Q: What is an astronaut’s favorite key on a keyboard?
A: Space!

Explanation:  Are you familiar with a computer keyboard?  Here is a picture.  The long key at the bottom is called the space bar or the space key.  Of course it is the favorite of the astronaut because the astronaut goes to space!

You see, space can mean the long key on a computer keyboard and it can mean the area outside of the earth’s atmosphere, outer space.

Here is the Space Shuttle Blasting off into space for the last time: