Asked by: Ray Grech, Malta
There is no direct effect, although the density of space debris is now so great that astronomical observations are often degraded by it. The main problem is that of collisions with operational spacecraft. With an average impact speed of 10km/s, any piece of debris larger than 1cm in diameter can cause a catastrophic impact.
There are more than 100,000 such objects, including several dropped by astronauts during spacewalks, such as a camera, a glove and a pair of pliers. Most, however, have come from exploding rocket stages and satellites. The larger objects are tracked and spacecraft (including the space shuttle) occasionally have to manoeuvre to avoid them.
The main threat to our weather from space junk is rather indirect: the density of the junk may become so great that it could hinder our ability to use weather satellites, and hence to monitor weather changes caused by our own ground-based pollution. The US, Russia, Japan, France and the European Space Agency have now issued orbital debris mitigation guidelines.