Asteroid markers are circles 40mm in diameter. They represent a small cluster of asteroids. They are not solid objects, but obscure line of sight and movement.
An attack that goes through a cluster has to make a roll to succeed. For each FireCon used, roll a d6. On 4+ the attack can proceed as usual. Otherwise the attack is wasted.
An escort class vessel can park itself within a cluster. It can only be targeted from within 3” of the cluster.
If a ship moves through a cluster, roll 1D6. If the roll is less than the current velocity of the ship, then it takes a number of D6 damage equal to what was rolled. If a ship ends its movement within a cluster, the check is made as it leaves. This allows a ship to come to a complete stop within a cluster if it's capable.
A FireCon can be used to scan a cluster, but only at short range. Within the cluster, success is automatic. Within 1“, success is on 3+, within 3” success is on 5+. On success, the player can look to see the value of the cluster.