to validate the changes. The U.S. Space Force will also determine what work remains before national security payloads fly again.

Amazon is using several launch vehicles because it is assembling a large internet-from-space constellation through many missions. The company has previously used Atlas 5, Ariane 6, and Falcon 9, while booking 38 Vulcan launches. Using multiple rockets gives the rollout access to different launch programs and schedules described in the article.

Vulcan was especially attractive because Amazon expected it to launch more Leo satellites than any rocket other than Blue Origin’s New Glenn. The Vulcan Leo 1 mission will carry 40 satellites, adding to nearly 400 already in orbit. A second Vulcan vehicle is already assembled for the Leo 2 mission.

The constellation’s deployment has faced setbacks. The first New Glenn rocket intended to carry Leo satellites was lost in a May launch-pad explosion, although no satellites were attached. Amazon therefore continues using its existing launch providers while Vulcan returns after its nine-month grounding.

A launch vehicle combines stages because different parts of the flight need different kinds of propulsion. Vulcan’s solid rocket boosters provide additional thrust early in flight. The methane-fueled first stage then powers the main ascent, while the hydrogen-fueled Centaur upper stage continues the journey and places the payloads into orbit.

On Vulcan’s affected flights, a booster nozzle failure reduced thrust or made it uneven. The first stage and upper stage compensated, allowing the rocket to reach its intended orbits. This shows how the vehicle’s propulsion systems work together rather than relying on the boosters alone.

For Vulcan Leo 1, the Centaur upper stage will carry the satellite adapter and release 40 Amazon Leo satellites over about half an hour. The mission will use six solid rocket boosters, the first Vulcan flight with that number, and will provide data on the improved booster nozzles.