Rational curves on $V_5$ and rational simple connectedness

In this paper the notion of rational simple connectedness for the quintic Fano threefold $V_5subset mathbb{P}^6$ is studied and unirationality of the moduli spaces $overline{M}_{0,0}^{text{bir}}(V_5,d)$, with $d ge 1$, is proved. Many further unirationality results for special moduli spaces of rational curves on quadric hypersurfaces and del Pezzo surfaces are obtained via explicit birational methods.