Phylax Depot - Ratchet & Clank: A Crack In Time
Use your galactic map to find the depot, and then land on it. There's a robot near the landing pad. Talk to him, and then say "Yes" to start a mission.
( ) Clean up Irradiated Asteroids.
Get back in your ship and fly over to where the green asteroids are. Simply shoot them with your blasters to destroy them, but don't fly in to the green gas the give off when the explode as this damages your ship. Destroy all 15 green asteroids to get 1,000 bolts.