According to NASA, America’s space agency, the skies high above the Earth are cluttered up with around 23,000 pieces of man-made space junk measuring 10cm or more across, zipping along at great speed and posing a threat to working satellites.
Science is supposed to be precise in its definitions, proofs and theorems. Its something today that we just expect so it may come as something of a shock that the definition of one of the most fundamental of celestial bodies, a planet, wasn’t actually defined until the 1990’s !
Astronauts first moved into the International Space Station in October 2000 and since then they have been supplied with oxygen created by a process discovered by the chemist William Nicholson over 200 years ago : Electrolysis
If you’re one of the human races few that are going to “boldly go where no man has gone before”, then keeping clean could be a problem in zero-gravity