Battlestation: First Contact episode 5 tips and advice

Phew I finally beat it, it took me about six different tries but I finally managed it although it took me to wave 71 ahaha; but I tried several ways including a bunch of fighters or just using alot of defenses it turned out that in order to survive the constant bombardmebt of lazers from those orbs of death, is to just spam most of all your population centered on engineers then once you get in game be sure to put them all on repairs so that way you can repair every time those lazers hit you and eventually you'll be saving up and lucky enough to get the plasma cannon or the missile launcher then once you have those you can repel most any attacker once you get into the higher waves and eventually I had five plasma cannons or whatever they're called I'm not entirely sure but along with those I had two missile carriers and a battleship and it was just an amount of time before my cannons were steadily destroying the ship so once you get into that position the main thing you do is wait and boom congratulations you beat the unknown threat