Can you use aerodynamic steering at these altitudes? The atmosphere is very thin. How can the Zircon perform complex maneuvers in such a thin atmosphere? Wetkore thrust on the engine nozzle.
How do you think the US Space shuttle manouvers inside the atmosphere?
It uses small rockets to spin around 180 degrees to point its main engines backwards and fires its main engines for a few seconds to slow down to below orbital speeds and then uses small rockets to rotate back to pointing forward with the correct nose up attitude for the re-entry...
It essentially uses entire body braking with a high angle of attack in the upper atmosphere to slow down from enormous speeds to much slower speeds where it can land like a conventional aircraft... big heavy conventional aircraft with low lift so steep landing, but still aerodynamic.
The Zircon uses a jet engine and flys all the way to the target... a cruise missile is more like a bomber than an artillery projectile...
They could use fins for control and for stabilisation, but such things also create drag, but they could just as easily use TVC engine nozzles on the scramjet motor that provides thrust.
Very high speed means you create a lot of lift and also means a high g turn is not necessarily a tight one. The maneuverability of such missiles is not destined to "dodge" anything but to ruin the calculation of interception points and the kinematics of interceptors, since at those speeds a few degrees deviation mean many tens of km of difference between what your AD calculated and where the missile actually is going to be. Remember, kinematics is the real issue here.
Exactly... the speed makes it like a bullet... it is not that a bullet is manouverable but it is often moving too fast to dodge.
A (rifle) bullet fired from 1km away means you have at least 3-4 seconds to get out of the way... but the problem is that when it hits you it will still be moving at hundreds of metres per second... to fast to see and not enough time to see and physically moved out of the way of... so generally if you see the muzzle flash... yes, I know, unlikely, but if you see the muzzle flash and know it is coming the best way to evade is to move if you were still or stop moving if you were moving... if you were still then remaining still makes you and easier target for them to hit... but then they might have anticipated you saw the shot and therefore aimed for the ground at your feet assuming you see the shot fired and you dive to the ground to avoid being hit.
If you were walking at a steady pace and see the shot then if the shooter is a good shot they likely would have allowed for the speed you were walking at so if you stop walking the round would be aimed to hit you several metres in front of where you are where you will be when the round arrives.
Obviously if you are walking directly towards or away from the shooter then one or two steps to either side and you should avoid being hit.
Obviously if the projectile can shift its trajectory even only by a few degrees all the way to you then you need to get to cover because it should be able to compensate for any move you do make faster than you can respond to the changes.
As KVS points out above when the speeds are very high then the problems increase... imagine the incoming target is a tennis ball and the interceptor is a tennis racket.
The tennis ball is not particularly fast although it can move rather quick, while the reach of the tennis racket is limited by the arm length of the player.
The enemy will likely know where the opposition player is before they launch the tennis ball and what their reach is, but the game of tennis is designed so that most of the time a player has some chance of reaching the ball to intercept it and return it... the rules of serves and the height of the net and size of the courts and the in areas of a tennis court makes scoring aces on your serve rather harder, but not impossible.
In the real world the speed and distances involved magnify the interception problems immensely... a surface to air interceptor racket like an S-400 moves at eye watering speeds, and the eyes of the player are enormously powerful and can observe enormous volumes of air space from near ground level out to space and beyond... but the problem when talking about very fast moving targets and very fast moving interceptors is that the other player can fake a shot so you think it will be fast and it ends up being a rather slow lob... with a tennis racket you can wait a second for the ball to arrive, though if it is an ace and you think it will be slower and it zips through there is not much you can do.
Very simply if you have an air defence battery sitting in the path of a mach 10 missile there is no trajectory to calculate... it is flying in a level path like an aircraft... in comparison a ballistic missile has a flight path like an artillery shell so it is much faster but predictable... you can work out the target area it will land in and you know it is not going to do a lot of manouvering because that would burn up its speed and actually make it easier to intercept.
A Zircon is an aircraft and it will be flying waypoints and might climb or descend and change direction at any time.
Unlike most normal aircraft however this thing is covering 3.2km of distance every second... so say it is flying level and straight at 30km altitude at 3.2km/s... if it remains flying straight and level it is an easier target to hit, though certainly not an actually easy target... remember S-400 can hit targets moving at 4.8km/s so it can actually cope with a straight flying target like this though it is ballistic or predictable targets that fly at that speed that it can intercept.
The location of the Zircon is established and its flight path can be estimated so you look along that path for an S-400 battery and you get them to power up and prepare to launch... calculating an intercept point is easy as long as the target maintains speed and altitude and does not make any flight changes... so for example say the S-400 calculates an intercept point that is 200km away from the S-400 battery north of its position... the speed and performance of the S-400 missile to be fired is known so the interception location is the distance at which a launched S-400 missile will get to that interception position at the same time the Zircon target does... from that location the S-400 missile will take X number of seconds to reach the intercept point... so when the Zircon reaches a position where its X number of seconds to reach the same intercept point equals the S-400s missiles X position the S-400 missile is launched, so then we have these two objects rapidly closing in on each other at enormous speeds... but the Zircon is not stupid... it detects the radar signals that are being used to track it and it realises that the territory it is flying over... there are S-400 batteries there, so just then it decides to pull a 40g turn to the left for a few seconds... it sounds like a hard turn... and it is but it will only be a few degrees angle because at that speed g force turns are magnified immensely... the ground systems will detect and change in trajectory and their computers will be shifting the interception point in real time but the interception point will continue to shift until the Zircon stops turning, so the S-400 will receive new interception points continuously... the speeds it is travelling at they can't afford to wait to see how far off course the Zircon is turning... the Zircon stops turning but the interception location has now shifted 50km.... well the S-400 is moving fast but it is not moving at 3.2km/s like the Zircon is so the extra 50km might take an extra 20 seconds to reach... remember the interception point is the four dimensional coordinates of the two objects in space and time... it is not good enough for your interceptor missile to reach the same interception point that the target is going to occupy if it gets there 1 second after the target... 1 second late means you miss by 3.2km... even a small 2KT nuclear warhead wont get you a kill with such a miss distance, and what if it is 10km or 20km miss.
Most importantly the Zircon can not just turn randomly... it can climb or even slow down... if it does not turn or climb or dive it can slow down and your interceptor will get to the point of interception too early... it is a missile... it can't stop and wait for a second or two while the target catches up...
S-400 is rocket powered so it has fixed acceleration and while it can manouver it has limited energy... after the missile is half way to the target interception point the Zircon might turn and then turn back the other way leaving the interception missile 100km away from the new interception point with not enough speed or energy to turn to get to that interception point by the time the Zircon missile blows past.
It is not impossible to intercept but you definitely need to develop a strategy with coordination and lots of missiles and for now perhaps nuclear warheads... getting a missile to an intercept point and then turning the missile to head directly at the incoming target and detonating a nuke as their paths are about to cross would be the likely goal.
The thing is that in the near future the S-600 and S-700 will likely be scramjet powered air defence missiles with flight speeds of mach 10 to mach 20... and of course lasers and directed energy weapons where the intercepting material is moving at light speeds starts to become worth the enormous costs...