In order to decrease the risk of creating new debris while in orbit, some procedures and technology innovations have been put in place during the years.
It is common practice today to reduce the amount of mission-related debris released in spacecraft deployment and operations. The term “mission-related debris” includes all objects that are separated, or released as part of the planned mission like clamps, protective covers for lenses or sensors, spin-up devices, spring release mechanism, debris from explosive bolts and pyrotechnic devices, large dispenser in case of multiple mission and so on. Even though these objects are not a major contributor to the space debris population, they tend to stay in orbit much longer than larger debris. In the past the common practice in the past was to simply jettison such objects from the launch vehicle at separation or during the deployment of antennae, solar panels and other appendages. Nowadays the in-orbit release of such items can be decreased by using tethers or devices to trap debris when released from spacecraft or upper stages.
The combustion product of solid rocket motors (SRM) represents a particular category of debris and the most serious non-fragmentation debris source. Solid rocket motors are often used in upper stages, or directly integrated into some satellites to perform an orbital transfer between the geostationary transfer orbit (GTO) and GEO. When a solid rocket motor fires, it releases particles of aluminum oxide (Al2O3) as large as one centimeter. These particles, however, don’t spend much time in orbit because they are released in the opposite direction with respect to the velocity vector of the spacecraft. The Requirements for Space Debris Mitigation for ESA Projects prevents from using SRM with a releasing burn product larger than 1mm.
Collision avoidance (COLA), which is the process of preventing a spacecraft from colliding with any other vehicle or object, is also an important part of the mitigation measures helping protect especially active spacecraft. The International Space Station (ISS) has performed more than 16 debris-maneuver firings in the 15 years of life in orbit. An ISS COLA maneuver consists of a short burn by usually the main engines of a docked cargo spacecraft in order to raise or lower the orbit of the station by a few kilometers and therefore avoid an incoming debris threat.