As the human footprints in space expand, so does the problem of space debris: dead satellites, spent rocket stages, and fragments from collisions and disintegration. This challenge threatens operational satellites and future space missions, raising urgent questions about the sustainability of our activities outside Earth.
Sputnik 1 was the world's first artificial satellite, launched in 1957. It marked the beginning of the space age. Since then, tens of thousands of satellites have been launched into orbit; along with these was a huge quantity of debris that now fills up the orbit. Already more than 34,000 pieces greater than 10 cm in size are orbiting Earth, while millions of smaller pieces are also in orbit. The amount of debris has created dangerous and hostile orbit conditions for operational satellites and for crewed missions as well, because even the smallest fragments can catastrophically impact because of their high velocity.
Collisions among satellites or between satellites and debris can create even more fragments, complicating the situation. Major incidents, as in the case of Iridium 33 which collided with Cosmos 2251 in 2009, have reminded the world of the dangers posed by space debris. The collision created thousands of additional pieces, and there were concerns about the risk of a cascade effect, sometimes called the Kessler Syndrome, in which debris in low Earth orbit becomes so dense that space-related activities become impossible.
