Criminals, terrorists and military have been using  tunnels since long time to evade detection as surface based detection methods are ineffective underground .  There has been an explosion of underground warfare in the last five years. From sophisticated cross-border Hezbollah attack tunnels discovered in northern Israel to defensive tunnels that …

The primary function of the space propulsion system is to provide thrust, which helps in the functioning of the launch vehicle or satellite. In propulsion systems, the fluid (either solid, liquid, or electric) reacts to initiate acceleration and provide force in the system.   An ion thruster is a form …