NASA has announced a delay in the arrival of the NG-23 Cygnus spacecraft at the International Space Station (ISS). The delay stems from a thruster problem encountered during orbit-raising maneuvers. The spacecraft's main engine shut down prematurely during two burns on September 16th, preventing its scheduled arrival near the ISS on September 17th.
Neither NASA nor Northrop Grumman, the operator of the Cygnus spacecraft, has offered specific details regarding the nature of the thruster malfunction. However, NASA confirmed that all other systems on board the Cygnus are functioning normally. The Cygnus spacecraft launched aboard a SpaceX Falcon 9 rocket on September 14th, carrying approximately 5,000 kilograms of cargo. The planned transit to the ISS was a 60-hour journey, followed by grappling and berthing to the Unity module via the station's robotic arm.
This mission marks the maiden voyage of the larger Cygnus XL variant. This upgraded version boasts a longer pressurized cargo module, resulting in a 33% increase in payload capacity compared to its predecessor. Northrop Grumman has reported no modifications to the spacecraft's service module, which houses the main thruster, power systems, and other essential subsystems. This incident is not the first instance of thruster problems affecting a Cygnus mission. The NG-21 Cygnus mission, launched in August 2024, experienced a similar issue – an initial orbit-raising burn failure attributed to a "late entry to burn sequencing" problem, accompanied by slightly low pressures within the main thruster. Despite these complications, the NG-21 mission successfully reached the ISS without delay.