1. Create a loose hit-map: Having a near-accurate means of determining collisions without needing complex calculations is very useful, as your tests turn more complex. Assuming a discrete MxN array, a boolean hitmap can be devised with minimal loss of resolution.
They mean, that i can create two-dimensional array with size(map_width,map_height). And make something like minimap? But how i can determine is there any planets(or ships) in specifical area(e.g. on position x=12,y=50 ) There aren't such opportunity in API.