Well, it comes as kind of a suprise, that one is expecting a scientific explanation to such fact, even though other facts, from which the question is basically derived, are pure scientifical impossibility.
The Ocean produced phantoms out of the mysterious "neutrino field" (as far as I remember). According to the current knowledge of science, creating anything from neutrinos is just as possible as dissasembling it with a proton accelerator.
Then again, Lem wrote that Sartorious' experiment proved that if the phantom was destroyed with his method, it wouldn't come back. No explanation, just as simple.
I guess none of Solaris' inhabitants wanted their guests distroyed. Except that one Kelvin guy.