You can use this thread instead, Naomi.
Panspermia is the theory that life is common throughout the Universe, found particularly in Asteroids and the like, so that planets with the right conditions can develop life when an asteroid carrying the raw materials crashes into it -- or in to a neighbouring planet. So far, so reasonable, although as yet there is no conclusive evidence. Still, it seems to make some sense if you believe that life on Earth was likely not a one-off event in the Universe.
Directed Panspermia is slightly different, that life on this planet is the deliberate consequence of some other intelligent being wanting to set it up. Alternatively it's the name for the process whereby Humans can spread life from this planet around the Universe before we eventually die off. The last is controversial on a sort of "Prime Directive" ground (what about life which may already be out there?); the first because it seemingly lacks evidence and anyway doesn't solve the problem of how [i]that[] intelligent life emerged. Just passes the buck, so to speak.
Francis Crick was an early advocate of this theory, although he has since apparently retracted it:
Crick, F. H.; Orgel, L. E. (1973). "Directed Panspermia". Icarus 19: 341–348;
http://www.fasebj.org/cgi/reprint/7/1/238.pdf
But when I noted this in another thread Naomi leapt to the defence of the theory, though "that was not the place".
Hence this thread, so that it can be more fully discussed.