A Comprehensive Study on Space Debris, Threats Posed by Space Debris, and Removal Techniques

After exploring space for more than 50 years for research, study and defense purposes, the region above the atmosphere of earth is highly polluted by orbital debris. Figure 1 shows the total number of rocket launches in period of nine years. This has become a concern for placing satellites in their respective orbits and their safe functioning during their mission. Space debris or orbital debris colloquially known as space junk are parts of the non-functional satellites, thermal blankets, booster stages of the rockets. Those satellites are placed in the several orbits according to their missions. Mainly, they are placed in LEO (Low Earth Orbit), an earth centered orbit ranging from 200 to 2000 kilometers. Some are also placed in GEO (Geostationary Earth Orbit), at an altitude of 36000 kilometers and some are placed in the Higher Earth Orbit. Since the dawn of space age, approximately 7000 rockets have been launched, placing their payloads in several orbits of the Earth, revolving at several kilometers per second. And more than half of these objects are present in LEO. It is estimated that their sizes vary from a few millimeters to few meters, the largest being the European Envisat. Because of their high speeds, pieces of debris not more than a millimeter apart also poses a huge risk to current and upcoming space missions. Since the risk is increasing exponentially and is of great concern for all the space-faring nations, there is a need for the active removal of space debris. Hence, in this paper, the authors have analyzed the threat that space debris poses, and some of its removal techniques that have been proposed by scientists and space organizations. The authors have also suggested a few more of these Active Debris Removal techniques.