Engine Issue Delays Cygnus XL's ISS Resupply Mission

Northrop Grumman's Cygnus XL spacecraft, carrying over 11,000 pounds of supplies and experiments, has encountered a main engine issue that will delay its scheduled arrival at the International Space Station (ISS). The problem occurred early Tuesday when the spacecraft's main engine shut down prematurely during two orbital adjustment burns. NASA stated that ground teams are evaluating backup plans to enable the Cygnus XL to reach the ISS, though not on the original schedule. All other systems on the spacecraft are reported to be functioning as designed. The Cygnus XL was launched on Sunday at 6:11 p.m. EDT aboard a SpaceX Falcon 9 rocket from Cape Canaveral Space Force Station, Florida. This mission marks the first flight of the larger Cygnus XL model, which is 5.2 feet longer and can carry 33% more cargo than its predecessor. The spacecraft's main engine uses a hypergolic propellant mixture of hydrazine and nitrogen tetroxide, known for its reliability. In the event the main engine is deemed unusable, engineers are considering using the spacecraft's smaller reaction control system thrusters to gradually adjust its orbit for a rendezvous with the ISS. However, the viability of this option is still under assessment. Unlike SpaceX's Cargo Dragon, the Cygnus is not designed for intact return to Earth. It is typically filled with trash before departing the ISS and undergoes a destructive reentry over the Pacific Ocean. Therefore, failure to reach the ISS would result in the loss of all onboard cargo. The supplies on this mission, designated NG-23, include fresh food, hardware for various experiments, and spare parts for the station's urine processor and toilet, aiming to replenish dwindling stocks of these items.