Rocket Launch Sequence - JS

Rocket Launch Sequence - JS - student project

I'm a f/e web dev who is struggling to get my head around JS (waiting for this eureka moment, it will happen one day *I hope*).
This tutorial really helped me to understand how JS can be used alongside HTML and CSS!

Here is a link to my rocket launcher for anyone interested:

Also any hints as to how I can get the rocket back to bottom position after it's launched to space and I press the retry button (currently it comes back down slowly from the top).

*** UPDATE ***
Sorted out the issue above ;D