United Launch Alliance (ULA) postponed its Vulcan Leo 1 rocket launch for a second consecutive day on November 14, 2026, after a network communication problem developed between ground equipment and the launch vehicle at Cape Canaveral Space Force Station in Florida. The company announced that correcting the problem would require a countdown hold extending beyond the mission’s 29-minute launch window.
The mission was rescheduled for Sunday, November 15, with liftoff targeted for 12:11:30 p.m. Eastern Standard Time, equivalent to 17:11:30 UTC. The official ULA mission schedule lists a launch window extending to 12:40 p.m. ULA reported that the Vulcan rocket and its payload of 40 Amazon Leo broadband satellites remained healthy.
A Communication Problem Interrupts the Countdown
The November 14 postponement followed a separate delay the previous day. ULA had planned to launch Vulcan Leo 1 on November 13 before moving the attempt to November 14 at 12:32:30 p.m. EST.
During preparations for the November 14 attempt, a network communication issue developed between the launch vehicle and ground equipment. ULA stated that the problem required reconfiguration and that the necessary work would exceed the available launch window.
The company announced the second postponement on November 14, selecting November 15 as its next opportunity, subject to approval from the launch range.
The problem involved communication with the vehicle during ground operations. Ground systems exchange commands and information with rocket equipment throughout the countdown, allowing launch teams to monitor system conditions and coordinate preparations.
The ability to complete those operations within a designated launch window determines whether a launch attempt can proceed on a particular day. A launch window is the period during which the mission can lift off under its operational and orbital requirements.
For Vulcan Leo 1, Saturday’s window lasted approximately 29 minutes. The time required to reconfigure the affected communication system would have extended the countdown beyond that period, resulting in the postponement.
ULA’s announcement distinguished the ground communication problem from the condition of the rocket and payload. The company reported that both remained healthy when the launch attempt was rescheduled.
Two Different Ground Issues Affect Consecutive Attempts
The November 14 postponement followed a November 13 interruption involving a ground-support supplier rather than the rocket’s communication network.
On November 13, a power interruption at an Air Liquide gaseous nitrogen facility disabled high-pressure pumps supplying the launch operation. ULA reported that the team could not establish the sustained supply required to proceed with the countdown.
The company moved the launch to November 14. Its November 13 announcement identified the nitrogen-system interruption as the reason for the first postponement.
Gaseous nitrogen is used in rocket ground-support operations because it is chemically inert under ordinary operating conditions. It can support equipment purging and other activities that require controlled gas supplies during vehicle preparation.
The interruption at the nitrogen facility affected a service required by the launch operation. The subsequent communication problem concerned information exchange between ground equipment and the rocket. The two announcements identified separate technical causes for the consecutive postponements.
The mission’s launch schedule changed from November 13 at 12:54 p.m. EST to November 14 at 12:32:30 p.m., and then to November 15 at 12:11:30 p.m.
New Space Economy previously reported the November 15 launch target and the earlier nitrogen-supply interruption. The November 14 communication-related postponement established the reason the second scheduled attempt could not proceed.
Vulcan’s Return-to-Flight Mission
Vulcan Leo 1 is also ULA’s planned return-to-flight mission following a solid rocket booster nozzle anomaly during a February 2026 launch.
Following that flight, ULA worked with solid rocket motor manufacturer Northrop Grumman, the United States Space Force and other government organizations to investigate the nozzle behavior.
In its November 10 technical mission account, ULA reported identifying three credible causes and implementing changes to the nozzle design and manufacturing process. The work included laboratory material analysis, component testing and a full-scale firing of a GEM 63XL solid rocket motor.
ULA stated that the modified solid rocket boosters had been installed on the Vulcan vehicle assigned to Amazon Leo 1. The return-to-flight mission provides operational flight data from the updated hardware.
The rocket is configured as Vulcan VC6L, incorporating six GEM 63XL solid rocket boosters, two BE-4 first-stage engines, an extended payload fairing and a Centaur V upper stage optimized for low Earth orbit.
The two BE-4 engines burn liquefied natural gas and liquid oxygen. The six solid rocket boosters provide additional thrust during the initial ascent. ULA reports that the combined propulsion system produces approximately 17.2 meganewtons of thrust at liftoff.
The Centaur V stage uses two RL10 engines burning liquid hydrogen and liquid oxygen. Its low Earth orbit configuration is approximately 1.8 meters shorter than the high-energy version used on earlier Vulcan missions and carries about one-third less propellant.
The reduced upper-stage mass allows the rocket to carry a larger satellite payload to the intended orbit.
Forty Amazon Leo Satellites Await Deployment
The mission carries 40 spacecraft for Amazon Leo, Amazon’s low Earth orbit broadband satellite network. It is the first of 38 Vulcan launches contracted by Amazon to deploy more than 1,500 first-generation satellites.
Amazon plans to operate a constellation containing more than 3,000 satellites, providing broadband communications through spacecraft in coordinated low Earth orbits.
Vulcan Leo 1 is intended to deliver more than 22,700 kilograms of payload to orbit. ULA identifies that payload mass as a company record.
The planned flight profile calls for the Centaur V upper stage to perform two engine burns, separated by an orbital coast period, before beginning satellite deployment approximately 70 minutes after liftoff.
ULA expects to release the 40 satellites during 16 separation events over approximately 25 minutes. The first four events will each deploy one spacecraft, followed by 12 events releasing three satellites each.
Amazon has also funded additional launch infrastructure at Cape Canaveral, including a dedicated Vertical Integration Facility and mobile launch platform. These facilities allow ULA to prepare two Vulcan vehicles simultaneously. Amazon reports that preparations for its next Vulcan mission, LV-02, are already underway.
Following the November 14 communication-related postponement, ULA established November 15 at 12:11:30 p.m. EST as the next launch target, pending range approval. The scheduled mission remains the first Vulcan flight for Amazon Leo and the first planned use of the rocket’s six-booster configuration.
