Space debris covers defunct artificial objects in outer space, particularly in those orbits that are important for human use.
Those pieces of debris can include non-functional spacecraft or defunct spacecraft, launched vehicles, mission-related debris or fragmentations form breakups of derelict rocket bodies and spacecraft. It has been measured by the US Space Surveillance Network that nearly 25.000 artificial objects are moving though low earth orbit including 2218 operational satellites. These are those objects that are big enough to be tracked. More than 128 Mil. pieces of debris smaller than 1 cm and about 900.00 pieces of debris between 1 – 10 cm as well as around 34.000 pieces of debris larger than 10 cm are estimated in orbits around the Earth. Below 2000 km altitude, pieces of debris are denser than meteorites. Most are dust from solid rocket motors, surface erosion debris like paint flakes and frozen coolant from RORSAT which are nuclear powered satellites. Most recent events of producing large pieces of debris include the 2007 Chinese anti-satellite weapons testing and a 2009 satellite collision of a Russian and an American satellite.
The whole situation with regard to space debris is of major concern because of the so-called Kessler-effect. Because of the very high velocity of debris pieces in outer space even very small debris particles can crash and thus produce more pieces of debris. One speaks of the so-called Cascade or Kessler – effect.
As concerns legal mechanisms against space debris one must say that current international space legislation and particularly the Outer Space Treaty, Article IX, are not directly or even indirectly addressing the problem. Therefore since 1998 a so-called Interagency Debris Committee (IADC) met and eventually adopted the so-called Space Debris Mitigation Guidelines which in 2005 were accepted by the United Nations General Assembly. These nonbinding guidelines try to mitigate the creation of space debris in that they e.g. recommend not to continue ASAT testing. Moreover, before the end of the mission, those responsible for the mission should either propel the space object (mostly satellites) into a graveyard orbit or to bring it down to earth so that it will be destroyed whilst re-entering the earth atmosphere.
More difficult and thus less advanced is the legal coverage of space debris remediation. Here not even non-binding principles have been agreed upon so far. This is however, necessary all the more techniques like harpooning or catching in a tether to secure pieces of space debris are already known and could be used. However, the problem of costs is the overall problem with regard to space debris remediation. And here it is particularly difficult to establish a causal link between the tiny piece of space debris and its authorship.
Therefore, in the future it could be advisable to leave away costs for the remediation of already existing space debris but for the future to make any use of outer space depending on the payment of a fee. This is the old idea that the use of nature must cost which could come to a recovery of the external costs of this activity. And the money to be paid in the fund could be used for the cleaning up of outer space through professional cleaning up enterprises.