thunderbolt adaptor?

Is there a way to connect a thunderbolt drive to an older mac with no thunderbolt using the firewire connector? I understand the drive will be slower but I could perhaps buy thunderbolt now and use on my old mac while I wait to save until I upgrade.

I would imagine that there should be something like this for folks who have a new thunderbolt equipped machine (desktop for example) and a non thunderbolt laptop with firewire.

thanks