What is space debris?

Space debris implies the remains of all the past space travel missions, such as, old non-functional satellites, blasted rocket parts, tools used by astronauts, and engine dust, that are encircling the Earth in an orbit. Space authorities can observe the parts that are larger than 10 cm. There are about 10,000 such parts and about 15 times as many smaller parts encircling the Earth in an uncontrolled way. The debris poses a constant threat to future satellites and to the ISS. In case of a collision at high speed, vital parts of spaceships can get damaged.