UFO Research Tree
Fusion Ball Defenses require (obviously) the Blaster Launcher + Blaster Bomb and then the Fusion Ball Launcher. As for the Grav Shield, you'll need to have Alien Alloys + Elerium 115 + UFO Navigation + UFO Power Source. Those lead to UFO Construction, Firestorm and Lightning which will then open up Grav Shield.
My X-COM Patch Kit For UFO Defense | Emergency XCOM Meeting spoof on YouTube
Zombie: Empirical data's your only man, when formulating a research plan.
A soldier's death is never in vain if it makes the formula more plain.
A few dozen make a better case for refining that third decimal place.
They call me Zombie because I don't sleep, as I slowly struggle to climb this heap,
of corpses, data points, and trials, but from the top - I'll see for miles!