All of the guides say that a single colony ship can start a colony on an asteroid and that if you build a weapons platform in space it will kill the bombarding ship and the asteroid colony will survive. 

I've tried this 3 times now and have lost the asteroid every time.  It's not even close.  The asteroid colony is dead long before the Krosov planet bombarding ship is dead.  This last time I had a scout and the colony ship shooting the krosov the whole time and that wasn't enough either.  Has there been a change to the game?  If not how do you suppose I'm screwing this up?

edited for pertinent info: i've got the original version of the game version 1.91, but haven't got the upgraded editions... so I don't have starbases and a few other game upgrades... is this my problem?