NASA’s Space Launch System (SLS) rocket and Orion spacecraft are undergoing integrated testing inside the Vehicle Assembly Building at NASA’s Kennedy Space Center in Florida to ensure they are “go” for launch of the Artemis I mission early next year.
After stacking the Orion atop the SLS rocket, the engineers completed several tests to ensure the rocket and spacecraft are ready to roll to the launch pad ahead of the Artemis I wet dress rehearsal. These tests included ensuring Orion, the core stage, and boosters can communicate with the ground systems and verification testing to make sure all the pieces of the rocket and spacecraft can power up and connect to the consoles in the Launch control Center.
During a recent core stage power test, engineers identified an issue with one of the RS-25 engine flight controllers. The flight controller works as the “brain” for each RS-25 engine, communicating with the SLS rocket to provide precision control of the engine as well as internal health diagnostics. Each controller is equipped with two channels so that there is a back-up, should an issue arise with one of the channels during launch or ascent. In the recent testing, channel B of the controller on engine four failed to power up consistently.
The controller had powered up and communicated successfully with the rocket’s computers during preliminary integrated testing, in addition to performing a full duration hot fire during Green Run testing with all four RS-25 engines earlier this year at NASA’s Stennis Space Center near Bay St. Louis, Mississippi. NASA and lead contractor for the RS-25 engines, Aerojet Rocketdyne, also test all RS-25 engines and flight controllers for Artemis missions at Stennis prior to integration with the rocket.
After performing a series of inspections and troubleshooting, engineers determined the best course of action is to replace the engine controller, returning the rocket to full functionality and redundancy while continuing to investigate and identify a root cause. NASA is developing a plan and updated schedule to replace the engine controller while continuing integrated testing and reviewing launch opportunities in March and April.
Verification testing of the Interim Cryogenic Propulsions Stage is ongoing along with closeouts of the boosters, and parallel work continues with core stage engineering testing. Communication end-to-end testing is underway, and countdown sequence testing will begin as early as next week to demonstrate all SLS and Orion communication systems with the ground infrastructure and launch control center. Integrated testing will culminate with the wet dress rehearsal at historic Launch Complex 39B. NASA will set a target launch date after a successful wet dress rehearsal test.
SLS will be the most powerful rocket in the world and is the only rocket that can send Orion, astronauts, and supplies to the Moon in a single mission. With the Artemis missions, NASA will land the first woman and the first person of color on the Moon and establish long-term exploration in preparation for missions to Mars. SLS and Orion, along with the commercial human landing system and the Gateway that will orbit the Moon, are NASA’s backbone for deep space exploration.