Space junk

Space debris, junk, waste, trash, or litter is the collection of defunct man-made objects in space – old satellites, spent rocket stages, and fragments from disintegration, erosion, and collisions – including those caused by debris itself. As of December 2016 there were 5 satellite collisions with space waste.


A computer-generated image representing space debris as seen from high Earth orbit (HEO). The two main debris fields are the ring of objects in geosynchronous Earth orbit (GEO) and the cloud of objects in low Earth orbit (LEO). image: wikipedia/NASA Orbital Debris Program Office

As of 5 July 2016, the United States Strategic Command tracked a total of 17,852 artificial objects in orbit about the Earth, including 1,419 operational satellites.

However these are just objects large enough to be tracked. As of July 2013, more than 170 million debris smaller than 1 cm (0.4 in), about 670,000 debris 1–10 cm, and around 29,000 larger debris were estimated to be in orbit. 

Space junk can crash into other spacecraft

Collisions with debris have become a hazard to spacecraft; they cause damage akin to sandblasting, especially to solar panels and optics like telescopes or star trackers that can not be covered with a ballistic Whipple shield (unless it is transparent).

Below 2,000 km (1,200 mi) Earth-altitude debris are denser than meteoroids; mostly dust from solid rocket motors, surface erosion debris like paint flakes, and frozen coolant from RORSAT nuclear-powered satellites. For comparison, the International Space Station orbits in the 300–400 kilometres (190–250 mi) range and the 2009 satellite collision and 2007 antisat test occurred at 800 to 900 kilometres (500 to 560 mi) altitude. 

 The ISS has Whipple shielding, however known debris with a collision chance over 1/10000 are avoided by maneuvering the station.

The Kessler syndrome, 

This is a runaway chain reaction of collisions exponentially increasing the amount of debris, has been hypothesized to ensue beyond a critical density. This could affect useful polar-orbiting bands, increases the cost of protection for spacecraft missions and could destroy live satellites. Whether it is already underway is debated. The measurement, mitigation and potential removal of debris are conducted by some participants in the space industry.

source adapted from:Space debris. (2017, May 26). In Wikipedia, The Free Encyclopedia. Retrieved 07:07, June 2, 2017, from