US Missile Defense Agency

So US is able to detect incoming threat afterall!!

A single launch of one rocket from Baikonur that heads south over the south pole and comes up over the continent of north america... what is the US going to do about it?

Shoot it down with the ABM system in Alaska?

They wont know it is a FOBs till it detonates and it doesn't have to detonate the first time around... or the 5th.

Just put the warhead in a stable orbit and every 90 minutes you can send a signal and it will fire a retro rocket and deorbit over the US to an optimum height to create an EMP pulse that covers the entire US (except maybe Hawaii).

My understanding is (you can prove me wrong Very Happy ) that once the ICBM is in terminal phase i.e its warheads reenter the atmosphere at a speed <<10Mach no one can predict its trajectory owing to the presence of maneuverable reentry vehicle.

Most MARVs are designed to initiate course corrections as the warhead falls to earth to improve accuracy. The manouvers are nothing like the manouvers needed to evade an interceptor and the targets are fixed items.
Western MARVS are designed for maximum accuracy to get as close to the target as possible and has no way of detecting incoming interceptors or being able to manouver off target to evade those interceptors and then manouver again back on target.
The exception is of course the MARV of the TOPOL-M which has been specifically designed to perform manouvers to evade interceptors directed at intercepting it.

& also one can't predict while its in boosting phase; I think while in mid-phase being in orbit makes its movement somewht known however do the US have means to pinpoint this threat even in orbital coarse!!

Ballistic missiles are actually ballistic... in other words for 5-10 minutes the rockets burn, usually three stages of burn, with the first the largest, and the last normally to get the missile to the correct speed and correct trajectory to hit the target area. The third stage carries the warhead bus that releases MIRVs on targets as it flys past them.
Because of the distance between targets after the boost phase the targets can be estimated but until the warheads are released from the bus you really don't know what the actual targets are.

EW satellites use all sorts of methods for detection, and include IR. TOPOL-M has a high energy shorter burn rocket motor designed to minimise the amount of time during the boost phase it can be intercepted.
During the boost phase an ICBM or SLBM is extremely vulnerable because they are emitting enormous amounts of heat and to target them you just fire a missile or projectile at the dark spot on top of the enormous plume of fire.
In the mid course phase the warhead bus might perform some manouvers to correct its flight path, but likely it will use low power cold gas thrusters and its temperature will purely be determined by whether the sun is shining on it or if it is in shadow.

If you look at the suggested ABM system in Europe it consisted of a very large X band radar to detect the incoming target and plot its trajectory and several high speed interceptors launched to reach potential intercept points at specific times.

It requires calculations in 4 dimensions but for most targets it is not a huge problem because most targets try to keep to a strictly ballistic path and are relatively predictible.

For terminal guidance a mix of IIR and radar are your main options and for targets that are merely correcting their path for accuracy purposes that should be fine.
For a target actively trying to evade then it is almost impossible.

The intercept point for a target travelling at a modest 8km per second, if it is out by 1 second you miss the target by 8kms. That is over the targets 10,000km flight, if you are out by 1 degree or one second you miss. Your interceptor rocket is travelling very fast too but it can't get to the intercept point and hover and wait, you are hitting a bullet with a bullet... hard at the best of times, near impossible if the target is manouvering specifically to evade your interceptor... and there is no reason why that incoming target wont have an active jammer or flares too.
Above the atmosphere a decoy acts like a warhead... even when the decoy is mms thick sheet metal hollow cone... your warhead bus could carry hundreds stacked inside each other.

Does Russia have any concern this could be a tactical weapon and part of the missile defense shield or even a tactical weapon:

It would be a very inefficient weapon.

An easy target.

Early telescopes used shaped glass to bend light to magnify the image and make it appear closer. As the bits of glass got bigger however to make the image appear closer and closer it was found that there is a problem with bending light with glass.

Any glass prism will show that white light is made up of all the colours of the rainbow and when you shine light through glass the light tends to separate into its separate colours so images got colourful halos of bright colours.

The solution was to use a mirror so the light coming from a long way away comes into an open tube with no glass at the front to hit the bottom of the tube which is lined with a large flat mirror which both reflects and focuses the image back up to about half way up the tube to a small mirror that redirects the focused image sideways out of the tube to a small lens that can be used to adjust the focus to get a sharp clear image.

In big powerful telescopes replace the small mirror half way up the tube with an incredibly expensive CCD light sensor with a 100 mega pixel or better performance.
The sensor blocks some of the light so the mirror in the bottom of the telescope might have a bare centre, but to look at things as close as 100km away or as far away as distant galaxies you need to be able to very accurately flex the mirror to the correct focal length to properly focus the image. Because of the huge range of distances the CCD detector might move up and down the tube a bit as well, but the point is that the long tube in front of the mirror will make it very very difficult to catch sunlight and redirect it at something on the Earth... especially as the telescope itself will be zipping along at orbital speeds.

In this system however the mirrors are exposed and shielded from sunlight by a large shield.

The CCD sensor will be mounted somewhere on the craft and the mirrors will be angled to direct a view of the target into the sensor.

The system will be located near a Lagrange point to avoid entering the earths shadow... which is perfectly normal for a solar powered satellite

A Lagrange point is an area of zero real gravity.

In Earth orbit an object like the ISS is subject to Earths gravity... it keeps falling in a curve but because it is going so fast it misses landing on earth, or conversely it is trying to fly away from the earth but keeps falling back towards it enough so that its distance from earth never increases.
On board the ISS everything is "falling" at the same rate and appears to be weightless, but from an energy point of view every once in a while the engines need to be fired to maintain its orbital height.

To explain a Lagrange point it is a point of balanced or doubled or halved gravity. Think about the Earth and the moon.
Both have their own gravity though the Earths gravity is more powerful than the Moons gravity because the Earth has more mass.
If you were to move in a direct line from the Earth to the Moon for the first three quarters of the trip the Earths gravity would be the dominant force on you so if released or suddenly stopped in relation to both objects you would fall to Earth and not the the Moon.
As you get closer to the moon however the effect of the moons gravity will increase and the effect of the Earths gravity will diminish because gravity is directly related to the square of distance. Eventually you will reach a point where the earths gravity equals the moons gravity and they balance out. If you stopped there you would stay there and not fall towards either the moon or the Earth... the gravity of the Earth would stop you falling toward the Moon but the gravity of the Moon would stop you falling toward the Earth.
That is a Lagrange point.
Lagrange point 1 actually.
Lagrange point 2 for the Earth and the moon would be beyond the moon the distance where the gravity of the moon and the earth are equal again.

In this case L2 for the Sun and the Earth is shown on this diagram:



As anyone knows the closer to the sun the faster an object needs to go to prevent falling into that sun, so an object at the L2 position will be in about an 800,000km larger radius orbit than the Earth is... so if it wasn't an L2 point... if it was ahead or behind the Earth it would rapidly fall behind Earth. In the L2 point however it has the Sun and the Earths combined gravity to nudge it along and keep it in place so only a tiny amount of energy will be needed to keep it in place.

It is a bit like Cyclists using slipstreaming in a bike race to reduce the amount of energy they need to burn to hold position by getting in behind another cyclist. Of course this works because the cyclist in front is doing work pushing through the undisturbed air, which is work the cyclist behind does not have to expend energy doing. In space there is no air.

There is a stable Lagrange point between the Earth and the Sun though the passage of Venus and Mercury will upset an object at that point.

This satellite will orbit the L2 Lagrange point so it will fly in a circle around the L2 point. It is called a Halo orbit because from the ground looking directly up at the L2 point the satellites orbital path looks like a circle around that point.
At the L2 point the Earth would be constantly blocking some of the sunlight, but flying a halo orbit around L2 gives you all the gravity boost advantages of the L2 point plus the constant sunlight to the solar panels.
The sunshield also never needs adjusting because the telescope will always point away from the Sun (and Earth).

Personally I think if they really wanted a space based energy weapon they wouldn't put it on anything so public.

Equally space based energy weapons are overrated. A laser weapon will suffer about a 1mm divergence per metre of travel, so from 100km up the laser when it hits the ground will be 100m across... which is pointless for anything except ranging.

A over 1 million kms past Earths orbit this system (ie the CCD sensor and mirrors) would be damaged by exposure to the solar wind and the intense heat of direct sunlight.
To retain its shape the mirrors need to be kept at a constant temperature... shining sunlight on them would unevenly heat them leading to warped and useless mirrors till they were cooled down again or fully heated to an even max temperature. That even high temperature would probably melt or damage the mirrors which will normally be kept cryogenically cool to observe deep space objects.

It is designed to take light coming from millions of kms or trillions of light years and focus it on a point within the area of the spacecraft itself... it says it has a focal distance of 131m which means focusing on targets on Earth would be impossible anyway. At 800,000km away from the Earth and facing away from the Earth and the Sun there is zero chance this system could be used against anything on Earth or the Satellites in Earth orbit... even geostationary objects are much lower than this.

What is the point of saboteur teams if you can't find the targets with satellites?

remember the problems the US had finding Scud missiles in Iraq even though Iraq is not a huge country and they had total air control, not to mention it is further south so satellites in geostationary orbits get a better view and there was no one interfering with their satellites...

How on earth are those saboteur teams supposed to track down and attack those trains before they find a siding... pull over and launch their missiles?

Next you will be claiming they can send those very same teams to follow Russian SSBNs around the ocean able to sink them on command too....

Nakidka defeats PGMs because if the munition can't see a target then it can't hit it. Just the same as optical guidance is effected by colour camouflage... if you can't see the man in the trees then you can't effectively shoot him...

you got it wrong . PGSS means Persistent Ground Surveillance Systems . NOT PGS Prompt Global Strike . US thinks it is The Best Defense Against Cruise Missiles . It is a giant surveillance Blimp .It is just like JLENS Joint Land Attack Cruise Missile Defense Elevated Netted Sensor . JLENS is basically a way for folks (like NORAD) to watch for low-flying cruise missiles (a.k.a. exploding drones without round trip tickets) and aircraft .

So it is a defensive system that flys over your own territory watching for incoming cruise missiles... WTF has that to do with trains carrying ICBMs?

Do you think the Russians will just let the US move a couple of large airships to operate over their airspace and look for missile trains?

A train vs an airship sounds like one of those crap US movies... snakes vs crocodiles or sharktapus.... part shark and part octapus...

The missile armed train would probably have a few S-400s and S-500s on it that could shoot down the air ship...

JLENS aerostats are deployed in pairs called "orbits." One blimp carries a giant search radar system while the other has high-powered targeting radar. The search radar looks for interesting stuff — up to 340 miles away — so that the tracking radar can pinpoint the interesting thing and pass that info along to other people in the air defense ecosystem, who can then check it out, shoot at it, or whatever.

So two airships emitting enormous beams of radar waves that any anti radiation missile could spot from enormous distances.... an ARM version of Iskander would be ideal I suspect... especially with a cluster munition warhead...

Actually i wanted to discuss this stuff here earlier that how come JLENS or PGSS surevillance blimps will pinpoint russian cruise missiles so that their air defenses norad can shoot it down ?

The Russians have already sold airship based monitoring systems to China for use in mountainous areas... I rather suspect they are working on all sorts of variations...