Northrop Grumman has completed vital tests of some key elements of its planned ground-based intercontinental ballistic missile (ICBM) Sentinel system, the defense contractor reports. These tests represent a crucial milestone in the planned modernization of this critical part of the United States' aging existing nuclear deterrent "triad."
During the tests, the front and rear parts of a Sentinel ICBM missile underwent a series of tests at the company's Strategic Missile Test and Production Complex in Promontory, Utah. These tests, Northrop Grumman explains, have helped to reduce the risks associated with the program by providing essential data about the missile's structural dynamics during flight.
The information gathered during the tests is being used by engineering teams to improve their models, minimize risks, and ensure the success of future flights. As part of the engineering, manufacturing, and development (EMD) or design contract for Sentinel, the company conducted shroud fly-off and missile modal tests.
Northrop Grumman is working closely with the Air Force to achieve key milestones during the EMD phase.
A key milestone in the Sentinel program
The shroud of a missile or spacecraft is a cover that shields the payload, such as a warhead or a satellite, during its launch and flight through the atmosphere. Tests on this system help ensure that the shroud can separate successfully from the missile or spacecraft once it has exited the atmosphere or reached a certain altitude where protection is no longer required.
This test verifies that the shroud separation mechanism works as intended without causing any harm to the payload or altering the missile's trajectory. A modal test, which is also called a modal analysis or vibration test, is carried out to determine the vibration characteristics of a missile.
This includes identifying its natural frequencies, mode shapes, and damping ratios. Understanding these aspects is crucial to ensure the missile's structural integrity during the launch, flight, and re-entry phases. Vibrations can be caused by engines, aerodynamic forces, and other external factors. Knowing how the missile responds to these vibrations is essential for its design and reliability.
"Working with the Air Force and our team of suppliers, we put key elements of the missile's hardware to the test to mature our design and lower risk. The shroud fly-off test proved our modeling predictions are solid, while the missile stack test demonstrated inflight missile performance, helping validate assumptions and fine-tune models," said Sarah Willoughby, vice president and program manager, Sentinel, Northrop Grumman.
"These successes give us confidence as we continue progressing on the path to deliver a safe, secure, and reliable capability to the nation," she added.
Sentinel is replacing the Minuteman III
The LGM-35, also known as the Sentinel or Ground Based Strategic Deterrent (GBSD), is a new ICBM that is currently in the early stages of development. Its primary purpose is to replace the aging Minuteman III ICBMs currently deployed in North Dakota, Wyoming, Montana, and Nebraska. These veteran missiles are scheduled to be replaced from 2029 onwards.
Sentinel is also planned to be viable until at least 2075.
Northrop Grumman is leading a team across the country to work on Sentinel's EMD contract. The team is responsible for designing the most technologically advanced component of America's ground-based strategic deterrent. They are working closely with the Air Force to continue refining the design while minimizing risk as key EMD milestones are reached.
Previously under EMD, advancements included static fire tests for stage-one and stage-two solid rocket motors, as well as hypersonic wind tunnel testing.
