[gregebowman]

I don't think it's that useless. ONce I discover this technology, I'll usually start putting on planets, except for the ones that I've already filled up. For those, I'll make mines, weapon platforms and satellites to guard my planets. But if I have a big planet with lots of room to put stuff on, then a planetary shielf would be nice. Also, if I have a planet on the edge of my empire, then I include a shield to make sure no one destroys my planet.