Which statement is a MAIN idea of the article? The increase in orbital traffic means there will be even more space junk and more problems for future space missions. The increase in orbital traffic means there will be even more space junk and more problems for future space missions.

Many spacecraft don't come back to Earth after they stop working but in fact keep traveling through the sky.
Many spacecraft don't come back to Earth after they stop working but in fact keep traveling through the sky.

Astronauts are afraid to go on spacewalks outside of the International Space Station because of large space debris.
Astronauts are afraid to go on spacewalks outside of the International Space Station because of large space debris.

The 2017 European Conference on Space Debris has come up with more ideas than NASA has for cleaning up space debris.