Resupply missions for the International Space Station (ISS) typically proceed without much fanfare, but Northrop Grumman’s Cygnus vehicle is currently attracting attention for all the wrong reasons. After reaching orbit without incident on Sunday, NASA has reported that the spacecraft’s engines failed to fire as scheduled. While Cygnus is not in immediate danger, Northrop Grumman is now tasked with figuring out how to guide it to the ISS.
Cygnus launched on August 4 atop a SpaceX Falcon 9 rocket, which has proven reliable even after last month’s Starlink anomaly. NASA successfully established contact with Cygnus in orbit and confirmed that the vehicle deployed its solar panels. However, Cygnus reported it had not performed the planned engine burns as instructed.
The spacecraft was supposed to execute a targeted altitude burn (TB1) 42 minutes after liftoff. According to NASA, Cygnus missed this burn due to a “late entry to burn sequencing.” Mission managers rescheduled the burn for 50 minutes later, but the vehicle skipped that one as well due to a “slightly low initial pressure state” inside the engine.
The good news is that Cygnus is at a safe altitude and won’t tumble back into the atmosphere if it has to orbit for a bit. As an uncrewed cargo vessel, there’s no risk of stranded astronauts. However, the spacecraft is carrying thousands of pounds of important materials and supplies for the ISS crew.
Cygnus is set to deliver 8,503 pounds (3,857 kilograms) of cargo to the ISS. The cargo is split about evenly between vehicle components, science experiments, and crew supplies. Included are some additional items for astronauts Butch Wilmore and Suni Williams, who have been at the station for the past few months while NASA and Boeing investigate problems with the Starliner spacecraft. Some personal items were removed from Starliner before launch to make room for station components, but that was considered manageable given the originally planned short eight-day mission duration. Now, two months later, Williams and Wilmore will likely be pleased to receive a care package of clothing and personal food items. NASA notes that the Cygnus cargo delivery will not include SpaceX pressure suits for Williams and Wilmore, which are necessary for their return home aboard a Crew Dragon. SpaceX plans to launch a new crew rotation mission later this month, potentially delivering the required suits if NASA opts for that route.
Northrop Grumman is currently developing a new burn and trajectory plan to get Cygnus to the ISS. With the upcoming crew launch on or around August 18, there is some time to get this cargo vehicle back on track.
This situation underscores the complexities and challenges of space missions, even those as routine as resupply missions to the ISS. As Northrop Grumman works to resolve the issue, the space community watches closely, hoping for a successful resolution and delivery of the much-needed supplies to the ISS crew.