Ship Upgrades
Occasionally when you shoot an asteroid a symbol will be produced. These symbols represent upgrades to your ship. Fly over the symbol to install it in your ship. The upgrades have a cumulative effect, up to a maximum of 5.
The improvements available are:
Brakes 	Brakes stop your ship as quickly as possible. The more brake upgrades you have the faster you can stop, with lower fuel usage.
Shields 	Shields absorb the collision with asteroids, but use a lot of fuel. You need at least two shield upgrades to survive a hit from a medium sized rock, and 3 to survive a large rock. You will also need to have enough fuel to maintain the shield during the strike.