Northrop Grumman test fires first stage of Sentinel nuclear missile• https://newatlas.com, By David Szondy
Since the 1960s, the strategic defense of the United States has depended on the nuclear triad consisting of heavy bombers, ballistic missile submarines, and land-based ICBMs carrying nuclear warheads. The strategy behind this is to face a potential enemy with three different systems based in three different domains. This not only divides any attack, but increases the chances of enough of the triad surviving a first strike to deliver overwhelming retaliation.
Since 1970, the land-based leg of the triad has consisted of about 450 Minuteman III missiles located in hardened underground bunkers in the middle of the continental United States. Though these have been maintained and upgraded over the years, they are reaching the end of their service life and beginning in 2029 they will be phased out in favor of the Sentinel, which will be based in refurbished Minuteman III silos.
Though it's hard to tell one giant missile from another from the outside, the Sentinel is designed to require fewer operating personnel than the Minuteman III, less maintenance, and to be cheaper with a 50-year operating budget of US$264 billion for the fleet.
The three-stage launcher will carry the 300-kiloton W87-0 warhead and from 2030 will be armed with the W87-1 with a yet to be determined yield. The basic design of the Sentinel is modular with open-architecture software, which will make it much easier to maintain and upgrade while encouraging competition by defense contractors.
The live-fire test of the first stage was carried out at the Northrop's facility in Promontory, Utah. Preliminary findings show that the motor fired for the expected duration and within the predicted performance parameters.