Space debris, also known as orbital debris, space junk, and space waste, is simply the collection of defunct objects in orbit around Earth. It is estimated that about 10 tons of space garbage clutter low earth orbits of up to 2,000 km. Russia has recently lost a nano-satellite in a collision with a piece of Chinese debris.
o Sources of Debris
Sources of Debris include everything from spent rocket stages, boosters, lost equipment, dead satellites, and fragments from disintegration, erosion, and collisions. One major source of debris in the past was the testing of anti-satellite weapons carried out by the developed nations.
Space debris in Low Earth Orbits
The most commonly used orbits for both manned and unmanned space vehicles are Low Earth Orbits, which cover an altitude range low enough for residual air drag to be sufficient to help keep the zone clear. That is, the junk often comes down to Earth.
At altitudes above the levels where atmospheric drag is significant, the time required for orbital decay (to reduce the altitude of the orbit by gravitational pull) is much longer. Hence space debris there poses more serious threat.
In Geosynchronous orbits, there is no question of orbits of the satellites clashing with one other but the junk may be created by left overs.
o Kesslers Syndrome/ Snowball Effect
The Kessler syndrome, proposed by NASA scientist Donald J. Kessler in 1978, is a scenario in which the density of objects in low Earth orbit (LEO) is high enough that collisions between objects could cause a cascade – each collision generating space debris which increases the likelihood of further collisions.
If a collision occurs, resulting fragments can become an additional collision risk. As the chance of collision is influenced by the number of objects in space, there is a critical density where the creation of new debris occurs faster than the speed with which various natural forces remove them. Beyond this point a runaway chain reaction may occur that pulverizes everything in orbit, including functioning satellites. Thus a runaway Kessler syndrome would render the useful polar-orbiting bands difficult to use, and greatly increase the cost of space launches and missions.
Handling Debris
o Monitoring and mitigating debris producing events by regulations like the effective design of space vehicles etc
o Self-removal for rocket stages or satellites that retain enough propellant to power themselves into a decaying orbit. Geostationary satellites are supposed to remove themselves to a graveyard orbit at the end of their lives.
o External removal using space vehicles, using laser technology to ablate (wear away through erosion or vaporization) material etc
ADMIN : LAV
The rockets, satellites and probes we have sent into orbit over the decades have created a fast-moving debris field that contains hundreds of thousands of pieces of space junk.No one country or agency has taken ownership over the growing problem, but it seems Japan has decided to step up and take control.Space debris getting dust from solid rocket motors, surface degradation products such as paint flakes & impacts of these particles cause erosive damage similar to sandblasting.Keeping these things in mind Japan to start thinking seriously about a militarized program focusing on space.
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