A ballistic missile is a missile that follows a ballistic, sub-orbital flight path to bombard a predetermined target with one or more warheads (often nuclear). The missile is guided only during its relatively short initial flight phase, and thereafter its trajectory is governed by the laws of orbital mechanics and ballistics. To this day, ballistic missiles are propelled in flight, with various types of chemical rocket engines.
The trajectory of a ballistic missile consists of three stages: the launch stage, the free-flight stage, which also accounts for most of the total flight time, and the re-entry stage, where the missile re-enters the Earth’s atmosphere.
Ballistic missiles can be launched from fixed locations or from mobile launch platforms, including vehicles (self-propelled missile launchers – TELs), aircraft, ships and submarines. The launch phase can last from a few tens of seconds to several minutes and can consist of multiple rocket launch stages.
Once in space, no further thrust is provided and so the rocket enters the free flight phase. To cover long distances, ballistic missiles are usually launched at a height comparable to a sub-orbital space flight. The highest altitude (apex) achieved for ICBMs during the free flight phase is around 1,200 km.
The re-entry stage begins at an altitude where the drag force due to atmospheric resistance plays a significant role in the missile’s trajectory and lasts until impact.
Ballistic Missile Types Launch of the Trident II SLBM from a Royal Navy Vanguard-class submarine. Ballistic missiles can vary greatly in their range and use, and are usually divided into categories based on range.
Different schemes are used by different countries to categorize the ranges of ballistic missiles:
Tactical ballistic missile: Range between 150 km and 300 km Long Range Ballistic Missile (BRBM): Range less than 200 km
Operational Theater Ballistic Missile (TBM): Range between 300 km and 3,500 km
Short-range ballistic missile (SRBM): Range 1,000 km or less.
Ballistic medium range missile (MRBM): Range between 1,000 km and 3,500 km.
Ballistic missile intermediate-range ballistic missile (IRBM) or long-range ballistic missile (LRBM): Range between 3,500 km and 5,500 km
Intercontinental ballistic missile (ICBM): Range over 5,500 km
Ballistic submarine-launched missile (SLBM): Submarine-launched ballistic missiles (SSBNs).
All contemporary designs are intercontinental in scope. Short- and medium-range missiles are often referred to collectively as tactical ballistic missiles or theater operations missiles (TBMs).
Intermediate- and long-range ballistic missiles are usually designed to carry nuclear weapons because their payloads are too limited for conventional warheads to be effective (although the US is considering the idea of an intercontinental ballistic missile armed with conventional warheads that would provide the capability of close-in, instantaneous airstrikes worldwide, despite the high cost).
The free-flight phase of ballistic missiles is the same for all (and ICBMs) except for missiles with a range of less than 350 km, which have no extra-atmospheric activity.
#ballistic #missile
