All The Weyrs Of Pern( Series - A Dragonriders Of Pern )

For generations, the dragonriders had dedicated their lives to fighting Thread, the dreaded spores that periodically rained from the sky to ravage the land. On the backs of their magnificent telepathic dragons they flew to flame the deadly stuff out of the air before it could reach the planeta (TM)s surface. But the greatest dream of the dragonriders was to find a way to eradicate Thread completely, so that never again would their beloved Pern be threatened with destruction.
Now, for the first time, it looks as if that dream can come true. For when the people of Pern, led by Masterharper Robinton and Fa (TM)lar and Lessa, Weyrleader and Weyrwoman of Benden Weyr, excavate the ancient remains of the planeta (TM)s original settlement, they uncover the colonistsa (TM) voice-activated artificial intelligence system a" which still functions. And the computer has incredible news for them: There is a chance a" a good chance a" that they can, at long last, annihilate Thread once and for all.