The Space jump is a rather powerful and important upgrade, it allows its user to continually spin jump in the air for an infinite amount of time.
When you have both the Screw Attack and Space Jump, this becomes lethal weapon destroying most things in its path.
Space Jump functions differently in the Metroid Prime Trilogy: it allows Samus to jump a second time whilst in the air.
 Metroid 2
Metroid 2 marks the first appearance of the Space jump and functions as mentioned earlier.
It is obtained in the 3rd Chozo City.
 Super Metroid
Once obtained, you are allowed to essentially "fly" anywhere in the game and can obtain any items previously unreachable such as two rooms in upper Crateria.
The Space jump works better in liquids than it does anywhere else.
When combined with the Screw Attack it becomes a vortex of death destroying nearly anything unfortunate enough to cross it.
Related ThreadsSPACE JUMP FIRST - last post by @ Mar 8, 2005
Getting Space Jump first - last post by @ May 2, 2004
Acquire Space Jump Boots - first thing??? - last post @ May 24, 2013
Double Jump does not work - last post by @ Mar 8, 2006
The Boost and Jump Guardians - last post by @ Dec 29, 2004