Although combat isn't implemented, there are three non-moving pirate targets in each star system.
You can blow them up with five shots (the explosion is quite satisfying).
The controls are a little problematic in the browser when not in full screen -- specifically, when in
first person mode, the cursor gets re-enabled which hoses parts of the UI, including radar.
If you run out of ammo on the ground, use ~ to go into console and simply set ammo 100 (or whatever).
Similarly, set power 100 will restore spaceship ammo.