Space debris
Space above Earth is turning progressively crowded. Space debris, or orbital debris, refers to the accumulation of non-operational items around Earth’s orbit, including old satellites, rocket stages that no longer operate, and pieces from collisions or explosions. As the number of space constellations and exploration grows at a never-before-seen rate, one question becomes important about space junk: This debris itself poses a great degree of danger to operational satellites, space missions, and other future exploratory undertakings. In these respects, battling orbital pollution is actually of the essence in order to guarantee that space operations are sustained appropriately for future generations.
Space debris refers to any human-made object that is no longer serving its functional purpose but still in Earth’s orbit. The sizes vary from tiny paint flecks to large and derelict satellites. The majority of the debris is housed in what is termed the Low Earth Orbit, which extends up to 2,000 kilometers above Earth’s surface. It is, particularly, pretty congested, as it is where most of the satellite operations take place: communication, Earth observation, and scientific research, among others. Some of the reasons why such buildups of space debris occur include the following: failed spacecraft, spent rocket stages, and fragments from explosions or collisions. The first significant awareness of the problem was the collision between the defunct Russian satellite Kosmos-2251 and an operational Iridium communications satellite back in 2009, adding several thousand fragments of debris into LEO. Since that accident happened, things have only gotten worse due to the increased number of launches.
Space debris poses a number of different risks to current and future space operations. Active satellites, space stations, and manned missions face the risk of being hit by debris with velocity mostly exceeding the speed of 28,000 kilometers per hour. In such great speed, even small fragments may cause serious damage: a paint chip is able to puncture the surface of a spacecraft, and collision with a big piece can destroy the whole satellite, thus contributing to the problem of debris. The Kessler Syndrome (1978), theorized by NASA scientist Donald Kessler, is an exponential growth cascade where space debris collides with satellites and other debris, creating fragments that collide further until possibly rendering parts of space unusable for decades or longer. Not yet collective, the Kessler Syndrome is a reason for concern due to the growing density of objects in LEO, which should be met with proactive measures.
Recently, the efforts to reduce space debris have been gaining momentum. Most of the efforts now go toward prevention rather than removal of debris. International guidelines such as those by UNOOSA and IADC, for instance, recommend designing satellites in such a way that they can deorbit no longer than 25 years after the end of their mission. This is often done by lowering their orbits so their re-entry into the atmosphere causes them to burn up.
In addition, satellite operators are also summoned to carry out end-of-life maneuvers that safely remove those spacecraft from operational orbits. For geostationary satellites, that normally includes separation in a “graveyard orbit,” a place far away from the critical orbital zones where those defunct satellites can stay in without interfering with operational spacecraft.
While prevention is paramount, guidelines and best practices alone cannot solve the issue of the already existing debris.
