A rocket part set to slam into the far side of the moon Friday morning highlights the growing issue of space junk in orbit around Earth, experts say

Astronomers noticed it was unlikely the piece of space junk was from the Falcon 9 launch in 2015, due to the gap between the rocket's trajectory and object.

The three astronauts who blasted off Thursday from the Jiuquan launch center in northwestern China will stay three months in the Tianhe, or Heavenly Harmony.

The two countries' space agencies say the proposal, which sets no time frame, could include an orbiting station, a base on the surface, or both.

It's the first time in over 40 years that fresh lunar samples are being brought back to Earth. Scientists hope to gain a better understanding of lunar volcanic activity and the age of various craters.