> I'm sure its usefull to have solid fuel rockets on the side tanks of the
> shuttle

The SSMEs (shuttle main engines) cannot lift the fully fueled shuttle
off the ground.  Without the SRB's the shuttle won't go anywhere (not
at least until enough propellant burned off).

> but what is more interesting is how it is possible to reuse them. I
> think that they are not made of solid fule for the purpose of reuse since I
> would imagine that they will be damaged after ejection and dropping several
> miles back to earth?

After seperation they deploy a series of parachutes to slow
themselves down for a water landing.

An earlier design did call for liquid fueled strap-ons, but the money
required for research and development was not available.

Lloyd