Let me take into the year A.D 2125. Human colonies are developed on mars and moon. One day evening a mysterious asteroid driven by aliens coming towards our colonies, then International Space Soldiers Army (ISSA) which is developed by all the nations have come into the picture. They pointed a multi satellite-based Laser gun (MSLG) towards it and destroyed the asteroid. This MSLG is working with the radiation coming from the sun, it has debris collector inbuilt and it requires no other source of energy.