Now the final frontier has turned into a rather messy one.
New computer-generated images show planet Earth as you've never seen before.
Yeah, and if you like people who tidy up after themselves, this might disturb you.
Now what we're discovering is that the Earth is surrounded by orbiting space junk.
Jackie Kabler reports on how the galactic junkyard may pose a threat now, even to those who are trying to explore space.
This extraordinary image proves it's not just our streets and our oceans that are polluted with litter.
There are more than 12,000 pieces of space junk known to be circling the planet,
and probably tens of thousands more bits too small for scientists to track.
Frozen rocket fuel, dead satellites, human waste from manned spacecraft -- they're all circling around up there.
With things like rocket parts and literally screws and in some cases bolts, perhaps even tools that astronauts have dropped, a whole range of things,
and it's a massive issue, simply because there is so much of it.
The biggest space litter lout is China.
When it destroyed its aging weather satellite, there was suddenly more than 150,000 extra pieces of space junk orbiting the earth.
It all poses little risk to us down here. Anything coming close will be burned up in the atmosphere.
But for those who venture into space it's a different story.
Look at this damage on space shuttle Endeavor caused by space debris.
If a spacecraft is hit by a piece of debris, the closing impact can be about 52,000 kilometers an hour in some cases,
and that's moving pretty fast, and it will destroy anything in its path.
Only professional astronomers with telescopes much larger than this one can actually see all that space junk.
Now one of the most unusual things ever seen up there was back in the '60s after the first U.S. space walk when an astronaut dropped a glove.
That glove went on to be the most dangerous garment in history,
hurtling around the earth at over 17,000 miles an hour for several months until it finally burnt up.
So far, there's been no serious damage caused by space junk, but it's probably only a matter of time.