Kessler Syndrome

The Kessler Syndrome is a scenario, proposed by NASA consultant Donald J. Kessler, in which the volume of space debris in Low Earth Orbit is so high that objects in orbit are frequently struck by debris, creating even more debris and a greater risk of further impacts. The implication of this scenario is that the escalating amount of debris in orbit could eventually render space exploration, and even the use of satellites, too prone to loss to be feasible for many generations.

Every satellite, space probe and manned mission has the potential to create space debris. As the number of satellites in orbit grow and old satellites become obsolete, the risk of a cascading Kessler Syndrome becomes greater.

Fortunately, at the most commonly used Low Earth Orbits residual air drag helps keep the zones clear. Altitudes under around 300 miles (480 km) will be swept clear in a matter of months. Fact|date=January 2008 Collisions that occur under this altitude are also less of an issue, since the resulting orbits of the fragments inherently have perigee below this altitude.

At altitudes above this level lifetimes are much greater, but drag gradually brings debris down to lower altitudes where it finally re-enters. At very high altitudes this can take millennia.

eriousness

The Kessler Syndrome is especially insidious because of the "domino effect" and "feedback runaway." Any impact between two objects of sizable mass spalls off shrapnel debris from the force of collision. Each piece of shrapnel now has the potential to cause further damage, creating even more space debris. With a large enough collision (such as one between a space station and a defunct satellite), the amount of cascading debris could be enough to render Low Earth Orbit essentially impassable.

The Kessler Syndrome presents a unique problem to human space travel. Space debris is very difficult to deal with directly, as the small size and high velocities of most debris would make retrieval and disposal impractically difficult. Given thousands of years, most debris in Low Earth Orbit would eventually succumb to air resistance in the rarefied atmosphere and plunge to the Earth. If magnetically susceptible, the debris could fall in a few decades due to the drag of the Earth's magnetic field.Fact|date=January 2008

Avoidance and reduction

To minimize the chances of damage to other vehicles, designers of a new vehicle or satellite are frequently required to demonstrate that it can be safely disposed of at the end of its life, for example by use of a controlled atmospheric reentry system or a boost into a graveyard orbit.

Kessler Syndrome in Popular Culture

In the manga/anime series "Planetes" a terrorist group tries to provoke a catastrophic impact into a space station in order to produce enough space debris to create a Kessler Syndrome, rendering space travel to and from Earth impossible.

In the 1988 Novelette "Under The Covenant Stars" by John Barnes, space travel has long been rendered unsafe, since a US/USSR ballistic-missile exchange was thwarted by a third nation who fired a large amount of junk into LEO.

ee also

* Space debris
* Ablation cascade
* Laser broom
* 2007 Chinese anti-satellite missile test

References

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External links

* [http://lasp.colorado.edu/~lix/class/asen5335/hw6.html Mathematical Modeling of debris flux]
* [http://www.nytimes.com/2007/02/06/science/space/06orbi.html New York Times: Orbiting Junk, Once a Nuisance, Is Now a Threat ]
* [http://www.wired.com/wired/archive/15.05/st_houston.html Wired: Houston we have a trash problem]