http://xcraft.guru/en/terran/faq/moons/from what it says, you don't need any special tech for it, it's random. whenever fleets are destroyed at your planet (from attacks or any other method) they leave debris, the bigger amount of debris, the higher the chance of moon creation, up to 25% chance, even if you've enough debris for 50% chance, the highest will still be 25%... so in conclusion, moon creation is mostly random, I heard you can force it somehow.. for example, have a friend attack your planet or multi-accounting... you can check in the simulator as well for moon creation chances
http://xcraft.net/simulator.php?notopnav=1 put some random amount of fleets in it and check out the numbers, ofc it costs 1k vespene each time so don't over do it xD