Editing Multiple independently targetable reentry vehicle (section)

== Operation ==

In a MIRV, the main rocket motor (or [[booster (rocketry)|booster]]) pushes a "bus" into a free-flight [[suborbital]] ballistic flight path. After the boost phase, the bus maneuvers using small on-board rocket motors and a computerized [[inertial guidance system]]. It takes up a ballistic trajectory that will deliver a re-entry vehicle containing a warhead to a target and then releases a warhead on that trajectory. It then maneuvers to a different trajectory, releasing another warhead, and repeats the process for all warheads.

[[Image:Minuteman III MIRV path.svg|thumb|upright=1.5|[[LGM-30 Minuteman|Minuteman III]] MIRV launch sequence:

1. The missile launches out of its silo by firing its first-stage boost motor (''A'').
2. About 60 seconds after launch, the first-stage drops off and the second-stage motor (''B'') ignites. The missile shroud (''E'') is ejected.
3. About 120 seconds after launch, the third-stage motor (''C'') ignites and separates from the second-stage.
4. About 180 seconds after launch, the third-stage thrust terminates and the post-boost vehicle (''D'') separates from the rocket.
5. The post-boost vehicle maneuvers itself and prepares for re-entry vehicle (RV) deployment. 
6. While the post-boost vehicle backs away, the RVs, decoys, and chaff are deployed (this may occur during ascent).
7. The RVs and chaff reenter the atmosphere at high speeds and are armed in flight.
8. The nuclear warheads detonate, either as air bursts or ground bursts.]]

The precise technical details are closely guarded [[military secret]]s, to hinder any development of enemy counter-measures. The bus's on-board [[propellant]] limits the distances between targets of individual warheads to perhaps a few hundred kilometers.<ref name=airliners>{{Cite web |url=http://www.airliners.net/discussions/military/read.main/68181/ |title=Question Re Mirv Warheads — Military Forum {{!}} Airliners.net<!-- Bot generated title --> |access-date=2008-07-02 |archive-url=https://web.archive.org/web/20071016214658/http://www.airliners.net/discussions/military/read.main/68181/ |archive-date=2007-10-16 |url-status=live }}</ref> Some warheads may use small [[hypersonic]] [[airfoil]]s during the descent to gain additional cross-range distance. Additionally, some buses (e.g. the [[UK|British]] [[Chevaline]] system) can release [[decoy]]s to confuse interception devices and [[radar]]s, such as [[aluminium|aluminized]] balloons or electronic noisemakers.

[[Image:Peacekeeper-missile-testing.jpg|thumb|Testing of the [[LGM-118 Peacekeeper|Peacekeeper]] reentry vehicles: all eight (of a possible ten) were fired from only one missile. Each line shows the path of an individual warhead captured on reentry via long-exposure photography.]]

Accuracy is crucial because doubling the accuracy decreases the needed warhead energy by a factor of four for radiation damage and by a factor of eight for blast damage. Navigation system accuracy and the available geophysical information limits the warhead target accuracy. Accuracy is expressed as [[circular error probable]] (CEP). This is the radius of the circle that the warhead has a 50 percent chance of falling into when aimed at the center. CEP is about 90–100 m for the [[Trident missile|Trident II]] and [[LGM-118A Peacekeeper|Peacekeeper]] missiles.<ref name="Cimbala2010">{{cite book|last=Cimbala|first=Stephen J.|title=Military Persuasion: Deterrence and Provocation in Crisis and War|url=https://books.google.com/books?id=rMe9guZoyIUC&pg=PA86|access-date=3 May 2013|year=2010|publisher=Penn State Press|isbn=978-0-271-04126-1|page=86|archive-url=https://web.archive.org/web/20160426054128/https://books.google.com/books?id=rMe9guZoyIUC&pg=PA86|archive-date=26 April 2016|url-status=live}}</ref>