Tennessee: In a significant milestone for the LGM-35A Sentinel nuclear missile program, Northrop Grumman confirmed the successful test firing of the second-stage solid-rocket motor. The full-scale static fire test, conducted at the U.S. Air Force’s Arnold Engineering Development Complex in Tennessee, simulated the high-altitude and space flight conditions that the intercontinental ballistic missile (ICBM) would encounter during an actual launch. 

The test aimed to replicate the challenging conditions of high-altitude and space flight, crucial for assessing the performance of the rocket motor. The vacuum chamber at the Arnold Engineering Development Complex provided a controlled environment to evaluate how well the second-stage solid-rocket motor would function during the missile's journey. 

Data analysis for risk mitigation 

Northrop Grumman emphasized the importance of data analysis from the test to assess how closely the motor's actual performance aligned with predictions made in digitally engineered models. This comprehensive evaluation is part of the company's strategy to mitigate risks associated with the Sentinel program. 

Sarah Willoughby, Northrop Grumman's vice president and Sentinel program manager, stated, “The test’s data gives us an accurate reading of our design’s performance and now informs our modeling and designs. This lowers risk and builds confidence in our approach to deliver the next-generation ICBM capability to the Air Force.” 

Sentinel program overview 

The Sentinel program, initiated by the Air Force, aims to develop a new nuclear-armed intercontinental ballistic missile to replace the aging LGM-30G Minuteman III. With an estimated total cost of around $100 billion, Northrop Grumman secured a $13.3 billion contract in 2020 for the development of the Sentinel missile. Currently in the engineering, manufacturing, and development phase, the program has faced challenges, as reported by the Government Accountability Office in June 2023.

The GAO highlighted staffing shortfalls, supply chain issues, and software challenges, leading to a projected delay in the weapon's rollout from 2029 to approximately the spring of 2030. Air Force Secretary Frank Kendall expressed concerns about the program's struggles and mentioned being more nervous about its development than the B-21 Raider stealth bomber, also built by Northrop. Additionally, he acknowledged the possibility of rising costs for the Sentinel program. 

Daunting scale and complexity 

Kendall emphasized the sheer scale and complexity of the Sentinel program, labeling it as one of the most significant endeavors the Air Force has ever undertaken. Beyond the production of the missile itself, the program encompasses real estate development, civil engineering, and the establishment of communications and command-and-control infrastructure.

Looking ahead, Northrop Grumman plans to initiate a series of rocket motor qualification tests in collaboration with the Air Force for both the first and second stages of the three-stage missile. This follows the earlier announcement in early 2023 regarding a static test of the missile’s first-stage motor and hypersonic wind tunnel tests to validate its design. The company remains committed to addressing challenges, ensuring the reliability and effectiveness of the LGM-35A Sentinel nuclear missile.