NPS Minuteman Missile
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  • 8. IMPSS

    The white pole of the IMPSS tower stands over a silo.

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    The Improved Minuteman Physical Security System

    The tall white pole to the left of the launcher is the Improved Minuteman Physical Security System.  In 1989 this replaced a previous intrusion-detection system that, less able to discriminate threats, caused numerous nuisance alarms.  While designed to detect intrusion by humans, deer near the fence, rabbits, snakes, flocks of birds, and even a swarm of locusts inside the site, could sometimes set it off.  


    When motion was detected, the Delta-01 crew was the first to know.  They’d notify the Flight Security Controller who would dispatch his Alarm Response Team to the site.  Times varied, but at this location, Security could reach the site within 15 minutes. They followed strict checklists to detect intruders, report damage, confirm the site was secure, then waited off-site until the capsule reset the alarm, before returning to Delta-01.  


    There were few human intrusions over the years.  Most were peace activists protesting at the gate.  Though isolated miles from base, Launch Facilities were high-security U.S. military installations and site signage provided ample warning.  If a person attempted intrusion of a manned Launch Facility, site security challenged them with M-16 rifles. If the site were undergoing maintenance, challenges could be less pleasant.  Intruders at an unmanned site heard no audible alarm. Within minutes an armed Security team detained them, turning them over to civilian police. No Soviets ever attempted to breach a site or gain access to the missile or warhead.