The anomaly in an upper stage component was detected during a routine mission assurance check.

WASHINGTON — United Launch Alliance on July 17 announced the Delta 4 launch of an Air Force GPS satellite scheduled for July 25 will be delayed until at least August 22. This follows a July 11 announcement that the Atlas 5 launch of the Air Force Advanced Extremely High Frequency satellite planned for July 17 was rescheduled until no earlier than August 8.

In both announcements, ULA said the delays were “due to an anomaly during component testing at a supplier which has created a cross-over concern.”

ULA on Wednesday confirmed that the anomaly was in a component in the upper stage which is common to both vehicles and thus affected both the Atlas and the Delta launches. The announcements cited a “cross-over concern” because any testing anomalies in the upper stage of the Atlas would require additional testing for Delta as well.

The announcements in both instances noted that “upon further evaluation, additional time is needed to replace and retest the component on the launch vehicle. “

The Air Force declined to comment. According to a DoD official who spoke with SpaceNews on condition of anonymity, the anomaly was detected during a routine mission assurance check but declined to discuss specifics.

Both vehicles use the RL10 upper stage engine, made by Aerojet Rocketdyne. An Aerojet spokesperson noted that the delays are not caused by the RL10 engine itself, but rather by a component procured by ULA for the upper stage.

A ULA spokesperson told SpaceNews the company “identified a component concern with a sub-tier supplier on our upper stage, so we are doing our due diligence and taking any identified corrective actions to ensure the rockets are ready to be launched. Our top priority is our customer and ensuring mission success.”

Launch delays are a normal part of business and happen routinely. But these two delays are occurring at an inopportune time when the Air Force Space and Missile Systems Center has been promoting a “Summer of Launch ‘19” campaign during which it planned to carry out four launches within 31 days between June 24 and July 25.

The first two were executed successfully. On June 25 the SpaceX Falcon Heavy flew the STP-2 mission from Kennedy Space Center carrying two dozen small satellites. On July 2 at Cape Canaveral, a refurbished Peacekeeper rocket motor lifted a NASA mission to demonstrate the abort system for its Orion spacecraft. The final two missions of the campaign would have been AEHF-5 and the Global Positioning System 3 satellite, which is also the last mission for the “single stick” Delta 4 medium.

The first delay of the AEHF-5 launch, originally set for June 27, was not related to the upper stage of the Atlas 5 but to a vehicle battery failure discovered during final processing at Cape Canaveral. The launch had been rescheduled for July 17 before the upper stage issue led to this latest delay.