What is a Fractional Orbital Bombardment System (FOBS)?
A Fractional Orbital Bombardment System (FOBS) is a warhead delivery system that uses a low earth orbit towards its target destination.
FOBS is the highest-velocity missile deployment system that currently exists.
How Fractional Orbital Bombardment System (FOBS) works?
A big rocket places a nuclear warhead in orbit. Attached to that warhead is a small rocket motor. The little motor could be fired (a retrograde engine burn) to slow the warhead, bringing it back down wherever wanted.
What is the idea behind Fractional Orbital Bombardment System (FOBS)?
The idea behind Fractional Orbital Bombardment System (FOBS) is to put a warhead into a stable orbit and deorbit it over the target.
If the target and the launch position is lined up and the warhead keeps going round, it will complete a circle.
Obviously, with the earth moving during this, it is more of a spiral than a ring, but the horizontal movement is countered in such a way that the warhead still goes over the target.
The real point is that missile can be flown directly to the target, or it is fired in the opposite direction the other way around the planet and still arrive at the target from the opposite direction.
What is the principle behind cruise missile systems?
Broadly speaking, the slowest missiles are cruise missiles, which are essentially drone planes.
Though they may initially ride a rocket booster launched from the ground or a submarine, they go on to cruise through the atmosphere like a jet-powered plane.
What is the principle behind ballistic missile systems?
Ballistic missiles are essentially suborbital rockets, operating on the principle that what goes up must come down.
When launched, they can climb to altitudes up to 2,000 kilometers — much higher than satellites or space stations in low Earth orbit.
They can also reach speeds of up to several miles per second before reentering the atmosphere.
However, their ballistic nature also makes their trajectories predictable, and therefore vulnerable to missile defense systems.
What is the principle behind fractional orbital bombardment system?
In a fractional orbital bombardment system, the rocket achieves low Earth orbit, which requires more energy than a ballistic missile has.
But before completing one full orbit, a FOBS rocket deorbits by turning around and performing a retrograde engine burn. This allows it to slow down so that its trajectory intersects with its target on the ground.
What are the advantages of fractional orbital bombardment system?
Being able to strike from low Earth orbit carries several advantages.
By staying relatively low, never climbing above 240 km or so, they remain below the line-of-sight of radar designed to pick up arcing ballistic missiles.
Orbital trajectories also allow militaries to strike from unexpected directions.
And since it is impossible to tell where the FOBS will impact until it deorbits, the precise target would have only a few minutes of warning.
What are the challenges associated with FOBS?
The FOBS also had some serious downsides. Accurate reentry from orbit is very difficult.
It takes a lot more of a rocket’s energy to put a warhead into orbit, plus a nuclear warhead has to carry a small rocket stage to get it back down again, which meant it couldn’t carry more than one warhead.
Which country originally developed the FOBS?
The FOBS concept was originally developed by the Soviet Union in part to bypass international agreements that prevent weapons of mass destruction from being stationed in Earth orbit.
But after being deployed in 1969, it was explicitly banned in the 1979 SALT II treaty.
In August 2021, the People’s Republic of China tested a weapon that combined a FOBS with a hypersonic glide vehicle.
For more information https://en.wikipedia.org/wiki/Fractional_Orbital_Bombardment_System
PRACTICE QUESTIONS
QUES 1 . Which one of the following statements best reflects the idea behind the “Fractional Orbital
Bombardment System” often talked about in media?
(a) A hypersonic missile is launched into space to counter the asteroid approaching the Earth and
explode it in space.
(b) A spacecraft lands on another planet after making several orbital motions.
(c) A missile is put into a stable orbit around the Earth and deorbits over a target on the Earth.
(d) A spacecraft moves along a comet with the same speed and places a probe on its surface.
Answer: (c)
