Ballistic missile guidance is generally well understood. Ballistic missiles get to where they’re going using a variety of navigational tools, from satellite sensors to gyroscope inertial guidance. A normal, non-hysterical missile flies up into the atmosphere and begins its descent onto target following a ballistic trajectory. But, what if I were to tell you that some act completely randomly?
That’s right, random number generation has a place in the Iskander-M aeroballistic missile’s evasive maneuvering. Specifically, the ballistic missile defense evasion system of the Iskander-M is apparently able to perform evasive maneuvers in the terminal phase of its trajectory. This keeps the target’s ballistic missile defenses, as well as the creators and operators of the missile system, guessing as to the missile’s terminal phase location at any given time during the last phase of its flight.
Iskander Brigade Commander describing designers’ statements on the Iskander-M aeroballistic trajectory. ‘The Iskander-M Missile System – An Equal to Nuclear Weapons’
Valery Drobinoga, the Deputy Head of the Iskander-M R&D at KB Mash in Russia, states that even in the unlikely event that an Iskander-M aeroballistic missile gets picked up on radar, ‘rest assured that the missile will perform some erratic maneuvers on its aeroballistic trajectory.’ Interesting point, but what we know about ballistic missiles is that they, like other missiles, are intended to be highly precise instruments of war. So how does ‘erratic maneuvering’ fit into the trajectory equation without betraying that precision? The answer seems to be some sort of random number generation.
In a pikabu.ru1 post, the unnamed author describes an ‘evasive algorithmic maneuvering technique’ that is supposed to be the 9M723’s ballistic missile defense evasion method.
Imagine a missile in flight. In the direction it is flying, imagine a chess board-like grid projected out in front of the missile, perpendicular to its trajectory, maybe a few hundred meters to a kilometer in distance. Each of the squares in that grid is represented by a number, and an onboard computer randomly selects one of those numbers as a target. The missile then adjusts its trajectory to fly through that selected square within the grid. It then repeats that entire sequence a number of times until the missile begins its final approach onto the target 2. As a result of this trajectory alteration, ballistic interception is very difficult.
This presents an interesting question regarding the onboard computer systems of the Iskander ballistic missile. With a little internet sleuthing, we found a graphic diagramming the export version of the 9M723 ballistic missile which likely provides some valuable insights into the operation of the missile during its flight. For example, we can see that there is only one system that has direct input into the steering motors. That onboard system has a direct two-way connection with the ‘onboard special-purpose computer’ via an information transmission line.
БСВ is an acronym for ‘вортовой спец. вычислител’ in Russian, ‘onboard special calculator/computer’ in English
This onboard computer is likely the computing unit responsible for the actual calculation of these random-number grids and then receives input from the gyroscope via the ‘onboard electronic device,’ which then sends the information to the actuators, steering the missile.
ПБЭ is an acronym for ‘прибор бортовой электроники’ in Russian, ‘onboard electric device’ in English.
Admittedly, there is the possibility that the missile diagram for the Iskander-E does not match the Iskander-M exactly in regards to these specific features. Additionally, the same evasive maneuvering capabilities may not be provided to the Iskander-E, but that seems unlikely. Thus outlines a reasonable theory of the ‘erratic maneuvers’ of the Iskander-M as a ballistic missile defense evasion technique. Having been hinted at by Russian military experts and missile engineers, and outlined by unnamed Russian bloggers, there seems to be enough evidence on the open side to support the possibility that their claims are true. Whether the random number generating component of interest is that ‘onboard special calculator/computer’ is simply an educated guess – we have no way of knowing concretely whether or not this is the case. But that is where I am placing my bet.
