A Northrop Grumman Cygnus cargo spacecraft bound for the International Space Station (ISS) experienced an engine malfunction during its final approach on Monday, September 16, 2025. The incident forced NASA to postpone the scheduled docking indefinitely while engineers investigate the issue.
The uncrewed vehicle, carrying approximately 11,000 pounds of essential supplies and scientific equipment, remains in a stable orbit. Mission controllers are working to diagnose the problem before attempting another docking maneuver.
Key Takeaways
- A Cygnus resupply spacecraft suffered an engine shutdown during its approach to the ISS.
- The docking, planned for Monday morning, has been postponed indefinitely.
- The spacecraft is carrying around 11,000 pounds of cargo for the station's crew.
- Engineers are analyzing data to determine the cause of the malfunction and plan the next steps.
Engine Anomaly Halts ISS Approach
The problem occurred during a critical orbital maneuver designed to position the Cygnus spacecraft for its capture by the station's robotic arm. According to NASA officials, the vehicle's engines shut down prematurely, preventing it from reaching the correct trajectory for docking.
Mission control immediately confirmed the spacecraft was in a safe and stable configuration. However, the unexpected shutdown means the delivery of vital supplies is now on hold. A new timeline for the docking attempt has not yet been established.
This mission, designated NG-21, is Northrop Grumman’s 21st commercial resupply flight to the orbiting laboratory. These missions are a cornerstone of the logistics chain that keeps the ISS operational.
Successful Launch Preceded On-Orbit Issue
The Cygnus spacecraft, named S.S. Francis R. Scobee, began its journey with a successful launch. It lifted off from Cape Canaveral Space Force Station on Sunday night, September 15, 2025, aboard a SpaceX Falcon 9 rocket.
The launch and initial phases of the flight proceeded without any issues, making the subsequent engine problem during the final approach particularly unexpected. The transition to using the Falcon 9 rocket is part of an updated launch strategy for the Cygnus program.
A Crucial Supply Line
The Cygnus program, along with SpaceX's Dragon capsule, forms the backbone of NASA's Commercial Resupply Services (CRS). These privately operated spacecraft are responsible for transporting all necessary supplies, science experiments, and hardware to the International Space Station, ensuring its continuous operation and research capabilities.
Details of the Cargo Manifest
The 11,000-pound (approximately 5,000-kilogram) payload is a diverse mix of essential items for the station and its crew. The manifest includes:
- Crew Supplies: Food, water, and personal items for the astronauts living aboard the ISS.
- Scientific Investigations: New experiments in biology, technology development, and human health.
- Spacewalk Equipment: Tools and hardware needed for maintenance and upgrades on the exterior of the station.
- Vehicle Hardware: Spare parts and components to maintain the station's complex systems.
The delay in receiving these supplies is not immediately critical, as the ISS maintains a reserve of essentials. However, a prolonged delay could impact the scheduling of scientific research and future operations.
Payload by the Numbers
The total cargo mass for this mission is one of the larger payloads sent on a Cygnus flight, highlighting the vehicle's importance in station logistics. The weight is equivalent to that of two average-sized cars.
Investigation and Next Steps
Engineers from NASA and Northrop Grumman are now focused on analyzing telemetry data from the Cygnus spacecraft. Their primary goal is to understand the root cause of the engine shutdown. This involves reviewing every system command and performance metric leading up to the anomaly.
"Mission managers are investigating the cause of the malfunction, which occurred as ground crews were attempting to position the capsule for its final approach to the space station," a NASA statement confirmed.
Once the cause is identified, the team will develop a recovery plan. This could involve software patches, changes to operational procedures, or using backup systems if available. Only after a solution is verified will a new docking attempt be scheduled.
The spacecraft will remain in a safe, stable orbit, trailing the ISS at a safe distance while the investigation continues. The crew aboard the space station is not in any danger and has been informed of the situation.