Space debris mitigation by pulsed laser

The fragmentation in Earth orbits and the major collision events between large spacecraft systems in addition to the poor housekeeping in space for more than five decades has generated millions pieces of orbital debris at different altitude above the Earth. Space debris in Low Earth Orbit (LEO) are now sufficiently dense that it threatens our space assets in this band by runaway collision cascading. The critical density in this band has now reached the point where collisions between debris are the most dominant debris-generating mechanism; the number of orbital junk in this band is increasing exponentially with actual and potential collision events. The average relative velocity between orbiting objects in LEO is very high, between 9-10 km/s, with maximum values around 14 km/s and the number of debris with a size range bigger than 1 cm in this band is large. Therefore, due to their hypervelocity and the massive number of debris, the space debris situation requires significant mitigating measures to protect our assets in space as the debris can cause deadly harm to both manned and unmanned space missions in orbit and produce more space junk, which renders this very useful band difficult to use. The length of time small debris stays in, for example, 1000 km altitude orbit before re-entering the atmosphere is of the order of 100 years. Therefore, reducing the altitude of the orbital debris will reduce its lifetime in orbit. Recent studies have suggested a proposed solution uses a repetitively pulsed ground based laser to target space debris using the laser beam to slow them slightly and lower their perigee, by the amount necessary, to cause them to re-enter the atmosphere where they will burn up. However, only very few studies have been done using this approach. In this paper, we discuss and assess the treatment of space debris and the engagement between the laser pulses and different shapes and sizes of debris. Beyond that, we believe that understanding the most common on-orbit debris materials will help the design of the laser beam system and give a more accurate picture of this debris clearing strategy. Using a pulsed laser to mitigate orbital debris is a most feasible and cost-effective method to clean up space without adding extra debris. No other solutions have been suggested to solve this debris dilemma without launching a new satellite, which without doubt would be costly and produce new debris itself.