The term “space debris” refers to the unusable remnants of various space missions in Earth orbit, and this is increasingly posing a serious problem for manned and unmanned space travel.
The decommissioned Mir space station was hit, as were the American Space Shuttle and the Hubble Space Telescope. The European Space Agency (ESA) had to perform evasive maneuvers with the Envisat earth observation satellite several times to prevent a catastrophe. The International Space Station (ISS) also performs at least one evasive maneuver on average every year to avoid a collision with a large piece of space debris.
Since the beginning of the space age in 1957, there have been around 6,500 rocket launches and some 16,990 satellites have been carried into orbit, most of which no longer function today. 10,000 larger pieces, such as satellites or rocket debris that are no longer in use, and around 100,000 smaller pieces of debris, including tools, with a diameter of less than 10 cm, are now traveling around the Earth at high speeds (around 28,000 km/h) at various altitudes.
The problem is therefore man-made, and in April 2005, there was an international conference in Darmstadt at which initial measures were discussed. In the future, burning out the engines should prevent fuel residues in a rocket stage from spontaneously combusting and creating more space debris as a result of the explosion. In addition, the aim was to test procedures so that the remains burn up more quickly in the Earth's atmosphere during future missions and no longer orbit for decades or centuries.
Another problem is posed by satellites that are no longer needed, as so far only around a third of them have been properly lifted into a so-called graveyard orbit. The rest remain in or near the coveted orbits, posing a threat to future generations of satellites.
To a certain extent, space can “cleanse” itself, as the particles gradually lose altitude, crash, and burn up in the atmosphere. But not only are astronauts in orbit at risk, larger pieces could also fall to Earth and, at least theoretically, crash onto inhabited areas.
However, all the measures discussed so far do not contribute to the disposal of existing space debris, as such a disposal mission would entail considerable costs.
In Europe and the USA, there is a greater awareness of this problem than in the up-and-coming space nation of China. Here, people want to do a lot of space travel for little money, and all waste avoidance measures initially incur costs.
Radar systems and telescopes can at least detect the larger pieces, but even smaller pieces of debris pose a considerable potential danger. A collision with space debris was also seriously considered as the cause of the Columbia crash. In addition, a French reconnaissance satellite has already been destroyed.
Special protective shields are one way of protecting against a catastrophe. These are used by the ISS, among others, and are made of ceramic and polymer materials.
The European Space Agency (ESA) recently introduced a zero-debris concept to ensure that the agency's activities do not generate any new space debris in valuable orbits by 2030.
ESA plans to launch the ClearSpace-1 mission in 2026 to demonstrate the technologies required for active debris removal and take a first step towards building a new and sustainable commercial sector dedicated to removing high-risk objects from our valuable and limited orbital slots. [1]
Note: You can find out more about this topic in my book “Space - Die Zukunft liegt im All” (2019).
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