  Today\'s world of space\'s primary concern is the uncontrolled growth of
space debris and its probability of collision with spacecraft, particularly in
the low earth orbit (LEO) regions. This paper is aimed to design an optimized
micro-propulsion system, Cold Gas Thruster, to de-orbit the PSLV debris from
668km to 250 km height after capturing process. The propulsion system mainly
consists of a storage tank, pipes, control valves, and a convergent-divergent
nozzle. The paper gives an idea of the design of each component based on a
continuous iterative process until the design thrust requirements are met. All
the components are designed in the CATIA V5, and the structural analysis is
done in the ANSYS tool for each component where our cylinder tank can withstand
the high hoop stress generated on its wall of it. And flow analysis is done by
using the K-$\epsilon$ turbulence model for the CD nozzle, which provides the
required thrust to de-orbit PSLV from a higher orbit to a lower orbit, after
which the air drag will be enough to bring back to earth\'s atmosphere and burn
it. Hohmann\'s orbit transfer method has been used to de-orbit the PSLV space
debris, and it has been simulated by STK tools. And the result shows that our
optimized designed thruster generates enough thrust to de-orbit the PSLV debris
to a very low orbit.
